EA, today and tomorrow

This article presents the European co-operation for Accreditation (EA) as it is to day and tries to focus on the main goals on which we will be challenged in the very near future.     

Machine learning modelling of chemical reaction characteristics: yesterday,today, tomorrow

The synthesis of the desired chemical compound is the main task of synthetic organic chemistry. The predictions of reaction conditions and some important quantitative characteristics of chemical reactions as yield and reaction rate can substantially help in the development of optimal synthetic routes and assessment of synthesis cost. Theoretical assessment of these parameters can be performed with the help of modern machine-learning approaches, which use available experimental data to develop predictive models called quantitative or qualitative structure–reactivity relationship (QSRR) modelling. In the article, we review the state-of-the-art in the QSRR area and give our opinion on emerging trends in this field.     

Tin in the world of today

Summary A review is given on the importance of tin as a raw material and on its various uses. Analytical problems are briefly discussed. The following subjects are dealt with: tinplate, solders, bearing metals, copper-tin alloys, other metallurgical uses, inorganic tin compounds, organotin compounds.The author has also compiled the new volume Tin of the Handbook of Analytical Chemistry (Handbuch der analytischen Chemie), edited by W. Fresenius and published by Springer-Verlag     

Industrial research on polymeric materials,today and in the future

Academic as well as industrial researchers, active in the field of chemistry and more specific in the field of polymers and polymeric materials, are worrying about the future of their research field because they see so many changes happening simultaneously in their environment. The chemical industry is going through a thorough restructuring, the whole society is changing rapidly and new technologies are drawing the attention away from the traditional disciplines like chemistry and polymer science.     

Tin in the world of today

An ion exchanger on the basis of cellulose containing 1,2-dihydroxybenzene-3,5-disulphonic acid (Tiron) as a functional group was synthesized applying the principle of the reactive dye stuffs “Remazol” (TM of Hoechst AG). The capacity was 0.2 mmol/g, the exchange equilibrium with Fe³⁺-ions was reached within 3 min. The distribution coefficients K _d for Cu²⁺, Hg²⁺, Fe³⁺ and the alcaline earth ions were determined for the region pH 0–3. Tiron contains two kinds of functional groups, phenolic groups in orthoposition and sulphonic acid groups in meta-position. Fe³⁺ ions are bound relatively strongly by chelate formation, whereas alkaline earth ions are bound only by the sulphonic acid groups, in the sequence Ba²⁺ > Ca²⁺ > Sr²⁺ > Mg²⁺.     

One Setup, Three Systems

The system—surroundings concept is one of the most important in thermodynamics. Precisely defining a system is of critical importance to thermodynamic analysis. Even when studying the same problem, different individuals may opt to select different systems; therefore, choosing the correct system requires skill. In order to help students understand the various systems and their differences, a simple distillation setup is used to demonstrate the three thermodynamic systems: open, closed, and isolated.     

A One Pot,One Step Method for the Preparation of Clickable Hydrogels by Photoinitiated Polymerization

Current preparation methods for hydrogels based on redox or photopolymerization of water soluble monomers are simple to use, and flexible, but have the drawback of requiring additional modification steps for tuning or introducing properties for specific purposes. We have devised a simple and rapid synthetic strategy to prepare hydrogels possessing reactive sites to incorporate any molecules of interest by “Click Chemistry”. The strategy is based on the use of propargyl acrylamide (PAm) as comonomer together with acrylamide (AAm) and N,N′‐methylene bisacrylamide (BAAm) as crosslinker in photoinitiated polymerization. With the selective reactivity of photochemically generated free radicals towards acrylic function of PAm, hydrogels with clickable acetylene groups can be prepared in one pot, one step manner. Based on the acetylene functionality, any molecule possessing azide groups can be conjugated onto hydrogel by “Click Chemistry” as demonstrated on the example of fluoroscent azide functional pyrene.     

Synthetic polymers today and in the future of pharmacy

Synthetic polymers have since a long time played a relatively important role in present-day medicinal practice. Many devices in medicine and even some artificial organs are constructed with success from synthetic polymers. It is possible that synthetic polymers may play an important role in future pharmacy, too. This lecture should but scratch the surface of several directions in this particular field.     

Real-time,single-particle measurements of ambient aerosols in Shanghai

As one of the major components of the earth’s atmosphere, airborne particulate matter (or aerosol) has strong effects on air quality, regional and global climate, and human health. In ambient atmosphere, the different sources and complex evolutionary history of aerosol particles make the study of their chemical and physical properties extremely challenging. The invention of an online single-particle aerosol mass spectrometer provides a powerful technique to determine the size and chemical composition of individual aerosol particles in real time. We deployed an aerosol time-of-flight mass spectrometer (ATOFMS) to carry out single particle measurement in the urban area of Shanghai in the past few years. In this review paper, we summarize our recent work on the identification of particle type, mixing state and aging process, and the application of the individual particle information to the source apportionment of primary aerosol, and the investigation of the formation mechanism of secondary aerosol in Shanghai. The special capabilities of single particle mass spectrometry are proven essential to these studies. Multi-functional technique combinations of ATOFMS with other state-of-art aerosol instruments are also discussed for future studies.     

Some fundamental measurements of the atmospheric-pressure,microwave-induced discharge

Measurements of several fundamental parameters in a microwave-induced atmospheric-pressure flowing plasma are presented. Optical and electrical measurements were performed on argon and argon/nitrogen plasmas in the region 1–7 cm outside the cavity, as the applied microwave power, and plasma composition were varied.The stability of the plasma, atomic emission from the argon support gas, and emission from the analyte species, are proportional to the electron density. The observed electron density was varied when the power was changed,-when an electrophilic species was added, and as the observation zone was moved relative to the microwave field. In all cases, the change in the emission signal followed the change in electron density.The electron temperature, as measured by the double-probe method, is related to the kinetic energy of the fastest-moving electrons in the plasma. It is unchanged by variations in power, plasma gas composition, flow rate, and is independent of the location of the probes relative to the cavity. The spectroscopic and electrical data are consistent with excitation by ion—electron radiative recombination.     

Synthesis, Structure and Photoluminescence of One Zinc-based Metal-metallosalen Framework

<正>Dicarboxyl-functionalized salen ligand 1,2-phenylendiamine-N,N?-bis(3-tert-butyl- 5- (carboxyl)-salicylide-ene (H_4L) was synthesized in good yield from 3-tert-butyl-5-formyl-4-hy- droxybenzoic acid and used to construct a 2D zinc complex, [(ZnL)Zn3/2(BDC)1/2(DMSO)2]?3DMSO [(ZnL)Zn_(3/2)(BDC)_(1/2)(DMSO)_2]·3DMSO (1, BDC = 1,4-benzenedicarboxylate), under mild reaction conditions. 1 was characterized by IR, microanalysis, TGA and single-crystal X-ray crystallography. It crystallizes in triclinic space group P_1~- with a = 11.3860(4), b = 13.2636(5), c = 17.5503(7) , α = 92.2240(10), β = 94.5070(10), γ = 96.0580(10)°, V = 2624.52(17) ~3, Z = 2, M_r = 1143.62, D_c = 1.448 g/cm3, F(000) = 1186, μ = 1.395 mm~(-1), GOOF = 0.993, the final R = 0.0380 and wR = 0.1280 for 21752 observed reflections with I > 2σ(I). The 2D coordination polymer 1 is further assembled into a 3D supramolecular network structure via π…π interactions between the aromatic rings of the ligands in adjacent layers. Thermal gravimetric analysis demonstrates that 1 is a thermally robust structure with network decomposition temperatures of 420 ℃ and it also exhibits strong photoluminescence in the visible region.     

Traditional and non-traditional,innovative and ephemeral materials and techniques in today’s cultural heritage

When working with products of contemporary art, one must consider traditional, innovative, and ephemeral materials, depending on the artist’s intentions, to which concepts of originality and authenticity do not always apply. Case studies are discussed to compare the conservation and restoration procedures of works of art from different periods. The importance of involving historical-technical experts, authors, and manufacturers of materials used in artifacts is highlighted. Conservation procedures cannot be the same for all works of contemporary art. One must employ a methodology based on the critical study of not only the materials used, but also the philosophy and creative conceptual intentions of the artist.