LIDFT method with classic data windows and zero padding in multifrequency signal analysis

This paper presents an advanced discrete Fourier transform linear interpolation method (LIDFT) using classic data windows and a zero padding technique that is well understood from its common use in spectrum analysis with FFT. This advancement of the LIDFT method allows for substantial improvement of its accuracy without deteriorating the condition of the initial location for sinusoidal components in the spectrum, as required in the traditional LIDFT method. Application of classic data windows instead of parametric data window specifically dedicated to the LIDFT method provides numerous opportunities for using this method in multifrequency signal analysis.     

Investigation of the poly(vinyl chloride) extrusion process using a feed throat with a feed pocket

The effectiveness of the extrusion process depends on a number of factors, the most important being barrel design, e.g., longitudinal or helical grooves; screw, feed opening, and polymer hopper designs are significant in this respect, too. The effect of these factors on the extrusion process has been thoroughly discussed in the available literature. This notwithstanding, there is little information providing insight on the effect of a feed pocket made below the feed opening, on the side of the barrel toward which the screw rotates, on the main characteristics of the extrusion process. For the experiments, five special profile inserts with different feed pocket depths were made and then mounted in the extruder barrel equipped with a 25‐mm diameter screw. The extrusion of plasticized poly(vinyl chloride) (PVC) at the screw speed ranging from 30 to 150 rpm was investigated. Presented graphically as charts, the obtained results show the dependences of extrudate temperature, extruder screw torque, polymer output, power supplied to the extruder and conveyed by the polymer, unit energy consumption and energy efficiency on the feed pocket depth, and screw speed. It has been found that the feed pocket made in the extruder barrel has little effect on the course and effectiveness of plasticized PVC extrusion and does not worsen the studied properties of the received extrudate; yet, it should be taken into account to ensure the highest polymer output and lowest energy consumption. POLYM. ENG. SCI., 54:2037–2045, 2014. © 2013 Society of Plastics Engineers     

Analysis of a cross wedge rolling process for producing drive shafts

The paper discusses the problems of forming parts such as stepped shafts by cross wedge rolling (CWR). In industrial practice, this rolling process is performed at stages, i.e., in several passes, when large cross-sectional reductions are involved. The same can also be done using a different design of this forming process, namely, multi-wedge cross rolling (MWCR), in which the workpiece is simultaneously formed by several pairs of tools (wedges). This paper compares the above two methods with respect to forming a drive shaft. Wedge tools used in both forming processes are described, and the numerical results of the simulations performed to verify the adopted solutions are reported. The results demonstrate that the MWCR method offers more advantages than the classical CWR technique. Consequently, MWCR is then verified in experimental tests. The experimental results confirm that parts such as stepped shafts can be formed by the MWCR method.     

Development and Characterization of the Injection-Molded Polymer Composites Made from Bicomponent Fibers

The results of this study are related to the implementation of the concept of self-reinforced composites. The input materials in preparation process were the bicomponent fibers. The studies were carried out on three types of fibers, HDPE/PP, cPP/PP, LPET/PET. In each case, the matrix material was a low melting polymer, and the core was made of a higher melting point polymer. The research was conducted for the materials shaped by an injection-molding technique. The analyses confirmed the two-component structure. Properties of the resulting composites confirmed the applicability of bicomponent fibers in the preparation of self-reinforced composites.     

Effect of different concentration of rapeseed‐oil‐based polyol and water on structure and mechanical properties of flexible polyurethane foams

Flexible polyurethane foams (FPURFs) with varied concentration of water from 3.2 to 4.2% and rapeseed oil based polyol (ROP) in the range of 13–22% in polyol premix were obtained. Effects of changes in polyurethane (PUR) formulation on the foaming process and mechanical properties of FPURFs were analyzed. It was found that the change of water content in PUR formulation influences its foaming process. Higher water content in the PUR formulation increases the growth velocity and the temperature of reaction mixture. In the case of foams modified with ROP, an opposite effect can be observed, where higher content of that component resulted in overall downturn of the foaming process and decreases of registered temperature inside the foams core. An addition of ROP beneficially influences on foams cellular structure favoring creation of finer cells. Such modification of PUR formulation with ROP increased apparent density, reduced hardness, and resilience of flexible foams. What is more the support factor of FPURFs with ROP was higher in comparison to the reference foam. Along with higher water content in the PUR formulation, apparent density and hardness has decreased and foams ability to absorb energy has been increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42372.     

Functional Modification of Fibronectin by N‐Terminal FXIIIa‐Mediated Transamidation

A straightforward strategy is presented for the site‐specific incorporation of fluorophores or reactive probes into the extracellular matrix (ECM) protein fibronectin (Fn) by using the enzyme‐catalyzed transamidation by activated factor XIII. Characterization by SDS‐PAGE, western blotting, absorption measurements, mass spectrometry, and stepwise photobleaching for labeling quantification at the single‐molecule level showed that the labeling was efficient and restricted to the N‐terminal tails. The introduction of labels did not interfere with Fn fibrillogenesis, as verified by the incorporation of fluorescently labeled Fn into ECM and manually pulled Fn fibers. Site‐specific incorporation of an azide was used to create a template for bioorthogonal click chemistry reactions in a second bioconjugation step, thus offering versatile modification and application possibilities in the context of matrix biology and tissue engineering.     

Identification of Novel CERT Ligands as Potential Ceramide Trafficking Inhibitors

A highly compartmentalized enzymatic network regulates the pro‐apoptotic and proliferative effects of sphingolipids. Over‐conversion of ceramide (Cer) correlates with insensitivity to apoptosis signaling (in response to chemotherapy) and to drug resistance of cancer cells. De novo sphingomyelin biosynthesis relies on non‐vesicular ceramide trafficking by the CERT (CERamide Transfer) protein. Therefore, blocking CERT transfer, thus leading to increased intracellular ceramide availability, represents a potential anticancer strategy. Our study is based on the implementation of an in vitro binding assay, supported by in silico molecular docking. It constitutes the first attempt to explore at the molecular level for the identification of novel CERT ligands. This approach is the first step toward in silico design and optimization of CERT inhibitor candidates, potentially relevant as innovative ceramide‐transfer‐targeting therapeutic agents.     

Targeting DNA G‐Quadruplexes with Helical Small Molecules

We previously identified quinoline‐based oligoamide helical foldamers and a trimeric macrocycle as selective ligands of DNA quadruplexes. Their helical structures might permit targeting of the backbone loops and grooves of G‐quadruplexes instead of the G‐tetrads. Given the vast array of morphologies G‐quadruplex structures can adopt, this might be a way to achieve sequence selective binding. Here, we describe the design and synthesis of molecules based on macrocyclic and helically folded oligoamides. We tested their ability to interact with the human telomeric G‐quadruplex and an array of promoter G‐quadruplexes by using FRET melting assay and single‐molecule FRET. Our results show that they constitute very potent ligands—comparable to the best so far reported. Their modes of interaction differ from those of traditional tetrad binders, thus opening avenues for the development of molecules specific for certain G‐quadruplex conformations.     

On Dimensionality of Halogen-Bonded Thiophene Solid-State Assemblies

We report on the structures of three dibromothiophene compounds ( 4 , 5 , and 12 ) and the analysis of the patterns of self-assembly in the solid state by C Br⋅⋅⋅Br C halogen bonds of a selected set of 16 di- or poly-bromine (poly)thiophene monomers sorted according to the dimensionality of their halogen-bonded, extended frameworks thereby identifying syn- or anti-strings and layers. We conclude that in 1 , 2 , 9 , and 10 , the antiparallel orientation of successive C Br⋅⋅⋅Br C halogen-bonded dibromothiophene units along extended anti-strings is linked to the occurrence of solid-state polymerization.