A methodology for choosing parameters for ESR readout of alanine dosimeters for radiotherapy

Spectrometer settings for ESR readout of alanine dosimeters for radiotherapy have been investigated. Several ESR parameters were studied and determined. The main reason for this work is to choose the suitable parameters to increase signal-to-noise ratio and to reduce the uncertainty on ESR readout, which is one of the main components of uncertainty of alanine/ESR dosimetry system for radiotherapy. The new spectrometer settings have been applied for ESR readout of alanine dosimeters irradiated from 1 to 10 Gy. A higher signal-to-noise ratio has been achieved compared to our old spectrometer settings. The extended uncertainty (k=2) has been evaluated in the dose range 2–10 Gy (maximum uncertainty of 4.9% for 2 Gy, while minimum uncertainty of 1.4% for 10 Gy), which implies that the alanine/ESR dosimetry system can be applied to radiotherapy dose level that needs a global accuracy of 5%.     

Prospects for development of a technology for production of butene-1

Industrial technologies for production of butene-1 are described, including the most promising process for recovery of butene-1 of polymerization purity from C₄ fractions formed in pyrolysis and catalytic cracking of hydrocarbons. It is shown that this technology can be improved and suggested to use as a raw material the recycle butene fraction formed from these C₄ fractions upon isolation of 1,3-butadiene and isobutene. A technological scheme for recovery of butene-1 of polymerization purity is suggested.     

Preparation of PVA membrane for immobilization of GOD for glucose biosensor

A membrane was prepared using polyvinyl alcohol (PVA) with low and high degree of polymerization (DOP), acetone, benzoic acid (BA) and was cross-linked by UV treatment. Membrane composition was optimized on the basis of swelling index. Membrane prepared with 12% low DOP and 8% high DOP of PVA, 2% BA, dissolved in buffer containing 20% acetone and cross-linked with UV treatment exhibited lower swelling index. Fourier transform infrared (FTIR) study of the membranes showed appearance of a strong band at approximately 2337 cm(-1) when UV was used for cross-linking in the presence of benzoic acid. Scanning electron microscope (SEM) study revealed that membrane cross-linked with UV treatment was smoother. Glucose oxidase (GOD)-PVA membrane was associated with the dissolved oxygen (DO) probe for biosensor reading. Glucose was detected on the basis of depletion of oxygen, when immobilized GOD oxidizes glucose to gluconolactone. A wide detection range, 0.9-225 mg/dl was estimated from the linear range of calibration plot of biosensor reading. Membranes were reused for 32 reactions without significant loss of activity and stored for 30 days (approximately 90% activity) at 4 degrees C. Membranes were also used with real blood samples.     

Potential of FTIR spectroscopy for analysis of tears for diagnosis purposes

It has been widely reported that the tear film, which is crucially important as a protective barrier of the eye, undergoes biochemical changes as a result of a wide range of ocular pathology. This tends to suggest the possibility of early detection of ocular diseases on the basis of biochemical analysis of tears. However, studies of tears by conventional methods of biomolecular and biochemical analysis are often limited by methodological difficulties. Moreover, such analysis could not be applied in the clinic, where structural and morphological analyses by, mainly, slit-lamp biomicroscopy remains the recommended method. In this study, we assessed, for the first time, the potential of FTIR spectroscopy combined with advanced chemometric processing of spectral data for analysis of raw tears for diagnosis purposes. We first optimized sampling and spectral acquisition (tears collection method, tear sample volume, and preservation of the samples) for accurate spectral measurement. On the basis of the results, we focused our study on the possibility of discriminating tears from normal individuals from those of patients with different ocular pathologies, and showed that the most discriminating spectral range is that corresponding to variations of CH₂ and CH₃ of lipid aliphatic chains. We also report more subtle discrimination of tears from patients with keratoconus and those from patients with non-specific inflammatory ocular diseases, on the basis of variations in spectral ranges attributed notably to lipid and carbohydrate vibrations. Finally, we also succeeded in distinguishing tears from patients with early-stage and late-stage keratoconus on the basis of spectral features attributed to protein structure. Therefore, this study strongly suggests that FTIR spectral analysis of tears could be developed as a valuable and cost-saving tool for biochemical-based detection of ocular diseases, potentially before the appearance of the first morphological signs of diseases. Combined with supervised modelling methods and with use of a spectral data base acquired for representative patients, such a spectral approach could be a useful addition to current methods of clinical analysis for improvement of patient care.

Application of thermal analysis for investigations of polymer powders for coatings

Polypropylene coatings obtained by the fluidized bed method were investigated. It was proved that the application of thermal analysis methods for their characterization gave many useful data, as a consequence of the similar conditions of thermal measurements and plastics powder processing. Significant correlations were found between the thermal properties and the standard coating poperties.

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Zusammenfassung Durch Fluidisationsverfahren erhaltene Polypropylenbeschichtungen wurden untersucht. Es wurde festgestellt, daß infolge der ähnlichen Bedingungen von thermischen Messungen und Plastpulverisierungsverfahren die Anwendung von thermischen Untersuchungsmethoden zu deren Charakterisierung viele nützliche Angaben liefern. Es konnten eindeutige Beziehungen zwischen thermischen Eigenschaften und Standardbeschichtigungseigenschaften gefunden werden.

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New method for prefractionation of plasma for proteomic analysis

The depth of proteome analysis is severely limited in complex samples with a wide dynamic range of protein abundance such as plasma. Removal of high‐abundance proteins should reveal the signal of lower abundance plasma proteins. However, smaller proteins may be part of larger protein complexes and hence the removal of proteins involved in complexes with high‐abundance proteins such as albumin may inhibit the search for disease biomarkers. Prefractionation of a sample divides it into fractions of reduced complexity, allowing improved detection of lower abundance proteins. Using a prefractionation device, which employs Gradiflow? technology, we were able to separate small volume plasma samples into multiple fractions based on the molecular weight and/or charge. The resulting samples of reduced complexity were directly compatible with 2‐DE. The use of this prefractionation machine may therefore be useful in the hunt for disease biomarkers.     

Adhesives for assembly procedures for products of radioelectronic industry

A list of adhesive materials, sealants, and potting compounds used at the enterprise is given. The basic properties of these materials are discussed, and particular process procedures in which they are employed are described.     

Piperazine-based buffers for liposome coating of capillaries for electrophoresis

Anionic liposomes can be coated on fused-silica capillaries for electrophoresis in the presence of N-(hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) (HEPES) as background electrolyte (BGE) solution. In this work, the interaction of various compounds with zwitterionic and anionic phospholipid coatings was studied with HEPES at pH 7.4 as BGE solution. The chromatographic and electrophoretic behavior of three test sample solutions (anionic, cationic, and neutral) was investigated for evaluation of the phospholipid coatings. Our results show that hydrophobic interactions between analytes and the phospholipid coating are important for the migration of charged analytes. In addition, the performances of other piperazine-based buffers, i.e., N-(2-hydroxyethyl)piperazine-N'-(2-hydroxypropanesulfonic acid), piperazine-N,N'-bis(2-ethanesulfonic acid), and piperazine-N,N'-bis(hydroxypropane sulfonic acid), at pH 7.4, as liposome solvent and BGE solution were evaluated and compared with the performance of HEPES at pH 7.4. The anionic liposome solution comprised 80/20 mol% phosphatidylcholine/phosphatidylserine. A simple test solution was selected and the chromatographic and electrophoretic migration behavior of the analytes was evaluated. The results show that, in addition to HEPES, other piperazine-based buffers at pH 7.4 are suitable for coating of fused-silica capillaries with anionic liposomes.     

Prospects for the use of fluidized-bed devices for production of coatings

It is shown that, currently, the most effective grinding and dispersant equipment in the technology of coating production are fluidized-bed devices—devices in which grinding and dispersion of pigments and fillers occur via ferromagnetic bodies driven by an electromagnetic field.     

缓冲溶液pH计算公式的推导

酸碱缓冲溶液在分析化学中的应用是多方面的 ,因此酸碱缓冲溶液 ｐＨ的计算是分析化学中必不可少的一个内容。目前 ,高师院校的分析化学多采用华中师范大学等校编的《分析化学》(第 2版 ) ,笔者在几年的教学中 ,发现该教材在缓冲溶液 ｐＨ计算的公式推导中存在疏漏。为此 ,在比较其他教材中该章节的内容后 ,从酸碱平衡最本质的内容ＰＢＥ出发 ,提出一种新的缓冲溶液ｐＨ计算公式推导方法。1　华中师范大学版教材中的问题[1]　　以一元弱酸及其共轭碱体系进行讨论 ,设弱酸ＨＡ浓度为ｃａ,共轭碱ＮａＡ浓度为ｃｂ。将ＨＡ Ａ-体系以Ｈ2 Ｏ作媒…     

Rules for selection of oxide catalysts for oxidative dehydrocombination of hydrocarbons

Based on the mechanism of oxidative dimerization of hydrocarbons the rules for the selection of catalysts for this kind of reactions has been discussed. It has been shown that an efficient dehydrodimerization catalyst must contain on its surface electron acceptor centers (metal cations) of moderate strength, strongly bound nucleophilic oxygen, and possess the corresponding collective properties. The elements have been discussed, the oxides of which satisfy the above requirements.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 366–370, May–June, 1988.     

有机物结构分析模型建构的教学策略研究

在认识发展理论指导下构建有机物结构分析模型, 可以在教学中落实有机化学学科思想, 帮助学生形成分析有机物的思路和方法。为了建立结构分析模型, 发展学生对有机物的认识, 制定了2种不同的教学组织策略, 并在高二新授课中进行了教学实施。通过对教学前后2个班学生问卷测查并结合学生访谈, 对学生理解和应用结构分析模型, 对有机物结构的认识发展等方面进行对比, 分析、讨论了2种策略的效果, 总结了有机物结构分析模型的功能与价值。     

A single-laboratory validated method for the generation of DNA barcodes for the identification of fish for regulatory compliance

The U.S. Food and Drug Administration is responsible for ensuring that the nation's food supply is safe and accurately labeled. This task is particularly challenging in the case of seafood where a large variety of species are marketed, most of this commodity is imported, and processed product is difficult to identify using traditional morphological methods. Reliable species identification is critical for both foodborne illness investigations and for prevention of deceptive practices, such as those where species are intentionally mislabeled to circumvent import restrictions or for resale as species of higher value. New methods that allow accurate and rapid species identifications are needed, but any new methods to be used for regulatory compliance must be both standardized and adequately validated. "DNA barcoding" is a process by which species discriminations are achieved through the use of short, standardized gene fragments. For animals, a fragment (655 base pairs starting near the 5' end) of the cytochrome c oxidase subunit 1 mitochondrial gene has been shown to provide reliable species level discrimination in most cases. We provide here a protocol with single-laboratory validation for the generation of DNA barcodes suitable for the identification of seafood products, specifically fish, in a manner that is suitable for FDA regulatory use.     

Principles for efficient utilization of light for mass production of photoautotrophic microorganisms

Outdoor production of microalgae could be set on a sound industrial basis if solar energy were utilized at a much higher efficiency than presently obtained. Many types of photobioreactors have been developed in the past in an attempt to answer this challenge, but their photosynthetic efficiency has been rather similar to the basically inefficient open raceway commonly used today. Efficient utilization of the oversaturating solar energy flux mandates that reactors should have a narrow lightpath to facilitate ultra-high cell densities, be maximally exposed to sunshine, and have an efficient mixing system to create strong turbulent streaming to affect dark–light cycles of the highest possible frequency.     

A combinatorial approach for development of materials for optical sensing of gases

We present a combinatorial approach for development of materials for use in optical gas sensors, with oxygen being used as an exemplary target gas. Combinatorial chemistry is shown to be a promising tool for speeding up the search for new sensor materials. The method is based on the use of various polymers, solvents, indicators, plasticizers, and other additives. Solutions of the respective materials are prepared in appropriate organic solvents, and a robotic station is programmed to mix the components. Spots of the sensing materials are deposited in the wells of glass substrates resembling microtiterplates. After drying off the solvent, the sensor spots are automatically analyzed in a test stand, where they are exposed to a carrier gas containing oxygen in various concentrations. Changes in the decay time of fluorescence of the indicator probes are measured and used (along with sensor response time) as a main criterion for sensor assessment. It is shown that the combinatorial approach can reduce the time and effort needed to establish libraries of sensor materials by a factor of at least 1000. We describe in detail the device for preparation of sensor libraries and for testing the respective materials. The potential of the system is demonstrated for the characterization of optical oxygen sensors.     

Evaluation of membranes used for electroblotting of proteins for direct automated microsequencing

Protein purification and characterisation have been age-old problems for the biochemist. A new era has arisen with the advent of one- and two-dimensional gel electrophoresis and high sensitivity automated protein microsequencing. These two tools along with electroblotting have made it possible to separate and analyse complex protein mixtures. We studied six different membranes compatible with Edman degradation chemistry to determine their efficiencies at binding proteins electroblotted from one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Their overall blotting-sequencing properties were also evaluated. We found that the polyvinylidene difluoride-based membranes out-performed the glass-based and polypropylene-based membranes under our selected experimental conditions. The problems associated with electroblotting and microsequencing are discussed.     

Polyrotaxane approach for synthesis of continuous beds for capillary electrochromatography

The polyrotaxane formation approach was evaluated for synthesis of continuous beds for capillary electrochromatography. This approach has the advantage of generating diverse electroosmotic and chromatographic properties without chemical reactions. The polyrotaxane derivatized continuous beds were formed adding the macrocyclic compounds to the solution of neutral acrylic monomers and crosslinker prior to the initiation of the polymerisation. Cationic and anionic derivatives of beta-cyclodextrin were used as macrocyclic compounds. Investigation of the electroosmotic properties indicated a template directed and enthalpy controlled self-assembly of the polyrotaxanes during the polymerisation of the continuous beds. This process was monomer-composition dependent and favored by the hydrophobicity of the polymeric skeleton. The morphology of the continuous beds was evaluated using high-resolution optical microscopy with CCD camera and atomic force microscopy. Reversed-phase capillary chromatography driven by electroosmosis, originating from the polyrotaxane structure, was performed using several test mixtures. Not primarily designed for the chiral chromatography the polyrotaxane derivatized continuous beds demonstrated enantioselective separation of D,L-metoprolol. The stability of the polyrotaxane derivatized continuous beds was tested. The beds demonstrated reproducible electroosmotic properties in the range from pH 4 to pH 9 (RSD=0.69%).     

Ultrafiltration membrane for electrophoretic capturing of pathogens for AFM imaging

This communication describes a simple and rapid technique for electrophoretically assisted capture of phages, viruses, and other pathogens on the surface of an ultrafiltration membrane that can be considered smooth at the nanoscale. The surface was prepared by coating commercial dialysis membrane with a micrometer-thick layer of cross-linked dextran or globular proteins. To ensure strong adherence of the coating, the surface of the dialysis membrane was activated in cold plasma. It was shown that the root-mean-square roughness of the coating was well below 1 nm when the polymer solution used for coating was allowed to slowly dry through a dialysis membrane left in direct contact with mica. Relatively small viral particles (e.g., fd phages 0.7 microm long and only 3.5 nm high in the dry state) are readily visible by AFM following electrophoretic capture from suspensions containing as few as 1 x 10(6) particles/mL onto membranes prepared as described.     

Biomaterials for molecular electronics development of optical biosensor for retinol

Molecular electronics involves expertise from several branches of science. Various biomaterials and electronics are involved in the fabrication of such devices. While passive biomaterials are involved in anchoring the active biomolecules, the latter are involved in switching and/or signal transduction. In the present investigation we have used a glass-capillary-based approach to design a biosensor for retinol. The sensing element is retinol-binding protein (RBP). The affinity of retinoic-acid-horseradish peroxidase (conjugate) to RBP is tested using a surface plasmon resonance technique. A simple photomultiplier-tube-based system is exploited to monitor the chemiluminescent signal generated upon reaction of hydrogen peroxide and luminol with the conjugate bound to RBP. The photomultiplier tube is directly coupled to a computer for data logging.