Customizing MRI-Compatible Multifunctional Neural Interfaces through Fiber Drawing

Fiber drawing enables scalable fabrication of multifunctional flexible fibers that integrate electrical, optical, and microfluidic modalities to record and modulate neural activity. Constraints on thermomechanical properties of materials, however, have prevented integrated drawing of metal electrodes with low-loss polymer waveguides for concurrent electrical recording and optical neuromodulation. Here, two fabrication approaches are introduced: 1) an iterative thermal drawing with a soft, low melting temperature (T_m) metal indium, and 2) a metal convergence drawing with traditionally non-drawable high T_m metal tungsten. Both approaches deliver multifunctional flexible neural interfaces with low-impedance metallic electrodes and low-loss waveguides, capable of recording optically-evoked and spontaneous neural activity in mice over several weeks. These fibers are coupled with a light-weight mechanical microdrive (1 g) that enables depth-specific interrogation of neural circuits in mice following chronic implantation. Finally, the compatibility of these fibers with magnetic resonance imaging is demonstrated and they are applied to visualize the delivery of chemical payloads through the integrated channels in real time. Together, these advances expand the domains of application of the fiber-based neural probes in neuroscience and neuroengineering.     

Flow and temperature patterns in an inductively coupled plasma reactor: Experimental measurements and CFD simulations

Measurements of temperature patterns in an inductively coupled plasma (ICP) have been carried out experimentally. Plasma torch was operated at different RF powers in the range of 3–14 kW at near atmospheric pressure and over a wide range of sheath gas flow rate (3–25 lpm). Measurements were made at five different axial positions in ICP torch. The chordal intensities were converted into a radial intensity profile by Abel Inversion technique. Typical radial temperature profile shows an off‐axis temperature peak, which shifts toward the wall as the power increases. Temperatures in the range of 6000–14,000 K were recorded by this method. The temperature profiles in the plasma reactor were simulated using computational fluid dynamics (CFD). A good agreement was found between the CFD predictions of the flow and temperature pattern with those published in the literature as well as the temperature profiles measured in the present work. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3647–3664, 2014     

The affinity of an oligodeoxynucleotide-peptide conjugate for an RNA hairpin loop depends on stereochemistry at the DNA-peptide junction

Molecular models of an oligodeoxynucleotide-peptide conjugate complexed to an RNA hairpin loop were constructed to assess the effect of stereoisomerism at the point of attachment of the peptide to the oligodeoxynucleotide on the affinity of the conjugate for an RNA target. The peptide portion of the oligodeoxynucleotide-peptide conjugate, (L-lysine)8, was covalently attached to the N-allyl group of (D)- or (L)-aspartic alcohol that was incorporated into the interior of an antisense oligodeoxynucleotide. The stereocenter in the oligodeoxynucleotide interior originates from either (D)- or (L)-aspartic alcohol. The oligodeoxynucleotide portion of the oligodeoxynucleotide-peptide conjugate forms Watson-Crick base pairs with the single-stranded RNA that flanks the RNA hairpin loop. The positively charged peptide makes specific electrostatic contacts with the negatively charged phosphate backbone of the RNA hairpin loop when attached to the N-allyl of (D)-aspartic alcohol but does not have the proper orientation to make these electrostatic contacts when attached to the N-allyl of (L)-aspartic alcohol. This modelling study emphasizes the importance of stereocontrol at the point of branching in synthesizing oligodeoxynucleotide-peptide conjugates for binding of RNA hairpin loops.     

Thrombospondin-1 CD47 Signalling: From Mechanisms to Medicine

Recent advances provide evidence that the cellular signalling pathway comprising the ligand-receptor duo of thrombospondin-1 (TSP1) and CD47 is involved in mediating a range of diseases affecting renal, vascular, and metabolic function, as well as cancer. In several instances, research has barely progressed past pre-clinical animal models of disease and early phase 1 clinical trials, while for cancers, anti-CD47 therapy has emerged from phase 2 clinical trials in humans as a crucial adjuvant therapeutic agent. This has important implications for interventions that seek to capitalize on targeting this pathway in diseases where TSP1 and/or CD47 play a role. Despite substantial progress made in our understanding of this pathway in malignant and cardiovascular disease, knowledge and translational gaps remain regarding the role of this pathway in kidney and metabolic diseases, limiting identification of putative drug targets and development of effective treatments. This review considers recent advances reported in the field of TSP1-CD47 signalling, focusing on several aspects including enzymatic production, receptor function, interacting partners, localization of signalling, matrix-cellular and cell-to-cell cross talk. The potential impact that these newly described mechanisms have on health, with a particular focus on renal and metabolic disease, is also discussed.     

Application of thin-layer chromatography to the quantitative estimation of tissue triglycerides. I. Triglyceride distribution in the livers of calf,pig and rat

A multiple technique (TLC-GLC) has been applied to the quantitative estimation of triglycerides in the livers of calf, pig and rat. The results are in general agreement with the triglyceride pattern calculated from the fatty acid distribution as suggested by Vander Wal (15). Presented at the AOCS meeting in Houston, Texas, April 1965.     

Improved depth map through optimal axis stereo

Feature-based stereo correspondence techniques suffer from the major limitation that it is difficult to match along epipolar lines and this often results in a sparse set of depth points. Past researchers attempted to solve this problem through trinocular stereo. In this paper, a new method has been proposed for reducing the sparsity of depth points by orienting the epipolar line of the cameras in a direction that maximizes the number of feature points. The corresponding epipolar axis has been termed as the optimal axis. Our analytical as well as simulation results have established that for a limited edge scenario, the proposed approach can lead to considerable improvement in the number of feature points that can be matched. We have introduced a figure-of-merit for the optimal axis and discussed how it is qualitatively related to the variance of the probability density function (pdf). We have also presented the results of our simulation experiment, termed as the random stick experiment. Finally, we have also shown the results of improved reconstructed surface of a synthetic image using optimal axis alignment.     

Fast algorithm for the solution of banded linear systems

Linear systems can be solved by converting the coefficient matrix into a triangular matrix. If it is known, apriori, that the coefficient matrix is a banded matrix having only few non zero diagonals, then a substantial saving in both the time and the storage on the computer can be achieved. In this paper a new algorithm has been developed for triangularisation of the banded matrix. The algorithm is computationally economical and advantageous as compared to the existing known algorithms. The advantage decreases with the increase in bandwidth and the break even point being approximately N/√3 where N is the size of the square matrix.     

A chromatographic method for the analysis of propylene glycol fatty acid esters in shortenings containing mono- and diglycerides

A procedure is described for the separation, identification, and quantitative estimation of propylene glycol mono- and diesters of lauric, myristic, palmitic, stearic, and oleic acids in shortenings and lard containing mono- and diglycerides. Lipid classes are separated on a silicic acid column, and individual esters are estimated by gas chromatography. Analyses of several control mixtures and commercial samples are reported. Recoveries for individual components range from 92 to 105%, and total recoveries range from 96 to 100%.