Generators for comonoids and universal constructions

We investigate cofree coalgebras, and limits and colimits of coalgebras in some abelian monoidal categories of interest, such as bimodules over a ring, and modules and comodules over a bialgebra or Hopf algebra. We find concrete generators for the categories of coalgebras in these monoidal categories, and explicitly construct cofree coalgebras, products and limits of coalgebras in each case. This answers an open question in Agore (Proc Am Math Soc 139:855–863, 2011) on the existence of a cofree coring, and constructs the cofree (co)module coalgebra on a B-(co)module, for a bialgebra B.     

Improving the design stresses of high density polyethylene pipes and vessels used in reverse osmosis desalination plants

Nanocomposite materials have been used on a wide scale in industrial and structural applications. The present work aims at studying the mechanical properties of high density polyethylene (HDPE) grade TR-401 hexene copolymer reinforced by montmorillonite nanoparticles (MMT), used to fabricate pipes and membranes vessels for reverse osmosis desalination plants. Different volume fractions and particle sizes of the MMT clay were used to investigate the effect of this filler on the mechanical properties of the produced composite. Mechanical properties tests were carried out and good improvements of the composite properties were obtained compared to the parent polymer. The test results showed a significant enhancement of the mechanical properties at low filler proportions. Pipe fabricated from these composites had many outstanding and desirable features. For example, by adding 4.75% MMT to the HDPE produced quality pipes and fittings with the highest design stress basis of any polyethylene. A significant increase in the modulus of elasticity observed, together with an unusual increase in the design stress, approved the HDPE/MMT composite for high pressure piping and membrane vessels used in reverse osmosis desalination plants.     

Synthesis of Hg metal complex and its application to reduce the optical band gap of polymer

This study explored a new approach to fabricate the Schiff base ligand system from both ethylenediamine and 3-chloro-2-butanone. Through coordination chemistry, the mercury Hg (II) complex was achieved from the ligand and then embedded in the polyvinyl alcohol (PVA) host using a solution casting technique to prepare polymer composites (PCs). Both UV–visible and Fourier-transform infrared (FTIR) spectroscopies highlighted the formation of the Hg (II) metal complex. These techniques confirmed the synthesis of the Hg (II) metal complex. The X-ray diffraction (XRD) pattern of the polymer composite has shown a significant enhancement in its amorphous nature compared to the pure PVA host. The thermal analysis spectra for the Hg (II) complex revealed high thermal stability. The occurrence of the complexation between the Hg (II) and host matrix of the PVA was identified from the wide shifting of UV–vis absorption and peak shifting with intensity reduction of the FTIR spectra. Tauc's method has been employed to evaluate the optical band gap, and determine the types of electronic transitions. The results have shown that the samples were exhibiting an indirect forbidden electron transition, with a significant reduction in the optical band gap of a doped sample that approaching inorganic semiconductor based-materials. In addition, the optical study has exposed the role of the Hg (II) complex in tuning the refractive index of the host polymer. Ultimately, the absorption edge was found to be shifted to the lower photon energy upon the insertion of the Hg (II) complex. The PVA doped sample displayed a substantial shift in band gap from 6.2 eV to 1.2 eV.     

Throughput improvement and PAPR reduction for OFDM-based VLC systems using an integrated STC-IMADJS technique

Optical and Quantum Electronics - Three kinds of nonlinear ring resonators were used for designing an all optical encoder based on photonic crystals. The simulation results show that when more than...