Environmentally Benign Solution-Based Procedure for the Fabrication of Metal Oxide Coatings on Metallic Pigments

Aluminum pigments were coated with Fe₂O₃ and CuO by solution-based thermal decomposition of the urea nitrate compounds hexakisureairon(III)nitrate and tetrakisureacopper(II)nitrate. The deposition process was optimized to obtain homogeneously coated aluminum pigments. The growth of the surface coatings was controlled by investigation with scanning electron microscopy, energy dispersive X-ray spectroscopy and static light scattering as well as infrared, X-ray diffraction and thermogravimetric analysis. The iron precursor showed an incomplete decomposition in solution, incorporating traces of urea molecules inside the coatings while the copper precursor showed complete dissociation accompanied by in situ formation of amine complexes. The amount of organic residues resulting from ligand fragments in the final oxide coatings could be reduced to 22 % for the iron oxide and 12 % for the copper oxide by further temperature treatment in solution (259 °C). Colorimetric investigations of the obtained pigments revealed an excellent hiding power, outperforming the pigments used in current state-of-the-art formulations.     

Colorimetric Procedure for the Microdetermination of the Antibilharzial Drug Praziquantel and its Applications to Pharmaceutical Formulations

 A procedure for the colorimetric assay of praziquantel has been developed. The method is based on the formation of charge-transfer complexes with p-chloranil (I), dichloronitrophenol (II), 2,3-dichloro-5,6 dicyano-p-benzoquinone (III), 7,7,8,8-tetracyanoquinodimethane (IV) and tetracyanoethylene (V) as π-acceptors to give highly coloured species. The coloured products are measured spectrophotometrically at 550, 425, 460, 844 and 393 nm for I, II, III, IV and V, respectively. Optimization of the different reaction conditions is described. The colour system obeyed Beer’s law in non-aqueous media in the concentration range 2.0–48 μg ml⁻¹. It was stable for at least 4.0 h. The detection limit was found to be 0.6 μg ml⁻¹. Applications of the procedure to the analysis of various pharmaceutical samples gave reproducible and accurate results. Further, the validity of the procedure was confirmed by applying the standard addition technique. The total average recovery was 100.2%. Received June 10, 2000. Revision December 23, 2000.     

青铜表面GPTS/MTMS复合防蚀涂层的成分分析

利用缓蚀剂BTA及NBS等助剂改性的GPTS/MTMS复合材料,在青铜表面制成透明防蚀涂层,用XPS分析了涂层组成。结果表明,涂层主要由C、Si、O、N以及Cu元素组成,改性前后C、Si、O、N元素的价态不变,Cu元素以Cu2 形式存在,其含量在改性后有明显增加。     

Fluoropolymer Composite Materials and Protective Coatings for the Extreme Conditions of the Arctic Zone

Russian Journal of General Chemistry - Specific aspects of the use of radiation-synthesized tetrafluoroethylene telomers for creation of new fluoropolymer composite materials and protective...     

A Fiber Optode for p-Nitrophenol Based on Covalently Bound 9-Allylaminoacridine

 Using 9-allylaminoacridine synthesized in this laboratory as the fluorescent agent an fiber optode for p-nitrophenol (p-Np) has been prepared. 9-Allylaminoacridine has a polymerizable olefin unit and can be copolymerized with hydrophilic monomer 2-hydroxypropyl methacrylate (HPMA) under UV irradiation. On silanized activated glass surface a 9-allylaminoacridine containing HPMA membrane has been covalently bound forming a stable optode membrane free of leaching problem. The analytical performance characteristics including reversibility, reproducibility, short-term stability and interference have been evaluated. The optode has relatively long lifetime with the spectral response characteristics not changing after one month use. The plot of log(I ₀/I − 1) versus logarithm of the p-NP solution concentration can piecewise be fitted with the straight line of the form of Stern-Volmer equation, with a detection limit of 9.0 × 10⁻⁸ mol L⁻¹. The relative standard deviation obtained from eight separate determinations for two p-NP concentrations, 1.0 × 10⁻⁵ and 4.0 × 10⁻⁴ mol L⁻¹, are 2.36% and 1.34%, respectively. p-Np can be determined in water samples with satisfactory recoveries. Received April 13, 2000. Revision September 28, 2000.     

A Fiber Optic Biosensor for Uric Acid Based on Immobilized Enzymes

Abstract

A simplified enzyme based fiber optic uric acid biosensor is reported. It is constructed by coimmobilizing uricase and horseradish peroxidase [HRP] to bovine albumin via glutaraldehyde. A new fluorimetric substrate, thiamine, is used to indicate the sensing process. Under optimized conditions, the linear range of uric acid concentration is 0.5 to 5.0 ug/mL with a correlation coefficient of 0.997, and the detection limit is 0.15 ug/mL with excellent reversibility and stability. The sensor can be used at least two months at room temperature. It is possibly to determine uric acid directly in serum and urine samples with satisfactory results.     

A New Procedure for Voltammetric Lead Determination Based on Coprecipitation and Centrifugation Preconcentration

An arrangement of a voltammetric cell specially designed to be compatible to both centrifugation and voltammetry was designed, allowing direct measurement without any need for dissolution or filtration steps. The procedure for the preconcentration via coprecipitation is described. The system was succesfully tested using trace amounts of Pb(II) ions in aqueous solution preconcentrated with Al(OH)₃ as the carrier precipitate and resulting peak currents were found much higher than those without applying centrifugation. The effects of the parameters on the resulting signal were examined and the detection limit was found as 2.2×10^?9 M.     

A Bulk Acoustic Wave Viscosity Sensor for Determination of Lysozyme Based on Lysis of Micrococcus Lysodeikeicus

 A method for determination of lysozyme with a Bulk Acoustic Wave (BAW) viscosity sensor is presented. It is based on the bacteriolytic action of lysozyme on Micrococcus lysodeikeicus (M. lysodeikeicus) and the response of the sensor to the viscosity and density change of this process. There was a good correlation between the frequency shift and the concentration of lysozyme in the range 10–100 μg/ml. The content of lysozyme in human saliva was determined by this method and the results obtained were in good agreement with those from the conventional turbidimetric method. This method has an advantage over the conventional turbidimetric method in that the amount of sample needed is smaller, the procedure is simpler and the concentration range of the bacterium suspension which can be used in the detection was extended. Received September 11, 1998. Revision March 15, 1999.     

A Novel Fiber Optic Biosensor for the Determination of Adrenaline Based on Immobilized Laccase Catalysis

Abstract

A novel fiber optic biosensor for the determination of adrenaline based on immobilized laccase catalysis and fluorescence quenching was designed and fabricated. The immobilized laccase formed by the immobilization of laccase on the CuTAPc-Fe₃O₄ nanoparticles composite were used to catalyze the oxidation of adrenaline and the fluorescent oxygen-sensing membrane was used to detect the consumption of oxygen. The effects of pH and temperature on laccase activity using adrenaline as the substrate were studied. The optimal pH and temperature for the activity of immobilized laccase are 5.0 and 55°C, respectively. The immobilized laccase has good thermal, storage and operation stability. The lock-in technology was used to detect the change of the life time of the oxygen-sensing membrane. By using ABTS as the electron mediator, the biosensor showed a response time of 30 sec. The biosensor has good performance in the adrenaline concentration ranges of 2.0 × 10^?7 to 9.0 × 10^?7 mol/l and 1.0 × 10^?8 to 9.0 × 10^?8 mol/l, and it also shows good stability.     

Complex Formation in Electrolyte Solutions in the Course of Plating Protective Coatings on Titanium

Conditions for complex formation in aqueous electrolyte solutions containing salts of aluminum and hydroxy carboxylic acids were studied by ^{2 7}Al and ^{1 9}F NMR spectroscopy. The formation of complex anions in the electrolytes at various pH and their discharge on the anode under conditions of a microplasma process allowed preparation of surface layers containing -Al₂O₃ on VT1-0 titanium. The interrelation between the composition and properties of the coatings was studied.     

A Convenient Procedure for the Alkylation of Acetylenes

Internal acetylenes are traditionally prepared by the alkylation of terminal acetylenes in liquid ammonia using sodium amide as the base.¹ Although the yields of internal acetylenes prepared in this manner are sometimes good, they are usually in the range of 30–60%. Normant has previously pointed out the efficacy of hexamethylphosphoramide (HMPA) as a solvent for alkylations of sodium acetylide.² In connection with other synthetic work, we have worked out a facile procedure which allows the synthesis of certain internal acetylenes in high yield. A typical experimental procedure follows     

A Convenient Procedure for the Preparation of Adamantanone

Sinoe adamantanone is a useful and versatile startin material for secondary substituted and ring-transformed adamantanes¹we wish to report on a convenient synthesis of this ketone from adamantans with 98 percent sulfuric acid. Adamantanone may be prepared in basionally the same way, starting from 1-adamantanol, which gives abtter yield and needs a shorter reaction tine²but adamantane affords a more direot routs. The producer reported here is based on a 100-g scale, but this scale may be extended to 1 kg.     

A Novel Flow Injection Optical Fiber Biosensor for Hypoxanthine Based on Luminol Electrochemiluminescence

IntroductionIn the food industry,the determination of hy-poxanthine in fish meatcan be regarded as a simplemethod for evaluating fish freshness.When a fishis caught and killed,the breakdown of adenosine-5 - triphosphate( ATP) in the fish meat results inthe release of adenosine- 5 - diphosphate ( ADP) ,and further degradation products are adenosine- 5 -monophosphate( AMP) ,inosine- 5 - monophosphate( IMP) ,inosine( Hx R) ,hypoxanthine( Hx) ,xan-thine( X) and uric acid( UA) . It has be…     

Synthesis and Characterization of Flexible Hydrogel Electrodes for Electrochemical Impedance Measurements of Protective Coatings on Metal Sculptures

A novel conductive anionic hydrogel was synthesized for use as a solid electrolyte for electrochemical impedance spectroscopy (EIS) characterization of the barrier properties of protective coatings on outdoor metalworks, such as bronze sculptures. The AMPS‐co‐PAA hydrogel was soaked in a variety of aqueous salt solutions and characterized by swelling capacity and conductivity in order to determine the most appropriate gel/liquid electrolyte combination for use on culturally significant objects. K₂PIPES‐equilibrated hydrogels were selected as the preferred electrodes for this particular application and were used to measure the impedance of a coated substrate, yielding spectra similar to those from standard liquid cells.     

A Novel Spectrophotometric Method for the Determination of Zolmitriptan in Pharmaceutical Formulations

A simple, rapid, cost effective and extraction‐free spectrophotometric method has been developed for the determination of zolmitriptan in pharmaceutical raw and dosage forms. The method is based on the charge‐transfer reaction of zolmitriptan in acetonitrile medium with 0.2% 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone to form a colored product peaking at 555 nm. Beer's law is obeyed in the concentration range 10‐250 μg mL^?1 with molar absorptivity of 1.7 × 10³ L mole^?1 cm^?1. The effects of variables such as reagent concentration, time of reaction, color stability and interferences have been investigated to optimize the procedure. The results have been validated analytically and statistically. The proposed method has been successfully applied for the determination of zolmitriptan in pharmaceutical formulations. Results indicate that the method is accurate, precise and reproducible (relative standard deviation < 2%).     

Zinc Oxide Based Coatings for the UV-Protection of Wood for Outdoor Applications

Summary: Nano-sized zinc oxide (ZnO) was chosen as a suitable candidate for the UV-protection of coatings. ZnO-based acrylate coatings were applied to polycarbonate plates, glass plates and impregnated wood. Coated samples were artificially weathered (Xenon test) for at least 1500 hours and studied with regards to their optical and mechanical properties, such as color shifts (yellowing), as well as to changes in brightness, transparency or hydrophobicity. The prepared wood coatings showed reduced yellowing and improved optical properties.     

A New Spectrophotometric Method for the Determination of Maneb in Commercial Formulations

Abstract

A new rapid, selective and sensitive method has been developed for the determination of maneb using pyrocatechol-violet(PV) as chelating reagent in the pH range of 7.5–11.0 in the presence of CTAB producing a complex which shows maximum absorption at 640 nm. Working range of the method is 0.2–3.0 μg ml^?1 maneb (manganese ethylenebisdithiocarbamate). The molar absorptivity of the color system is 79600 1 mol^?1 cm^?1 and Sandell's sensitivity is 0.0033 μg cm^?2. The reproducibility of the method has been checked by the 10 replicate analysis of 15 μg of maneb in 10 ml of solution. The method is quite sensitive and has been applied for the determination of maneb in various commercial samples, crops, grains and synthetic samples.     

A Novel Fluorescent Probe for Determination of pH and Viscosity Based on a Highly Water-Soluble 1,8-Naphthalimide Rotor

A novel highly water-soluble 1,8-naphthalimide with pH and viscosity-sensing fluorescence was synthesized and investigated. The synthesized compound was designed as a molecular device in which a molecular rotor and molecular “off-on” switcher were integrated. In order to obtain a TICT driven molecular motion at C-4 position of the 1,8-naphthalimide fluorophore, a 4-methylpiperazinyl fragment was introduced. The molecular motion was confirmed after photophysical investigation in solvents with different viscosity; furthermore, the fluorescence-sensing properties of the examined compound were investigated in 100% aqueous medium and it was found that it could be used as an efficient fluorescent probe for pH. Due to the non-emissive deexcitation nature of the TICT fluorophore, the novel system showed low yellow–green emission, which represented “power-on”/“rotor-on” state. The protonation of the methylpiperazine amine destabilized the TICT process, which was accompanied by fluorescence enhancement indicating a “power-on”/“rotor-off” state of the system. The results obtained clearly illustrated the great potential of the synthesized compound to serve as pH- and viscosity-sensing material in aqueous solution.