An exact depth-first algorithm for the pallet loading problem

This paper proposes a fast exact algorithm to solve the Pallet Loading Problem (PLP) using depth-first strategy. A new concept called Maximal Breadth Filling Sequence (MBFS) is introduced to bring down the size of the search tree. The algorithm makes use of two pruning rules — lower-bound pruning and state-dominance pruning. Although depth-first search, by itself, requires very little memory, the dominance pruning rule makes effective utilization of the available memory. For large problems, more the memory available, more effective is the dominance pruning. The algorithm has been tested on standard problem sets. It has been found to be quite fast in outputting optimal solutions. Empirical findings are given in detail.     

Heavy-metal pollution and its state in algae in Kakehashi river and Godani river at the foot of Ogoya mine, Ishikawa Prefecture.

Alga as Achnanthes minutissima among diatoms is a widely adaptable taxon on the state of an aquatic environment. In this study, it was found that diatom had a specific tolerance to heavy metals (Cu, Zn, Pb, and Cd etc.) in river water samples, because the diatom assemblage consisted of almost only Achnanthes minutissima in Kakehashi river and Godani river, which were polluted with waste water from Ogoya copper mine. The relationship between the concentrations of heavy metals (Cu, Zn, Pb and Cd) in river water and the attached substances (algae and silt etc.) and the relative abundances of diatom taxa were investigated in detail. The results indicated that the higher is the concentration of heavy metals in the river environment, the higher is only the relative abundances of Achnanthes minutissima. Thus, the taxon can be used as a bioindicator of heavy metal pollution. The relative rates of toxic chemical forms of copper in algae were 61 - 92% in the attached substances and 49-70% in the sediment on the river bed, respectively. Therefore, it was found that diatom as Achnanthes minutissima had a tolerance to heavy metals in river water, being able to live in such an environment. Since the water treated with calcium hydroxide from the deposition reservoir of Ogoya mine enters in Godani river, the river is polluted by heavy metals (Cu, Zn, Pb and Cd etc.). From the viewpoint of both biological and chemical analyses, Godani river is still polluted with heavy metals, because their concentrations in the river samples were very high. On the other hand, in Kakehashi river, the concentrations of heavy metals were very low and the distributions of some diatoms appeared in an unpolluted Nishimata river were observed. Therefore, Kakehashi river seems to be considerably recovered from heavy-metal pollution after closing the Ogoya mine.     

Effect of hydrogen-bonding interactions on the self-assembly formation of sodium N-(11-acrylamidoundecanoyl)-L-serinate, L-asparaginate, and L-glutaminate in aqueous solution

Aggregation behavior of three N-acyl amino acid surfactants, sodium N-(11-acrylamidoundecanoyl)-l-serinate (SAUS), sodium N-(11-acrylamidoundecanoyl)-l-asparaginate (SAUAS), and sodium N-(11-acrylamidoundecanoyl)-l-glutaminate (SAUGL), was studied in aqueous solution by use of surface tension, fluorescence, dynamic light scattering, and transmission electron microscopic techniques. The amphiphiles have been shown to initially form flexible bilayer structures, which upon increase of surfactant concentration transform into closed spherical vesicles. The transmission electron micrographs of the aqueous solutions of the surfactants confirmed the existence of spherical vesicles. Dynamic light scattering measurements were performed to obtain hydrodynamic radii of the vesicles. Circular dichroism spectra of the amphiphiles indicated formation of chiral helical aggregates in the case of SAUS. The self-assembly formation of the amphiphiles has been discussed in light of the intermolecular hydrogen bonding interaction of the amide groups.     

Reducible properties of draw temperature,rate of strain and filler content in tensile yield stress of polymethylmethacrylate filled with ultrafine particles

The yield stress of polymethylmethacrylate (PMMA) composites filled with ultrafine SiO₂ particles was measured as a function of the draw temperature, rate of strain and filler content. The yield stress of the composites increased with increasing filler content and decreasing filler size. The tensile yield stress was found to be reducible with regard to draw temperature, rate of strain and filler content. At a given filler content, a master curve was obtained for the yield stress plotted versus the logarithm of the strain rate. The Arrhenius plot of the shift factors (a _T ) used to produce the strain rate-temperature master curve formed a single curve for all sizes and loadings of the filler. The master curves obtained for different loadings of a filler of given size could be further reduced into a master-master curve by shifting them along the axis of strain rate, with the logarithm of the second shift factors (loga _c ) proportional to the 4/5th power of the filler volume fraction (V _f ). The proportionality constant and the exponent represent the extent of the filler reinforcing effect in the polymer. These values were found to be correlated with the critical surface tension of the polymers.     

Acid‐Promoted Chemoselective Introduction of Amide Functionality onto Aromatic Compounds Mediated by an Isocyanate Cation Generated from Carbamate

Carbamates have been used as precursors of isocyanates, but heating in the presence of strong acids is required because cleavage of the C? O bond in carbamates is energy‐demanding even in acid media. Direct amidation of aromatic compounds by isocyanate cations generated at room temperature from carbamoyl salicylates in trifluoromethanesulfonic acid (TfOH) was examined. Carbamates with ortho‐salicylate as an ether group (carbamoyl salicylates) showed dramatically accelerated O? C bond dissociation in TfOH, which resulted in facile generation of the isocyanate cation. These chemoselective intermolecular aromatic amidation reactions proceeded even at room temperature and showed good compatibility with other electrophilic functionalities and high discrimination between N‐monosubstituted carbamate and N,N‐disubstituted carbamate. The reaction rates of secondary and tertiary amide formation were markedly different, and this difference was utilized to achieve successive (tandem) amidation reactions of molecules with an N‐monosubstituted carbamate and an N,N‐disubstituted carbamate with two kinds of aromatic compounds.     

Pre-treatment of polyethylene terephthalate by Grignard reagents for high quality polypyrrole coatings and for altering the hydrophobicity

Polypyrrole-coated polyethylene terephthalate is very attractive for various applications as electrically conductive fiber. This paper investigates the importance of polyester pre-treatment on the quality of the polypyrrole coating and its conductivity efficiency. The results showed nucleophilic pre-treatments by Grignard reagents resulting in the significantly higher surface quality and strongest adhesion of the polypyrrole coating to the polyester fibers compared to the other published methods. Moreover, several Grignard reagents were used for altering the hydrophobicity and morphology of the surface.     

An ESR study of polymer-Cu(II) complexes in poly(vinyl alcohol), polyacrylamide,and poly(vinyl pyrrolidone) films

Optical and ESR spectra of polymer-Cu(II) complexes in polymer films have been studied. The dependence on F₁ = [Cu²⁺]/[MU] and F₂ = [OH^?]/[Cu²⁺], where [MU] is the molar concentration of monomeric units of the polymer, has been obtained. Optical spectra and potentiometric titration curves in solution have also been studied. There exists a buffer region 0 ? F₂ ? 2. Optical spectra in films are slightly different from those in solutions. At least five different ESR signals, designated as A, B, C or D, and E, have been found in poly(vinyl alcohol)-Cu(II). These signals appear successively with increasing F₂. Assignments are proposed as follows. Signal A (F₂ ≈ 0), also found in poly(acrylamide)-Cu(II) and poly(vinyl pyrrolidone)-Cu(II), is due to a single Cu(II) coordinated with two water molecules and chelated with two oxygens or nitrogens attached to the polymer. A chain of Cu(II) ions singly and double bridged with OH^? ions is responsible for the B signal (F₂ ≈ 1). The C and D signals (F₂ ≈ 2) appear to be caused, respectively, by a dimeric Cu(II) complex singly or doubly bridged with OH^? ions. The E signal (F₂ ≈ 7) appears to be due to a monomeric Cu(II) complex, different from that responsible for the A signal.     

Efficiently accounting for ion correlations in electrokinetic nanofluidic devices using density functional theory

The electrokinetic behavior of nanofluidic devices is dominated by the electrical double layers at the device walls. Therefore, accurate, predictive models of double layers are essential for device design and optimization. In this paper, we demonstrate that density functional theory (DFT) of electrolytes is an accurate and computationally efficient method for computing finite ion size effects and the resulting ion-ion correlations that are neglected in classical double layer theories such as Poisson-Boltzmann. Because DFT is derived from liquid-theory thermodynamic principles, it is ideal for nanofluidic systems with small spatial dimensions, high surface charge densities, high ion concentrations, and/or large ions. Ion-ion correlations are expected to be important in these regimes, leading to nonlinear phenomena such as charge inversion, wherein more counterions adsorb at the wall than is necessary to neutralize its surface charge, leading to a second layer of co-ions. We show that DFT, unlike other theories that do not include ion-ion correlations, can predict charge inversion and other nonlinear phenomena that lead to qualitatively different current densities and ion velocities for both pressure-driven and electro-osmotic flows. We therefore propose that DFT can be a valuable modeling and design tool for nanofluidic devices as they become smaller and more highly charged.