Crystallization and characterization of an inflammatory lectin purified from the seeds of Dioclea wilsonii

DwL, a lectin extracted from the seeds of Dioclea wilsonii, is a metalloprotein with strong agglutinating activity against rabbit and ABO erythrocytes, inhibited by glucose and mannose. DwL was purified by affinity chromatography on a Sephadex G-50 column and ion exchange chromatography on a HiTrap SP XL column. SDS-PAGE revealed three electrophoretic bands corresponding to the α (25,634 ± 2 Da), β (12,873 ± 2 Da) and γ (12,779 ± 2 Da) chains. Protein sequencing was done by Tandem Mass Spectrometry. The primary sequence featured 237 amino acids and was highly homologous to other reported Diocleinae lectins. A complete X-ray dataset was collected at 2.0 ? for X-Man-complexed DWL crystals produced by the vapor diffusion method. The crystals were orthorhombic and belonged to the space group I222, with the unit-cell parameters a = 59.6, b = 67.9 and c = 109.0 ?. DWL differed in potency from other ConA-like lectins and was found to induce neutrophil migration in rats, making it particularly useful in structural/functional studies of this class of proteins.     

A Three-Channel Spectrometer for Wide-Field Imaging of Anisotropic Plasmonic Nanoparticles

A three-channel spectrometer (3CS) based on a commercial digital camera was developed to distinguish among tens of large (>100 nm), anisotropic plasmonic particles with various shapes, orientations, and compositions on a surface simultaneously. Using band pass filters and polarizers, the contrast of 3CS images could be enhanced to identify specific orientation and composition characteristics of gold and gold-silver nanopyramids and as well as the direction of the longest arm of gold nanostars.     

A study of early career teachers’ practices related to language and language diversity during mathematics instruction

The role of language in mathematics teaching and learning is increasingly highlighted by standards and reform movements in the US. However, little is known about teachers’, and especially early career teachers’ (ECTs) practices and understandings related to language in mathematics instruction. This multiple case study explored the language-related understandings and practices of six ECTs in diverse elementary classrooms. Using iterative cycles of analysis, we found that all ECTs regularly attended to students’ mathematical vocabulary use and development. Yet, there was variability in ECTs’ focus on how to teach mathematical vocabulary, expectations for students’ precise use of mathematical terminology, and the use of multiple languages during instruction. These findings indicate that ECTs need more targeted support during teacher preparation and early career teaching in order to better support all students’ language development in the mathematics classroom.     

Size-selected Ni catalyst islands for single-walled carbon nanotube arrays

Many properties of single-walled carbon nanotube (SWCNT) arrays are determined by the size and surface coverage of the metal catalyst islands from which they are nucleated. Methods using thermal fragmentation of continuous metal films frequently fail to produce size-uniform islands. Hybrid numerical simulations are used to propose a new approach to controlled self-assembly of Ni islands of the required size and surface coverage using tailored gas-phase generated nanocluster fluxes and adjusted surface temperatures. It is shown that a maximum surface coverage of 0.359 by 0.96–1.02 nm Ni catalyst islands can be achieved at a low surface temperature of 500 K. Optimized growth of Ni catalyst islands can lead to fabrication of size-uniform SWCNT arrays, suitable for numerous nanoelectronic applications. This approach is deterministic and is applicable to a range of nanoassemblies where high surface coverage and island size uniformity are required.

     

Quasiclassical trajectory studies of H(D)+HBr(DBr) abstraction and exchange reactions

The abstraction and exchange reaction dynamics for H(D)+HBr(DBr) systems have been investigated on three LEPS potential-energy surfaces whose features are in accord with the surface topography suggested by recent molecular-beam and thermal experiments (abstraction barrier less than 1.0 kcal/mole, exchange reaction barriers of =5.0 kcal/mole, and no attractive wells with a depth greater than 0.209 kcal/mole). The surfaces differ primarily in the magnitude of the abstraction barrier which varies from 0.19 to 1.01 kcal/mole. Reaction cross sections have been computed on each surface as a function of relative collision energy from the results of 139000 quasiclassical trajectoris. Comparison of these results with measured relative abstraction cross sections suggests that the true abstraction barrier is very small, perhaps between 0.0 and 0.25 kcal/mole. However, thermal rate coefficients computed on the - best- surface at 300 K are about a factor of 2 larger than the most recently measured values. The calculated (H,D)/(D,H) isotope ratio at 300 K lies between the two reported experimental results. The computed thermal activation energy for abstraction is 835 cal/mole, which is in good agreement with a very early measurements but a factor of 2.5 less than the most recently reported experimental result. These results suggest that the molecular-beam and thermal rate measurements are inconsistent. The average fraction of the available energy which is partitioned into internal product modes <f_E> is found to be nearly independent of relative collision energy and the small topographical differences present in the potential surfaces used in these calculations. We find <f_E> = 0.40. In all reactions, the differential scattering cross sections are peaked in the backward direction for the molecular products, indicating a rebound mechanism.     

Atomic force microscopy study of beta-substituted-T7 oligothiophene films on mica: mechanical properties and humidity-dependent phases

The structural and mechanical properties of Langmuir-Blodgett monolayer and multilayer films of 3",4"-didecyl-5,2'; 5',2"; 5",2'; 5',2"; 5",2''; 5'',2"-heptathiophene-4'-acetic acid on mica have been studied by atomic force microscopy (AFM) as a function of humidity, temperature, and applied force. The molecules orient with the carboxylic acid group pointing toward the mica surface and expose the alkyl side chains to the air interface. As the load applied by the AFM tip increases, the film is compressed easily from an initial height of 2 to 1.2 nm. After compression the films can support much higher loads without loss of height. The state of aggregation of the molecules was found to be sensitive to the environmental humidity, which induced reversible changes. Annealing the samples with monolayer or multilayer films resulted in irreversible changes when the temperature exceeded approximately 100 degrees C.     

Synthesis, characterization, and cytotoxicity of a novel highly charged trinuclear platinum compound. Enhancement of cellular uptake with charge

Charge delocalization (6+ to 8+) in "noncovalent" linear trinuclear platinum complexes produces compounds with cytotoxicity in some cases equivalent to cisplatin. The cellular uptake of a novel 8+ compound is greater than that of neutral cisplatin as well as other multinuclear Pt compounds.     

Synthesis of bombesin-functionalized iron oxide nanoparticles and their specific uptake in prostate cancer cells

The imaging of molecular markers associated with disease offers the possibility for earlier detection and improved treatment monitoring. Receptors for gastrin-releasing peptide are overexpressed on prostate cancer cells offering a promising imaging target, and analogs of bombesin, an amphibian tetradecapeptide have been previously demonstrated to target these receptors. Therefore, the pan-bombesin analog [β-Ala11, Phe13, Nle14]bombesin-(7–14) was conjugated through a linker to dye-functionalized superparamagnetic iron oxide nanoparticles for the development of a new potential magnetic resonance imaging probe. The peptide was conjugated via click chemistry, demonstrating a complementary alternative methodology to conventional peptide-nanoparticle conjugation strategies. The peptide-functionalized nanoparticles were then demonstrated to be selectively taken up by PC-3 prostate cancer cells relative to unfunctionalized nanoparticles and this uptake was inhibited by the presence of free peptide, confirming the specificity of the interaction. This study suggests that these nanoparticles have the potential to serve as magnetic resonance imaging probes for the detection of prostate cancer.