Showing papers in "International Journal of Chemistry in 2012"

Synthesis of 4,4’-(Arylmethylene)bis(1H-pyrazol-5-ols) Using Silica-bonded Ionic Liquid as Recyclable Catalyst

Abstract: N -(3-Silicapropyl)- N -methyl imidazolium hydrogen sulfate ([Sipmim]HSO 4 ) is prepared and employed as a recyclable catalyst for the synthesis of 4,4’-(arylmethylene)bis(1 H -pyrazol-5-ols) from aromatic aldehydes with 3-methyl-l-phenyl-5-pyrazolone in refluxing ethanol. [Sipmim]HSO 4 could be recycled for several times without any additional treatment.

Microwave Assisted Reactions in Organic Chemistry: A Review of Recent Advances

Abstract: Revolution in organic compound synthesis has been promoted by microwave assisted organic syntheses (MAOS) by which small molecules are built up into large polymers in a fraction of time. The need for different organic compound libraries for drug discovery, biomaterial development, automated library screening; proteomics etc has supported the emergence of innovative technologies for rapid combinatorial organic synthesis using MAOS synthesis. In previous reviews on this subject the focus of MAOS has been on the process of MAOS reactions rather than the importance given to the related applications. This review focuses on solid-phase synthesis, biopolymer synthesis, applications in proteomics, parallel processing in microwave reactors and automated library generation by means of sequential microwave irradiation methods. This article has discussed the different applications of Microwave assisted synthesis of organic polymeric compounds most thoroughly by focusing on aspects of speed, reproducibility and scalability. From this review it is clearly identified that independent on the type of organic material, data consistently points out to MW as a novel and powerful tool which has enable synthesis of a number of new compounds and presents the need for future research in this area.

Chemical Kinetics for Synthesis of Triacetin from Biodiesel Byproduct

Abstract: The reaction kinetic of the glycerol acetylation with acetic acid catalyzed by sulfuric acid has been studied in the frame of continuous triacetin production. Glycerol, acetic acid and sulfuric acid catalyst were reacted in a batch reactor, in order to get reaction kinetics data. The mole ratio of catalyst to glycerol and temperature were studied during the experience. This study concluded that the selectivity of triacetin increased with increase in mole ratio of catalyst to glycerol. Increasing temperatures lead to increase selectivity of triacetin. It will decreased at the time of acetic acid has begun to evaporate. Triacetin synthesis is an exothermic reaction, a higher reaction temperature will cause in shifting the balance toward formation of reactants. This needs to be anticipated by taking one of the products so that the equilibrium shifting toward product formation.

Obtaining Some Polymer Composites Filled with Rice Husks Ash-A Review

Abstract: Rice husks are an important by-product of rice milling process and are major waste product of the agricultural industry. Rice husk contain nearly 20 mass% silica, which is present in hydrated amorphous form. They have now become a great source as a raw biomass material for manufacturing of value-added silicon composite products, including silicon carbide, silicon nitride, silicon tetrachloride, magnesium silicide, pure silicon, zeolite, fillers of rubber and plastic composites, cement, adsorbent and support of heterogeneous catalysts. The rice husk was subjected to pyrolysis in fluidized-bed pilot plant in air or nitrogen atmosphere. The controlled thermal degradation of the rice husks in air or nitrogen leads to production of white rice husks ash (WRHA) and black rice husks ash (BRHA) respectively. WRHA contains almost pure (95mass %) silica in a hydrated amorphous form, similar to silica gel, with high porosity and reactive surface OH groups. BRHA contains different amounts of carbon and silica in amorphous form with high specific surface area and porosity. The raw rice husks and the obtained pyrolysis products were used as fillers of polypropylene (PP) and tetrafluoroethylene-ethylene copolymer (TFE-E) composites. The kinetics and thermodynamics of water adsorption onto filled polypropylene composites during soaking were studied at different temperatures, quantities and nature of fillers. It was established, that the adsorption kinetics was limited by intra-particle diffusion in plane sheet particles. The sorption process is exothermal in nature and accompanied with decrease of the entropy. The physicomechanical properties of composite materials were determined. The fillers introduced in polypropylene change the mechanical strength and make the composites brittle. This change is more pronounced for the composites with BRHA and RRH, followed by WRHA. The composites studied showed lower elongation at break. The biggest decrease was observed for the composites with BRHA where e decrease from 500 (for the initial PP) to 7 % at filling degree of 20 mass %. The effects of the amount of adsorbed water, temperature and treatment time on the composites tensile properties were estimated. It was found after immersion in water that the composites improve their tensile strength compared to initial non-treated samples. The thermal stability and kinetics of non-isothermal degradation of PP and TFE-E composites filled with 10 or 20 mass % vigorously grounded and mixed RRH, BRHA, WRHA and Aerosil Degussa (AR) were studied. Using different calculation procedures the most probably kinetic mechanism was found to be described by kinetic equations of n -th order (Fn mechanism). The kinetic parameters were obtained, and a linear dependence between ln A and E was observed, known also as kinetic compensation effect. The abundance of a waste from paddy milling industry, as well as its interesting complex of behaviors are prerequisite for success for obtaining of cheap and valuable products and gives a new alternatives for its applications. The production of value added materials from rice husks not only facilitates utilization of an abundantly available agro waste, but also reduces the environmental pollution and solves a serious ecological problem.

Studies on the Gelatinization Temperature of Some Cereal Starches

Abstract: Gelatinization temperature of starches from different varieties of cereals, deep-red sorghum, red sorghum, white sorghum, mixed sorghum, white fonio (Digitaria exilis), black fonio (Digitaria iburua), Eleusine coracana (tamba), proso millet (p. miliacium), brown top millet (p. ramosum) and finger millet (Eleusine coracana) were determined by electrical conductivity (EC) method. Among the untreated starches, the results showed that tamba recorded the least onset and peak gelatinization temperatures of 53.0 o C and 63.0 o C respectively while the highest onset gelatinization temperature, 76 o C was recorded with proso millet. Proso millet and finger millet had the highest peak gelatinization temperature. deep-red sorghum and red sorghum had the least end gelatinization temperature while proso millet recorded the highest value. The 0.1MKCl treatment of cereals starches produced elevated onset gelatinization temperatures (62.0-78.0 o C). Mixed sorghum had the least onset gelatinization temperature while proso millet and finger millet recorded the highest gelatinization temperature. Following the 0.1MKCl treatment, starches from tamba and proso millet recorded the least and highest peak gelatinization temperatures respectively. Deep-red and red sorghum recorded the least end gelatinization temperatures while proso millet, brown top millet and finger millet recorded the highest end gelatinization temperatures. The treatment of the cereals starches with 0.10MKCl significantly (p < 0.05) delayed the onset gelatinization temperature of the starches and narrowed the gelatinization temperature range. The results of the conductivity of both the 0.1MKCl treated and untreated starch showed nonlinearity within the gelatinization range. This finding has important implication on the energy and time requirement to gelatinize the starch for specific industrial use.

Spatial and Temporal Distribution of Nitrate Pollution in Groundwater of Abuja, Nigeria

Abstract: Groundwater has been recognized as playing a very important role in the development of Abuja, Nigeria’s Capital as many households, private and government establishments depends solely on hand-dug wells and boreholes for their daily water needs. Exploitation of groundwater is rather delicate because of its potency to contamination and difficulty to remediate when compared to surface water. The purpose of this paper is to present the occurrence of nitrate in groundwater of Abuja and discuss the implication and sources of the nitrate. High nitrate level in drinking water leads to infant methaemoglobinaemia (blue-baby syndrome), gastric cancer, metabolic disorder and livestock poisoning. A simplified map of nitrate occurrences in Abuja indicates that some areas have nitrate concentration above the WHO and NSDWQ guide limit of 50 mg/l and it is dominant in the rainy season than dry season. The number of people drinking water with nitrate concentration above the permissible level cannot be quantified presently. The sources of nitrate in the groundwater were attributed to bedrock dissolution in the course of groundwater migration and more importantly anthropogenic activities such as on-site sanitation, waste dumpsites and agricultural chemicals. Water treatment by bio-denitrification and nitrate pollution control programs should be introduced at local, state and federal levels in order to educate people on the need to protect groundwater from nitrate pollution caused by agricultural activity and indiscriminate disposal of wastes.

A Simple and Efficient Green Method for the Deprotection of N-Boc in Various Structurally Diverse Amines under Water-mediated Catalyst-free Conditions

Abstract: A simple, efficient and eco-friendly protocol has been developed for the deprotection of N-Boc on structurally diverse amines. Selective removal of N-Boc groups was achieved with excellent yields using water around reflux temperatures. In the absence of any additional reagents, this method represents a reasonable alternative to previously reported deprotection procedures.

Removal of Zn(II) from Aqueous Acetate Solution Using Di (2-Ethylhexyl) Phosphoric Acid & Tributylphosphate

Abstract: The extraction of Zinc (II) in acetate medium with di (2-ethylhexyl) phosphoric acid (D2EHPA) in chloroform diluent was investigated under different experimental conditions, in order to have a better understanding of the extraction mechanism. The extraction yield was found to depend on the concentrations of Zinc (II) and D2EHPA, and the equilibrium pH. The effects of acetic acid and the salting-out agent were also studied. The nature of the extracted species was investigated by the slope analysis method. Graphs of log D vs. log [D2EHPA] and log D vs. pH were plotted for Zn (II), and the species extracted into the organic phase was found to have the composition (ZnCH3COO)R.HR. The best performance was reached (80%) with zinc concentrations lower than 5 mM in a neutral medium. The extraction yield of metals decreased as the acetic acid concentration increased with any given extractant concentration. The addition of sodium acetate to the aqueous phase strongly increased the zinc extraction yield (99.5%). A synergistic effect was observed by the addition of tributhylphosphate (TBP) with the organic phase.

Phytoremediation of Cd2+ by Marine Phytoplanktons, Tetracelmis chuii and Chaetoceros calcitrans

Abstract: The use of marine phytoplankton, Tetracelmis chuii and Chaetoceros calcitrans as phytoremediator has already been reported. However their use as phytoremediator on the cadmium polluted marine has not yet well understood. Therefore, this study was conducted to evaluate the influence of the Cd2+ concentration, interacting time, and medium pH on accumulation of Cd2+ in the phytoplankton. Methods of analysis and data collection were carried out on 1) the growth rate, the number of phytoplankton cells, and the content of chlorophyl-A; 2) the Cd2+ concentration in phytoplankton at various interacting times and medium pHs; and 3) infrared spectra of phytoplankton biomasses before and after interaction with Cd2+. The growth of phytoplankton and the content of chlorophyl-A after the addition of Cd2+ into the T. Chuii medium decreased, while that after the addition of Cd2+ into the C. Calcitrans medium increased. The optimum accumulation occurred after 15 min at the pH of 8, i.e. 13.46 mg Cd2+ per g T. Chuii and 1055.27 mg per g C. Calcitrans. The functional groups of T. chuii involved in the bioaccumulation of Cd2+ are OH, -CN, S=O, N-O, S-S and M-S, while that of C. Calcitrans are OH, C=O, S-S, M-S and C=C.

A Laborsaving, Timesaving, and More Reliable Strategy for Separation of Low-Molecular-Mass Phosphoproteins in Phos-tag Affinity Electrophoresis

Abstract: Reversible phosphorylation is a key signaling mechanism for modulating the functional properties of proteins involved in numerous cellular events. Abnormal protein phosphorylation causes many human diseases. Experimental procedures for the determination of the phosphorylation status of certain proteins are therefore very important in relation to studies on a diverse range of physiological and pathological processes. We have previously reported a novel phosphate-affinity sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) technique using a dizinc(II) complex of the phosphate-binding ligand Phos-tag in conjunction with a neutral-pH gel system to detect shifts in the mobilities of phosphoproteins (Zn 2+ –Phos-tag SDS-PAGE). However, this handmade gel-based procedure is often laborious and time-consuming to perform, and requires a skillful analyst. More recently, SuperSep Phos-tag precast gel has been developed on the basis of the Zn 2+ –Phos-tag SDS-PAGE methodology. This novel ready-to-use system employs a neutral-pH gel containing 12.5% (w/v) polyacrylamide and the immobilized Zn 2+ –Phos-tag (50 µM), which is generally used in conjunction with a Tris–glycine-based electrophoretic running buffer. We examined the potential usage of a Tris–N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine (Tris–Tricine) buffer as an alternative running buffer for the SuperSep Phos-tag precast gel system in the analysis of low-molecular-mass phosphoproteins. Compared with Tris–glycine, the Tris–Tricine running buffer improved the resolution of 8.8-35 kDa phosphoproteins and phosphopeptides. We can therefore provide a laborsaving, timesaving, and more reliable strategy for separation of low-molecular-mass phosphoproteins in Phos-tag affinity electrophoresis.

Assessment of Physico-chemical Status of Groundwater Samples of Dholpur District, Rajasthan, India

Abstract: In the present study efforts has been made to assess the extent of water pollution due to the excess use of fertilizers and pesticides in agriculture and its impact on ground water quality of three different dug wells in Dholpur district of Rajasthan, India. The different Physico chemical parameters like pH, Temperature, TDS, Conductivity, Nitrate, Sulphate, Dissolved oxygen Hardness, sodium, Potassium, Chlorides and chemical oxygen Demand were determined. The present study reveals that water quality of the selected sampling station is within the limit prescribed by WHO and can be used for domestic purpose.

Structural and Antimicrobial Studies of Coordination Compounds of Phenylalanine and Glycine

Abstract: Coordination compounds of glycine and phenylalanine were synthesized, characterized using electronic and infrared spectroscopy, magnetic susceptibility measurement and mass spectrometry. The ligands coordinated to the metal in a bidentate fashion using N and O donor atoms. Square planar geometry is proposed for the Mn(II), Co(II), Ni(II) and Cu(II) complexes based on the results obtained from their characterization. Tetrahedral geometry is however proposed the Cd(II) complexes. The in-vitro biological effect of the synthesized compounds was investigated. The compounds were tested against three gram-negative bacteria, E.coli, P. aeruginosa, P. vulgaris, three gram positive bactria, S. aureus, B. subtilis, MRSA and a fungus C. Albicans. A comparative study of the zones of inhibition observed for the ligand and coordinated synthesized compounds indicated that the synthesized compounds, in some cases, showed higher zones of inhibition than that of the free ligands. It is therefore suggested that increasing the number of chelate rings may increase the lipophilicity of the coordinated complex and therefore its antimicrobial activity.

Preparation and Voltammetric Study of a Composite Titanium Phosphate/Nickel Hexacyanoferrate and Its Application in Dipyrone Determination

Abstract: This paper describes the preparation, characterization and electroanalytical application of a composite consisting of titanium phosphate modified with nickel hexacyanoferrate. Titanium phosphate (TiPh) was formed from the reaction of titanium isopropoxide with H3PO4 and deionized water. Next, the reaction of TiPh was performed with a metal ion (Ni+2) and potassium Hexacyanoferrate, designated as TiPhNIHCF. Spectroscopic techniques such as vibrational spectroscopy, X-ray diffraction (XRD), diffuse reflectance and cyclic voltammetry were used to characterize the TiPh and TiPhNiHCF. The graphite paste electrode containing TiPhNiHCF exhibited a redox couple with average potential (Eq’) of 0.61V vs Ag/AgCl (KNO3 1.0 mol L-1; v = 20 mV s-1) attributed to redox process FeII(CN)6/FeIII(CN)6. The redox couple presents a sensitive response for determining dipyrone. The system showed a detection limit of 3.75 x 10-4 mol L-1 and standard deviation of 1.8 % for n = 3, with an amperometric sensitivity of 34.84 mA / mol L-1. The modified electrode was electrochemically stable and showed good reproducibility.

Analysis of the Essential Oils of Leaves and Stems of Crassocephalum crepidioides Growing in South Western Nigeria

Abstract: The essential oils from fresh leaves and stems of Crassocephalum crepidioides (Asteraceae) growing wild in south western Nigeria and used as food supplement by the local population were extracted. The essential oils were extracted using Clevenger- type hydrodistiller and analysed by GC- MS. The percentage yields of oils were 0.12 %v/w and 0.09 %v/w, respectively. The essential oils of the leaves contained alpha-caryophyllene (10.29 %), beta-cubebene (13.77 %) and alpha-farnesene (13.27 %) as major constituents while the dominant constituents of the stems oil were thymol (43.93 %), alpha-caryophyllene (15.16 %) and 4-cyclohexybutyramide (20.94 %).

A Simple Preparation Process of Pure Mn3-xCoxO4 (x = 1, 1.5 and 2) Desert Rose-Like Nanoparticles and Their Optical Properties

Abstract: Monodisperse CoMn2O4, Co15Mn15O4 and Co2MnO4 nanoparticles were prepared by a rapid and low cost method The organic and complex dispersing agent free synthesis of stable colloidal suspensions containing pure nanoparticles of spinel oxides was optimized at low temperature (T<100 °C) The key point of the synthesis is the fast introduction of the precursor solution into a much larger volume of alkaline solution buffered with LiOH XRD, SEM-FEG and HRTEM performed on desert rose-like nanoparticles showed that nanoparticles are crystallized and of uniform shape/size distributions Thermogravimetric analyses give an insight into the sample composition of nanopowders in relation with semiconductor ceramic counterparts The UV-Vis absorption spectra of these pure spinel oxide nanoparticles in solution are discussed

Adsorption of reactive dye by a novel activated carbon prepared from thevetia peruviana

Abstract: This investigation was to evaluate the adsorption capability of activated carbon prepared from Thevetia Peruviana wood for removal of reactivetextile dye (RO4) from aqueous solution. Batch adsorption experiments were performed as a function of initial dye concentration, contact time,temperature and pH. The amount of dye adsorbed increased while increasing the initial concentration and temperature of the solution. Theexperimental data fitted well to Pseudo second order kinetic model with Intra particle diffusion as the rate determining step. Adsorption data fittedwith Langmuir model. The negative value of Gibb’s free energy (∆G°) indicated that the adsorption was spontaneous in nature. The results showedthat the activated carbon of Thevetia Peruviana was suitable for the removal of the reactive dyes from the aqueous solutions. The positive value ofenthalpy (∆H° ) indicated that the adsorption of the selected dyes were endothermic.

Mercury(II) Selective Membrane Electrode Based on Calix[2]thieno[2]pyrrole

Abstract: The construction, performance, and applications of mercury(II) ion selective electrode based on calix[2]thieno[2]pyrrole receptor are described. The influences of membrane composition and pH on the potentiometric response of the electrode were investigated. The electrode exhibits Nernstian response (27.8 mV per decade) for Hg2+ ion over a wide concentration range (1.0 x 10-6 to 1 x 10-2 M). The response time of the electrodes is 20 s for the solution of Hg2+ ions in the concentration range of 1 x 10-6 – 1 x 10-2 M. The selectivity coefficient values showed better sensitivity and selectivity of this sensor for mercury(II) ions over various mono-, di, and trivalent cations studied. The sensor was also applied as indicator electrode in the potentiometric titrations.

UV-Irradiation Effect on the Photodegradation of Plasticized Poly (Ortho, Meta, and Para-Fluorostyrene) Isomers in Solid Films

Abstract: The photostability of thin films of poly (Fluorostyrene) isomers was studied by irradiation with UV-light, in presence of air at room temperature. The irradiated polymer films were exposed to different intervals of time and the degradation process was investigated with absorption, fluorescence and FT-IR spectroscopic methods. The influence of phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated. Blending with these plasticizers was found to decrease the stability of the irradiated polymers. The same observation was noticed in the photodegradation of other substituted polystyrenes films. The intensity of absorption was also found to increase with time of irradiation and in the intensity of a new absorption band at longer wavelength. In addition the formation on new fluorescence band at longer wavelength for the irradiated film is an evidence of photodegradation of the irradiated polymer films. The FT-IR spectra of irradiated polymers and for blended polymer films with phthalates and terephthalate, showed an increase in the absorption bands of these isomers indicating the possibility of degradation. The mechanism of photodegradation of these isomers was found to be similar to that of polystyrene. The order of photostability of these isomers was found that poly ( p -fluorostyrene) is the most stable isomer and, poly ( o -fluorostyrene) is the lowest stable isomer towards irradiation effect.

Heavy metal and nutrient loading of river rwizi by effluents from mbarara municipality, western uganda

Abstract: This study, carried out in the wet annual April seasons during the period 2010-2011, was geared towards the quantification of heavy metal and nutrient levels in the surface water of River Rwizi, the main Mbarara municipal drainage system. The effect of Mbarara municipal effluents on heavy metal and nutrient (phosphate, nitrite, nitrate and ammonium) loading of River Rwizi was investigated along with the changes in some basic water quality parameters, i.e., pH, conductivity and hardness. The filtered water samples were digested with a perchloric acid/nitric acid/hydrochloric acid mixture. Total heavy metals Cu, Zn, Cd and Pb were determined by flame atomic absorption spectrophotometry. Nutrients were determined by standard Wagtech methods. The results showed that there was a significant difference in concentration of lead (p = 0.047) and zinc (p = 0.018) between 2010 and 2011, with average concentrations being higher downstream. The concentrations of lead and cadmium were much higher than the WHO guideline values in drinking water (0.01 μg ml -1 and 0.003 μg ml -1 , respectively). There was no significant difference in concentration of cadmium in 2010 along River Rwizi around Mbarara Township (p = 0.180). Nutrient loading in the domestic water source also indicated a gradual annual increase - hence a call for early pollution control measures by the relevant authorities.

Phytochemical Screening and Anti-Microbial Activity Studies of the Root Extract of Anthocleista Djalonensis (Cabbage Tree)

Abstract: The phytochemical screening of the root extract of Anthocleista djalonensis were carried out and indicated the presence of saponins, flavonoids, tannins, reducing sugar, steroids, phlobatanins, volatile oils and alkaloids which are active components present in the plant that makes it medicinal. 44.0 g of the powdered plant root extract using hexane gave a yield of 9.6 %, 39.77 g extract using methanol gave a 27.3 % yield, 28.9 g extracted using chloroform gave a yield of 11.2%. The thin layer chromatographic analyses carried out showed that two components separated from the hexane extract, two from chloroform extract, and one from methanol extract using the solvent mixture of ethanol/benzene/chloroform (1:1:3), ethanol/benzene (2:1), ethyl acetate/chloroform /petroleum ether (4:4:3). The anti microbial activity studies carried out showed that the plant extract is an antibacterial agent. It showed sensitivity towards disease causing organisms like Escherichia coli, Salmonella typhill and Staphylococci. This result reveals more on the the use of the plant Anthocleista djalonensis for herbal medicine.

Kinetics and Mechanism of Non-Isothermal Decomposition of Ca(II)-, Sr(II)- and Ba (II)- Cross-Linked Divalent Metal-Alginate Complexes

Abstract: The kinetics of thermal decomposition of Ca(II)-, Sr(II)- and Ba(II)- cross-linked metal–alginate biopolymeric complexes as biocatalysts have been studied using thermogravimetric (TG) and differential thermogravimetric (DTG) techniques in static air. The TG curves showed three stages of weight loss, whereas the DTG indicated the presence of a series of thermal peaks associated with the TG curves. The thermal dehydration of the coordinated water molecules was found to occur in the first stage, followed by decomposition of the formed dehydrated complexes through the other following stages. The second stage was corresponding to the formation of oxalates as intermediate fragments, whereas the third stage indicated the formation of metal oxides as final product of such decomposition. The kinetic parameters were computed by different models and tentative decomposition mechanism is discussed.

Catalytic pyrolysis of dairy industrial waste ldpe film into fuel

Abstract: Disposal of commonly used plastic wastes to landfill was becoming more undesirable due to environmental concerns, rising costs and poor biodegradability. Therefore, recycling through mechanical or chemical method seems to be the only route of plastic waste management. Polyfilms, mainly Low Density Poly-Ethylene (LDPE) is a major type of thermoplastic used for packing milk throughout India. In the present investigation the recycling dairy waste LDPE film is examined via catalytic pyrolysis. Pyrolysis of LDPE was investigated with the use of catalyst, NiMo/Al2O3. Experiments were carried out in a laboratory conditions. High yields of liquid fraction in the boiling range of 65-380°C and gases were obtained along with a small amount of coke. The liquid and gaseous products were analyzed using Gas Chromatograph Mass Spectrometer (GC MS) and Gas Chromatograph (GC) respectively. It is found that the derived liquid products were hydrocarbons, consist of alkanes and alkenes. The pyrolysis liquid has a calorific value 10810 Cal g-1, ash content 0.02%, relative density 0.876, flash point greater than 45°C and sulphur content of 0.083%. The liquid can be used as a feed stock in the steam boiler.

Colorimetric Detection of Copper (II) Based on the Self-Assembly of Schiff’s Base-Functionalized Gold Nanoparticles

Abstract: A simple and highly selective colorimetric sensor for Cu2+ is fabricated in this work based on the Cu2+-induced self-aggregation of gold nanoparticles (GNPs). In this new design, GNPs are first functionalized with cysteamine molecules on their surface through the well-known strong Au-S interaction. Then salicylaldehyde is introduced to link with the cysteamine through a simple Schiff’s base reaction. Since the Schiff’s bases formed on the GNPs surface may serve as efficient and selective complexing reagents for Cu2+, Cu2+ can specifically react with the Schiff’s base complexes and thus result in the self-assembly of GNPs accompanied with color changes. Therefore, a facile and low-cost colorimetric sensor for visual detection of Cu2+ was developed without requirement of any instrument.

Effect of Natural Products on the Corrosion of Titanium and Its Alloy in NaOH Solutions

Abstract: The corrosion behavior of pure titanium and Ti-6Al-4V alloy in different concentrations of NaOH was investigated by using different techniques. The effect of bovine serum albumin and egg albumin on corrosion behavior of pure titanium and Ti-6Al-4V alloy has been studied. It has been found that natural products such as (bovine serum albumin and egg albumin) inhibit the corrosion process of Ti-6Al-4V alloy more than pure titanium. The inhibition efficiency increases as the concentration of protein in the solution increases, as was confirmed by SEM.

Ionic-Interaction of Potassium Iodide in Edible Oils + DMF System by Viscosity Method

Abstract: Ionic-Interactions of Potassium Iodide (KI) in binary solvent systems of edible oil (maize oil and sunflower oil) + N, N-dimethylformamide (DMF) were studied at different temperatures by viscosity method. The viscosities of KI in sunflower oil + DMF and maize oil + DMF were found to increase with the increase in the concentration of edible oil and also with an increase in the concentration of KI from 1.0 x 10-2 to 9.0 x 10-2 mol.dm-3. Ion-ion interaction and ion-solvent interaction were evaluated in terms of A and B coefficients of the Jones-Dole equation and its applicability checked by Moulik equation. Ion-solvent interaction was found positive in the edible oil + DMF solvent system. The parameter dB/dT was used as a criterion for the evaluation of structure-making or the structure-breaking ability of salt (KI) in the edible oil + DMF solvent system. It was concluded that KI behaves as a structure-breaker in edible oils + DMF solvent system.

Synthesis of New Derivatives of Heterocyclic Compounds Containing Pyridine, Pyrimidine and Triazole Ortho-Fused to Isoquinoline Moiety

Abstract: 4-Amino-9,10-dimethoxy-2-phenyl-6,7-dihydro-2(H)-pyrido[2,1-a]isoquinoline-1,3-dicarbonitrile derivatives 4a-c were obtained from the reaction of 6,7-dimethoxy-3,4-dihydroisoqinoline-1-acetonitrile 1 with arylidenemalononitrile 2a-c in boiling acetonitile in the presence of piperidine. The reaction of 4a-c with triethyl orthoformate in acetic anhydride at reflux give the ethoxymethyleneamino derivatives 5a-c. Compounds 5a-c were reacted with hydrazine hydrate and give the corresponding 4-amino-3-imino-2-aryl-3,4,8,9-tetrahydro-2(H)-pyrimido[5?,4?:5,6]pyrido[2,1-a]isoquinoline-1-carbonitrile derivatives 6a-c. Refluxing compound 6a in an excess of triethyl orthoformate give 7a. When compounds 6a-c were refluxed with acetic anhydride or benzoyl chloride in pyridine, they afford the corresponding 4-methyl and 4-phenyl derivatives 8a-c and 9a-c, respectively. Compound 6a was refluxed in diethyloxalate and give product 10. Also, the reaction of 6a with C-acylhydrazonoyl halides 13a,b in refluxing chloroform in the presence of triethylamine afford 14a,b. Correct elemental analyses and spectral data (IR, 1H NMR, 13C NMR and MS) confirm the structure of the synthesized compounds.

Medical Dressing Treated with Honey/Chitosan Microencapsules

Abstract: Wound normally left to dry and dressing keeps infections out as well as reducing the trauma. Advanced technology is used to reduce pain and fast healing with avoiding the deformation of the injured skin. In this work previously UV/ozone irradiated medical dressing samples were treated by honey capsulated in chitosan. Treatment conditions were optimized with respect to weight; air-permeability; whiteness; yellowness and antibacterial. All treated samples showed good antimicrobial performance with sufficient air permeability and weight. The sticky nature of the honey was avoided by formation of microencapsules. Treated gauze samples showed good performance for injured rates with no inflammation.

Molecular Dynamics Simulations on trans- and cis-Decalins: The Effect of Partial Atomic Charges and Adjustment of "Real Densities"

Abstract: A molecular dynamics (MD) simulation of the organic compounds trans- and cis-decalin is performed with the adjustment of their experimentally observed densities. For a trans-decalin model system, the energy and structural properties are studied for different atomic charge distributions. The relationship between the main interaction forces (Coulombic and van der Waals) of the trans- and cis-decalin systems has been examined, and the status of the molecular forces governing the nature of the processes in the crystal or liquid phases has been established. The obtained results on the density peculiarities are interpreted in terms of a non-uniform charge distribution and van der Waals forces efficiently inhibiting the electrostatic ones. Possible applications of the obtained MD simulations results in magnetic fluid physics are discussed.

Lipase Catalysed Kinetic Resolution of Stiripentol

Abstract: Kinetic resolution of rac-Stiripentol, catalysed by lipase A from Candida antarctica by esterification with vinyl butanoate was performed with an E-value of 24. This allowed isolation of (3S)-Stiripentol with an ee of 86 % and the corresponding (3R)-butanoate with an ee of 87 %. Enzymatic hydrolysis of the ester product gave (3R)-Stiripentol with 94 % ee.

SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF SUBSTITUTED p-AMINO AZOBENZENE WITH THYMOL MOIETY- A GREEN PROTOCOL

Abstract: As a part of systematic investigation of synthesis and antimicrobial activity of p-amino azobenzene with thymol moiety from different substitutedaromatic amines has been achieved by simple diazotization and coupling method. The synthesized compounds have been screened in vitro for theirantimicrobial activity against B. subtilis, S. aureus and E.coli. Some of the compounds displayed pronounced biological activity. The resultingproducts were characterized by IR, 1H NMR and Mass spectroscopic method.