A qualocation method for Burgers’ equation

In this paper, a qualocation method for the one-dimensional Burgers’ equation is proposed. A semidiscrete scheme along with optimal error estimates is discussed. Results of a numerical experiment performed support the theoretical results.     

Molecular dynamics simulations,docking and MMGBSA studies of newly designed peptide-conjugated glucosyloxy stilbene derivatives with tumor cell receptors

Molecular Diversity - In this work, for the first time, we designed derivatives of beta-D-glucosyloxy-3-hydroxy-trans-stiblene-2-carboxylic acid (GHS), by conjugating GHS with tumor targeting...     

Finite element approximation to global stabilization of the Burgers’ equation by Neumann boundary feedback control law

In this article, we discuss global stabilization results for the Burgers’ equation using nonlinear Neumann boundary feedback control law. As a result of the nonlinear feedback control, a typical nonlinear problem is derived. Then, based on C ⁰-conforming finite element method, global stabilization results for the semidiscrete solution are analyzed. Further, introducing an auxiliary projection, optimal error estimates in \(L^{\infty }(L^{2})\), \(L^{\infty }(H^{1})\) and \(L^{\infty }(L^{\infty })\)-norms for the state variable are obtained. Moreover, superconvergence results are established for the first time for the feedback control laws, which preserve exponential stabilization property. Finally, some numerical experiments are conducted to confirm our theoretical findings.     

Erratum to: Osmo-dehydration of apple pulp studied by means of classical and Knudsen Thermogravimetric approach

Classical thermogravimetry and its modification with Knudsen cells were employed to quantitatively investigate the osmo-dehydration of apple pulp samples. The data allowed realization of the complex mechanism of the process, which is not a mere solvent depletion, since it also implies sugar exchanges between the apple tissue and the hypertonic syrup used to dehydrate the fruit. The comparison between different hypertonic syrups, all at the same water activity, showed that maltose is more effective than either sucrose or a mixture of sugars that mimics the saccharide content of the apple. The conclusions are supported by a thermodynamic analysis of the aqueous solutions of these sugars at a concentration level as large as that of the hypertonic syrups used for the osmo-dehydration process.     

Application of host-guest chemistry in nanotube-based device fabrication: photochemically controlled immobilization of azobenzene nanotubes on patterned alpha-CD monolayer/Au substrates via molecular recognition

Azobenzene-functionalized nanotubes recognized and attached onto well-defined complementary regions of thiolated alpha-CD SAM/Au substrates via host-guest molecular recognition. The binding between the azobenzene nanotubes and the alpha-CD SAM/Au substrates was controlled by UV irradiation. The light-induced attachment-detachment of the azobenzene nanotubes on the alpha-CD SAMs was reversible. Some of the nanotubes were capable of interconnecting two Au substrates. This smart building block may be applied to build photoactive nanometer-sized mechanical switches in electronics.     

Smart polymeric materials: emerging biochemical applications

Smart polymeric materials respond with a considerable change in their properties to small changes in their environment. Environmental stimuli include temperature, pH, chemicals, and light. "Smart" stimuli-sensitive materials can be either synthetic or natural. This review discusses the application of smart materials as tools to solve biological problems such as bioseparation, drug delivery, biosensor design, tissue engineering, protein folding, and microfluidics. The goal for these endeavors is to mimic the "smartness" of biological systems and ultimately moderate complex systems such as immune responses at desired levels. The versatility and untapped potential of smart polymeric materials makes them one of the most exciting interfaces of chemistry and biology.     

Room-temperature Wurtzite ZnS nanocrystal growth on Zn finger-like peptide nanotubes by controlling their unfolding peptide structures

ZnS nanocrystal, a class of wide-gap semiconductors, has shown interesting optical, electrical, and optoelectric properties via quantum confinement. For those applications, phase controls of ZnS nanocrystals and nanowires were critical to tune their physical properties to the appropriate ones. The wurtzite ZnS nanocrystal growth at room temperature is the useful fabrication; however, the most stable ZnS structure in nanoscale is the zinc blende (cubic) structure, and scientists have just begun exploring the room-temperature synthesis of the wurtzite (hexagonal) structure of ZnS nanocrystals. In this report, we applied the Zn finger-like peptides as templates to control the phase of ZnS nanocrystals to the wurtzite structure at room temperature. The peptide nanotubes, consisting of a 20 amino acids (VAL-CYS-ALA-THR-CYS-GLU-GLN-ILE-ALA-ASP-SER-GLN-HIS-ARG-SER-HIS-ARG-GLN-MET-VAL, M1 peptide) synthesized based on the peptide motif of the Influenza Virus Matrix Protein M1, could grow the wurtzite ZnS nanocrystals on the nanotube templates in solution. In the M1 protein, the unfolding process of the helical peptide motif via pH change creates a linker region between N- and C-terminated helical domains that contains a Zn finger-like Cys2His2 motif. Because the higher pH increases the uptake of Zn ions in the Cys2His2 motif of the M1 peptide by unfolding more helical domains, the pH change can essentially control the size and the number of the nucleation sites in the M1 peptides to grow ZnS nanocrystals with desired phases. Here we optimized the nucleation sites in the M1 peptides by unfolding them via pH change to obtain highly monodisperse and crystalline wurtzite ZnS nanocrystals on the template nanotubes at room temperature. This type of peptide-induced biomineralization technique will provide a clean and reproducible method to produce semiconductor nanotubes due to its efficient nanocrystal formation, and the band gaps of resulting nanotubes can also be tuned simply by phase control of ZnS nanocrystal coatings via the optimization of the unfolding peptide structures.     

Biological bottom-up assembly of antibody nanotubes on patterned antigen arrays

Application of biotechnology in nanofabrication has an advantage to produce functional building-block materials that may not have synthetic counterparts. Here we introduced a new type of building block, antibody nanotubes, and demonstrated anchoring them on complementary antigen arrays via antibody-antigen recognition. Biological recognition between the antibody nanotubes and the antigen arrays permitted recognition-driven assembly of ordered nanotube arrays. The array of antigens was written by using the tip of an atomic force microscope (AFM) on alkylthiol self-assembled monolayer (SAM)-coated Au substrates via nanografting. After antigens were immobilized onto the shaved regions of the alkylthiol SAMs with the AFM tip, antibody nanotubes, produced by incubating antibodies in template nanotube solutions, were selectively attached onto the antigen regions. This technique is very useful when multiple building blocks are necessary to address specific locations on substrates because simultaneous immobilization of multiple antibody nanotubes at specific complementary binding positions can be achieved in a single process.     

Purification of a bacterial pullulanase on a fluidized bed of calcium alginate beads

Pullulanase from Bacillus acidopullulyticus was purified on a packed bed and a fluidized bed of calcium alginate beads. The binding of enzyme activity to the medium was found to follow Langmuir isotherm pattern. The maximum binding capacity was 1476 U ml⁻¹ matrix and the dissociation constant was 142 U ml⁻¹. The dynamic binding capacities at 5% breakthrough in the packed and fluidized beds were 472 U ml⁻¹ and 644 U ml⁻¹, respectively. In the packed bed as well as the fluidized bed, an activity recovery of more than 95% with fold purification in the range of 46–59 was observed. The elution with a competitive inhibitor, viz. maltose, and high-fold purification indicate an affinity-based process. The purification process worked equally well with columns of bed volumes of 3.8 and 10 ml.