Search results for: reversible addition−fragmentation chain-transfer polymerization

Authors: Akhtar Rasool, Tasneem Zahra Rizvi

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In this study, a series of the cadmium sulphide quantum dots/polyaniline nanocomposites with varying compositions were prepared by in-situ polymerization technique and were characterized using X-ray diffraction and Fourier transform infrared spectroscopy. The surface morphology was studied by scanning electron microscopy. UV-Visible spectroscopy was used to find out the energy band gap of the nanoparticles and the nanocomposites. Temperature dependence of DC electrical conductivity and temperature and frequency dependence of AC conductivity were investigated to study the charge transport mechanism in the nanocomposites. DC conductivity was found to be a typical for a semiconducting behavior following Mott’s 1D variable range hoping model. The frequency dependent AC conductivity followed the universal power law.

Keywords: conducting polymers, nanocomposites, polyaniline composites, quantum dots

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Authors: Alex Ellery

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Geoengineering approaches to climate change mitigation are unpopular and regarded with suspicion. Of these, space-based approaches are regarded as unworkable and enormously costly. Here, a space-based approach is presented that is modest in cost, fully controllable and reversible, and acts as a natural spur to the development of solar power satellites over the longer term as a clean source of energy. The low-cost approach exploits self-replication technology which it is proposed may be enabled by 3D printing technology. Self-replication of 3D printing platforms will enable mass production of simple spacecraft units. Key elements being developed are 3D-printable electric motors and 3D-printable vacuum tube-based electronics. The power of such technologies will open up enormous possibilities at low cost including space-based geoengineering.

Keywords: 3D printing, in-situ resource utilization, self-replication technology, space-based geoengineering

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Authors: Duygu Çimen, Nilay Bereli, Adil Denizli

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In this study is to synthesis magnetic nanoparticles for purify protein C. For this aim, N-Methacryloyl-(L)-histidine methyl ester (MAH) containing 2-hydroxyethyl methacrylate (HEMA) based magnetic nanoparticles were synthesized by using micro-emulsion polymerization technique for templating protein C via metal chelation. The obtained nanoparticles were characterized with Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), zeta-size analysis and electron spin resonance (ESR) spectroscopy. After that, they were used for protein C purification from aqueous solution to evaluate/optimize the adsorption condition. Hereby, the effecting factors such as concentration, pH, ionic strength, temperature, and reusability were evaluated. As the last step, protein C was determined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Keywords: immobilized metal affinity chromatography (IMAC), magnetic nanoparticle, protein C, hydroxyethyl methacrylate (HEMA)

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Authors: Mohammadreza Biabani, Mohammad Azadfallah

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A facile and robust strategy is required to fabricate films with high special optical properties for application in the field of anti-counterfeit marking. Nanocellulose, derived from bioresources, is a renewable material with broad application prospects. In this paper, a method for grafting the eco-friendly Berberine cationic dye on cellulose nanofiber is proposed. A functional modification was carried out by in-situ polymerization along with a grafting approach with acrylic acid(AA) in order to develop cationic dyeability of the cellulose nanofiber (CNF). The Berberine grafting on nanocellulose was significantly influenced by the reaction time and temperature during the dyeing process. The dyed CNF-films exhibited appropriate characteristics like appearance, color strength, and fastness for anti-counterfeiting application.

Keywords: Cellulose nanofiber, Berberine, Grafting, anti-counterfeiting, film

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Authors: Wasiu Oyeleke Oyediran

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Maize is a common staple food for human consumption and livestock feeds. It provides employment and means of livelihood for women in both rural areas and urban centres in Nigeria. However, the entrepreneurial skills of women engaged in its processing and value addition has not been fully enhanced. This study was therefore carried out to investigate rural women entrepreneurial skills in maize processing and value addition in Ogun State, Nigeria. Snow ball sampling technique was used in the selection of 70 respondents for this study. Data were analyzed with descriptive statistics and chi-square. Results revealed that majority (50.0%) of the respondents were 31 - 40 years of age and 60% of the respondents had spent 6 – 10 years in maize processing. The respondents have great entrepreneurial skills in popcorn (85.7%), corn cake (80.0%), corn balls (64.3%) and kokoro (52.9%) making. The majority of the respondents accessed information and entrepreneurial skills through fellow processors (88.6%) and friends and neighbours (62.9%). Major constraints to maize processing and value addition were scarcity of raw materials during off season periods (95.7%), ineffective preservation methods (88.6%), lack of modern processing equipment (82.9%), and high cost of processing machines (72.9%). Result of chi-square showed that there is significant association between personal characteristics of the respondents and entrepreneurial skills of the women at p < 0.05. It is hereby recommended that subsidized processing equipment should be made available to the maize processors in the study area by the government and NGOs.

Keywords: women, entreprenuerial skills, maize prcessing, value addition

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Authors: Eric Asare, Jamie Evans, Mark Newton, Emiliano Bilotti

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High-density polyethylene (HDPE) filled with silver coated glass flakes (5µm) was investigated and the effect on PTC by addition of a second filler (100µm silver coated glass flake) or matrix (polypropylene elastomer) to the composite were examined. The addition of the secondary filler promoted the electrical properties of the composite. The bigger flakes acted like a bridge between the small flakes and this helped to enhance the electrical properties. The PTC behaviour of the composite was also improved by the addition of the bigger flakes due to the increase in separation distance between particles caused by the bigger flakes. Addition of small amount of polypropylene elastomer enhanced not only PTC effect but also improved substantially the flexibility of the composite as well as reduces the overall filler content. SEM images showed that the fillers were dispersed in the HDPE phase.

Keywords: positive temperature coefficient, conductive polymer composite, electrical conductivity, high density polyethylene

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Authors: Tewfik Bouchaour, Salah Hamri, Yasmina Houda Bendahma, Ulrich Maschke

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Stimuli-responsive materials based on UV crosslinked acrylic polymer networks are fabricated. A various kinds of polymeric systems, hydrophilic polymers based on 2-Hydroxyethyl methacrylate have been widely studied because of their ability to simulate biological tissues, which leads to many applications. The acrylic polymer network PHEMA developed by UV photopolymerization has been used for dye retention. For these so-called smart materials, the properties change in response to an external stimulus. In this contribution, we report the influence of some parameters (initial composition, temperature, and nature of components) in the properties of final materials. Optimization of different parameters is examined by experimental design.

Keywords: UV photo-polymerization, PHEMA, external stimulus, optimization

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Authors: Alaa Alshaikh

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While digital technologies were initially seen as harbingers of globalisation and cosmopolitanism, scholars increasingly acknowledge their role in the rise of nationalism. This paper studies the national identity in light of the digital media in Saudi Arabia. It offers an extensive meta-analysis of the evolution of the national identity on social media. It examines the national identity and its components and deals with the difference between it and digital nationalism, which is formed and affected by the country's fulfillment of the citizen's needs. Hereto a systematic examination of all 40 articles published between October 2016 and December 2022 was conducted. Findings indicate that three characteristics of contemporary nationalism are partly linked to recent shifts in digital communication: diversification, fragmentation, and commodification. The paper concludes by considering the implications of our arguments for future research in the field.

Keywords: meta analysis, Saudi Arabia, nationalism, social media

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Authors: M. Şahi̇n, E. Erdem, M. Saçak

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In this study, Na-smectite crystals purificated of bentonite were used after being swelling with benzyltributylammonium bromide (BTBAB) as alkyl ammonium salt. Swelling process was carried out using 0.2 g of BTBAB for smectite of 0.8 g with 4 h of mixing time after investigated conditions such as mixing time, the swelling agent amount. Then, the conductive poly(o-anisidine) (POA)/smectite nanocomposite was prepared in the presence of swollen Na-smectite using ammonium persulfate (APS) as oxidant in aqueous acidic medium. The POA content and conductivity of the prepared nanocomposite were systematically investigated as a function of polymerization conditions such as the treatment time of swollen smectite in monomer solution and o-anisidine/APS mol ratio. POA/smectite nanocomposite was characterized by XRD, FTIR and SEM techniques and was compared separately with components of composite.

Keywords: clay, composite, conducting polymer, poly(o-anisidine)

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Authors: Peter Pomlenyi, Orsolya Semperger, Gergely Hegedus

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The purpose of the project is to develop a complex composite component with visible class ‘A’ surface. It is going to integrate more functions, including continuous fiber reinforcement, foam core, injection molded ribs, and metal inserts. Therefore we are going to produce recyclable structural composite part from thermoplastic polymer in serial production with short cycle time for automotive applications. Our design of the process line is determined by the principles of Industry 4.0. Accordingly, our goal is to map in details the properties of the final product including the mechanical properties in order to replace metal elements used in automotive industry, with special regard to the effect of each manufacturing process step on the afore mentioned properties. Period of the project is 3 years, which lasts from the 1st of December 2016 to the 30th November 2019. There are four consortium members in the R&D project evopro systems engineering Ltd., Department of Polymer Engineering of the Budapest University of Technology and Economics, Research Centre for Natural Sciences of Hungarian Academy of Sciences and eCon Engineering Ltd. One of the most important result that we can obtain short cycle time (up to 2-3 min) with in-situ polymerization method, which is an innovation in the field of thermoplastic composite production. Because of the mentioned method, our fully automated production line is able to manufacture complex thermoplastic composite parts and satisfies the short cycle time required by the automotive industry. In addition to the innovative technology, we are able to design, analyze complex composite parts with finite element method, and validate our results. We are continuously collecting all the information, knowledge and experience to improve our technology and obtain even more accurate results with respect to the quality and complexity of the composite parts, the cycle time of the production, and the design and analyzing method of the composite parts.

Keywords: T-RTM technology, composite, automotive, class A surface

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Authors: Salah Hamri, Tewfik Bouchaour, Ulrich Maschke

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The aim of this works is the study of swelling ratio of cross-linked polymer networks poly (2-hydroxyethyl methacrylate) (PHEMA). The system composed of erythrosine and Triethanolamine, in aqueous medium, is used as photo-initiator and 1,6-Hexanediol diacrylate as cross-linker. The analysis of UV-visible and infrared spectra, which were taken at different times during polymerization/cross linking, makes it possible to obtain useful information on the reaction mechanism. The swelling behavior was study by changing the nature of solvent, dye sensitizer (erythrosine, rose Bengal and eosin), and pH of the medium. The exploitation of experimental results using Fick diffusion model is also expected and shows a good correlation between theoretical and experimental results.

Keywords: cross-linker, photo-sensitizer, polymer network, swelling ratio

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Authors: N. Singh, G. K. Darbha

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Since the last decade, a wave of research has begun to study the prevalence and impact of ever-increasing plastic pollution in the environment. The wide application and ubiquitous distribution of plastic have become a global concern due to its persistent nature. The disposal of plastics has emerged as one of the major challenges for waste management landfills. Microplastics (MPs) have found its existence in almost every environment, from the high altitude mountain lake to the deep sea sediments, polar icebergs, coral reefs, estuaries, beaches, and river, etc. Microplastics are fragments of plastics with size less than 5 mm. Microplastics can be classified as primary microplastics and secondary microplastics. Primary microplastics includes purposefully introduced microplastics into the end products for consumers (microbeads used in facial cleansers, personal care product, etc.), pellets (used in manufacturing industries) or fibres (from textile industries) which finally enters into the environment. Secondary microplastics are formed by disintegration of larger fragments under the exposure of sunlight, mechanical abrasive forces by rain, waves, wind and/or water. A number of factors affect the quantity of microplastic present in freshwater environments. In addition to physical forces, human population density proximal to the water body, proximity to urban centres, water residence time, and size of the water body also affects plastic properties. With time, other complex processes in nature such as physical, chemical and biological break down plastics by interfering with its structural integrity. Several studies demonstrate that microplastics found in wastewater sludge being used as manure for agricultural fields, thus having the tendency to alter the soil environment condition influencing the microbial population as well. Inadequate data are available on the fate and transport of microplastics under varying environmental conditions that are required to supplement important information for further research. In addition, microplastics have the tendency to absorb heavy metals and hydrophobic organic contaminants such as PAHs and PCBs from its surroundings and thus acting as carriers for these contaminants in the environment system. In this study, three kinds of microplastics (polyethylene, polypropylene and expanded polystyrene) of different densities were chosen. Plastic samples were placed in sand with different aqueous media (distilled water, surface water, groundwater and marine water). It was incubated at varying temperatures (25, 35 and 40 °C) and agitation levels (rpm). The results show that the number of plastic fragments enhanced with increase in temperature and agitation speed. Moreover, the rate of disintegration of expanded polystyrene is high compared to other plastics. These results demonstrate that temperature, salinity, and mechanical abrasion plays a major role in degradation of plastics. Since weathered microplastics are more harmful as compared to the virgin microplastics, long-term studies involving other environmental factors are needed to have a better understanding of degradation of plastics.

Keywords: environmental contamination, fragmentation, microplastics, temperature, weathering

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Authors: Yogesh S. Patel

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Novel polyimides were synthesized by Diels–Alder polymerization. Bisfuran was reacted with a couple of bismaleimides containing diglycidyl ether of bisphenol-A and F (epoxy) segment to obtain Diels–Alder polyadducts. Polyadducts were then aromatized and imidized (i.e. cyclized) through carboxylic and amide groups to afford polyimides. Synthesized polyadducts and polyimides were characterized by elemental analysis, spectral features, the number of average molecular weight (Mn) and thermal analysis. The ‘in situ’ glass fiber reinforced composites were prepared and characterized by mechanical, electrical, and chemical properties. These properties were compared with the other reported polyimides. All the composites showed good mechanical and electrical properties and good resistance to organic solvents and mineral acids.

Keywords: Diels-Alder reaction, bisfuran, bismaleimides, polyimide

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Authors: Shimaa M. Elsaeed, Reem K. Farag, Ibrahim M. Nassar

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Hydrogel conductive polymer nanocomposite fabricated via in-situ polymerization of polyaniline (PANI) inside thermosensitive hydrogels based on hydroxy ethyl meth acrylate (HEMA) copolymer with 2-acrylamido-2-methyl propane sulfonic acid (AMPS). SEM micrographs show the nanometric size of the conductive material (polyaniline, PANI) dispersed in the hydrogel matrix. The swelling parameters of hydrogel are measured. The incorporation of PANI improves the mechanical properties and swelling up to 30,000% without breaking. X-ray diffraction shows that typical polyaniline crystallization is formed in composite, which is advantageous to increase the electrical conductivity of the composite hydrogel. Open-circuit voltage (I-V) curve fill factor of the highest photo-conversion efficiency and enhanced to use in solar cell.

Keywords: hydrogel, solar cell, conductive polymer, nanocomposite

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Authors: Salem Ali Jebreil

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In this work, a polyaniline/Iron oxide (PANI/Fe2O3) composite was chemically prepared by oxidative polymerization of aniline in acid medium, in presence of ammonium persulphate as an oxidant and amount of Fe2O3. The composite was characterized by a scanning electron microscopy (SEM). The prepared composite has been used as adsorbent to remove Tartrazine dye form aqueous solutions. The effects of initial dye concentration and temperature on the adsorption capacity of PANI/Fe2O3 for Tartrazine dye have been studied in this paper. The Langmuir and Freundlich adsorption models have been used for the mathematical description of adsorption equilibrium data. The best fit is obtained using the Freundlich isotherm with an R2 value of 0.998. The change of Gibbs energy, enthalpy, and entropy of adsorption has been also evaluated for the adsorption of Tartrazine onto PANI/ Fe2O3. It has been proved according the results that the adsorption process is endothermic in nature.

Keywords: adsorption, composite, dye, polyaniline, tartrazine

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Authors: Pornsiri Kaewpradit, Chalisa Pourneaw

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Temperature control improvement of a membrane reactor with exothermic and reversible esterification reaction is studied in this work. It is well known that a batch membrane reactor requires different control strategies from a continuous one due to the fact that it is operated dynamically. Due to the effect of the operating temperature, the suitable control scheme has to be designed based reliable predictive model to achieve a desired objective. In the study, the optimization framework has been preliminary formulated in order to determine an optimal temperature trajectory for maximizing a desired product. In model predictive control scheme, a set of predictive models have been initially developed corresponding to the possible operating points of the system. The multiple predictive control moves have been further calculated on-line using the developed models corresponding to current operating point. It is obviously seen in the simulation results that the temperature control has been improved compared to the performance obtained by the conventional predictive controller. Further robustness tests have also been investigated in this study.

Keywords: model predictive control, batch reactor, temperature control, membrane reactor

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Authors: D. Majumdar, M. Baskey, S. K. Saha

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Graphene has already been identified as a promising material for future carbon based electronics. To develop graphene technology, the fabrication of a high quality P-N junction is a great challenge. In the present work, we have described a simple and general technique to grow single crystalline polyaniline (PANI) films on graphene sheets using in situ polymerization via the oxidation-reduction of aniline monomer and graphene oxide, respectively, to fabricate a high quality P-N junction, which shows diode-like behavior with a remarkably low turn-on voltage (60 mV) and high rectification ratio (1880:1) up to a voltage of 0.2 Volt. The origin of these superior electronic properties is the preferential growth of a highly crystalline PANI film as well as lattice matching between the d-values [~2.48 Å] of graphene and {120} planes of PANI.

Keywords: epitaxial growth, PANI, reduced graphene oxide, rectification ratio

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Authors: Mehmet Doğan, Mahir Alkan, Yasemin Turhan, Zürriye Gündüz, Pinar Beyli, Serap Doğan

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Advances and new discoveries in the field of the material science on the basis of technological developments have played an important role. Today, material science is branched the lower branches such as metals, nonmetals, chemicals, polymers. The polymeric nano composites have found a wide application field as one of the most important among these groups. Many polymers used in the different fields of the industry have been desired to improve the thermal stability. One of the ways to improve this property of the polymers is to form the nano composite products of them using different fillers. There are many using area of boron compounds and is increasing day by day. In order to the further increasing of the variety of using area of boron compounds and industrial importance, it is necessary to synthesis of nano-products and to find yourself new application areas of these products. In this study, PMMA/boronoxide nano composites were synthesized using solution intercalation, polymerization and melting methods; and PAA/boronoxide nano composites using solution intercalation method. Furthermore, rheological properties of nano composites synthesed according to melting method were also studied. Nano composites were characterized by XRD, FTIR-ATR, DTA/TG, BET, SEM, and TEM instruments. The effects of filler material amount, solvent types and mediating reagent on the thermal stability of polymers were investigated. In addition, the rheological properties of PMMA/boronoxide nano composites synthesized by melting method were investigated using High Pressure Capillary Rheometer. XRD analysis showed that boronoxide was dispersed in polymer matrix; FTIR-ATR that there were interactions with boronoxide between PAA and PMMA; and TEM that boronoxide particles had spherical structure, and dispersed in nano sized dimension in polymer matrix; the thermal stability of polymers was increased with the adding of boronoxide in polymer matrix; the decomposition mechanism of PAA was changed. From rheological measurements, it was found that PMMA and PMMA/boronoxide nano composites exhibited non-Newtonian, pseudo-plastic, shear thinning behavior under all experimental conditions.

Keywords: boronoxide, polymer, nanocomposite, rheology, characterization

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Authors: Robert J. Sutton, Jon Elvins, Sean Casey, Eifion Jewell, Justin R. Searle

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Thermochemical storage utilises chemical salts which store and release energy a fully reversible endo/exothermic chemical reaction. Highly porous vermiculite impregnated with CaCl2, LiNO3 and MgSO4 (SIMs – Salt In Matrices) are proposed as potential materials for long-term thermochemical storage. The behavior of these materials during typical hydration and dehydration cycles is investigated. A simple moisture experiment represents the hydration, whilst thermogravimetric analysis (TGA) represents the dehydration. Further experiments to approximate the energy density and to determine the peak output temperatures of the SIMs are conducted. The CaCl2 SIM is deemed the best performing SIM across most experiments, whilst the results of MgSO4 SIM indicate difficulty associated with energy recovery.

Keywords: hydrated states, inter-seasonal heat storage, moisture sorption, salt in matrix

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Authors: Konstantinos Sotiriadis, Olesia Mikhailova

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In the present work, fly ash geopolymer based composites including polyester (PES) waste were studied. Specimens of three compositions were prepared: (a) fly ash geopolymer with 5% PES waste, (b) fly ash geopolymer mortar with 5% PES waste, (c) fly ash geopolymer mortar with 6.25% PES waste. Compressive and bending strength measurements, water absorption test and determination of thermal conductivity coefficient were performed. The results showed that the addition of sand in a mixture of geopolymer with 5% PES content led to higher compressive strength, while it increased water absorption and reduced thermal conductivity coefficient. The increase of PES addition in geopolymer mortars resulted in a more dense structure, indicated by the increase of strength and thermal conductivity and the decrease of water absorption.

Keywords: fly ash, geopolymers, polyester waste, composites

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Authors: Mei-Jen Lin, Yuan-Yuan Yu

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Low heat stability of goat milk limited the application of ultra-high temperature (UHT) sterilization on producing sterilized goat milk in order to keep excess goat milk in summer for producing goat dairy products in winter in Taiwan. Therefore, this study aimed to add stabilizers in goat milk to increase the heat stability for producing UHT sterilized goat milk preserved for making goat dairy products in winter. The amounts of 0.05-0.11% blend of sodium phosphates (Na) and blend of sodium/potassium phosphates (Sp) were added in raw goat milk at different seasons a night before autoclaved sterilization at 135°C 4 sec. The coagulation, ion calcium concentration and ethanol stability of sterilized goat milk were analyzed. Results showed that there were seasonal differences on choosing the optimal stabilizers and the addition levels. Addition of 0.05% and 0.22% of both Na and Sp salts in Spring goat milk, 0.10-0.11% of both Na and Sp salts in Summer goat milk, and 0.05%Na Sp group in Autumn goat milk were coagulated after autoclaved, respectively. There was no coagulation found with the addition of 0.08-0.09% both Na and Sp salts in goat milk; furthermore, the ionic calcium concentration were lower than 2.00 mM and ethanol stability higher than 70% in both 0.08-0.09% Na and Sp salts added goat milk. Therefore, the optimal addition level of blend of sodium phosphates and blend of sodium/potassium phosphates were 0.08-0.09% for producing sterilized goat milk at different seasons in Taiwan.

Keywords: coagulation, goat milk, phosphates, stability

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Authors: Jintang Zhou, Zhengjun Yao, Tiantian Yao

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Li₀.₃₅Zn₀.₃Fe₂.₃₅O₄(LZFO) grafted with polyaniline (PANI) fibers was synthesized by in situ polymerization. FTIR, XRD, SEM, and vector network analyzer were used to investigate chemical composition, micro-morphology, electromagnetic properties and microwave absorbing properties of the composite. The results show that PANI fibers were grafted on the surfaces of LZFO particles. The reflection loss exceeds 10 dB in the frequency range from 2.5 to 5 GHz and from 15 to 17GHz, and the maximum reflection loss reaches -33 dB at 15.9GHz. The enhanced microwave absorption properties of LZFO/PANI-fiber composites are mainly ascribed to the combined effect of both dielectric loss and magnetic loss and the improved impedance matching.

Keywords: Li₀.₃₅Zn₀.₃Fe₂.₃₅O₄, polyaniline, electromagnetic properties, microwave absorbing properties

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Authors: Haotian Wu

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This article examines the figure Zhao Tao in Jia Zhangke’s films in light of Carl Jung’s psychoanalytical theory. Zhao is a recurring aesthetic trope in Jia’s films, and the characters she plays often have an intimate relationship with the past. Nevertheless, this relationship has not been systematically investigated, especially its symbolism of the typical relationship between the past and the self in post-social China. To fill this research gap, the article will explore how Zhao’s characters discover, preserve, and adapt the past in I Wish I knew (2010), Mountains May Depart (2015), and Ash Is Purest White (2018). Through a Jungian lens, these three levels of engagement with the past will be demonstrated as corresponding with Jung’s psychoanalytical theory of self-realisation, which entails the confrontation with the shadow, the embodiment of the archetype, and individuation. Thus, by articulating a film-philosophy dialogue between Jia and Jung, this article will develop a new philosophy of self-realisation based on the symbolism of Zhao. Through the reintegration of the past, the individuals can overcome the fragmentation of temporality and selfhood in the postmodern world and achieve self-realisation.

Keywords: Jia Zhangke, Jung, psychoanalysis, self-realisation

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Authors: Seok Woo Chang

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Aim: Capseal I and Capseal II are calcium silicate and calcium phosphate based experimental root canal sealer. The aim of this study was to evaluate the biocompatibility and mineralization potential of Capseal I and Capseal II. Materials and Methods: The biocompatibility and mineralization-related gene expression (alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN)) of Capseal I and Capseal II were compared using methylthiazol tetrazolium assay and reverse transcription-polymerization chain reaction analysis, respectively. The results were analyzed by Kruskal-Wallis test. P-value of < 0.05 was considered significant. Result: Both Capseal I and Capseal II were favorable in biocompatibility and influenced the messenger RNA expression of ALP and BSP. Conclusion: Within the limitation of this study, Capseal is biocompatible and have mineralization promoting potential, and thus could be a promising root canal sealer.

Keywords: biocompatibility, mineralization-related gene expression, Capseal I, Capseal II

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Authors: A. Kasmi, N. E. Abriak, M. Benzerzour, I. Shahrour

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Large volumes of river sediments are dredged each year in Europe in order to maintain harbour activities and prevent floods. The management of this sediment has become increasingly complex. Several European projects were implemented to find environmentally sound solutions for these materials. The main objective of this study is to show the ability of river sediment to be used in road. Since sediments contain a high amount of water, then a dehydrating treatment by addition of the flocculation aid has been used. Firstly, a lot of physical characteristics are measured and discussed for a better identification of the raw sediment and this dehydrated sediment by addition the flocculation aid. The identified parameters are, for example, the initial water content, the density, the organic matter content, the grain size distribution, the liquid limit and plastic limit and geotechnical parameters. The environmental impacts of the used material were evaluated. The results obtained show that there is a slight change on the physical-chemical and geotechnical characteristics of sediment after dehydration by the addition of polymer. However, these sediments cannot be used in road construction.

Keywords: rive sediment, dehydration, flocculation aid or polymer, characteristics, treatments, valorisation, road construction

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Authors: C. Busuioc, I. Stancu, A. Nicoara, A. Zamfirescu, A. Evanghelidis

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The field of tissue engineering has expanded its potential due to the use of composite biomaterials belonging to increasingly complex systems, leading to bone substitutes with properties that are continuously improving to meet the patient's specific needs. Furthermore, the development of biomaterials based on ceramic and polymeric phases is an unlimited resource for future scientific research, with the final aim of restoring the original tissue functionality. Thus, in the first stage, composite scaffolds based on polycaprolactone (PCL) or polylactic acid (PLA) and inorganic powders were prepared by employing the electrospinning technique. The targeted powders were: commercial and laboratory synthesized hydroxyapatite (HAp), as well as barium titanate (BT). By controlling the concentration of the powder within the precursor solution, together with the processing parameters, different types of three-dimensional architectures were achieved. In the second stage, both the mineral powders and hybrid composites were investigated in terms of composition, crystalline structure, and microstructure so that to demonstrate their suitability for tissue engineering applications. Regarding the scaffolds, these were proven to be homogeneous on large areas and loaded with mineral particles in different proportions. The biological assays demonstrated that the addition of inorganic powders leads to modified responses in the presence of simulated body fluid (SBF) or cell cultures. Through SBF immersion, the biodegradability coupled with bioactivity were highlighted, with fiber fragmentation and surface degradation, as well as apatite layer formation within the testing period. Moreover, the final composites represent supports accepted by the cells, favoring implant integration. Concluding, the purposed fibrous materials based on bioresorbable polymers and mineral powders, produced by the electrospinning technique, represent candidates with considerable potential in the field of tissue engineering. Future improvements can be attained by optimizing the synthesis process or by simultaneous incorporation of multiple inorganic phases with well-defined biological action in order to fabricate multifunctional composites.

Keywords: barium titanate, electrospinning, fibre networks, hydroxyapatite, smart scaffolds

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Authors: Rita Rostika, Junianto, Zulfiqar W. Ibrahim, Iskandar, Lantun P. Dewanti

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The purpose of this research is to determine the influence of asparagus bean powder and its most effective administration dose to improve the gonad maturity of nilem carp (Osteochilus hasselti). The research is conducted in October-July 2017 located at Cirata Reservoir and Aquaculture Laboratory, Faculty of Fisheries and Marine Sciences, Padjadjaran University, Jatinangor. The research employs an experimental method using a Complete Random Design (RAL) with six treatments and three repetitions. The treatments include the addition of asparagus bean powder by 0% (Control), 4% per kg of feed, 5% per kg of feed, 6% per kg of feed, 7% per kg of feed, as well as the addition of vitamin E essential as the control. The results show that the addition of asparagus bean powder to the feed may influence the gonad maturity of nilem carp shown by its Gonado Somatic Index (GSI) parameter, fecundity, egg diameter and egg reaching its maturity phase or GVBD (Germinal Vesicle Breakdown). The best administration dose influencing nilem carp is the addition of asparagus bean powder by 7% per kg of feed with the average GSI of 15.02%, relative fecundity of 137 eggs/g of fish parent weight, egg diameter of 1,263 mm, and egg reaching its maturity phase (GVBD) of 78.15%.

Keywords: asparagus bean powder, nilem carp, gonad maturity, Cirata reservoir

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Authors: Y. Sefir, Z. Aziz, S. Cherid, Z. F. Meghoufel, F. Bendahama, S. Terkhi, B. Bouadjemi. A. Zitouni S. Bentata

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This work is to study the effect of the variation of structural parameters on the band structure in the quasiperiodic Fibonacci superlattices AlxGa1-xAs/GaAs using the formalism of the transfer matrix and Airy function. Our results show that increasing the width of Fibonacci’s wells of allows to the confinement of subminibands with a widening of minigaps, this causes a consistent and coherent fragmentation. The barrier thickness of Fibonacci bf acts on the width of subminibands by controlling the interaction force between neighboring eigenstates. Its increase gives rise to singularly extended states. The barrier height Fibonacci Vf permit to control the degree of structural disorder in these structures. The variation of these parameters permits the design of laser with modulated wavelength.

Keywords: transmission coefficient – Quasiperiodic superlattices- singularly localized and extended states- structural parameters- Laser with modulated wavelength

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Authors: Hassina Hafida Boukhalfa, Mathieu Massinon, Fréderic Lebeau, Mohamed Belhamra

Abstract:

Drop behaviour during impact affects retention. The increase of adhesion is usually seen as the objective when applying crop protection products, while bouncing and shattering are seen as detrimental to spray retention. However, observation of drop impacts using high speed shadow graphy shows that fragmentation can occur in Wenzel wetting regime. In this case, a part of the drop sticks on the surface, what contributes to retention. Using simultaneous measurements of drop impacts with high speed imaging and of retention with fluorometry for 3 spray mixtures on excised barley leaves allowed us to observe that about 50% of the drops fragmented in Wenzel state remain on the leaf. Depending on spray mixture, these impact outcomes accounted for 25 to 50% of retention, the higher contribution being correlated with bigger VMD (Volume Median Diameter). This contribution is non-negligible and should be considered when a modelling of spray retention process is performed.

Keywords: drop impact, retention, fluorometry, high speed imaging

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Authors: Gaurav Malik, Satyendra Mourya, Jyoti Jaiswal, Ramesh Chandra

Abstract:

The attractive and multifunctional properties of ZnO make it a promising material for the fabrication of highly sensitive and selective efficient gas sensors at room temperature. This presented article focuses on the development of highly selective and sensitive H₂ gas sensor based on the Pd-Pt decorated ZnO framework and its sensing mechanisms. The gas sensing performance of sputter made Pd-Pt/ZnO electrode on anodized porous silicon (PSi) substrate toward H₂ gas is studied under low detection limit (2–500 ppm) of H₂ in the air. The chemiresistive sensor demonstrated sublimate selectivity, good sensing response, and fast response/recovery time with excellent stability towards H₂ at low temperature operation under ambient environment. The elaborate selective measurement of Pd-Pt/ZnO/PSi structure was performed towards different oxidizing and reducing gases. This structure exhibited advance and reversible response to H₂ gas, which revealed that the acquired architecture with ZnO framework is a promising candidate for H₂ gas sensor.

Keywords: sputtering, porous silicon, ZnO framework, XPS spectra, gas sensor

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