Sensitivity and specificity of MRI in detecting malignant spinal cord compression and in distinguishing malignant from benign compression fractures of vertebrae

The accuracy of magnetic resonance (MR) imaging in the detection of metastatic compression of the spinal cord and the cauda equina (MCCE) in 75 patients with known primary malignancy outside the central nervous system is determined retrospectively by comparing the MR results with findings of myelography, surgery, clinical follow-up and autopsy. The sensitivity is 93%, the specificity 97% and the overall accuracy 95%. The signal intensity measured in the sagittal MR images of a collapsed vertebral body is divided by that of an average of three adjacent normal vertebrae to form a signal intensity ratio (SIR). The SIRs of 41 metastatic and 15 post-traumatic collapsed vertebrae are calculated. A ratio of 0.8 has the most differentiating power. All benign and one malignant compressed vertebrae have SIRs greater than 0.8.     

Uncharged Lewis bases yield polydimethylsiloxane ionomers with amidinium alkyldithiocarbamate side chains

Ionomers exhibiting good thermal stability have been prepared by mixing three uncharged components—a poly(dimethyl)siloxane (PDMS) with randomly substituted amidine side chains, an alkylamine, and carbon disulfide. In essence, the three uncharged components produce charged materials, polyelectrolytes with amidinium dithiocarbamate ion pairs. The preparation, structures, and properties of the ionomers at the microscopic and macroscopic levels are reported as a function of PDMS chain length, degree of amidine substitution, and length of the alky group of the amine component. Whereas ionomers with hexyldithiocarbamate anions are viscous liquids at room temperature, those with octadecyldithiocarbamate groups are semi-crystalline solids, exhibiting multiple thermal transitions between 0 °C and the temperature at which they become isotropic phases. The structural natures of those transitions have been characterized from analyses of data from differential scanning calorimetry, X-ray diffraction, and rheology measurements. Among the interesting properties exhibited by the ionomers are strong adhesion to different surfaces, and high ultimate shear stress considering their relatively low amidinium contents.     

Low‐Band Gap Polyplatinaynes with Electron‐Accepting Silole Units

Summary: The synthesis and thermal, redox and photoluminescence properties of a soluble donor‐acceptor polyplatinayne with the electron‐accepting silole ring and its model compound are described. The polymer has an optical band gap of 2.10 eV which is much lower than that of thienyl‐ or silyl‐bridged congeners. The incorporation of electron‐accepting silole unit in the metallopolymer main chain creates a new π‐conjugated system that features unique donor‐acceptor characteristics.

     

Electrospray ionization mass spectrometry for analysis of low-molecular-weight anticancer drugs and their analogues

In this study, several anticancer drugs and their analogues consisting of organic and organometallic compounds were analyzed by electrospray ionization mass spectrometry (ESI/MS) using a quadrupole mass spectrometer. Protonated molecular ions [M+H]⁺ were observed for all of the compounds studied, and in the case of the two steroid sulfates, deprotonated molecular ions [M-H]^? were obtained. Tandem mass spectrometry was performed on these quasimolecular ions, and the product ions formed provided useful fragmentation patterns that were characteristic for the compounds. This study provides evidence that ESI/MS is a sensitive technique for structure confirmation and identification of small organic and organometallic molecules.     

Pre-constructed dynamic geometry materials in the classroom – how do they facilitate the learning of ‘Similar Triangles’?

The use of dynamic geometry software (DGS) is becoming increasingly familiar among teachers, but letting students conduct inquiries using computers is still not a welcome idea. In addition to logistics and discipline concerns, many teachers believe that mathematics at the lower secondary level can be learned efficiently through practice alone. Thus, the application of DGS remains limited to demonstration and explanation. This article discusses how a set of pre-constructed dynamic geometry (DG) materials was designed to teach the ‘similar triangles’ concept. The reactions and behaviour of students with relatively low levels of mathematic achievement are also analysed. Finally, the potential value of pre-constructed DG materials, with lab sheets and teacher intervention, in inquiry activities for junior-level students is discussed.