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  • Open access
  • 91 Reads
Snail Deterrent Properties of a Soot based Flexible Superhydrophobic Surface
Snails enjoying eating the leaves of many garden plants and deterring this pest without resorting to chemicals can present a significant challenge. A previous report (PLoS ONE 7(5): e36983) suggested that loose soot was a surface to which snails found adhesion difficult. Soot may also be embedded into PDMS substrate making a flexible membrane with superhydrophobic properties (Appl. Phys. Lett. 102 (21) 214104). In this article we investigate if the embedded soot has the same anti-adhesive properties to snails as the loose soot, so giving the possibility of a facile method for protecting crops from this pest. Data is presented showing the force required to remove snails from the soot/PDMS surfaces using a simple spinning technique. The advancing an receding contact angles have also been measured for various concentrations of an anionic surfactant on the soot/PDMS surface and compared to the data presented in the PLoS ONE article. In addition, simple time lapse video demonstrations are presented that show the reluctance of the snails to move over the soot based surfaces suggesting that the soot/PDMS structure does indeed provide a level of deterrence to this garden pest.
  • Open access
  • 105 Reads
Propertiy Relationship in Organosilanes and Nanotubes filled Polypropylene Hybrid Composites
Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3% wt. filler with polypropylene (PP). Three compounds with different silanols groups were synthetized in different media trough a sol-gel process where the acetic acid, formic acid and ammonium hydroxide were the different catalysts used to develop such process. Besides, three different nanotubular structures were also used to analyze their behavior and compare it with the impact caused by the silanols groups. These nanotubes comprises: unmodified halloysite (HNT) and carbon nanotubes (CNT) as well as functionalized carbon nanotubes (CNTF). Morphological characterization in SEM and STEM/TEM show the dispersion in the PP matrix. According to TGA measurements CNTF is the composite with better thermal properties when all samples are compared. DSC measurements show the presence of two main peaks for all samples were temperatures of melting and crystallization remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples but with major impact for PP containing silanols groups synthetized in formic acid and the lowest improvement was achieved for sample containing the silanols groups synthetized in base media. The oxygen transmission rate increased for all samples with exception of samples containing HNT. Finally, rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanols groups and HNT when compared to neat PP.
  • Open access
  • 75 Reads
New Mixed Ligand Co(II) Complexes as Possible Electrolytes for Dye-Sensitezed Solar Cells - A Combined Experimental and Computational Approach
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We report the synthesis and characterization of a new series of mixed ligand Co(II) complexes, [Co(AA)(BB)2]X2, where AA and BB are derivatives of 1,10-phenanthroline and 2,2'-bipyridil, X=Cl-, TFSI- (TFSI= bis(trifluoromethanesulfonyl)imide), as possible redox electrolytes for dye-sensitized solar cells (DSSC).  Compared to the I3-/I- system, the cobalt(III/II) polypyridyl complex redox shuttles have low visible light absorption, and the ease of tuning their redox potentials is a very significant aspect for accomplishing a photovoltage enhancement.  In particular, our goal is to increase the open circuit voltage and the overall photovoltaic conversion efficiency of the device.  The synthetic strategy of such heteroleptic compounds is a challenge due to the tendency of the Co(II) ion to form tris chelates compounds or to disproportionate and  includes in the first step the synthesis of [Co(AA)Cl2] and [Co(BB)2Cl2] complexes and then the addition of the second aromatic diamine and TFSI anion.  The compounds were characterized by spectral (IR and UV-VIS spectroscopy) and structural (X-ray diffraction and DFT calculation) analysis. We also performed molecular modeling of the complexes synthesized based on density functional theory (DFT) calculations.  The structures of all complexes with tris chelates and a pseudo-octahedral geometry were optimized for the low spin state, based on DFT calculations. The IR spectra were simulated using the B3LYP/ECP-LANL2-DZ method.  Optical absorption spectra of all complexes were simulated using the TD-DFT method, both in vacuum and in acetonitrile solvent.  DFT simulated optical and vibration spectra compare well with the experimental data, allowing for a reliable assignment of the various transitions.
  • Open access
  • 59 Reads
Cellulose@Fe2O3-SO3H: A Novel Magnetic Composite Nanomaterial for the Synthesis of Chromene Derivatives
Magnetic nanocomposites are one of the best catalysts for organic reaction beacause of their simple recoverable features. We can simply recover these catalysts from reaction pot with one external magnetic field. A possible method simple separation and recycling of the catalysts is immobilizing catalytically active species in the surface of magnetic particles which can be separated from the reaction system by applying an appropriate magnetic field. Cellulose, as an important and naturally abundant biopolymer, can be easily functionalized with various organic groups for desired purposes like applications as a support for heterogeneous catalysis, composites matrixes and immobilization processes. In this study, we have prepared a biopolymer-based magnetic nanocomposite via in situ synthesis of maghemite (gamma-Fe2O3) on cellulose and then its sulfonation. It has been proven that sulfonated catalyst shows very good activities for one-pot three-component synthesis of chromenes under mild reaction conditions. In general this catalyst is recoverable, green, easy separation because of its magnetic feature, environmentally friendly properties and good yield and low reaction time for this multicomponent reaction as a very good strategy for the synthesis of medicinal and pharmaceutical compounds.
  • Open access
  • 69 Reads
Magnetic Hybrid Iron Oxide-Based Composite Nanocatalyst for the Synthesis of Polyhydroquinolines U Solvent-Free Conditions at Room Temperature
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Nowadays, simple separation and recycling of the catalysts are essential steps in catalytic technology and frequently affect the overall process economy. A possible method is immobilizing catalytically active species in the surface of magnetic particles which can be separated and recovered from the reaction system by applying an appropriate magnetic field. In general, in order to prevent direct contact between magnetite nanoparticles and also provide a chemically inert surface for modification of magnetite nanoparticles, coating of the surface with silica shell is necessary. Silica surface can be easily functionalized with various organic groups for desired purposes such as applications as adsorbent, catalysis support and enzyme immobilization. Polyhydroquinoline (PHQ) derivatives contain a large family of medicinally important compounds that have attracted much attention because of their diverse pharmacological and therapeutic properties. In this work, a magnetic dichromate hybrid with triphenylphosphine surface modified iron oxide nanoparticles as a recoverable and efficient composite nanocatalyst is prepared and applied for the synthesis of polyhydroquinolines under solvent-free conditions at room temperature. This research can be classified as a green approach for efficient and rapid synthesis of biologically active substituted polyhydroquinoline derivatives by using a recyclable nanocatalyst under mild reaction conditions. In comparison with other classical reactions, this method consistently has the advantages of short reaction times, little catalyst loading, high yields, easy magnetic separation and reusability of the catalyst.
  • Open access
  • 114 Reads
Electrically Conductive Polyacrylamide-Polyaniline Superabsorbing Polymer Hydrogels
This paper reports two-steps methodology for preparation of three-dimensional (3D) network supercapacitor made from superabsorbing polyacrylamide (PAM) as 3D hydrogel host matrix and polyaniline (PAN) as inherently conductive polymer. In the first step, polyacrylamide hydrogels were prepared with high water swelling capacity (≈ 500 g water/g PAM).  In the second step, polyaniline was coated on the surface of the PAM hydrogels with simple oxidative polymerization procedure. PAM hydrogels were either fully or partially coated (≈ 2 mm coating thickness). The prepared conductive hydrogels exhibited electrical resistance in the range of 100-1000 Ohm/Sq., depending on the employed doping electrolyte. The conductive hydrogels will be utilized and tested as conductive electrodes for supercapacitor applications.
  • Open access
  • 76 Reads
Characterization of FeCo based catalyst for ammonia decomposition
Catalytic ammonia decomposition was studied  in order to obtain pure hydrogen for fuel cells, free of  COx that are being formed during reforming of hydrocarbons and alcohols. In comparison with hydrogen, ammonia is easy to store and transport, because it is liquid at the temperature of 25 °C under the pressure of 8 atm. In the presented studies a catalytic decomposition of ammonia over fused iron-cobalt catalysts was examined. Catalysts were prepared by alloying iron oxides with an addition of cobalt(II) oxide and promoters (Al2O3, CaO i K2O). Catalysts with various contents of potassium oxide were tested. Chemical composition of the prepared catalysts were determined with an aid of XRF method, whereas phase compositions of the catalysts were established with XRD method. Also the catalysts were characterized by programmed temperature techniques: H2-TPD, TPR. Measurements of the catalysts activity in the ammonia decomposition reaction were carried out in a differential reactor, which enabled to record mass changes and analyze the gas phase. Ammonia decomposition ran at an ambient pressure in the temperature range from 475 to 600oC. In the inlet of the reactor ammonia concentration from 5 to 100 %vol. were tested. On the basis of the analysis of gas sampled from the space above the catalyst bed, nitriding potential P=pNH3/pH23/2 and an ammonia decomposition rate r[mol/gcat ∙s] were calculated. An addition of potassium oxide into iron fused catalysts develops  their specific surface areas. An increase in potassium oxide content in the tested catalysts had a beneficial impact on their activity in the ammonia decomposition reaction.
  • Open access
  • 79 Reads
Rhodium Adsorption on Valonea Resol Polymer
A new adsorbent resin has been developed by immobilizing tannin acid with formaldehyde, and its adsorption properties to Rh3+ were investigated. Linear and nonlinear regression procedures have been applied to the Langmuir, Freundlich, Tempkin, Dubinin–Radushkevich, and Redlich-Peterson isotherms The resin exhibited good adsorption capacity towards Rh3+ from acidic aqueous solutions ([H+] = 1 M, [Cl-] = 10-3 M), which the equilibrium adsorption capacity was high up to 96,69 mg g−1 at 293 K. The adsorption isotherms could be well described by Langmiur equation. The experimental studies suggested that tannin formaldehyde resin was effective for the adsorption of Rh3+ from chloride acid solutions, and the loaded Rh3+ could be easily desorbed by 1 M HNO3 + 0,1 M NaClO3 solution mixture with hundred percent efficiency. Thermodynamic parameters such as the entropy change, enthalpy change and Gibb's free energy change were calculated. The adsorption of Rh3+ was an endothermic adsorption process. This suggested that the resin can be used as an active biosorbent for the recovery of Rh3+ from 1 M concentrated acidic solution.
  • Open access
  • 67 Reads
The Nanostructuring of the Functional Surface of the Oil Pipelines
The current state of oil pipelines is characterized by decrease of operational reliability and efficiency which are caused by intensive   corrosion processes and accumulation of asphaltens-resinous-wax formations on internal surfaces. Formation of accumulations    is the reason of essential increase in hydraulic resistance of pipeline. The most suitable way for decrease of hydraulic resistance of oil pipelines is the modifying of internal surfaces at the expense of formation of molecular fluorine SAS layers. Nano-structural modification of internal surfaces is carried out at the expense of the focused adsorption of fluorine SAS molecules from the transported environment and formation so-called «a paling of Lengmjura». It is established that updating of internal surfaces of the pipeline at the expense of formation on them of molecular fluorine SAS layers leads to reduction of their hydraulic resistance on 30 ÷ 23 %. Molecular fluorine SAS layers, generated on a metal surface, considerably improves its hydraulic characteristics without dependence from roughness size. This peculiarity of molecular fluorine SAS layers allows not only to restore hydraulic resistance of the oil pipelines which have grown during of operating process,   but also to improve their initial hydraulic characteristics. Characteristics of interaction of a stream of oil and an internal surface are optimized by nano-structural processing. The given technology allows to lower hydraulic resistance by changing the roughness of the internal surface of the pipeline, to lower power expenses for transportation of hydrocarbons raw materials, to raise operational reliability and to extend the between-repairs period.
  • Open access
  • 82 Reads
Synthesis of Dihydroquinazolinone Derivatives Using Fe3O4@GO as an Efficient and Reusable Composite Nanocatalyst
Metal nanoparticles, due to their unusual properties especially the high surface-to-volume ratio than bulk metal has recently become the focus of intense work. Physical and chemical properties of the particles differ considerably differ from those of the compact solids. On the other hand quinazolinone derivatives are fused organic aza-heterocyclic compounds which have attracted considerable attention, because they exhibits a wide range of biological properties such as anti-cancer, anti-inflammatory, anti-convulsant and anti-hypertensive activities. In view of the biological importance of quinazoline and its derivatives, several synthetic strategies have been employed including the reactions of anthranilamide with aldehyde derivatives using acids catalyst. In this research, we have used composite metal-graphene-based nanocatalyst to produce different derivatives of dihydroquinazolines in mild reaction conditions and with easy, simple and economical work-up procedure in good-to-high yields. Also the catalysts could be recycled and reused several times without considerable reduction in its activity.
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