Novel chalcone-based aromatic polyamides: synthesis,characterization, and properties

Two novel diacid-based monomers have been synthesized by anchoring a benzylideneacetophenone (chalcone) moiety through an amide or ester bridge at the fifth position of the isophthalic acid ring. Two series of new polyamides bearing chalcone side chains were prepared by direct polycondensation reaction of the aforementioned dicarboxylic acids and various aromatic diamines in N-methyl-2-pyrrolidinone, using triphenyl phosphite and pyridine as condensing agents. Their molecular structure and the basic properties were investigated by nuclear magnetic resonance, Fourier-transform IR and UV–vis spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction. The inherent viscosity, molecular weights measurements (by gel permeation chromatography), water uptake, and solubility tests completed the research study. Introduction of the rigid and bulky chalcone units into the polymer side chains improved remarkably the solubility of the aromatic polyamides, endowed them with an amorphous nature, good thermal stability, and photosensitivity. The resulting polymers were obtained in good yields, inherent viscosities varied between 0.49 and 0.86 dL/g, and their relative high molecular weights conferred them film-forming properties. They were soluble in amide-type polar solvents, such as N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These polyamides had glass transition temperatures between 219 and 264 °C, and 10% weight loss temperatures in the range of 394–436 °C and around 50% residue at 700 °C in nitrogen atmosphere. The polyamides underwent a [2 + 2] photocycloaddition reaction upon UV light irradiation both in solution and film state in the absence of a photoinitiator or photosensitizer. The polymer films became insoluble in solvents as a result of the crosslinking .     

Interactive simulation of needle insertion models

A novel interactive virtual needle insertion simulation is presented. The simulation models are based on measured planar tissue deformations and needle insertion forces. Since the force-displacement relationship is only of interest along the needle shaft, a condensation technique is shown to reduce the computational complexity of linear simulation models significantly. As the needle penetrates or is withdrawn from the tissue model, the boundary conditions that determine the tissue and needle motion change. Boundary condition and local material coordinate changes are facilitated by fast low-rank matrix updates. A large-strain elastic needle model is coupled to the tissue models to account for needle deflection and bending during simulated insertion. A haptic environment, based on these novel interactive simulation techniques, allows users to manipulate a three-degree-of-freedom virtual needle as it penetrates virtual tissue models, while experiencing steering torques and lateral needle forces through a planar haptic interface.     

4-D x 3-D ultrasound: real-time scan conversion, filtering, and display of displacement vectors with a motorized curvilinear transducer

Recent research in the field of elastography has sought to expand displacement tracking to three dimensions. Once the 3-D volumes of displacement data have been obtained, they must be scan converted so that further processing, such as inversion methods to obtain tissue elasticity, can take place in Cartesian coordinates. This paper details an efficient and geometrically accurate algorithm to scan convert 3-D volumes of displacement vectors obtained from a motorized sector transducer. The proposed algorithm utilizes the physical scan geometry to convert the 3-D volumes of displacement data to both Cartesian coordinates and Cartesian displacements. Spatially varying filters are also proposed to prevent aliasing while minimizing data loss. Validation of the system has shown the algorithm to be correct to floating point precision, and the 3-D scan conversion and filtering can be performed faster than the native rate of data acquisition for the motorized transducer.     

2-D high-frame-rate dynamic elastography using delay compensated and angularly compounded motion vectors: preliminary results

This paper describes a new ultrasound-based system for high-frame-rate measurement of periodic motion in 2-D for tissue elasticity imaging. Similarly to conventional 2-D flow vector imaging, the system acquires the RF signals from the region of interest at multiple steering angles. A custom sector subdivision technique is used to increase the temporal resolution while keeping the total acquisition time within the range suitable for real-time applications. Within each sector, 1-D motion is estimated along the beam direction. The intra- and inter-sector delays are compensated using our recently introduced delay compensation algorithm. In-plane 2-D motion vectors are then reconstructed from these delay-compensated 1-D motions. We show that Young's modulus images can be reconstructed from these 2-D motion vectors using local inversion algorithms. The performance of the system is validated quantitatively using a commercial flow phantom and a commercial elasticity phantom. At the frame rate of 1667 Hz, the estimated flow velocities with the system are in agreement with the velocity measured with a pulsed-wave Doppler imaging mode of a commercial ultrasound machine with manual angle correction. At the frame rate of 1250 Hz, phantom Young's moduli of 29, 6, and 54 kPa for the background, the soft inclusion, and the hard inclusion, are estimated to be 30, 11, and 53 kPa, respectively.     

Corrosion protection of new composite polymer coating for carbon steel in sulfuric acid medium by electrochemical methods

In this paper, electropolymerization technique has been used for the obtained of new composite: polypyrrole – dioctyl sulfosuccinate sodium/poly N-ethylaniline (PPY-AOT/PNEA) coatings over carbon steel of type OLC 45 electrode for anticorrosion protection. The PPY-AOT/PNEA coatings were successfully synthesized onto OLC 45 electrode by galvanostatic deposition from aqueous solutions 0.1 M NEA, 0.1 M PY, 0.01 M AOT and 0.3 M H₂C₂O₄ solution at different current densities (5, 3 and 1 mA/cm²) in different molar ratio. The anionic surfactant (AOT) as a dopant ion used during electropolymerization can have a significant result on the anticorrosion protection of the composite film by hindering the penetration of aggressive ions. The polymeric composite coatings have been analyzed by cyclic voltammetry (CV), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) methods. The corrosion resistance of PPY-AOT/PNEA coated carbon steel has been examined by potentiodynamic polarization techniques and electrochemical impedance spectroscopy (EIS) methods in 0.5 M H₂SO₄ solutions. The data of the corrosion samples demonstrated that PPY-AOT/PNEA coatings assure a great anticorrosion protection of OLC 45 electrode in corrosive media. The corrosion rate of PPY-AOT/PNEA coated OLC 45 has been indicated to be ~9 times lower than of uncoated electrode. The corrosion protection effectiveness of the composite coating is more than 89%. The best efficiency is accomplished of PPY-AOT/PNEA obtained by electrodeposition at 5 mA/cm² current densities applied in molar ratio 5:1.     

Motion estimation in ultrasound images using time domain cross correlation with prior estimates

In this paper we introduce a new speckle tracking method that is based on the standard time-domain cross correlation strain estimation (TDE). We call this method time-domain cross-correlation with prior estimates (TDPE), because it uses prior displacement estimates of neighboring windows to speed up computation. TDPE has all the advantages of TDE, but is much faster. Simulations, as well as experiments with phantoms and tissue, indicate that TDPE is capable of reliably estimating tissue displacement and strain over a large range of displacements in real time. The computational efficiency of TDPE is compared with current time-efficient methods that have been used in real time strain imaging systems. The results show that TDPE is the most time efficient algorithm to date, and is roughly 10 times faster than the TDE. The implementation of TDPE on an Ultrasonix RP500 ultrasound machine runs at 30 fps for strain images of 16 000 pixels.     

A systematic review on the use of quantitative imaging to detect cancer therapy adverse effects in normal-appearing brain tissue

Cancer therapy for both central nervous system (CNS) and non-CNS tumors has been previously associated with transient and long-term cognitive deterioration, commonly referred to as ‘chemo fog’. This therapy-related damage to otherwise normal-appearing brain tissue is reported using post-mortem neuropathological analysis. Although the literature on monitoring therapy effects on structural magnetic resonance imaging (MRI) is well established, such macroscopic structural changes appear relatively late and irreversible. Early quantitative MRI biomarkers of therapy-induced damage would potentially permit taking these treatment side effects into account, paving the way towards a more personalized treatment planning.

This systematic review (PROSPERO number 224196) provides an overview of quantitative tomographic imaging methods, potentially identifying the adverse side effects of cancer therapy in normal-appearing brain tissue. Seventy studies were obtained from the MEDLINE and Web of Science databases. Studies reporting changes in normal-appearing brain tissue using MRI, PET, or SPECT quantitative biomarkers, related to radio-, chemo-, immuno-, or hormone therapy for any kind of solid, cystic, or liquid tumor were included. The main findings of the reviewed studies were summarized, providing also the risk of bias of each study assessed using a modified QUADAS-2 tool. For each imaging method, this review provides the methodological background, and the benefits and shortcomings of each method from the imaging perspective. Finally, a set of recommendations is proposed to support future research.

     

Efficient address space generation for an OPC UA server

The new OPC Unified Architecture has been introduced as a replacement for the existing COM‐based specifications. The article describes a generalized algorithm for the automatic generation of the address space structure for an UA server. First, we present the general startup procedure of an OPC UA server, focusing on the address space generation step. Afterwards we introduce specialized algorithms for the generation of the type nodes, of object, variable, method and view nodes. Finally the additional references are added to the fully meshed address space. The basic ideas of the algorithms are: the splitting of the nodes into groups and the sequential addition of the groups to the address space, and the naming of a main reference for every target node. The algorithms have been applied for an aggregating UA server which models the devices of an assembly line. The main advantages are: shorter development time, easier maintenance and the possibility to add nodes to the address space in both online and offline mode. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparative analysis of the processes of collagen concentration by ultrafiltration using different types of membranes

Tangential flow filtration of the collagen protein solutions with a molecular weight 12, 14, and 24 kDa is investigated using flat sheet membranes. The effects of tangential ultrafiltration (UF) on the permeate properties using two regenerated celluloses (RCs) and two polyethersulfone (PES) membranes with molecular weight cut-off (MWCO) of 5 and 10 kDa are reported. The permeate and concentrate obtained in the UF experiments are characterized from a physical–chemical point of view by determining the temperature, pH, electrical conductivity, nitrogen content, and protein concentration. In addition, the experimental data are modeled using Hermia's model. The UF experiments demonstrated that permeate flux declined with increasing molecular weight of collagen at constant concentration (1%). Regardless of the molecular weight of collagen, the rejections decrease in the following order: PES 5 kDa > RC5kDa > RC10kDa > PES10kDa. In case of membrane with higher MWCO, the clogging phenomenon is mainly due to the blockage of the internal pores of the membrane than the formation of a polarization layer. Morphologies and characteristics of the membranes are characterized using scanning electron microscopy.     

Pyrene functionalized side chain alanine and histidine containing copolyacrylates prepared by free radical copolymerization

An optically active copolyacrylate, poly(N‐acryloyl‐L‐alanine‐co‐N‐acryloyl‐L‐histidine), is prepared by classical radical copolymerization of N‐acryloyl‐L‐alanine and N‐acryloyl‐L‐histidine, and further chemically modified with 1‐pyrene‐methanol. The structures of the synthesized compounds are confirmed by spectral analysis (FTIR, ¹H/¹³C‐NMR, UV, fluorescence spectroscopy), thermal methods, and molecular weight measurements. Also, their optical activity is studied using circular dichroism (CD) spectroscopy and optical rotation measurements. The specific rotation values reveal that the direction of rotation of the parent copolymer is dictated by the monomer containing L‐alanine. CD data suggest negative and positive Cotton effects regarding the monomers with amino acids. In the case of the unmodified copolymer it is noted the changes of ellipticity values with increasing pH while the random‐coil conformation is preserved, which makes it suitable as a pH‐responsive system. Photochemical and photophysical investigations reveal that the pyrene‐functionalized chiroptical copolyacrylate can be used as a fluorescent chemosensor for the detection of nitro‐derivatives in organic media. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44457.