On the origins of OR and its institutions

Operational Research (OR) is the science of decision-making. From its military origins on the eve of World War II, OR has over the past seven decades matured to become a discipline that is recognised worldwide for its contributions to managerial planning and complex operations on all levels within both private companies and public institutions. Besides being an indispensable tool as a means for decision support, OR is today a well-established academic discipline and a field with its own institutions. Thus, OR-professionals are joined in national societies worldwide, assembled since 1959 in the global organization International Federation of OR Societies (IFORS) which again is subdivided into four Regional Groupings. Among those is the Association of European OR Societies (EURO) having as members the national societies of 31 countries notably in Europe. Two questions will be addressed: what is OR all about? How do National OR societies fit within the frameworks of IFORS and EURO? Partial answers are provided to both.     

Laser-printed lithium-sulphur micro-electrodes for Li/S batteries

A novel path for the preparation of electrodes for lithium-sulphur cells was developed using a very fast laser-printing setup for the direct and dry i.e., solvent-free transfer of electrode materials onto the current collectors. Model electrodes could be prepared at very small dimensions enabling these batteries to be used even in portable small devices. The initial specific charge was remarkably high at about 1300 A h kg^?1 (relating to the active material content of the electrode) with a loss of specific charge of about 75% after about 400 cycles at 1C. In addition, the dry transfer technique has highly beneficial effects on the environmental sustainability and, therefore, supports the concept of the use of “green” power storage.     

Do halogen and methyl substituents have electronic effects on the structures of simple disilanes? An experimental and theoretical study of the molecular structures of the series X3SiSiMe3 (X = H, F, Cl and Br)

The gas-phase molecular structures of a series of halogen-substituted disilanes [X₃SiSiMe₃ (X = H, F, Cl and Br)], 1,1,1-trimethyldisilane (H₃SiSiMe₃), 1,1,1-trifluoro-2,2,2-trimethyldisilane (F₃SiSiMe₃), 1,1,1-trichloro-2,2,2-trimethyldisilane (Cl₃SiSiMe₃) and 1,1,1-tribromo-2,2,2-trimethyldisilane (Br₃SiSiMe₃), have been determined in the gas phase by electron diffraction. Ab initio calculations at the HF and MP2 level were used to support the experimental investigation using the SARACEN method. All of the investigated structures were determined to adopt a staggered structure with C _3v symmetry. The effect of substitution on the Si–Si bond and the Si–Si–X bond angle was investigated and these results were compared to results obtained from a recent study of halogen-substituted disilanes [X₃SiSiXMe₂ (X = F, Cl, Br and I)] to consider the effect of the methyl groups on the substituted disilanes.     

Conductivity as a Sensor for Monitoring Relative Magnesium Corrosion Rates in Real‐time,in Serum‐containing Media under Cell Culture Conditions

Because controlling the corrosion rate of magnesium metal will be crucial to the success of biomedical implants containing pure magnesium or magnesium alloys, many ways have been sought to improve in vitro tests to analyze corrosion rates, and also to identify new methods of preparing or post‐processing magnesium. In this work, for an in vitro assay, we explored the use of a commercially available conductivity sensor to study magnesium corrosion under cell culture conditions that duplicate many physiologically appropriate parameters. With this sensor, we studied the corrosion of two previously untested magnesium single crystal samples that differed in surface treatments that could alter corrosion rates. The results show that the relative conductivity changes in (mS/cm) over the total time of immersion were proportional to the corrosion rates in (mm/y) and also to the total magnesium released, as detected by inductively coupled plasma mass spectrometry (ICP‐MS).     

Homo‐ and diblock copolymers of poly(furfuryl glycidyl ether) by living anionic polymerization: Toward reversibly core‐crosslinked micelles

We report the synthesis and characterization of well‐defined homo‐ and diblock copolymers containing poly(furfuryl glycidyl ether) (PFGE) via living anionic ring‐opening polymerization using different initiators. The obtained materials were characterized by SEC, MALDI‐TOF MS, and ¹H NMR spectroscopy and molar masses of up to 9400 g/mol were obtained for PFGE homopolymers. If the amphiphilic diblock copolymer PEG‐block‐PFGE was dissolved in water, micelles with a PFGE core and a PEG corona were formed. Hereby, the hydrophobic PFGE core domains were used for the incorporation of a suitable bismaleimide and heating to 60 °C induced the crosslinking of the micellar core via Diels‐Alder chemistry. This process was further shown to be reversible. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A longitudinal view of mathematics achievement of primary students: case studies from Japan, Singapore, and the United States

This paper shares results from a secondary analysis of data from the participation of Japanese, Singaporean, and U.S. students in the International Project on Mathematical Attainment (IPMA). IPMA was a longitudinal study to assess the mathematics achievement of primary students from their first year of schooling through the end of fifth grade. Tests were constructed to enable achievement on the same items to be assessed over multiple years, thus permitting the assessment of growth in achievement throughout primary school. Achievement is compared to the grade at which the content is introduced so that achievement can be related to students’ opportunity to learn.     

MALDI-MS of drugs: Profiling,imaging, and steps towards quantitative analysis

Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique which can be used in mass spectrometry to produce ions from biomolecules without inducing the fragmentation associated with traditional methods of ionization. When used with small molecules, the lack of fragmentation allows identification of specific molecules against a background of alternative signals; thus, for example, the presence of drug molecules and metabolites can be distinguished from a range of alternative biomolecules present within a tissue sample. Using highly collimated lasers in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) allows imaging of a tissue sample whereby the laser is rastered across the sample and individual mass spectra are collected in a serial manner. Thus, the distribution of the molecules within the tissue sample can be presented in the form of a 2D image. While the detection of specific drug molecules and metabolites within biological samples has its uses, quantification of those same molecules would be of greater benefit in a clinical setting. However, accurate quantification presents additional challenges. We present an overview of the MALDI-MS technique followed by recent progress in profiling drugs and their metabolites through imaging drug distributions within tissues and finish with recent developments in the quantification of drugs in tissues by MALDI-MSI.