Peculiarities of microweighing of trace quantities of alkylamines on polymer and solid-state thin films

The development of various devices with sensing elements operating on the basis of quartz crystal microbalance technique for the determination of ammonia and volatile amines in air have been considered. The results on the formation of selective layers of piezoelectric sensors with the specified properties have been presented. The influence of the nature of modifier, solvent, sorbate, and method of their formation on the piezo element on the sorption properties of thin films has been considered. The mechanism of interaction in the studied systems has been discussed relying on the results of quartz crystal microbalance measurement and microstructural studies at different stages of sorption.     

Determination of formic and acetic acids in air by piezoelectric microweighing

The quantitative and kinetic parameters of sorption of formic and acetic acids on thin films of various modifiers of piezoelectric quartz resonator electrodes are determined. Parameters of film formation on the electrodes (application procedure and thickness) are optimized. Methods for joint and separate determination of formic and acetic acids in air by piezoelectric microweighing with single- and double-sensor devices are developed.     

Detection of synthetic components in food matrices using piezoelectric resonators

The adsorption of a mixture of volatile components from the vapor phase of synthetic flavoring agents on thin adsorbent films was studied using piezoelectric quartz microweighing. Conventional gas-chromatographic adsorbents and specific films of different nature were used as adsorbents. It was shown that synthetic flavoring agents, including those used in the production of foodstuffs, can be identified and their quality can be assessed. The use of an array of piezoelectric quartz microbalances with various films allowed the slightest changes in the composition of the equilibrium vapor phase of synthetic flavoring agents to be recorded. An algorithm using a universal database on piezoelectric quartz microweighing of flavoring agent vapors was proposed for detecting them in food products and revealing adulterations.     

Physicochemical characteristics of the reaction of vapors of organic liquids with divinyl-styrene and isoprene polymer films of piezoelectric chemical sorption sensors

The reaction of vapors of organic liquids with films of carbon-chain polymers was studied on piezoelectric quartz resonators. Physicochemical characteristics of sorption processes in the system vapor-film sorbent were determined in the region obeying Henry’s law. It was concluded that divinyl-styrene polymer can be used in piezoelectric chemical sensors for environmental control of trace organic toxicants.     

Sorption of Acetone and Phenol on Natural Film Coatings of Electrodes of a Bulk Acoustic Wave Piezoelectric Resonator

The sorption–desorption of acetone and phenol on thin-film coatings of electrodes of bulk acoustic wave piezoelectric resonators was studied. Natural materials (bee-glue and beeswax) were used as natural coatings. The sorption activity of the coatings was determined along with their sorption selectivity and stability for the analytical application of modified bulk acoustic wave piezoelectric sensors in the detection of acetone and phenol in the air.     

酸碱滴定中指示剂浓度的影响

从理论计算和实验两方面对酸碱滴定指示剂浓度的影响进行讨论。通过酸碱滴定通式计算了溴百里酚蓝和酚酞在氢氧化钠滴定盐酸过程中pH的变化情况。结果表明指示剂的浓度过高或过低均不利于判定滴定终点。必须采用合适的指示剂浓度才能实现好的变色和好的准确度。     

Combinatorial synthesis of thin mixed oxide films and automated study of their piezoelectric properties

The development of an automated production of thin films and the characterization of their piezoelectric properties in high-throughput are described. A library of 50 undoped as well as doped lead zirconate titanate Pb(Zr,Ti)O₃ (PZT) coatings was produced by sol deposition. Afterwards, the piezoelectric properties of the library films were analyzed by automated atomic force microscopy employing the ultrasonic piezo-mode.     

Spectrophotometric investigations on immobilized acid-base indicators

Diffuse reflectance spectra of four acid-base indicators immobilized on Amberlite XAD-2 resin are reported as a function of pH. Adsorption modifies the acid-base properties of the indicator by broadening the pH intervals over which the dyes change colour and by shifting these intervals to higher pH values. The different behaviour in the liquid and immobilized phases may be explained by multilayered adsorption of some indicators. The occurrence of hysteresis during a pH cycle is reported.     

Physicochemical properties of aminopolystyrene- and 4-amino-N-azobenzenesulfonamide-based sorbents

The acid-base properties of the functional analytical groups of new synthetic polymer sorbents manufactured on the basis of macroporous polystyrene, their physicochemical properties, and the conditions of sorption of chromate anions were studied.     

Sorption of aliphatic amines by monocarboxycellulose from aqueous and water-ethanol solutions

The features of the sorption of hydrochlorides of lower aliphatic amines by monocarboxycellulose (MCC) from aqueous and water-ethanol solutions are studied. The ion exchange character of the sorption is shown by IR spectroscopy and potentiometry. It is found that the sorption of all studied salts of aliphatic amines by MCC from dilute aqueous and water-ethanol solutions is thermodynamically advantageous due to the great contribution of Coulomb interactions between cations and polyanions. The selectivity of sorption is predetermined by solvophobic (hydrophobic) interactions, which are thermodynamically disadvantageous at any compositions of the binary solvent due to the formation of dimeric associates of carboxyl groups in the phase of MCC, which hinder the contacts of hydrocarbon radicals of aliphatic amines with hydrophobic sites of the cellulose adsorbent matrix. At high concentrations of aliphatic amines in aqueous and water-ethanol solutions, the process of nonexchange sorption proceeds intensely through the hydrogen bonding between nitrogen atoms and hydroxyl groups of MCC.     

Ferroelectric ceramics by sol–gel methods and applications: a review

New advances in the sol?Cgel processing of ferroelectric ceramic powders and thin films and recently, scientific and technological interests in ferroelectric ceramics have been focused particularly on thin films. This is mainly due to their great potential applications in integrated electronics as passive components and as non-volatile ferroelectric memories, optoelectronic devices, etc. Special attention has been paid to the effects of the microstructure and composition on the piezoelectric properties of ferroelectric ceramic powders and thin films, and various characterization techniques are reported. This paper introduces the basic principles governing ferroelectricity and lists the various materials which exhibit these properties. The processing of ferroelectric ceramics and thin films in general and sol?Cgel processing in particular, with some examples are described. Finally, important applications of ferroelectric films and microstructure examination as well as powerful techniques are briefly discussed.     

Physicochemical properties of complexing para-substituted polystyrene sorbents containing functional amino groups

The acid-base properties of the analytical functional groups of complexing polymer sorbents based on aminopolystyrene and the sorption capacity of the sorbents were investigated. The influence of various substituents on the acid-base properties of the sorbents was studied.     

Determination of Acetonitrile in Air Using a Piezoelectric Quartz Crystal Microbalance

The affinity of acetonitrile to different adsorbents used as modifiers of quartz crystal microbalance electrodes was estimated from quantitative sorption parameters. A piezoelectric quartz crystal microbalance with electrodes modified with a squalane solution in hexane was proposed for determining acetonitrile in air at a level of 0.5 MPC. The conditions of the formation of sensitive films (modifier weight and solvent) were optimized, and the interfering effect of alkyl acetates was studied.     

1-萘甲膦酸改性氧化锆固定相分离芳胺类化合物的色谱性能研究

研究了一些芳胺类化合物在1-萘甲膦酸改性氧化锆固定相上的色谱行为。分别考察了流动相中甲醇含量、缓冲液pH值和离子强度等对芳胺类化合物色谱保留的影响,并对这类化合物在该固定相上的保留机理进行了探讨。研究结果表明,芳胺类化合物在该固定相上表现出反相和阳离子交换的混合保留模式。以pH 10.1的Tris-甲醇(60/40,V/V)溶液为流动相,在1-萘甲膦酸改性氧化锆固定相上成功分离了间苯二胺、邻甲苯胺、N-甲苯胺、对硝基苯胺、邻硝基苯胺和α-甲萘胺6种芳胺类化合物。     

Orientation dependence of the dielectric and piezoelectric properties for the Ba0.98Ca0.02Ti0.96Sn0.04O3 thin films

Lead free Ba_0.98Ca_0.02Ti_0.96Sn_0.04O₃ (BCST) thin films with (110), (111) and (001) orientations were processed via chemical solution deposition, and effects of orientation on the dielectric and piezoelectric properties were investigated in some aspects. The (110) orientated BCST thin films exhibit highest Curie temperature (T _c of 85 °C) and lowest dielectric loss (tan δ of 0.02). While, the (111) orientated BCST thin films exhibit highest dielectric tunability (74 %) and largest piezoelectric coefficient (d ₃₃ of 78 pm/V), which indicate that it is a promising lead-free replacement for lead-based applications. The anisotropic dielectric and piezoelectric properties in the three kinds of oriented BCST films has been attributed to the difference of structure, in-plane stress and polarization rotation in orientation engineered BCST films. This work clearly reveals the dielectric and piezoelectric properties of BCST films exhibit a strong sensitivity to orientation.     

Piezoelectricity of ZnO Films Prepared by Sol-Gel Method

"ZnO piezoelectric thin films were prepared on crystal substrate Si(111) by sol-gel technology, then characterized by scanning electron microscopy, X-ray diffraction and atomic force microscopy (AFM). The ZnO films characterized by X-ray diffraction are highly oriented in (002) direction with the growing of the film thickness. The morphologies, roughness and grain size of ZnO film investigated by AFM show that roughness and grain size of ZnO piezoelectric films decrease with the increase of the film thickness. The roughness dimension is 2.188-0.914 nm. The piezoelectric coeocient d33 was investigated with a piezo-response force microscope (PFM). The results show that the piezoelectric coeocient increases with the increase of thickness and (002) orientation. When the force reference is close to surface roughness of the films, the piezoelectric coefficient measured is inaccurate and fluctuates in a large range, but when the force reference is big, the piezoelectric coeocient d33 changes little and ultimately keeps constant at a low frequency."     

Dispersion of functional tetraphenylporphyrin-ligated metal into ultra-thin flexible acrylate films. 2. Oxygen-uptake properties

Cobalt(II) meso-tetraphenylporphyrin (CoTPP)/acrylate hybrid thin films were prepared by CoTPP sublimation and reactive monomer evaporation onto the glass substrate in vacuum conditions. Deposited CoTPP/acrylate thin films were in situ photopolymerized. The oxygen-uptake behaviors of CoTPP/acrylate films were investigated by means of sorption measurements, monitored by gravimetric means, and analyzed using dual mode sorption model. The loading percent of CoTPP in the film was adjusted up to 60% by controlling the CoTPP sublimation rate. The thickness of the CoTPP/acrylate hybrid film was about 200 nm and oxygen-uptake data obtained from the sorption measurements indicated that CoTPP molecules in the CoTPP/acrylate hybrid films were able to bind oxygen molecules reversibly.     

Experimental setup for the determination of analytes contained in ultrasonically levitated drops

An automated technique for the determination of analytes in an ultrasonically levitated sample of 2 to 5 microL volume has been developed. Contactless dosing of reagents or solvents into an ultrasonically levitated drop was realized via piezoelectric micropumps. Drop size was continually controlled with a programmed CCD camera. A diode array spectrometer designed for the use with optical fibers was used for absorption and fluorescence measurements. Determinations via direct absorption measurements following the method of standard addition and acid-base titrations with an absorption indicator and a fluorescent indicator were carried out. The mean consumption of sodium hydroxide added via a piezoelectric micropump in five successive titrations with 18 nmol of sulfuric acid inside a levitated drop (indicator bromothymol blue) had a relative standard deviation of 0.7% and differed only by 0.2% from the expected value.     

Zinc and cadmium complexes of 2,2′-dipyridyl-2-pyridylhydrazone as visual acid-base indicators

The DPPH complexes of zinc and cadmium are suggested as very useful indicators in visual acid-base titrations in aqueous solution. The pH range of the indicators was determined and the apparent indicator constants were found to be 8.5 and 9.5, respectively. The indicators give sharp end point and have proved to be similar in behavior to phenolphthalein.     

Kinetic absorption of vapors of alkyl acetates C<Subscript>1</Subscript>-C<Subscript>4</Subscript> and diethyl ether on thin films of modified piezoelectric quartz resonators

Sorption of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and diethyl ether on thin films of esters: poly(ethylene glycol) sebacate and phthalate, dinonyl phthalate, tween-40, pentaerythritol tetrabenzoate, triphenyl phosphate, Triton X-305, and stearic acid was studied. The mass of sorbent films was optimized, the sensitivity and selectivity of modifiers toward analytes was evaluated, and the time of maximum sorption was determined.