Volume 78, Issue 1

International, national, and regional chemical societies; national academies; and professional bodies recognize scientists for their outstanding contributions by, for example, the award of medals, prizes, endowed lectureships, invitation to present plenary lectures at conferences/symposia, invitation to contribute to scholarly works, and the election to leadership positions in such professional bodies. In chemistry, the highest accolade remains the award of the Nobel Prize in Chemistry, or the immortalization of a scientist in the naming of an element. As an international nongovernmental scientific organization, IUPAC takes great interest in the worldwide achievements of chemists, particularly young chemists. Therefore, IUPAC established the annual prestigious Prize for Young Chemists. In doing so, we endeavor to encourage research in the chemical sciences and the participation of promising young chemists. The prizes are given for the most outstanding Ph.D. thesis in the general area of the chemical sciences, as described in a 1000-word essay; normally, IUPAC awards four of these prizes per year. An international panel of eminent chemists, chaired by the immediate Past President of IUPAC, adjudicates these essays, together with recommendations from senior scientists with whom the candidates collaborated. The prizewinners each receive a cash prize of USD 1000 and a free trip to an IUPAC Congress at which they are invited to present a poster describing their award-winning research findings. At IUPAC, we are delighted that since its inception, the IUPAC Prize for Young Chemists has attracted substantial attention from exceptionally gifted research students and their supervisors. The IUPAC Bureau remains in full support of this undertaking and took the decision to continue with this meritorious program on a long-term basis. It is heartening to note that we received 60 applications from 22 countries for the 2005 IUPAC Prize. The essays were of a very high standard and the adjudication process was a challenging task. All of the participants and their supervisors deserve the appreciation of the international scientific fraternity. Recipients of the 2005 IUPAC Prize for Young Chemists were: - Zev J. Gartner , University of California, Berkeley, CA, USA; "Evolutionary approaches for the discovery of functional synthetic small molecules" - Jiaxing Huang , University of California, Los Angeles, CA, USA; "Syntheses and applications of conducting polymer polyaniline nanofibers" - Hiromitsu Maeda , Kyoto University, Kyoto, Japan; "A dozen years of N-confusion: From synthesis to supramolecular chemistry" - Xun Wang , Tsinghua University, Beijing, China; "Solution-based routes to transition-metal oxide one-dimensional nanostructures" Congratulations to the winners and their mentors. It is evident from the topics of their theses that chemistry, as a molecular-based science, remains the core science. Chemistry is important not only as a scientific discipline, but also for its role at the interphases of many scientific disciplines and in cutting-edge areas such as nanotechnology, new materials, and molecular biology. Young chemists are crucially important to the future well-being of chemistry as a discipline and to the future of mankind. Therefore, the prizes are awarded at the opening ceremonies of the IUPAC Congresses. The practice became well established at the IUPAC Congresses held in Brisbane, Australia, 2001, and in Ottawa, Canada, 2003. The tradition was continued at a grand function during the opening ceremony of the 40th IUPAC Congress in Beijing during August 2005, at which occasion the awards were made to the winners of the prizes for 2004 and 2005. On a personal level, it was a great pleasure to meet and to interact with the new generation of highly talented young chemists. Since 2002, the winners of the IUPAC Prize for Young Chemists have been invited to submit manuscripts on aspects of their research topics, for consideration as short, critical reviews in Pure and Applied Chemistry (PAC) , the flagship publication of the Union. I am absolutely delighted that 2005 IUPAC prizewinners again enthusiastically responded to our invitation and submitted papers, culminating in the publication of the four critical reviews that appear on the ensuing pages. What a grand and laudable way to launch an illustrious career in the chemical sciences. Chemistry worldwide has a bright future! Piet Steyn IUPAC Immediate Past President and Chairman of the IUPAC Prize Committee

Trace elements may have different functions in human and animal metabolism: some are toxic (e.g., Hg), others are essential to maintain good health (e.g., Ca), or they can be essential but also toxic, depending on the concentration in the body or in parts thereof (e.g., Se). The importance of various aspects of trace elements in relation to food is steadily increasing in the perception of the consumer and the respective authorities: food contaminants, essential and toxic elements, bioavailability and speciation, nutritional value and fortified food, reliable measurement of contents, etc. In addition, through the many minor and major food-related incidents during recent years the consumer is becoming more concerned about the quality and safety of food. As a result, research and development efforts in this area have also been increased and/or been redirected. TEF-2 was organized in Brussels 7-8 October 2004 by the Institute of Reference Materials and Measurements of the Joint Research Centre of the European Commission, with the support of the Department of Food Analysis, Institute of Agricultural and Food Biotechnology of the University of Warzaw, Poland and the Centre National de la Recherche Scientifique, France. It was carried through under the auspices of IUPAC. The objectives laid down for the symposium were - presenting state-of-the-art analytical methods for the enforcement of legal limits of trace elements in food; - disseminating new ideas and findings within the scientific community; - providing a forum for the exchange of new knowledge and experience between R&D, authorities, and industry; and - bringing together experts in the field with newcomers. TEF-2 was attended by 93 participants from 60 different institutions in 23 countries. It consisted of 26 lectures and 56 posters, structured according to the following four main topics: - trace elements in the food chain (from the environment to shelf product) including the effects of processing and of legislation - trace element bioavailability-toxicological and nutritional aspects - fortified food and supplementation legislation, manufacturing and labeling, standards - advances in trace element analysis in food matrices It was emphasized that the field of trace elements in food is a lively research area, which generates interest and involvement from researchers, authorities, and industry, of course triggered and nurtured by the equally high interest of the consumer. A selection of the invited contributions to TEF-2 is presented in the subsequent seven papers in this issue. The importance of scientific exchange in this field was, again, recognized during TEF-2. Therefore, the continuation of this series of conferences was discussed, and the venue for the subsequent TEF-3 was decided. It will be organized by R. Lobinski of CNRS in Pau, France, at the beginning of October 2008. Michael Bickel Conference Editor

Directed evolution is a powerful method for the laboratory discovery of nucleic acids and proteins with desired functional properties. A hallmark of this approach is the iterative translation, selection, amplification, and diversification of genetic information. The potential of evolutionary methods to impact the discovery of synthetic small molecules has recently been explored by a variety of laboratories. Four methods encompassing some or all of the hallmarks of evolution are discussed, including dynamic combinatorial chemistry (DCC), genetic algorithms (GAs), DNA display, and DNA-templated synthesis (DTS).

Nanofibers with diameters of tens of nanometers appear to be an intrinsic morphological unit that was found to "naturally" form in the early stage of the chemical oxidative polymerization of aniline. In conventional polymerization, nanofibers are subject to secondary growth of irregularly shaped particles, which leads to the final granular agglomerates. The key to producing pure nanofibers is to suppress secondary growth. Based on this, two methods - interfacial polymerization and rapidly mixed reactions - have been developed that can readily produce pure nanofibers by slightly modifying the conventional chemical synthesis of polyaniline without the need for any template or structural directing material. With this nanofiber morphology, the dispersibility and processibility of polyaniline are now much improved. The nanofibers show dramatically enhanced performance over conventional polyaniline applications such as in chemical sensors. They can also serve as a template to grow inorganic/polyaniline nanocomposites that lead to exciting properties such as electrical bistability that can be used for nonvolatile memory devices. Additionally, a novel flash welding technique for the nanofibers has been developed that can be used to make asymmetric polymer membranes, form patterned nanofiber films, and create polymer-based nanocomposites based on an enhanced photothermal effect observed in these highly conjugated polymeric nanofibers.

The chemistry of N-confused porphyrin (NCP) and its analogs started in 1994. Since then, considerable progress has been made in understanding the unique properties of NCP and its analogs, which confer characteristic reactivity and metal complex formation. The evolved isomers, multiply NCPs, and expanded N-confused derivatives, have opened up new realms of NCP chemistry. Cis - and trans -doubly N-confused porphyrin (N 2 CP) stabilizes higher oxidation states such as Cu III in square-planar fashion in the core. Confused isomers with five or more pyrrole rings can coordinate several cations owing to their larger cavities compared to tetrapyrrolic system. The peripheral nitrogen(s) of NCP and its analogs can serve as hydrogen-bonding donor and acceptor, and metal coordination site as well. For example, NCP forms versatile dimers with the assistance of metal ions. The square-planar divalent metal complexes of C 6 F 5 -substituted NCP act as efficient anion-binding receptors. Furthermore, Cu III complexes of N 2 CP, possessing both N and NH at the periphery, form self-assembled one-dimensional (1D) hydrogen-bonding networks, whose orientations differ in cis (zigzag) and trans (straight) isomers.

One-dimensional (1D) nanostructures have drawn continuous research attention because of their unique electrical, optical, and magnetic properties different from that of bulk and nanoparticles, as well as their potential applications in mesoscopic research and nanodevices. The main challenge in this area is how to precisely control the sizes, dimensionalities, compositions, and crystal structures in nanoscale, which may serve as a powerful tool for the tailoring of physical/chemical properties of materials in a controllable way. Here, we review the advances in the solution-based routes to prepare 1D nanostructures. Particularly, three systems of MnO 2 , rare-earth compounds, and silicates have been chosen to show the synthetic strategy under hydrothermal conditions. As the main theme, a rolling mechanism has been given special attention to present a relative general understanding of the growth of various transition-metal oxide (TMO) 1D nanostructures under solution conditions.

The 2 nd IUPAC Symposium on Trace Elements in Food (TEF-2) presented contributions within a wide range of issues, from trace element bioavailability, toxicological and nutritional aspects of trace elements, to trace elements in fortified foods and in food supplements, discussed from both a speciation and a legislation point of view.

Over the past decade, the increasing use of car catalytic converters based on platinum-group elements (PGEs) has been raising more and more concern. Human exposure to these metals occurs indirectly also through the diet. Thus, a pilot investigation was undertaken in order to ascertain the actual intake of PGEs through bread and cow milk. All manipulations were performed in a Class-100 clean room so as to minimize the risk of sample contamination. Digestion of samples was achieved by means of a mixture of HNO 3 and H 2 O 2 with the assistance of microwave irradiation. Determinations were performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) to quantify Pd, Pt, and Rh. The isotopes 105 Pd + , 103 Rh + , and 195 Pt + were used for the quantification. Major interferences were caused by 40 Ar 65 Cu + on 105 Pd + , 179 Hf 16 O + on 195 Pt + , and 87 Rb 16 O + and 87 Sr 16 O + on 103 Rh + . Both physical and mathematical approaches for the interference correction were used. The mean values for PGEs were found to be as follows (in ng kg -1 ): full-cream milk: Pd, 3790; Pt, 83.2; Rh, 1680; skim milk: Pd, 12 400; Pt, 83.6; Rh, 1090; wholemeal bread: Pd, 3210; Pt, 171; Rh, 139; white bread: Pd, 27 400; Pt, 257; Rh, 2230. The preliminary data obtained in this study are probative of the significant portion of the total exposure to PGEs, which is due to the diet.

This paper summarizes speciation results in human milk samples. Information is presented about why these elements were speciated, which techniques were applied, and which speciation results were gained in human milk. We focus on a few selected elements, such as Zn, Se, I, and Mn. Each of these elements is regarded as an "essential" element and of specific importance for newborns. At the end of each element section, we attempt to extract the overall speciation information from the different literature sources. In short, for Zn it can be concluded that this element is bound predominantly to low-molecular-weight (LMW) compounds. Several papers identify the major Zn species as Zn-citrate. A few minor species are identified as well. The pattern of Se speciation seems to be dependent on the nutritional intake. Selenium speciation in milk from slightly Se-depleted regions shows Se bound in the LMW range, ligands were partly identified. In Se-rich regions, Se seems to be associated with proteins, e.g., glutathione peroxidase. The major I species in human milk is iodide, as found by several groups. Other I species, however, were seen as well. The results of Mn speciation from different groups agreed that Mn is to a considerable amount in the LMW fraction. Again, citrate seems to play an important role as ligand.

Gel electrophoresis is a fractionation/separation technique that yields valuable information in the field of metalloproteomics, often referred to as metallomics. This paper is based on four years of practical experience of the authors' lab in this domain and highlights the capabilities and limitations of gel electrophoresis. Pitfalls of the technique were recognized by identifying the origin of artefacts in the separation, species degradation being the most important. Gel electrophoresis can be accomplished under either native or denaturing conditions. The speciation of vanadium and selenium among serum and yeast proteins, respectively, is used to illustrate these two major modes. The most powerful approach is two-dimensional denaturing gel electrophoresis. This review of the methods used in our laboratory also describes the application of the two major detection techniques, autoradiography on the one hand and electrothermal vaporization - or laser ablation (LA) - inductively coupled plasma-mass spectrometry (ICP-MS) on the other.

Selenium yeast, produced by growing select strains of Saccharomyces cerevisiae in Se-rich media, is a recognized source of organic food-form Se, but the determination of its exact composition with respect to the Se species present produced conflicting results. Improved methods of analysis have since revealed it to contain 90+ % of its Se in the form of selenomethionine, the principal organic nutritional form of Se for higher animals and humans. The safety record of Se yeast is excellent: During the three decades of its world-wide use as a source of supplemental Se, no cases of Se poisoning have occurred due to dosage or formulation errors.

In the case of Se, the concentration range between essentiality and toxicity for terrestric animals and humans is rather narrow, while aquatic organisms are much less affected, and no essentiality to green plants and aquatic macrophytes has been established yet. This review focuses on the situation in Europe, where Se levels are generally low. Apart from industrial and mining activities, the main Se sources are the burning of coal and selenite additions to animal feedstuffs. Reduction processes in sediments, soils, and feedstuffs to yield elemental Se act as sinks for available Se forms. In soils and crops, Se levels get enhanced from recycling of manure, dung, and sewage sludge, which is beneficial for Europe. New data from Austria have been added to the detailed discussions. In human nutrition, Se is supplied via pork, liver and kidneys, seafood, and cereals, but main sources as well as blood Se levels vary between different countries and nutritional habits. Food processing, like boiling, baking, or grilling, results in Se losses.

The role of reference materials (RMs) in analytical quality assurance (QA) is outlined with special emphasis on trace element analysis of foodstuff. Crucial aspects for the development of such food RMs are illustrated by a recent example of trace elements in rice flour. Major influences on the uncertainty of certified values are discussed and possibilities to enhance the availability and fitness-for-purpose of RMs as well as their proper use are indicated.

The international standardizing organizations - International, ISO, and IUPAC - cooperated to produce the International Harmonized Protocol for the Proficiency Testing of (Chemical) Analytical Laboratories. The Working Group that produced the protocol agreed to revise that Protocol in the light of recent developments and the experience gained since it was first published. This revision has been prepared and agreed upon in the light of comments received following open consultation.