Surface modification of MWCNTs with glucose and their utilization for the production of environmentally friendly nanocomposites using biodegradable poly(amide‐imide) based on N‐trimellitylimido‐S‐valine matrix

In the present investigation, the preparation, characterization, and surface morphology of poly(amide‐imide) (PAI)/multi‐walled carbon nanotubes (MWCNTs) bionanocomposites (BNCs) were the main goals of the study. At first, an optically active PAI based on S‐valine as a biodegradable segment was synthesized. Then, carboxyl‐modified MWCNTs were functionalized with glucose (f‐MWCNT) as a biological active molecule in a green method to achieve a fine dispersion of f‐MWCNT bundles in the PAI matrix. The existence of S‐valine in the PAI matrix and functionalized MWCNT with glucose resulted in a series of potentially biodegradable nanocomposites. The obtained BNCs were characterized by various techniques. Field emission scanning and transmission electron microscopy micrographs of the composites showed a fine dispersion of f‐MWCNTs in the polymer matrix because of hydrogen bonding and π–π stacking interaction between f‐MWCNTs and polymer functional groups and aromatic moieties. Adding f‐MWCNTs into polymer matrix significantly improved the thermal stability of BNCs because of the increased interfacial interaction between the PAI matrix and f‐MWCNTs and also good dispersion of f‐MWCNT in the polymer matrix. Copyright © 2015 John Wiley & Sons, Ltd.     

A Priori Estimation of Organic Reaction Yields

A thermodynamically guided calculation of free energies of substrate and product molecules allows for the estimation of the yields of organic reactions. The non‐ideality of the system and the solvent effects are taken into account through the activity coefficients calculated at the molecular level by perturbed‐chain statistical associating fluid theory (PC‐SAFT). The model is iteratively trained using a diverse set of reactions with yields that have been reported previously. This trained model can then estimate a priori the yields of reactions not included in the training set with an accuracy of ca. ±15 %. This ability has the potential to translate into significant economic savings through the selection and then execution of only those reactions that can proceed in good yields.     

Preparation of <Superscript>166</Superscript>Dy/<Superscript>166</Superscript>Ho-chitosan as an in vivo generator for radiosynovectomy

¹⁶⁶Ho is one of the most effective radionuclides used for radiosynovectomy. One method to deliver this radioisotope to target tissue is via the ¹⁶⁶Dy/¹⁶⁶Ho in vivo generator system. The aim of this work was to prepare ¹⁶⁶Dy/¹⁶⁶Ho-chitosan (¹⁶⁶Dy/¹⁶⁶Ho-CHIT) in vivo generator for radiosynovectomy applications. ¹⁶⁶Dy obtained by the irradiation of natural ¹⁶⁴Dy target. ¹⁶⁶Dy was separated from ¹⁶⁶Ho by extraction chromatographic method (separation yield; 93% and separation factor;1.7). Chitosan labeling was performed in acetic acid with 99.3 ± 0.6% radiochemical purity. Biodistribution studies on intraarticular injected rats demonstrated high retention in the knee joint even 7 days showing no radioactivity leakage from the injection site into other organs as well as any translocation of the daughter nucleus after β^? decay of ¹⁶⁶Dy.     

Quasirecognition by prime graph of the simple group <Superscript>2</Superscript><Emphasis Type="Italic">G</Emphasis><Subscript>2</Subscript>(<Emphasis Type="Italic">q</Emphasis>)

Let G be a finite group. The main result of this paper is as follows: If G is a finite group, such that Γ(G) = Γ(²G₂(q)), where q = 3²ⁿ⁺¹ for some n ≥ 1, then G has a (unique) nonabelian composition factor isomorphic to ² G ₂(q). We infer that if G is a finite group satisfying |G| = |² G ₂(q)| and Γ(G) = Γ (² G ₂(q)) then G ? = ² G ₂(q). This enables us to give new proofs for some theorems; e.g., a conjecture of W. Shi and J. Bi. Some applications of this result are also considered to the problem of recognition by element orders of finite groups.     

Extracting the structure of highly reflecting fiber Bragg gratings by measuring both the transmission and the reflection spectra

We demonstrate a novel method that enables one to measure the structure of highly reflecting fiber Bragg gratings. The method is based on measuring both the transmission and reflection spectra of the grating and applying an inverse-scattering algorithm. The use of the transmission spectrum significantly reduces the sensitivity of the reconstruction to measurement noise, and therefore it significantly decreases the measurement duration. We experimentally demonstrate our method for reconstructing the structure of an apodized grating with a reflectivity of 99.91%.     

Characterization of water distribution in bread during storage using magnetic resonance imaging

A soy bread of fully acceptable quality and containing 49% soy ingredients (with or without 5% almond powder) has been recently developed in our laboratory.

An investigation on water distribution and mobility, as probed by proton signal intensity and T₂ magnetic resonance images, during storage was designed to examine possible relations between water states and hindered staling rate upon soy or soy–almond addition.

Water proton distribution throughout soy-containing loaves was found to be very homogeneous in fresh breads with and without almond, with minimal water migration occurring during prolonged storage. In contrast, traditional wheat bread displayed an inhomogeneous water proton population that tended to change (with higher moisture migration towards the outer perimeter of the slice) during storage. Similar results were found for water mobility throughout the loaves, as depicted in T₂ images. On intensity images of all considered bread varieties, the outer perimeter corresponding to the crust exhibited lower signal intensity due to decreased water content. Higher T₂ values were found in the crust of soy breads with and without almond, which were attributed to lipids.

The results indicated that the addition of soy to bread improved the homogeneous distribution of water molecules, which may hinder the staling rate of soy-containing breads. However, incorporation of almond had little effect on the water proton distribution or mobility of soy breads.     

Functional MR imaging in the awake monkey: effects of motion on dynamic off-resonance and processing strategies

Functional MR imaging of the alert, behaving monkey is being used more and more often to detect activation patterns and guide electrophysiological research investigating the neural basis of behavior. Several labs have reported fMRI data from the awake monkey, but none of them has studied and systematically corrected the effects of monkeys' motion on fMRI time series. In this study, a significant refinement of acquisition and correction strategies is reported that can be used to minimize magnetic susceptibility artifacts induced by respiration and by jaw and body movement. Real-time acquisition of sensor signals (e.g., signals induced by jaw and body movement) and MR navigator data were combined to optimize fMRI signal-correction strategies. Within trials, the artifact-induced off-resonance changes were small and mainly reflected the effects of respiration; between trials, movements caused major changes of global frequency and shim (>20 Hz/cm). Several methods were used to assess the stability of the fMRI series: k-space analysis ('dynamic intensity and off-resonance changes in k-space', dubbed DICK and DORK) and image analysis using a Laplace operator and a center-of-mass metric. The variability between trials made it essential to correct for inter-trial variations. On the other hand, images were sufficiently stable with our approach to perform fMRI evaluations on single trials before averaging of trials. Different motion correction strategies were compared: DORK, McFLIRT (rigid body model with three translations and three rotations) and 2D image alignment based on a center-of-mass detection (in-plane translation). The latter yielded the best results and proved to be fast and robust for intra- and inter-trial alignment. Finally, fMRI in the behaving monkey was tested for spatial and temporal reproducibility on a trial-to-trial basis. Highly activated voxels also displayed good reproducibility between trials. On average, the BOLD amplitude response to a short 3-s visual stimulus was close to 2%.