Photocatalytic TiO2/glass nanoflake array films

A new approach for the fabrication of oriented TiO2/glass nanoflake arrays has been developed. The ceramic nanoflake array was formed on a glass substrate via a simple, low temperature, and one-step hydrothermally induced phase separation approach without using any templates or additives. The factors affecting the formation of ceramic nanoflakes were examined by various characterization techniques. The results showed that the leaching of the soluble phase from the glass surface through hydrothermal processes resulted in oriented uniform ceramic nanoflake arrays. Electron microscope observations revealed that the nanoflakes formed a continuous porous three-dimensional-network array with a large surface-to-volume ratio. In addition, an anatase TiO2 film was successfully coated onto the nanoflake array by the sol-gel method. The TiO2/glass nanoflake array exhibited high activity for the photocatalytic degradation of acetone and for photoinduced hydrophilic conversion. Such enhancements were attributed to the beneficial effects of the new continuous porous three-dimensional-interconnected nanoflake network and its surface geometrical nanostructure. The present approach provides a convenient route to modify a photocatalytic coating with a porous nano-architectured substrate. This opens extensive new opportunities in the design of semiconductor/ceramic nanostructural array thin films with unusual properties for future optical and electronic applications.     

压电晶体传感器阵列用于混合有机溶剂蒸气中官能团的识别

为模拟生物化学传感体系, 提出了可用于识别有机官能团的传感器阵列, 用作人工气味识别系统。该阵列由八个压电晶体传感器组成, 每个传感器涂以具有广谱响应性能的不同吸附活性材料, 阵列对常见小分子有机溶剂混合蒸气的响应频移数据采用逐步判别分析(SDA)处理, 选出五个供信能力最佳的判别变量, 以此构成的阵列用于小分子有机溶剂混合蒸气中醇羟基、羰基与其它官能团的识别, 并采用主成分分析(PCA)法降维投影, 在二维空间含相同官能团的物质聚为一类; 阵列可用于酒类、软饮料的识别。     

Determination of Trace Chlorine in Fine Ceramics by ICP-AES Using Tungsten Boat Furnace Vaporizer and Exchangeable Sample Cuvette System as a Direct Solid Sampler

A new approach to simple solid sample digestion, subsequent vaporization, and introduction into an inductively coupled plasma was developed for the direct determination of chlorine in fine ceramic materials by atomic emission spectrometry. To each small sample cuvette made of tungsten, a powder sample was placed and weighed accurately. Following an addition of modifier solution, the cuvette was positioned on the tungsten boat furnace incorporated an electrothermal vaporizer. Then, the analyte in the sample cuvette was vaporized and introduced into the plasma; the major components of ceramic being retained. The solid ceramic samples were analyzed by using an external calibration curve prepared with the aqueous standard solutions. The detection limit of chlorine was estimated to be 0.71 ng, which corresponds to 59 ng g^?1 of the chlorine concentration in solid ceramic materials. The relative standard deviation was calculated to be 3.2%. The analytical results in various ceramic materials are described.     

High Performance Liquid Chromatography of Proteins on a Hydroxyapatite Column

Abstract

High performance liquid chromatography on a spherical ceramic type hydroxyapatite has been applied successfully for the separation of various kinds of proteins. Twenty-one proteins of various origin, having an isoelectric point of 3.3–11.0 and a molecular weight of 11,000–190,000 daltons, were loaded on the column and eluted by linear gradient of sodium phosphate at pH 6.8. The chromatography showed good resolution and high recovery for the proteins. The analysis of the retention behavior, relation between capacity ratio and physicochemical properties of proteins, showed a tendency that the capacity ratio of protein increased with the pI value of the protein.     

Interpretation of laser desorption mass spectra of unexpected inorganic species found in a cosmetic sample of forensic interest: fingernail polish

Monitoring of cell cultures in microbioreactors is a crucial task in cell bioassays and toxicological tests. In this work a novel tool based on a miniaturized sensor array fabricated using low-temperature cofired ceramics (LTCC) technology is presented. The developed device is applied to the monitoring of cell-culture media change, detection of the growth of various species, and in toxicological studies performed with the use of cells. Noninvasive monitoring performed with the LTCC microelectrode array can be applied for future cell-engineering purposes. Figure Microelectrode array for monitoring of cell cultures     

Polymeric membrane ion-selective and cross-sensitive electrode-based electronic tongue for qualitative analysis of beverages

An electronic tongue based on the sensor array of polymeric membrane ion-selective electrodes combined with pattern recognition tools was applied to qualitative analysis of various brands of orange juice, tonic, and milk. The capability of this device to reliably discriminate between different brands of those products was presented. The tests of the system were performed using products of the same brand, but with different manufacture dates (and thus comparable by the term of taste). The fusion of two types of sensors-classical selective ones and partially selective in one versatile array, and working out the sensor array's response by means of principal component analysis and back propagation neural network methods allowed the discrimination between different brands of various beverages with very high accuracy (90-100%). The real performance of the electronic tongue was evaluated applying testing samples from another manufacture lot, than the samples used in the learning set.     

Isolation and determination of estrogens in water samples by solid‐phase extraction using molecularly imprinted polymers and HPLC

Advanced SPE with molecularly imprinted polymers (MIP) was used in this study. A noncovalent imprinting approach was applied to separate 17β‐estradiol, estriol, and estrone from water samples. Polymer material was prepared by bulk polymerization with methacrylic acid as a functional monomer, divinylbenzene and ethyleneglycol dimethacrylate as crosslinkers, and acetonitrile, acetonitrile/toluene (3:1, v/v) or isooctane/toluene (1:99, v/v) as a porogen. We also prepared an MIP film on a silica gel surface with methacrylic acid and ethyleneglycol dimethacrylate as monomers and acetonitrile as a solvent. Qualitative and quantitative hormone analyses were carried out by HPLC with various detection techniques, including UV/visible spectroscopic detection (diode array detection) and electrochemical detection (CoulArray). The results of the study indicate that MIP technology is an excellent method for the quality control of estrogens in environmental analyses with a low quantification limit for 17β‐estradiol of around 26 (diode array detection) and 0.25 ng/mL (electrochemical detection). The proposed method was found to be suitable for routine determinations of the analyzed compound in environmental laboratories.     

3D printing of high solid Al2O3 ceramics based on green and renewable photosensitive resin with low viscosity and low shrinkage

A low-viscosity bio-based carbamate acrylate was synthesized by the reaction of pentamethylene diisocyanate derived from pentanediamine with a low molecular weight acrylate hydroxyl ester. The carbamate acrylate was used in the 3D printing of ceramics, and a correlation between the solid content and viscosity of the ceramic slurry was observed. The ceramic slurry exhibits good stability and low shrinkage. The results indicate that the viscosity of the ceramic slurry was 2.11 Pa s with a solid content of 80 wt%, which makes it suitable for digital light processing printing. In addition, a new type of photoinitiator called (2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide (TMO) has been applied, demonstrating excellent potential in ceramic slurry. According to its thermogravimetric curve, a debinding and sintering process was designed, and ultimately an Al₂O₃ device with a density of 94.49% was prepared.     

Ion-exchange separation and atomic-absorption determination of fifteen major, minor and trace elements in silicates

A scheme of ion-exchange separation of fifteen elements (major, minor and trace) determined mainly by atomic-absorption spectrophotometry (Ti by colorimetry) is applied to rock, mineral and ceramic analysis. Mn, Cu, Co, Fe and Zn are separated on an anion-exchanger and Li, Na, K, Mg, Ca, Sr, Ti, Al, Ni and Ba on a cation-exchanger. The method has been tested by analysis of a synthetic mixture of the fifteen ions in the ratios in common rock samples, and of various international standards (100-mg samples).     

Utilisation of enzymatic reactions in Al2O3 powder moulding process

Direct Coagulation Casting (DCC) method was applied for an alumina powder molding. In the paper the results of studies on the application of the reaction of acetic acid generation from glycerol triacetate catalyzed by lipase PPL for the flocculation of ceramic slips are presented. The ceramic samples obtained according this method were homogenous of a low content of organic binder (below 0.5 mass%), high tensile strength in the green state (>1 MPa) and high uniformity of thickening and a uniform structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of Various Deposition Techniques,Electrode Materials and Posttreatment with Tetrabutylammonium and Tetrabutylphosphonium Salts on the Electrochemical Behavior and Stability of Various Prussian Blue Modified Electrodes

The effect of various deposition techniques, electrode materials and posttreatment with tetrabutylammonium and tetrabutylphosphonium salts on the electrochemical behavior and stability of various Prussian blue (PB) modified electrodes, namely PB modified glassy carbon electrodes, silicate‐film supported PB modified glassy carbon electrodes, PB‐doped silicate glassy carbon electrodes, PB modified carbon ceramic electrodes using electrochemical deposition and PB modified carbon ceramic electrodes using chemical deposition is reported. Cyclic voltammetry and amperometric measurements of hydrogen peroxide were performed in a flow injection system while the carrier phosphate buffer (pH 7.0) with a flow rate of 0.8 mL min^?1 was propelled into the electrochemical flow through cell housing the PB modified working electrode as well as an Ag|AgCl|0.1 M KCl reference and a Pt auxiliary electrode. The results showed that the deposition procedure, electrode material and posttreatment with additional chemicals can significantly alter the stability and electrochemical behavior of the PB film. Among the studied PB modified electrodes, those based on carbon ceramic electrodes modified with a film of electropolymerized PB showed the best electrochemical stability.     

Application of Carbon Fiber-Reinforced Ceramic Composites in Active Thermal Protection of Advanced Propulsion Systems: A Review

Thermal protection is one of the crucial issues for the advanced propulsion systems of Reusable Launch Vehicles. New service requirements for materials, such as high strength, low density, low thermal expansion, high thermal stability, etc., are raised for the thermal structure with the increasing demand of flight Mach numbers and thrust-to-weight ratio. Carbon fiber-reinforced ceramic composites, which generally meet the aforementioned requirements, show great potential for various applications and they have been widely applied in the thermal protection for hypersonic vehicles. This paper gives a comprehensive and systematic review of current research status for carbon fiber-reinforced ceramic composites applied in the thermal structure of advanced propulsion systems. Three aspects are presented and discussed: the ceramic composites fabrication and the property characterization, the thermal performance of composite thermal structure used in practical engines, and the numerical methods for predicting mechanical and thermal properties of composites as well as the physicochemical phenomenon in the cooling channels. Firstly, the main manufacturing processes for the carbon-reinforced ceramic composites are presented and the corresponding advantages and disadvantages are analyzed. The high-temperature oxidation and ablation behaviors of composites are demonstrated and the improvement of oxidation and ablation resistance by introducing the ultra-high-temperature ceramics into C/C composites is discussed in detail. Then, several typical applications of carbon fiber-reinforced ceramic composites (mainly C/SiC), including the work of RCI, JAXA and NASA, have been reviewed and analyzed. After that, the current research status of macroscale equivalent and multiscale numerical methods for predicting the mechanical and thermal properties of composites as well as the complex physicochemical phenomenon occurring in hydrocarbon fuels are sorted out. Finally, several potential prospects are pointed out for the future research on the thermal protection of advanced propulsion systems based on the carbon fiber-reinforced ceramic composites.     

Remote NADH imaging through an ordered array of electrochemiluminescent nanoapertures

In this report, we present an ordered array comprising thousands of nanoapertures for the electrochemiluminescent (ECL) detection of NADH. It was fabricated on the distal face of a coherent optical fiber bundle. Such a high-density array of nanoapertures combines optical, imaging and electrochemical properties. Indeed, each nanoaperture is surrounded by a gold nanoring, which acts as an electrode material. The behavior of the array was characterized by cyclic voltammetry and it shows excellent electrochemical performances. NADH is the analyte, which is measured in presence of Ru(bpy)3(2+). The ruthenium complex mediates the NADH oxidation and this coenzyme acts as a co-reactant in the ECL mechanism. ECL light is generated at the distal face of the array by each gold ring electrode. A fraction of this ECL light is collected by the corresponding nanoaperture, transmitted through the optical fiber bundle and finally imaged on the proximal face with a CCD camera. In this work, we show that NADH concentration is remotely detected by an oxidative-reductive ECL mechanism. We present also some preliminary results about the ECL process of NADH with Ru(bpy)3(2+). The ECL behavior of NADH on gold surface is reported. The influence of the applied potential on the collected light intensity was investigated. The variation of the ECL intensity measured through the nanoaperture array with NADH concentration is linear. Remote ECL detection of NADH is spatially resolved over a large area with a micrometer resolution through the array. Therefore, such array integrates several complementary functions: ECL light generation, collection, transmission and remote imaging in an array format.     

The recognition of beer with flow-through sensor array based on miniaturized solid-state electrodes

Flow-through electronic tongue based on miniaturized solid-state potentiometric sensors has been developed. A simple technique, i.e. membrane solution casting on the surface of the planar Au transducers was applied for the preparation of classical ion-selective and partially selective microelectrodes, introduced in the flow-through sensor array. The performance of the designed electronic tongue was tested in the qualitative analysis of various brands of beer. Samples of the same brand of beer but with different manufacture dates, originating from different manufacture lots, have been applied in the studies. The combination of PLS and ANN techniques allowed the discrimination between different brands of beer with 83% of correct classifications.     

The absorption of iodine-131 on a ceramic matrix

The retention of ¹³¹I on ceramic rod coated with silver nitrate followed by coating with a polyurethane membrane to be applied in brachytherapy was studied. The concentration of silver nitrate (20 g/l), the volume of ¹³¹I as a sodium iodide solution (100 µl), the pH of the reaction mixture (pH 9) etc., were optimized to get a maximum uptake on the ceramic rod. The concentration of coating solution (5%, polyurethane in tetrahydrofuran) was also optimized to obtain a minimum leaching of ¹³¹I activity in normal saline solution. After coating with a polyurethane membrane, the ¹³¹I absorbed on the ceramic rod exhibited low leachability (0.03%). This method can be applied for the preparation of ¹²⁵I interstitial sources to be used in eye and prostate cancer therapy.     

The absorption of iodine-131 on a ceramic matrix

The retention of ¹³¹I on ceramic rod coated with silver nitrate followed by coating with a polyurethane membrane to be applied in brachytherapy was studied. The concentration of silver nitrate (20 g/l), the volume of ¹³¹I as a sodium iodide solution (100 μl), the pH of the reaction mixture (pH 9) etc., were optimized to get a maximum uptake on the ceramic rod. The concentration of coating solution (5%, polyurethane in tetrahydrofuran) was also optimized to obtain a minimum leaching of ¹³¹I activity in normal saline solution. After coating with a polyurethane membrane, the ¹³¹I absorbed on the ceramic rod exhibited low leachability (0.03%). This method can be applied for the preparation of ¹²⁵I interstitial sources to be used in eye and prostate cancer therapy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pyrolysis—mass spectrometry studies of atmospheric particles

Pyrolysis—mass spectrometry (Py—MS) as a taxonomic tool was applied to a series of atmospheric particulate samples. Seven pure and mixed source samples were individually pyrolyzed at 450°C directly into a mass spectrometer. The resulting spectra were summed and analyzed using an Euclidian Distance calculated from an n-dimensional array of peak intensity values weighted utilizing a Fisher ratioing procedure. The results of this study indicate that Py—MS can be used to distinguish various atmospheric particulate sources.     

Critical assessment of the performance of electronic moisture analyzers for small amounts of environmental samples and biological reference materials

Two electronic moisture analyzers were critically evaluated with regard to their suitability for determining moisture in small amounts (< or = 200 mg) of various environmental matrices such as leaves, needles, soil, peat, sediments, and sewage sludge, as well as various biological reference materials. To this end, several homogeneous bulk materials were prepared which were subsequently employed for the development and optimization of all analytical procedures. The key features of the moisture analyzers included a halogen or ceramic heater and an integrated balance with a resolution of 0.1 mg, which is an essential prerequisite for obtaining precise results. Oven drying of the bulk materials in a conventional oven at 105 degrees C until constant mass served as reference method. A heating temperature of 65degrees C was found to provide accurate and precise results for almost all matrices investigated. To further improve the accuracy and precision, other critical parameters such as handling of sample pans, standby temperature, and measurement delay were optimized. Because of its ponderous heating behavior, the performance of the ceramic radiator was inferior to that of the halogen heater, which produced moisture results comparable to those obtained by oven drying. The developed drying procedures were successfully applied to the fast moisture analysis (1.4-6.3 min) of certified biological reference materials of similar provenance to the investigated the bulk materials. Moisture results for 200 mg aliquots ranged from 1.4 to 7.8% and good agreement was obtained between the recommended drying procedure for the reference materials and the electronic moisture analyzers with absolute uncertainties amounting to 0.1% and 0.2-0.3%, respectively.     

1,3-Butadiene as an Adhesion Promoter Between Composite Resin and Dental Ceramic in a Dielectric Barrier Discharge Jet

A pencil-type floating electrode dielectric barrier discharge (FE-DBD) jet was designed to improve adhesion of composite resin to dental ceramic by plasma deposition. Among various monomers used for plasma deposition, 1,3-butadiene (BD) merged as a promising monomer. Shear bond strength (SBS) and fracture modes were evaluated with specimens prepared at various flow rates of BD. The SBS values of the experimental groups were significantly higher than that of the negative control group and approached that of the positive control group when flow rate was higher than or equal to 2 sccm. Surface characterizations of plasma polymer-deposited ceramic surfaces were performed with FTIR-ATR and XPS. The deposited polymer on the ceramic surface contained methyl and methylene groups, ether and ester groups, and carbon–carbon double bonds. Formation of plasma deposited layer from BD was verified with TEM and EDS from specimens prepared using a focused ion beam technique. Adhesion between ceramic and composite resin was enhanced with BD plasma deposition using the FE-DBD jet. The adhesion effect was stemmed from chemical reactions between C=C double bonds remaining in the plasma deposited polymer and those in the adhesive monomers as well as increased wettability due to the ester and ether groups involved in deposited polymer.     

Applications of SNMS in archaeometry

The recently developed High Frequency Mode HFM of electron gas SNMS allows investigations on insulating samples with the well known advantages of the SNMS Direct Bombardment Mode DBM for the analysis of conducting samples. HFM has been applied to analyses of different historic ceramic and glass samples in order to demonstrate the possibilities of SNMS in this field. It is shown that manufacturing places of ceramic samples could be distinguished by SNMS mass spectra ("fingerprints"). Furthermore questions of the constituents of colour remains on a painted ceramic ("Kaisermedaillon") could be answered by our SNMS analyses. SNMS investigations have been also applied to corrosion phenomena on different glass samples.