Development and evaluation of gas and liquid chromatographic methods for the analysis of fatty amines

In contrast to the plethora of publications on the separation of fatty acids, analogous studies involving fatty amines are scarce. A recently introduced ionic‐liquid‐based capillary column for GC was used to separate trifluoroacetylated fatty amines focusing on the analysis of a commercial sample. Using the ionic liquid column (isothermal mode at 200°C) it was possible to separate linear primary fatty amines from C₁₂ to C₂₂ chain length in less 25 min with MS identification. The log of the amine retention factors are linearly related to the alkyl chain length with a methylene selectivity of 0.117 kcal/mol for the saturated amines and 0.128 kcal/mol for the mono‐unsaturated amines. The sp² selectivity for unsaturated fatty amines also could be calculated as 0.107 kcal/mol for the ionic liquid column. The commercial sample was quantified by GC with flame ionization detection (FID). An LC method also was developed with a reversed phase gradient separation using acetonitrile/formate buffer mobile phases and ESI‐MS detection. Native amines could be detected and identified by their single ion monitoring chromatograms even when partial coelution was observed. The analysis of the commercial sample returned results coherent with those obtained by GC–FID and with the manufacturer's data.     

Graphenic Aerogels Decorated with Ag Nanoparticles as 3D SERS Substrates for Biosensing

A versatile and efficient surface-enhanced Raman scattering (SERS) substrate based on a hybrid aerogel composed of reduced graphene oxide (rGO) decorated with silver nanoparticles (AgNPs), suitable for highly sensitive label-free detection of chemical and biological species, is presented. The simple and low-cost one-pot hydrothermal synthesis allows obtaining of a 3D nanostructured spongy-like matrix that shows good spatial distribution of Ag nanoparticles in intimate contact with rGO flakes, characterized by means of several morphological, structural, and compositional techniques. The nanostructured material, tested by SERS analysis with both rhodamine 6G (R6G) and 4-mercaptobenzoic acid (MBA), shows a satisfying SERS efficiency, quantified in terms of minimum detectable concentration of 10⁻¹⁰ and 10⁻⁷ m , corresponding to on- and off-resonant excitation, respectively. The versatility of chemical/biochemical functionalization is successfully demonstrated by exploiting different routes, by immobilizing both protoporphyrin IX (PRPIX) and hemin (H) that take advantage of π−π non-covalent bonding with the graphene layers, as well as thiol-ended oligonucleotides (DNA probes/aptamers) directly grafted on the AgNPs. Finally, after the successful integration of the hybrid aerogel into a microfluidic chip, the biorecognition of miR222 is obtained demonstrating the reliability of the aerogel substrate as SERS platform for biosensing.     

Changing Assessment Practices in Science and Mathematics

One recommendation of the national reform movements in mathematics and science is to change the way students are assessed. In this article five formats of alternative assessment forms are described, and suggestions are given on how these methods can be implemented within science and mathematics classrooms. Benefits of each type of assessment are discussed and potential pitfalls are elucidated. Samples of the five formats, journal writing, open-ended problems, portfolios, interviews and performance assessments, are included.     

Nitric Acid on Silica Gel: A Useful Nitrating Reagent for Activated Aromatic Compounds

Phenols and arylmethyl ethers are rapidly mononitrated by nitric acid adsorbed in silica gel at room temperature in high yields.     

Natural Polymer Characterization

Summary : A review about the characterization of natural polymers is given, describing the polymers found in Nature, methods to distinguish natural from syntheticpolymers, and what modern Polymer Science can learn from Nature     

A Vision of Learning to Teach for the 21st Century

Glenda Lappan received her Ed. D. in mathematics and education from the University of Georgia in 1965 and has since worked at Michigan State University. From 1989–91 she took leave to serve as the program director for Teacher Preparation at the National Science Foundation. From 1997–2001 she is on leave to serve as president of the National Council of Teachers of Mathematics (NCTM). Her research and development interests are in the connected areas of students' learning of mathematics and mathematics teacher professional growth and change at the middle and secondary levels. She has published over a hundred scholarly papers and numerous books for middle grades students and teachers. She is currently the codirector of the Connected Mathematics Project II, which is funded by the National Science Foundation to revise and continue development of a complete middle school curriculum for teachers and for students. She served as the chair of the middle school writing group for the NCTM Curriculum and Evaluation Standards for School Mathematics (1989), and as Chair of the Commission that developed the NCTM Professional Standards for Teaching Mathematics (1991). She served on the NCTM Board of Directors from 1989 to 1992 and from 1997–2001. She has been a member of many national advisory boards, including the following: Glenn T. Seaborg Center for Teaching and Learning Science and Mathematics, the Ford Foundation/University of Pittsburgh QUASAR Project, the NSF/University of Maryland Teacher Preparation Collaborative, and the NSF/San Diego State University Mathematics for Elementary Teacher Preparation Materials Development Project.     

Expansive learning: lessons from one teacher’s learning journey

The provision of quality learning experiences for teachers is critical to mathematics reform agendas aimed at equitable and culturally responsive teaching. In this paper we use an activity theory framework to explore one teacher’s learning journey. Drawing on the teacher’s self-report of his journey 1 year after his participation in an intervention designed to support the introduction of mathematical inquiry practices we examine those factors that supported expansive learning. In seeking to understand our pedagogical stance within the intervention we gained new insights into the provision of research based tools to support learning, the provision of space for individual and collective learning, and the provision of a safe learning environment both within the programme, the class, and the wider professional community. These factors are important in understanding transformational changes associated with ambitious pedagogy.