Recent developments in intelligent biomedical polymers

Intelligent polymers or stimuli-responsive polymers may exhibit distinct transitions in physical-chemical properties, including conformation, polarity, phase structure and chemical composition in response to changes in environmental stimuli. Due to their unique 'intelligent' characteristics, stimuli-sensitive polymers have found a wide variety of applications in biomedical and nanotechnological fields. This review focuses on the recent developments in biomedical application of intelligent polymer systems, s...     

Infrared regular reflectance and transmittance instrumentation and standards at NIST

Instrumentation is described that has been constructed at the National Institute of Standards and Technology (NIST) for the measurement of regular reflectance and transmittance over the 2–25 μm wavelength region. This includes both specialized accessories used with Fourier-transform infrared (FT-IR) spectrometers and laser-based systems for high optical density transmittance measurements. The FT-IR systems have been used to develop standard reference materials for IR regular transmittance.     

Surveillance for human Salmonella infections in the United States

Surveillance for human Salmonella infections plays a critical role in understanding and controlling foodborne illness due to Salmonella. Along with its public health partners, the Centers for Disease Control and Prevention (CDC) has several surveillance systems that collect information on Salmonella infections in the United States. The National Salmonella Surveillance System, begun in 1962, receives reports of laboratory-confirmed Salmonella infections through state public health laboratories. Salmonella outbreaks are reported by state and local health departments through the Foodborne Disease Outbreak Reporting System, which became a Web-based, electronic system (eFORS) in 2001. PulseNet facilitates the detection of clusters of Salmonella infections through standardized molecular subtyping (DNA "fingerprinting") of isolates and maintenance of "fingerprint" databases. The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) monitors antimicrobial resistance in Salmonella by susceptibility testing of every 20th Salmonella isolate received by state and local public health laboratories. FootNet is an active surveillance system that monitors Salmonella infections in sentinel areas, providing population-based estimates of infection rates. Efforts are underway to electronically link all of the Salmonella surveillance systems at CDC to facilitate optimum use of available data and minimize duplication.     

New examples of the use of sulfur and selenium monochlorides in the synthesis of azoles

Sulfur and selenium monochlorides can be used in the synthesis of new heterocyclic systems: 1,2,5-thiadiazolo-and 1,2,5-selenodiazolo-[3,4-]pyrimidine-5,7-(4H,7H)dione N-oxides and isothiazolo- and isoselenoazolo[4,3-e]-5,6-dihydro-4H-1,4-diazepines.A. V. Bogatskii Physicochemical Institute, National National Academy of Sciences of Ukraine, Odessa 270080. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 997–999, July, 1996. Original article submitted May 27, 1996.     

Grouping of coefficients for the calculation of inter-molecular similarity and dissimilarity using 2D fragment bit-strings

This paper compares 22 different similarity coefficients when they are used for searching databases of 2D fragment bit-strings. Experiments with the National Cancer Institute s AIDS and IDAlert databases show that the coefficients fall into several well-marked clusters, in which the members of a cluster will produce comparable rankings of a set of molecules. These clusters provide a basis for selecting combinations of coefficients for use in data fusion experiments. The results of these experiments provide a simple way of increasing the effectiveness of fragment-based similarity searching systems.     

A Simplified Method for Determining Arsenic and Antimony by the Hydride Evolution-Atomic Absorption Method

Abstract

A plastic disposable syringe hydride generator and aspirator system coupled with atomic absorption spectroscopy is shown to give results comparable to complex systems costing many times more. Details of operation, sensitivity, range of linearity and detection limits are outlined. Analyses performed on National Bureau of Standards Orchard Leaves and Bovine Liver are given and the results compared with NBS provisional values.     

Dissolution of metallic uranium and its alloys

This review focuses on dissolution/reaction systems capable of treating uranium metal waste to remove its pyrophoric properties. The primary emphasis is the review of literature describing analytical and production-scale dissolution methods applied to either uranium metal or uranium alloys. A brief summary of uranium's corrosion behavior is included since the corrosion resistance of metals and alloys affects their dissolution behavior. Based on this review, dissolution systems were recommended for subsequent screening studies designed to identify the best system to treat depleted uranium metal wastes at Lawrence Livermore National Laboratory (LLNL). This revised version was published online in July 2006 with corrections to the Cover Date.     

A comparison of pulser-based analog and digital spectrometers

We have begun a program of updates to the instruments used by the Radiation Measurements Laboratory at the Idaho National Laboratory. This laboratory supports the Advanced Test Reactor as well as many other programs throughout the INL. The first step in this upgrade is the updating of the gamma-ray spectrometry systems. Currently, these gamma-ray spectrometers use a standard spectroscopy amplifier and a pulser-based ADC. We have performed a series of tests to determine if a digital-signal processor-based system can replace these analog electronics, with little to no loss in performance.     

On practical metrology and chemical analysis: etalons and traceability systems

 National measurement systems are infrastructures to ensure, for each nation, a consistent and internationally recognised basis for measurement. Such complex systems have historical, technical, legal, organisational and institutional aspects to connect scientific metrology with practical measurements. Underlying any valid measurement is a chain of comparisons linking the measurement to an accepted standard. The ways the links are forged and the etalons (measurement standards) to which they connect are defining characteristics of all measurement systems. This is often referred to as traceability which aims at basing measurements in common measurement units – a key issue for the integration of quantitative chemical analysis with the evolving physical and engineering measurement systems. Adequate traceability and metrological control make possible new technical capabilities and new levels of quality assurance and confidence by users in the accuracy and integrity of quantitative analytical results. Traceability for chemical measurements is difficult to achieve and harder to demonstrate. The supply of appropriate etalons is critical to the development of metrology systems for chemical analysis. An approach is suggested that involves the development of networks of specialised reference laboratories able to make matrix-independent reference measurements on submitted samples, which may then be used as reference materials by an originating laboratory using its practical measurement procedures. Received: 31 July 1995 Accepted: 19 August 1995     

The Slovak National Accreditation System

 After the split of the Czechoslovak Federation, the Slovak National Accreditation System was established in November 1993, being the only system in this country executing accreditation and certification. This system is strictly based on EN 45 000 and covers testing laboratories from both the mandatory and voluntary areas of metrological laboratories, products testing and certification, quality systems, and good laboratory practice. It seeks to reach the level of compatibility accepted and recognized by EU member countries. The development and basic features of the Slovak National Accreditation System, its basic principles, and the structure and competence of accreditation bodies are described in this article.     

Determination of chromium in biological matrices by neutron activation: Application to standard reference materials

Chromium is recognized to be an essential trace element in several biological systems. It exists in many biological materials in a variety of chemical forms and very low concentration levels which cause problems for many analytical techniques. Both instrumental and destructive neutron activation analysis were used to determine the chromium concentration in Orchard Leaves, SRM 1571, Brewers Yeast, SRM 1569, and Bovine Liver, SRM 1577. Some of the problems inherent with determining chromium in certain biological matrices and the data obtained here at the National Bureau of Standards using this technique are dicussed.     

Chemical sensors based on π-conjugated organic molecules and gold nanoparticles

Scientists have developed techniques for synthesizing and characterizing many new materials including conjugated small molecules, polymers and gold particles protected by conjugated organic chromophores for testing specific sensing properties in the past decade. Still, the design and synthesis or supermolecular systems fabrication of novel materials with controlled sensing properties is a significant and ongoing challenge within nanoscience and nanotechnology. Recently, our group has successfully constructed a series of chemosensors using small organic molecules, conjugated polymers and gold nanoparticles for real-time detection of specific analytes. The chemosensors show high selectivity and sensitivity in the detection of cations and biologic analytes and thus are potentially promising for applications in sensing assay system. In this review, recent sutdies on the design, synthesis and photo-physical properties of novel materials and construct of chemosensors are summarized with an emphasis on the development in our groups in recent years. Supported by the National Natural Science Foundation of China (Grant Nos. 20531060, 20721061 & 20873155), and the National Basic Research 973 Programme of China (Grant No. 2007CB936401)     

On practical metrology and chemical analysis: legal,institutional and technical evolutions in the Australian national measurement system

 Economic and technological change, regional and international trade and the globalisation of industry have led to intense pressures for improvements to analytical quality, reliability and comparability. Of central importance are national traceability structures connecting chemical measurements in the field with internationally accepted measurement units and their practical realisations. Australia has a developed physical and engineering measurement system, a legislative framework for analytical traceability and, in the National Association of Testing Authorities, a recognised laboratory accreditation system. The need has been identified to develop the technical capability to perform matrix-independent reference measurements for the certification of traceable reference materials, useable as practical analytical etalons to establish metrological control systems in field measurements for amounts of substance. Recently, a unique collaborative consortium has proposed a National Analytical Reference Laboratory (NARL). The NARL is designed to be a metrological mass spectrometry facility for the transference of measurement units to more widely useable chemical measurement standards and reference materials. Received: 10 October 1995 Accepted: 26 October 1995     

Recent developments in semiconductor gamma-ray detectors

Summary The successful development of lithium-drifted Ge detectors in the 1960s marked the beginning of the significant use of semiconductor crystals for direct detection and spectroscopy of gamma-rays. In the 1970s, high-purity Ge became available, which enabled the production of complex detectors and multi-detector systems. In the following decades, the technology of semiconductor gamma-ray detectors continued to advance, with significant developments not only in Ge detectors but also in Si detectors and room-temperature compound-semiconductor detectors. In recent years, our group at Lawrence Berkeley National Laboratory has developed a variety of gamma-ray detectors based on these semiconductor materials. Examples include Ge strip detectors, lithium-drifted Si strip detectors, and coplanar-grid CdZnTe detectors. These advances provide new capabilities in the measurement of gamma-rays, such as the ability to perform imaging and the realization of highly compact spectroscopy systems.     

Photochemical and photocatalytic properties of zeolites containing titanium(iv) complexes and metallic palladium

An attempt has been made to create organized, highly efficient photocatalytic systems in the example of composite materials consisting of blocks of a metallocomplex photocatalyst and a dark-stage catalyst, assembled on a zeolite matrix. The spectral and photochemical properties of these systems have been investigated, and also their use in catalysis of hydrogen evolution from alcohol-water media. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 103–108, March–April, 1998.     

如何精准做好化学教学实验室的建设

This paper focuses on the detailed construction of the National Demonstration Center for Experimental Chemistry Education of Xiamen University. It contains the accurate design and construction of engineering systems, supply and exhaust air, water, electricity, etc., and furniture. Therefore, this paper provides practical experience for the detailed design and construction of chemistry teaching laboratories in colleges and universities.     

Influence of the composition of the reaction mixture and the synthesis conditions on the formation of mesomorphous substances in the presence of glucose oxidase

The possibility of synthesizing mesoporous substances in silicate and aluminosilicate systems in the presence of combinations of glucose oxidase and cetyltrimethylammonium bromide has been demonstrated. Highly crystalline mesoporous molecular sieves of type MCM-41 with a high aluminum content were obtained from the aluminosilicate system with a reaction mixture pH close to neutral. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 3, 190–193, May–June, 1999.     

Chemical component exchange and transport phenomena accompanying phase transformations in minerals and materials

Chemical component exchange and transport phenomena accompanying the multistage phase transformations of several silicate and aluminosilicate-phosphate glasses and borates as model systems are considered. It is demonstrated that the component transport limitations modify the role of chemical affinity influence and determine the sequence of new compound formation.The work was supported by grant P040703406 from the National Committee of Scientific Research of Poland.     

Synthesis of analogues of Eunicea gamma-cembranolides containing cyclic ethers via saponification.

A method for the synthesis of derivatives of the lead structures euniolide (1), 12,13-bisepieupalmerin (2), and eupalmerin acetate (3) containing tetrahydrofuran and tetrahydropyran ring systems was developed on the basis of alkali-induced intramolecular oxacyclizations. Representatives of the new analogues were submitted to the in vitro antitumor cell-line-screening program of the National Cancer Institute (NCI). While it was shown that a variety of structural modifications are possible, these transformations led typically to nontoxic synthetic cembranoids.