Search results for: total synthesis

Authors: Mohamed Amine Ben Abdallah, Imed Khemili, Nizar Aifaoui

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This work denotes an insight into dynamic synthesis of multibody systems. A set of mechanism parameters design variable are synthetized based on a desired mechanism response, such as, velocity, acceleration and bodies deformations. Moreover, knowing the work space, for a robot, and mechanism response allow defining optimal parameters mechanism handling with the desired target response. To this end, evolutionary genetic algorithm has been deployed. A demonstrative example for imperfect mechanism has been treated, mainly, a slider crank mechanism with a flexible connecting rod. The transversal deflection of the connecting rod has been chosen as response to identify the mechanism design parameters.

Keywords: dynamic response, evolutionary genetic algorithm, flexible bodies, optimization

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Authors: Ei Ei Hlaing, Narissara Lailerd, Sittiruk Roytrakul, Pichapat Piamrojanaphat

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Type 2 diabetes is one of the most common metabolic diseases all over the world. The pathogenesis of type 2 diabetes is not the only dysfunction of pancreatic beta cells but also insulin resistance in muscle, liver and adipose tissue. High levels of circulating free fatty acids, an increased lipid content of muscle cells, impaired insulin-mediated glucose uptake and diminished mitochondrial functioning are pathophysiological hallmarks of diabetic skeletal muscles. Purple rice (Oryza sativa L. indica) has been shown to have antidiabetic effects. However, the underlying mechanism(s) of antidiabetic activity of purple rice is still unraveled. In this research, to explore in-depth cellular mechanism(s), proteomic profile of purple rice supplemented type 2 diabetic rats’ skeletal muscle were analyzed contract with non-supplemented rats. Diabetic rats were induced high-fat diet combined with streptozotocin injection. By using one- dimensional gel electrophoresis (1-DE) and LC-MS/MS quantitative proteomic method, we analyzed proteomic profiles in skeletal muscle of normal rats, normal rats with purple rice supplementation, type 2 diabetic rats, and type 2 diabetic rats with purple rice supplementation. Total 2676 polypeptide expressions were identified. Among them, 24 peptides were only expressed in type 2 diabetic rats, and 24 peptides were unique peptides in type 2 diabetic rats with purple rice supplementation. Acetyl CoA carboxylase 1 (ACACA) found as unique protein in type 2 diabetic rats which is the major enzyme in lipid synthesis and metabolism. Interestingly, DNA damage response protein, heterogeneous nuclear ribonucleoprotein K [Mus musculus] (Hnrnpk), was upregulated in type 2 diabetic rats’ skeletal muscle. Meanwhile, unique proteins of type 2 diabetic rats with purple rice supplementation (bone morphogenetic 7 protein preproprotein, BMP7; and forkhead box protein NX4, Foxn4) involved with muscle cells growth through the regulation of TGF-β/Smad signaling network. Moreover, BMP7 may effect on insulin signaling through the downstream signaling of protein kinase B (Akt) which acts in protein synthesis, glucose uptake, and glycogen synthesis. In conclusion, our study supports that type 2 diabetes impairs muscular lipid metabolism. In addition, purple rice might recover the muscle cells growth and insulin signaling.

Keywords: proteomics, purple rice bran, skeletal muscle, type 2 diabetic rats

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Authors: Norah Al Hokbany, Ibrahim Al Jammaz, Basem Al Otaibi, Yousif Al Malki, Subhani M. Okarvi

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Objective: The folate receptor is over-expressed in a wide variety of human tumors. Conjugates of folate have been shown to be selectively taken up by tumor cells via the folate receptor. In an attempt to develop new folate radiotracers with favorable biochemical properties for detecting folate receptor-positive cancers. Methods: we synthesized ⁶⁴Cu-NOTA- and ⁶⁴Cu-NOTAM-folate conjugates using a straightforward and simple one-step reaction. Radiochemical yields were greater than 95% (decay-corrected) with a total synthesis time of less than 20 min. Results: Radiochemical purities were always greater than 98% without high-performance liquid chromatography (HPLC) purification. These synthetic approaches hold considerable promise as a rapid and simple method for ⁶⁴Cu-folate conjugate preparation with high radiochemical yield in a short synthesis time. In vitro tests on the KB cell line showed that significant amounts of the radio conjugates were associated with cell fractions. Bio-distribution studies in nude mice bearing human KB xenografts demonstrated a significant tumor uptake and favorable bio-distribution profile for ⁶⁴Cu-NOTA- and ⁶⁴Cu-NOTAM-folate conjugate. The uptake in the tumors was blocked by the excess injection of folic acid, suggesting a receptor-mediated process. Conclusion: These results demonstrate that the ⁶⁴Cu-NOTAM-folate conjugate may be useful as a molecular probe for the detection and staging of folate receptor-positive cancers, such as ovarian cancer and their metastasis, as well as monitoring tumor response to treatment.

Keywords: folate, receptor, tumor imaging, ⁶⁴Cu-NOTA-folate, PET

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Authors: Mehdi Rahimi-Nasrabadi, Seied Mahdi Pourmortazavi

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Taguchi robust design as a statistical method was applied for optimization of the process parameters in order to tunable, simple and fast synthesis of europium (III) tungstate nanoparticles. Europium (III) tungstate nanoparticles were synthesized by a chemical precipitation reaction involving direct addition of europium ion aqueous solution to the tungstate reagent solved in aqueous media. Effects of some synthesis procedure variables i.e., europium and tungstate concentrations, flow rate of cation reagent addition, and temperature of reaction reactor on the particle size of europium (III) tungstate nanoparticles were studied experimentally in order to tune particle size of europium (III) tungstate. Analysis of variance shows the importance of controlling tungstate concentration, cation feeding flow rate and temperature for preparation of europium (III) tungstate nanoparticles by the proposed chemical precipitation reaction. Finally, europium (III) tungstate nanoparticles were synthesized at the optimum conditions of the proposed method and the morphology and chemical composition of the prepared nano-material were characterized by means of X-Ray diffraction, scanning electron microscopy, transmission electron microscopy, FT-IR spectroscopy, and fluorescence.

Keywords: europium (III) tungstate, nano-material, particle size control, procedure optimization

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Authors: Jasneet Kaur, Swapandeep Singh Chimni

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The unfavorable use of metal-based catalysts that are often extortionate and toxic can be overcome by using small organic molecules known as organocatalysts. A variety of small organic molecules, including Brønsted/Lewis bases and acids, based on sulfonic acids, phosphoric acids, amines, phosphines or carbenes, Cinchona alkaloids, have been used as organocatalysts. One of the key reasons for using organocatalysis is their ability to be effectively removed from the final product in comparison to the metallic counterparts, which are exceedingly difficult to remove. The present investigation seeks to explore the catalytic nature of Cinchona alkaloids as an organocatalyst for enantioselective synthesis of 3-substituted-3-aminooxindole, which is known to exhibit a variety of biological activities and pharmacological activities. In this context, an organocatalytic asymmetric route for the synthesis of 3-aminooxindoles via reaction of isatin imine with α-acetoxy-β-ketoesters has been developed. The bifunctional Cinchona derived thiourea catalyzed the reaction of α-acetoxy-β-ketoesters derivatives with isatin imine to afford 3-substituted-aminooxindole derivatives in up to 93% yield, 95% enantiomeric excess and >20:1 diastereomeric ratio. The reaction was performed at room temperature for two hours using 10 mol% of catalyst, in the presence of 4Å molecular sieves in tetrahydrofuran as a solvent at ambient temperature. After the completion of the reaction, the pure product could be easily separated by using column chromatography using hexane and ethyl acetate as solvents. In conclusion, the catalytic potential of Cinchona derived chiral thiourea-tertiary amine catalyst was explored for an organocatalytic enantioselective Mannich reaction of β-ketoester derivatives with various isatin imine derivatives under mild conditions.

Keywords: asymmetric synthesis, aminooxindoles, enantioselective, isatin imine

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Authors: Tasnuva Tamanna, Aimin Yu

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Application of nanoscience in biomedical field has come across as a new era. This study involves the synthesis of nano drug carrier with antibiotic loading. Based on the founding that polydopamine (PDA) nanoparticles could be formed via self-polymerization of dopamine at alkaline pH, one-step synthesis of rifampicin coupled polydopamine (PDA-R) nanoparticles was achieved by adding rifampicin into the dopamine solution. The successful yield of PDA nanoparticles with or without the presence of rifampicin during the polymerization process was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Drug loading was monitored by UV-vis spectroscopy and the loading efficiency of rifampicin was calculated to be 76%. Such highly capacious nano-reservoir was found very stable with little drug leakage at pH 3.

Keywords: drug loading, nanoparticles, polydopamine, rifampicin

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Authors: Andrey V. Samokhin, Nikolay V. Alekseev, Mikhail A. Sinaiskii

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The report presents the results of R&D of plasma-chemical production of W, W-Cu, W-Ni-Fe nanopowders as well as spherical micropowders of these compounds for their use in modern 3D printing technologies. Plasma-chemical synthesis of nanopowdersis based on the reduction of tungsten oxide compounds powders in a stream of hydrogen-containing low-temperature thermal plasma generated in an electric arc plasma torch. The synthesis of W-Cu and W-Ni-Fe nanocompositesiscarried out using the reduction of a mixture of the metal oxides. Using the synthesized tungsten-based nanocomposites powders, spherical composite micropowders with a submicron structure canbe manufactured by spray dryinggranulation of nanopowder suspension and subsequent densification and spheroidization of granules by melting in a low-temperature thermal plasma flow. The DC arc plasma systems are usedfor the synthesis of nanopowdersas well as for the spheroidization of microgranuls. Plasma systems have a capacity of up to 1 kg/h for nanopowder and up to 5 kg/h for spheroidized powder. All synthesized nanopowders consist of aggregated particles with sizes less than 100 nm, and nanoparticles of W-Cu and W-Ni-Fe composites have core (W) –shell (Cu or Ni-Fe) structures. The resulting dense spherical microparticles with a size of 20-60 microns have a submicron structure with a uniform distribution of metals over the particle volume. The produced tungsten-based nano- and spherical micropowderscan be used to develop new materials and manufacture products using advanced modern technologies.

Keywords: plasma, powders, production, tungsten-based

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Authors: Haythem Barrak, Gaetan Laroche, Adel M’nif, Ahmed Hichem Hamzaoui

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The use of semiconductor oxides, as chemical or biological, requires their functionalization with appropriate dependent molecules of the substance to be detected. generally, the support materials used are TiO2 and SiO2. In the present work, we used zinc oxide (ZnO) known for its interesting physical properties. The synthesis of nano scale ZnO was performed by co-precipitation at low temperature (60 ° C).To our knowledge, the obtaining of this material at this temperature was carried out for the first time. This shows the low cost of this operation. On the other hand, the surface functionalization of ZnO was performed with (3-aminopropyl) triethoxysilane (APTES) by using a specific method using ethanol for the first time. In addition, the duration of this stage is very low compared to literature. The samples obtained were analyzed by XRD, TEM, DLS, FTIR, and TGA shows that XPS that the operation of grafting of APTES on our support was carried out with success.

Keywords: functionalization, nanoparticle, ZnO, APTES, caractérisation

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Authors: A. Esra Pişkin, L. Yusuf Yivlik

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Polyurethane consumption in the world increases every year. Polyetherpolyol, which is the main raw material of polyurethane, is produced from petroleum, and bioresources are needed in polyol production due to the damage it causes to the environment and the consumption of too much energy during the production phase. In this present work, bio polyol was synthesized with castor oil and soybean oil, and its use in rigid polyurethane systems was investigated. Transesterification and ring opening methods were applied for polyol synthesis, and the obtained bio polyols were compared with polyols derived petroleum. The goal of the present study was to synthesize biopolyols and to investigate the mechanical, thermal, and chemical properties of the synthesized polyurethane in terms of bio polyols.

Keywords: polyurethane, polyol, biopolyol, vegetable oil, foam, rigid polyurethane foam, ring opening, transesterification

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Authors: B. M. Patil

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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.

Keywords: CaZrO3, CZO, NO2, NH3

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Authors: Malki Nadia Fatima Zahra, Kellal Cheimaa, Brahimi Houria

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Aim of the study is to show the role of total Quality Management on firm performance; the research relied on the views of sample managers working in the Marinel pharmaceutical company. The research aims to achieve many objectives, including increasing awareness of the concepts of Total Quality Management on Firm Performance, especially in the manufacturing firm, providing a future vision of the possibility of success, and the actual application of the Principles of Total Quality Management in the manufacturing company. The research adopted a default model was built after a review and analysis of the literature review in the context of one hypothesis main points at the origin of a group of sub-hypotheses. The research presented a set of conclusions, and the most important of these conclusions was there is a relationship between the Principles of TQM and Firm Performance.

Keywords: total quality management, TQM dimension, firm performance, strategies

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Authors: Ana Jurkeviciute, Larisa Grigorieva, Ksenia Moskvinа

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Oil shale alkylresorcinols are formed as a by-product in oil shale processing. They are unique raw material for chemical industry. Polycondensation resins obtaining is one of the worthwhile directions of oil shale alkylresorcinols use. These resins are widely applied in many branches of industry such as wood-working, metallurgic, tire, rubber products, construction etc. Possibility of resins obtaining using overall alkylresorcinols will allow to cheapen finished products on their base and to widen the range of resins offered on the market. Synthesis of polycondensation resins on the basis of alkylresorcinols was conducted by several methods in the process of investigations. In the formulations a part of resorcinol was replaced by fractions of oil shale alkylresorcinols containing different amount of 5-methylresorcinol (40-80 mass %). Some resins were modified by aromatic alkene at the stage of synthesis. Thermal stability and degradation behavior of resins were investigated by thermogravimetric analysis (TGA) method both in an inert nitrogen environment and in an oxidative environment of air. TGA integral curves were obtained and processed in dynamic mode for interval of temperatures from 25 to 830 °C. Rate of temperature rise was 5°C/min, gas flow rate - 50 ml/min. Resins power for carbonization was evaluated by carbon residue. Physical-chemical parameters of the resins were determined. Content of resorcinol and 5-methylresorcinol not reacted in the process of synthesis were determined by gas chromatography method.

Keywords: resorcinol, oil shale alkylresorcinols, aromatic alkene, polycondensation resins, modified resins

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Authors: Kyaw Zin Htut

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In this article, the synthesis of the efficiency of intelligent diagnostic system in the aircraft measuring devices is described. The technology developments of the diagnostic system are considered based on the model errors of the gyro instruments, which are used to measure the parameters of the aircraft. The synthesis of the diagnostic intelligent system is considered on the example of the problem of assessment and forecasting errors of the gyroscope devices on the onboard aircraft. The result of the system is to detect of faults of the aircraft measuring devices as well as the analysis of the measuring equipment to improve the efficiency of its work.

Keywords: diagnostic, dynamic system, errors of gyro instruments, model errors, assessment, prognosis

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Authors: Mohamed Arbi Khlifi, Badr M. Alshammari

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This paper discusses the general methods to saturation in the steady-state, two axis (d & q) frame models of synchronous machines. In particular, the important role of the magnetic coupling between the d-q axes (cross-magnetizing phenomenon), is demonstrated. For that purpose, distinct methods of saturation modeling of dumper synchronous machine with cross-saturation are identified, and detailed models synthesis in d-q axes. A number of models are given in the final developed form. The procedure and the novel models are verified by a critical application to prove the validity of the method and the equivalence between all developed models is reported. Advantages of some of the models over the existing ones and their applicability are discussed.

Keywords: cross-magnetizing, models synthesis, synchronous machine, saturated modeling, state-space vectors

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Authors: Ayed S. Al-Shihri, Abul Kalam, Abdullah G. Al-Sehemi, Gaohui Du, Tokeer Ahmad, Ahmad Irfan

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We report here the synthesis of nickel oxide (NiO) nanoparticles by microwave-assisted method, using a common precipitating agent followed by calcination in air at 400°C. The effect of the microwave and pH on the crystallite size, morphology, structure, energy band gap and surface area of NiO have been investigated by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV-vis) and BET surface area studies. X-ray diffraction studies showed the formation of monophasic and highly crystalline cubic NiO. TEM analysis led to decrease the average grain size of NiO nanoparticles from 16.5 nm to 14 nm on increasing the amount of NaOH. FTIR studies also confirm the formation of NiO nanoparticles. It was observed that on increasing the volume of NaOH, the optical band gap energy (2.85 eV to 2.95 eV) and specific surface area (33.1 to 39.8 m2/g) increases, however the average particles size decreases (16.5 nm to 14 nm). This method may be extended to large scale synthesis of other metal oxides nanoparticles and the present study could be used for the potential applications in water treatment and many other fields.

Keywords: BET surface area analysis, electron microscopy, optical properties, X-ray techniques

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Authors: Sakshi Gupta, Anupam Agrawal, Ekta Singla

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An exoskeleton design for rehabilitation purpose encounters many challenges, including ergonomically acceptable wearing technology, architectural design human-motion compatibility, actuation type, human-robot interaction, etc. In this paper, a passive architecture for upper limb exoskeleton is proposed for assisting in rehabilitation tasks. Kinematic modelling is detailed for task-based kinematic synthesis of the wearable exoskeleton for self-feeding tasks. The exoskeleton architecture possesses expansion and torsional springs which are able to store and redistribute energy over the human arm joints. The elastic characteristics of the springs have been optimized to minimize the mechanical work of the human arm joints. The concept of hybrid combination of a 4-bar parallelogram linkage and a serial linkage were chosen, where the 4-bar parallelogram linkage with expansion spring acts as a rigid structure which is used to provide the rotational degree-of-freedom (DOF) required for lowering and raising of the arm. The single linkage with torsional spring allows for the rotational DOF required for elbow movement. The focus of the paper is kinematic modelling, analysis and task-based synthesis framework for the proposed architecture, keeping in considerations the essential tasks of self-feeding and self-exercising during rehabilitation of partially healthy person. Rehabilitation of primary functional movements (activities of daily life, i.e., ADL) is routine activities that people tend to every day such as cleaning, dressing, feeding. We are focusing on the feeding process to make people independent in respect of the feeding tasks. The tasks are focused to post-surgery patients under rehabilitation with less than 40% weakness. The challenges addressed in work are ensuring to emulate the natural movement of the human arm. Human motion data is extracted through motion-sensors for targeted tasks of feeding and specific exercises. Task-based synthesis procedure framework will be discussed for the proposed architecture. The results include the simulation of the architectural concept for tracking the human-arm movements while displaying the kinematic and static study parameters for standard human weight. D-H parameters are used for kinematic modelling of the hybrid-mechanism, and the model is used while performing task-based optimal synthesis utilizing evolutionary algorithm.

Keywords: passive mechanism, task-based synthesis, emulating human-motion, exoskeleton

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Authors: Lin Cheng, Zijiang Yang

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Program synthesis is the task to automatically generate programs based on user specification. In this paper, we present a framework that synthesizes programs from flow charts that serve as accurate and intuitive specification. In order doing so, we propose a deep neural network called GRCNN that recognizes graph structure from its image. GRCNN is trained end-to-end, which can predict edge and node information of the flow chart simultaneously. Experiments show that the accuracy rate to synthesize a program is 66.4%, and the accuracy rates to recognize edge and node are 94.1% and 67.9%, respectively. On average, it takes about 60 milliseconds to synthesize a program.

Keywords: program synthesis, flow chart, specification, graph recognition, CNN

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Authors: Taha Ahmed Özbey, Sedat Nazlıbilek, Alparslan Çağrı Yapıcı

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Combline cavity filters have gained significant attention in recent years due to their exceptional narrowband characteristics, high unloaded Q, remarkable out-of-band rejection, and versatile post-manufacturing tuning capabilities. These filters play a vital role in various wireless communication systems, radar applications, and other advanced technologies where stringent frequency selectivity and superior performance are required. This paper represents combined cavity filter design and implementation by coupling matrix synthesis. Limited filter length, 50 dB out-of-band rejection, and agile design were aimed. To do so, CAD tools and intuitive methods were used.

Keywords: cavity, band pass filter, cavity combline filter, coupling matrix synthesis

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Authors: Carolin Anna Joy, Rohith K. R, Rehin Sulay, Parvathy Santhoshkumar, G.Anil Kumar, Vibin Ipe Thomas

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Ullmann coupling reactions are gaining great relevance owing to their contribution in the synthesis of biologically and pharmaceutically important compounds. Palladium and many other heavy metals have proven their excellent ability in coupling reaction, but the toxicity matters. The first-row transition metal also possess toxicity, except in the case of iron and manganese. The suitability of manganese as a catalyst is achieving great interest in oxidation, reduction, C-H activation, coupling reaction etc. In this presentation, we discuss the thermo chemistry of ligand free manganese catalyzed C-O coupling reaction between phenol and aryl halide for the synthesis of biaryl ethers using Density functional theory techniques. The mechanism involves an oxidative addition-reductive elimination step. The transition state for both the step had been studied and confirmed using Intrinsic Reaction Coordinate (IRC) calculation. The barrier height for the reaction had also been calculated from the rate determining step. The possibility of other mechanistic way had also been studied. To achieve further insight into the mechanism, substrate having various functional groups is considered in our study to direct their effect on the feasibility of the reaction.

Keywords: Density functional theory, Molecular Modeling, ligand free, biaryl ethers, Ullmann coupling

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Authors: Parvesh Singh, Vipan Kumar, Vishu Mehra

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Quinoline-4-ones represent an important class of heterocyclic scaffolds that have attracted significant interest due to their various biological and pharmacological activities. This heterocyclic unit also constitutes an integral component in drugs used for the treatment of neurodegenerative diseases, sleep disorders and in antibiotics viz. norfloxacin and ciprofloxacin. The synthetic accessibility and possibility of fictionalization at varied positions in quinoline-4-ones exemplifies an elegant platform for the designing of combinatorial libraries of functionally enriched scaffolds with a range of pharmacological profles. They are also considered to be attractive precursors for the synthesis of medicinally imperative molecules such as non-steroidal androgen receptor antagonists, antimalarial drug Chloroquine and martinellines with antibacterial activity. 2-Aryl-2,3-dihydroquinolin-4(1H)-ones are present in many natural and non-natural compounds and are considered to be the aza-analogs of favanones. The β-lactam class of antibiotics is generally recognized to be a cornerstone of human health care due to the unparalleled clinical efficacy and safety of this type of antibacterial compound. In addition to their biological relevance as potential antibiotics, β-lactams have also acquired a prominent place in organic chemistry as synthons and provide highly efficient routes to a variety of non-protein amino acids, such as oligopeptides, peptidomimetics, nitrogen-heterocycles, as well as biologically active natural and unnatural products of medicinal interest such as indolizidine alkaloids, paclitaxel, docetaxel, taxoids, cyptophycins, lankacidins, etc. A straight forward route toward the synthesis of quinoline-4-ones via the triflic acid assisted Fries rearrangement of N-aryl-βlactams has been reported by Tepe and co-workers. The ring expansion observed in this case was solely attributed to the inherent ring strain in β-lactam ring because -lactam failed to undergo rearrangement under reaction conditions. Theabovementioned protocol has been recently extended by our group for the synthesis of benzo[b]-azocinon-6-ones via a tandem Michael addition–Fries rearrangement of sorbyl anilides as well as for the single-pot synthesis of 2-aryl-quinolin-4(3H)-ones through the Fries rearrangement of 3-dienyl-βlactams. In continuation with our synthetic endeavours with the β-lactam ring and in view of the lack of convenient approaches for the synthesis of C-3 functionalized quinolin-4(1H)-ones, the present work describes the single-pot synthesis of C-3 functionalized quinolin-4(1H)-ones via the trific acid promoted Fries rearrangement of C-3 vinyl/isopropenyl substituted β-lactams. In addition, DFT calculations and MD simulations were performed to investigate the stability profles of synthetic compounds.

Keywords: dihydroquinoline, fries rearrangement, azetidin-2-ones, quinoline-4-ones

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Authors: Durata Haciu, Berti Manisa, Ozgur Birer

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ZnO nanoparticles have been synthesized by ultrasonic irradiation from simple linear alcohols and water/ethanolic mixtures, at 50 oC. By changing the composition of the solvent, the shape could be altered. While no product was obtained from methanolic solutions, in ethanol, sheet like lamellar structures prevail.n-propanol and n-butanol resulted in needle like structures. The morphology of ZnO could be thus tailored in a simple way, by varying the solvent, under ultrasonic irradiation, in a relatively less time consuming method. Variation of the morphology and size of Zn also provides a means for modulating the band-gap. Although the chemical effects of ultrasound do not come from direct interaction with molecular species, the high energy derived from acoustic cavitation creates a unique interaction of energy and matter with great potential for synthesis.

Keywords: ultrasound, ZnO, linear alcohols, morphology

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Authors: Yu Zhang, Il Kim

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Polypeptides with defined peptide sequences illustrate the power of remarkable applications in drug delivery, tissue engineering, sensing and catalysis. Especially the cyclic polypeptides, the distinctive topological architecture imparts many characteristic properties comparing to linear polypeptides. Here, a facile and highly efficient strategy for the synthesis of linear and cyclic polypeptides is reported using N-heterocyclic carbenes (NHCs)-mediated ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCA) in the presence or absence of primary amine initiator. The polymerization proceeds rapidly in a quasi-living manner, allowing access to linear and cyclic polypeptides of well-defined chain length and narrow polydispersity, as evidenced by nuclear magnetic resonance spectrum (1H NMR and 13C NMR spectra) and size exclusion chromatography (SEC) analysis. The cyclic architecture of the polypeptides was further verified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectra (MALDI-TOF MS) and electrospray ionization (ESI) mass spectra, as well as viscosity studies. This approach can also simplify workup procedures and make bulk scale synthesis possible, which thereby opens avenues for practical uses in diverse areas, opening up the new generation of polypeptide synthesis.

Keywords: α-amino acid N-carboxyanhydrides, living polymerization, polypeptides, N-heterocyclic carbenes, ring-opening polymerization

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Authors: Ali Zazi, Ouiza Cherifi

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Natural gas currently represents a raw material of choice for the manufacture of a wide range of chemical products via synthesis gas, among the routes of transformation of methane into synthesis gas The reaction of the oxidation of methane by gas vapor 'water. This work focuses on the study of the effect of cerieum on the nickel-based catalyst supported by silica for the methane vapor reforming reaction, with a variation of certain parameters of the reaction. The reaction temperature, the H₂O / CH₄ ratio and the flow rate of the reaction mixture (CH₄-H₂O). Two catalysts were prepared by impregnation of Degussa silica with a solution of nickel nitrates and a solution of cerium nitrates [Ni (NO₃) 2 6H₂O and Ce (NO₃) 3 6H₂O] so as to obtain the 1.5% nickel concentrations. For both catalysts and plus 1% cerium for the second catalyst. These Catalysts have been characterized by physical and chemical analysis techniques: BET technique, Atomic Absorption, IR Spectroscopy, X-ray diffraction. These characterizations indicated that the nitrates had impregnated the silica. And that the NiO and Ce₂O3 phases are present and Ni°(after reaction). The BET surface of the silica decreases without being affected. The catalytic tests carried out on the two catalysts for the steam reforming reactions show that the addition of cerium to the nickel improves the catalytic performances of the nickel. And that these performances also depend on the parameters of the reaction, namely the temperature, the rate of the reaction mixture, and the ratio (H₂O / CH₄).

Keywords: heterogeneous catalysis, steam reforming, Methane, Nickel, Cerium, synthesis gas, hydrogen

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Authors: M. D. H. Beg, John O. Akindoyo, Suriati Ghazali, Nitthiyah Jeyaratnam

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Over the period of time, several approaches have been undertaken to mitigate the challenges associated with bone regeneration. This includes but not limited to xenografts, allografts, autografts as well as artificial substitutions like bioceramics, synthetic cements and metals. The former three techniques often come along with peculiar limitation and problems such as morbidity, availability, disease transmission, collateral site damage or absolute rejection by the body as the case may be. Synthetic routes remain the only feasible alternative option for treatment of bone defects. Hydroxyapatite (HA) is very compatible and suitable for this application. However, most of the common methods for HA synthesis are either expensive, complicated or environmentally unfriendly. Interestingly, extraction of HA from bio-wastes have been perceived not only to be cost effective, but also environment friendly. In this research, HA was synthesized from bio-waste: namely bovine bones through three different methods which are hydrothermal chemical processes, ultrasound assisted synthesis and ordinary calcination techniques. Structure and property analysis of the HA was carried out through different characterization techniques such as TGA, FTIR, and XRD. All the methods applied were able to produce HA with similar compositional properties to biomaterials found in human calcified tissues. Calcination process was however observed to be more efficient as it eliminated all the organic components from the produced HA. The HA synthesized is unique for its minimal cost and environmental friendliness. It is also perceived to be suitable for tissue and bone engineering applications.

Keywords: hydroxyapatite, bone, calcination, biowaste

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Authors: Aicha Bensouici, Assia Mili, Naouel Rdjem, Nacera Baali

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Copper oxide decorated reduced graphene oxide (GO) was obtained successfully using two steps route synthesis was used. Firstly, graphene oxide was obtained using a modified Hummers method by excluding sodium nitrate from starting materials. After washing-centrifugation routine pristine GO was decorated by copper oxide using a refluxation technique at 120°C during 2h, and an equal amount of GO and copper acetate was used. Three CuO-rGO nanocomposite samples types were obtained at 30min, 24h, and 7 day stirring time. TAC results show dose dependent behavior of CuO-rGO and confirm no influence of stirring time on antioxidant properties, 30min is considered as an optimal stirring condition.

Keywords: copper oxide, reduced graphene oxide, TAC, GO

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Authors: Nneka Augustina Akwu, Yougasphree Naidoo

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Molecular advancement in technology has created a means whereby the atoms and molecules (solid forms) of certain materials such as plants, can now be reduced to a range of 1-100 nanometres. Green synthesis of silver nanoparticles (AgNPs) was carried out at room temperature (RT) 25 ± 2°C and 80°C, using the metabolites in the aqueous extracts of the leaves and stem bark of Grewia lasiocarpa as reductants and stabilizing agents. The biosynthesized AgNPs were characterized by UV-Vis spectrophotometry, attenuated total reflectance - Fourier transforms infrared (ATR-FTIR) spectroscopy, nanoparticle tracking analysis (NTA), Energy Dispersive X-ray fluorescence scanning electron microscope (SEM-EDXRF) and high-resolution transmission electron microscopy (HRTEM). The AgNPs were biologically evaluated for antioxidant, antibacterial and cytotoxicity activities. The phytochemical and FTIR analyses revealed the presence of metabolites that act as reducing and capping agents, while the UV-Vis spectroscopy of the biosynthesized NPs showed absorption between 380-460 nm, confirming AgNP synthesis. The Zeta potential values were between -9.1 and -20.6 mV with a hydrodynamics diameter ranging from 38.3 to 46.7 nm. SEM and HRTEM analyses revealed that AgNPs were predominately spherical with an average particle size of 2- 31 nm for the leaves and 5-27 nm for the stem bark. The cytotoxicity IC50 values of the AgNPs against HeLa, Caco-2 and MCF-7 were >1 mg/mL. The AgNPs were sensitive to all strains of bacteria used, with methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) being more sensitive to the AgNPs. Our findings propose that antibacterial and anticancer agents could be derived from these AgNPs of G. lasiocarpa, and warrant their further investigation.

Keywords: antioxidant, cytotoxicity, Grewia lasiocarpa, silver nanoparticles, Zeta potentials

Procedia PDF Downloads 141

Authors: Ujjawal Kumar Bhagat, Kamaluddin, Rama Krishna Peddinti

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The Huisgen’s 1,3-dipolar [3+2] cycloaddition of organic azides and alkynes often give the mixtures of both the regioisomers 1,4- and 1,5- disubstituted 1,2,3-triazoles. Later, in presence of metal salts (click chemistry) such as copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) was used for the synthesis of 1,4-disubstituted 1,2,3-triazoles as a sole products regioselectively. Also, the ‘click reactions’ of Ruthenium-catalyzed azides-alkynes cycloaddition (RuAAC) is used for the synthesis of 1,5-disubstituted 1,2,3-triazoles as a single isomer. The synthesis of 1,4- and 1.5-disubstituted 1,2,3-triazoles has become the gold standard of ‘click chemistry’ due to its reliability, specificity, and biocompatibility. The 1,4- and 1,5-disubstituted 1,2,3-triazoles have emerged as one of the most powerful entities in the varieties of biological properties like antibacterial, antitubercular, antitumor, antifungal and antiprotozoal activities. Some of the 1,4,5-trisubstituted 1,2,3-triazoles exhibit Hsp90 inhibiting properties. The 1,4-disubstituted 1,2,3-triazoles also play a big role in the area of material sciences. The triazole-derived oligomeric, polymeric structures are the potential materials for the preparation of organic optoelectronics, silicon elastomers and unimolecular block copolymers. By the virtue of hydrogen bonding and dipole interactions, the 1,2,3-triazole moiety readily associates with the biological targets. Since, the 4-aryl-1H-1,2,3-triazoles are stable entities, they are chemically robust and very less reactive. In this regard, the addition of 4-aryl-1H-1,2,3-triazoles as nucleophiles to α,β-unsaturated carbonyls and nucleophilic substitution with the epoxides constitutes a powerful and challenging synthetic approach for the generation of disubstituted 1,2,3-triazoles. Herein, we have developed aza-Michael addition of 4-aryl-1H-1,2,3-triazoles to 2-cycloalken-1-ones in the presence of an organic base (DABCO) in acetonotrile solvent leading to the formation of disubstituted 1,2,3-triazoles. The reaction provides 1,4-disubstituted triazoles, 3-(4-aryl-1H-1,2,3-triazol-1-yl)cycloalkanones in major amount along with 1,5-disubstituted 1,2,3-triazoles, minor regioisomers with excellent combined chemical yields (upto99%). The nucleophilic behavior of 4-aryl-1H-1,2,3-triazoles was also tested in the ring opening of meso-epoxides in the presence of organic bases (DABCO/Et3N) in acetonotrile solvent furnishing the two regioisomers1,4- and 1,5-disubstituted 1,2,3-triazoles. Thus, the novelty of this methodology is synthesis of diversified disubstituted 1,2,3-triazoles under metal free condition.The results will be presented in detail.

Keywords: aza-Michael addition, cycloalkenones, epoxides, triazoles

Procedia PDF Downloads 322

Authors: Erdem Meriç

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Measuring total temperature of air flow accurately is a very important requirement in the development phases of many industrial products, including gas turbines and rockets. Thermocouples are very practical devices to measure temperature in such cases, but in high speed and high temperature flows, the temperature of thermocouple junction may deviate considerably from real flow total temperature due to the effects of heat transfer mechanisms of convection, conduction, and radiation. To avoid errors in total temperature measurement, special probe designs which are experimentally characterized are used. In this study, a validation case which is an experimental characterization of a specific class of total temperature probes is selected from the literature to develop a numerical conjugate heat transfer analysis methodology to study the total temperature probe flow field and solid temperature distribution. Validated conjugate heat transfer methodology is used to investigate flow structures inside and around the probe and effects of probe design parameters like the ratio between inlet and outlet hole areas and prob tip geometry on measurement accuracy. Lastly, a thermal model is constructed to account for errors in total temperature measurement for a specific class of probes in different operating conditions. Outcomes of this work can guide experimentalists to design a very accurate total temperature probe and quantify the possible error for their specific case.

Keywords: conjugate heat transfer, recovery factor, thermocouples, total temperature probes

Procedia PDF Downloads 133

Authors: İsmail Çeli̇k, Gülgün Ayhan-Kılcıgi̇l, Arzu Onay-Beşi̇kçi̇

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In this study, some 2-(2-phenyl/substitutedphenyl)- lH-benzo[d]'imidazol-l-yl)-N'-(alkylthiosemicarbazide were designed and prepared. Firstly, 2-phenyl/ suhstitutedphenyl-lH-Benzo[d]imidazole was prepared via oxidative condensation of o-phenylenediamine, benzaldehyde and sodium metabisulfite. Treatment of the benzimidazole compound with ethyl chloroacetate in KOH/DMSO gave the ester compound ethyl 2-(2-substitutedphenyl)-1H-benzo[d]imidazol-l-yl)acetate. Hydrazine hydrate and the ester in ethanol were refluxed for 4 h to give 2-(2-phenyl/substitutedphenyl)-1H-benzo[d]imidazol-l-yl)acetohydrazide. Thiosemicarbazides were obtained by condensing acyl hydrazide with the alkylisothiocyanate in ethanol. Following the structure elucidation, benzimidazole compounds were tested for their EGFR kinase inhibitory activities by using ADP-GloTM Kinase Assay.

Keywords: benzimidazole, EGFR kinase inhibitor, synthesis, thiosemicarbazide

Procedia PDF Downloads 257

Authors: Sana Mohammad Jafar

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Salmonella is one of the major causes of foodborne diseases throughout the world. Shrimp are an important commodity in world fishery trade. The microbiological quality of shrimp must be evaluated for assurance of shrimp. The aim of this study was to evaluate the microbiological quality and to determine the prevalence of Salmonella in shrimp sold in Khuzestan province. In this study, a total of 245 samples of shrimp sold in Khuzestan province were tested for Salmonella prevalence and total microbial population. The mean aerobic bacterial count in 50.2% of samples was 2200, in 29.8% of samples was 13,600, in 20% of samples was 36,700, and the mean aerobic bacterial count in the total samples was 20,000. (20,000 cfu/cc). Of the total samples, 33 samples were positive for Salmonella and the prevalence of Salmonella was determined 13.4%. These results indicate the possibility that shrimp contribute to foodborne infections. The improvement of shrimp quality is an important issue, and shrimp before consuming should be washed with water containing chlorine, with the aim of increasing safety. In addition, it should be avoided to eat shrimp as raw or not cooked properly.

Keywords: determination, total microbial, Salmonella, shrimp

Procedia PDF Downloads 240