Recent Achievements (recent + achievement)

Distribution by Scientific Domains

Selected Abstracts

Toxicity Evaluation for Safe Use of Nanomaterials: Recent Achievements and Technical Challenges

Saber M. Hussain
Abstract Recent developments in the field of nanotechnology involving the synthesis of novel nanomaterials (NM) have attracted the attention of numerous scientists owing to the possibility of degradative perturbations in human health. This Review evaluates previous investigations related to NM toxicity studies using biological models and describes the limitations that often prevent toxicologists from identifying whether NM pose a real hazard to human health. One major limitation to assess toxicity is the characterization of the NM prior to and after exposure to living cells or animals. The most relevant physicochemical characteristics of NM are: size, surface chemistry, crystallinity, morphology, solubility, aggregation tendency, homogeneity of dispersions, and turbidity. All of these properties need to be assessed in order to determine their contribution to toxicity. Due to the lack of appropriate methods to determine the physicochemical nature of nanoparticles in biological systems, the exact nature of NM toxicity is not fully described or understood at this time. This Review emphasizes the need for state-of-the-art physicochemical characterization, the determination of appropriate exposure protocols and reliable methods for assessing NM internalization and their kinetics in living organisms. Once these issues are addressed, optimal experimental conditions could be established in order to identify if NM pose a threat to human health. Multidisciplinary research between materials scientists and life scientists should overcome these limitations in identifying the true hazards of NM. [source]

Conducting Polymer-Based Solid-State Ion-Selective Electrodes

Johan Bobacka
Abstract Conducting polymers, i.e., electroactive conjugated polymers, are useful both as ion-to-electron transducers and as sensing membranes in solid-state ion-selective electrodes. Recent achievements over the last few years have resulted in significant improvements of the analytical performance of solid-contact ion-selective electrodes (solid-contact ISEs) based on conducting polymers as ion-to-electron transducer combined with polymeric ion-selective membranes. A significant amount of research has also been devoted to solid-state ISEs based on conducting polymers as the sensing membrane. This review gives a brief summary of the progress in the area in recent years. [source]

Imaging of quantum array structures with coherent and partially coherent diffraction

I. A. Vartanyants
Recent achievements in experimental and computational methods open the possibility of measuring and inverting the diffraction pattern from a finite object of submicrometer size. In this paper the possibilities of such experiments for two-dimensional arrays of quantum dots are discussed. The diffraction pattern corresponding to coherent and partial coherent illumination of a sample was generated. Test calculations based on the iterative algorithms were applied to reconstruct the shape of the individual islands in such a quantum structure directly from its diffraction pattern. It is demonstrated that, in the case of coherent illumination, the correct shape and orientation of an individual island can be obtained. In the case of partially coherent illumination, the correct shape of the particle can be obtained only when the coherence of the incoming beam is reduced to match the size of the island. [source]

Doing Homogeneous Catalysis between Basic Research and Application

M. BellerArticle first published online: 3 AUG 200
Abstract Recent achievements in applied homogeneous catalysis are described. Special focus is given on the development of novel palladium catalysts which are of industrial interest for the synthesis of bulk and fine chemicals. Most of the reported work has been done in an intensive collaboration between the Degussa AG (DHC) and the Leibniz-Institut für Katalyse e.V. The clear vision of the goal and a close interaction of basic research and applied catalysis have led to a fast development from the initial discovery to the upscaling of the ligands. Such a combination of know how from academic and industrial partners will provide the basis for further innovations in catalysis in future. [source]

Disparate Scale Nonlinear Interactions in Edge Turbulence

M. Yagi
Abstract In this topical review, we explain the recent achievement in the study of nonlinear interactions, putting an emphasis on the relevance to edge turbulence. First, we start from the survey of the essence in the nonlinear theory of drift wave -zonal flows systems, and visit the experimental observations of the nonlinear interactions of tokamak edge turbulence. Secondly, the universality of intermittent convective transport in the SOL of different magnetic devices are shown. Then, we discuss evolution of collisional drift wave instability in the linear plasma configuration, which is bounded by end plates having analogy to SOL plasmas. By introducing the Numerical Linear Device, the intermittent evolution of large-amplitude instabilities, generation mechanism of the poloidal flow and other nonlinear process are examined. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Material progress and the challenge of affluence in seventeenth-century England

In the later seventeenth century, material progress was first identified in England as a recent achievement with boundless future promise, and it was welcomed despite fears about the threats that it was perceived to present to national and personal well-being. The article investigates the roots of that confidence, and finds them in political economy and other intellectual developments that shaped interpretations of changing standards of living. The civic and moral ,challenge of affluence' was fully recognized but never resolved. Progress was accepted, and had to be defended in war-time, as the route to general happiness, ,ease', and plenty. [source]

NMR studies of chiral organic compounds in non-isotropic phases

Marek J. Potrzebowski
Abstract In this article, new applications and perspectives of one- and two-dimensional NMR spectroscopy for study of chiral organic compounds in the non-isotropic phases (solid state and liquid crystals) are presented. The review is organized into five sections. In the first part, theoretical background and short introduction to solid state NMR are shown. The second part presents how NMR isotropic chemical shift can be used for distinguishing of racemates and enantiomers. In the third section, the power of the ODESSA pulse sequence for investigation of racemates, enantiomers and establishing of enantiomeric excess are discussed. The fourth part shows the application of analysis of principal elements of chemical shift tensors obtained by means of 2D NMR techniques for searching of absolute configuration and conformational changes in the solid state. The final part presents recent achievements of chiral liquid crystals NMR methodology for study of chiral compounds. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A:201,218, 2008. [source]

In situ on-line toxicity biomonitoring in water: Recent developments

Almut Gerhardt
Abstract ,In situ on-line biomonitoring is an emerging branch of aquatic biomonitoring. On-line biomonitoring systems use behavioral and/or physiological stress responses of caged test organisms exposed in situ either in a bypass system or directly instream. Sudden pollution waves are detected by several existing single-species on-line biomonitors, which until now have been placed mostly in streamside laboratories. However, recent achievements have been multispecies biomonitors, mobile biomonitors for direct in-stream use, development of new instruments, new methods for data analysis and alarm generation, biomonitors for use in soil and sediment, and scientific research supporting responses as seen in on-line biomonitors by linking them to other biological and ecological effects. Mobile on-line monitoring platforms containing an array of biomonitors, biosensors, and chemical monitoring equipment might be the future trend, especially in monitoring transboundary rivers at country borders as well as in coastal zones. [source]

Recent Developments in Synthetic Chemistry, Chiral Separations, and Applications of Tröger's Base Analogues

Sergey Sergeyev
Abstract Tröger's base is a well-known chiral molecule with a few unusual structural features. The chemistry of Tröger's base analogues has been greatly developed over the last 20 years, and numerous interesting applications in supramolecular chemistry and in molecular recognition have emerged. This Review gives a short overview of the chemistry of Tröger's base and its analogues, with particular focus on recent achievements in synthesis, enantiomer separations, and applications. [source]

Reversed Crystal Growth: Implications for Crystal Engineering

Wuzong Zhou
Abstract The discovery of reversed crystal growth routes in zeolite analcime and zeolite A implies that crystal growth does not always follow the classic theory established 100 years ago. Aggregation of nanoparticles may dominate in the early stages of crystal growth, followed by surface crystallization, and then extension from surface to core of the disordered aggregates. A perfect polyhedral morphology can be developed in a thin surface crystalline layer of a particle with a disordered core. Evidence of such a novel crystal growth phenomenon can be also found in many other materials. This article highlights the recent achievements in this topic, which might have a significant impact on crystal engineering, materials science, and mineralogy. [source]

Hollow Micro/Nanomaterials with Multilevel Interior Structures

Yong Zhao
Abstract In this Review, recent achievements in the multilevel interior-structured hollow 0D and 1D micro/nanomaterials are presented and categorized. The 0D multilevel interior-structured micro/nanomaterials are classified into four main interior structural categories that include a macroporous structure, a core-in-hollow-shell structure, a multishell structure, and a multichamber structure. Correspondingly, 1D tubular micro/nanomaterials are of four analogous structures, which are a segmented structure, a wire-in-tube structure, a multiwalled structure, and a multichannel structure. Because of the small sizes and complex interior structures, some special synthetic strategies that are different from routine hollowing methods, are proposed to produce these interior structures. Compared with the same-sized solid or common hollow counterparts, these fantastic multilevel hollow-structured micro/nanomaterials show a good wealth of outstanding properties that enable them broad applications in catalysis, sensors, Li-ion batteries, microreactors, biomedicines, and many others. [source]

How do cyanobacteria sense and respond to light?

Conrad W. Mullineaux
Cyanobacteria exhibit numerous responses to changes in the intensity and spectral quality of light. What sensors do cyanobacteria use to detect light and what are the mechanisms of signal transduction? The publication in 1996 of the complete genome sequence of the cyanobacterium Synechocystis 6803 provided a tremendous stimulus for research in this field, and many light-sensors and signal transducers have now been identified. However, our knowledge of cyanobacterial light-signal transduction remains fragmentary. This review summarizes what we know about the ways in which cyanobacteria perceive light, some of the ways which they respond to light signals and some recent achievements in elucidating the signal transduction mechanisms. Some problems in characterizing cyanobacterial signal transduction pathways are outlined and alternative experimental strategies are discussed. [source]

New molecular methods to study gene functions in Candida infections

MYCOSES, Issue 9-10 2002
S. Theiß
Candida; Molekulargenetik; Genfunktion; Genexpression; ABC-Transporter Summary.Candida albicans has become a model system for human pathogenic fungi in clinical research, mainly due to the increasing number of Candida infections. Molecular techniques to study C. albicans virulence properties have been improved over the last few years, despite difficulties in genetic manipulation of this fungus. Some of the recent achievements from our own laboratory or from other groups are described in this article. The molecular analysis of the recently identified ATP-dependent transporter Mlt1 using the green fluorescent protein (GFP) as reporter for protein localization and the dominant MPAR gene as a selection marker for gene inactivation provides an example for the study of gene functions in C. albicans. Zusammenfassung.Candida albicans ist für die klinische Forschung zu einem Modellsystem zur Untersuchung humanpathogener Pilze geworden, was nicht zuletzt auf die steigende Zahl an Candida -Infektionen zurückzuführen ist. Trotz der Schwierigkeiten, die eine genetische Manipulation dieses Pilzes mit sich bringt, konnten in den letzten Jahren molekularbiologische Techniken zur Erforschung der Virulenzfaktoren von C. albicans weiterentwickelt werden. Einige dieser neuen Methoden, zum Teil aus unserer Arbeitsgruppe, aber auch aus anderen Laboratorien, werden in diesem Artikel beschrieben. Zudem gibt die Analyse des kürzlich isolierten, ATP-abhängigen Transporters Mlt1 ein Beispiel für die Studie von Genfunktionen, wobei das GFP (green fluorescent protein) als Reporter für Proteinlokalisation und der dominante Selektionsmarkers MPAR zur Geninaktivierung verwendet wurden. [source]

The Impact of Devolution on Women's Political Representation Levels in Northern Ireland

POLITICS, Issue 1 2004
Tahnya Barnett Donaghy
Historically, Northern Ireland women have been severely under-represented in the formal political arena. Despite the main parties having failed to address this issue, women have notably increased their presence in elected positions since the establishment of the Northern Ireland Assembly in 1998. In the absence of any initiatives undertaken specifically to improve women's political status, it appears that the opportunities of devolution have facilitated these recent achievements. Specifically, the new political landscape has become more open and conducive to promoting women into positions of political power, and it is the impact of these developments that this article explores. [source]