Tractive performance of a bulldozer running on weak ground

To determine the tractive performance of a bulldozer running on weak ground in the driven state, the relations between driving force, drawbar pull, sinkage, eccentricity and slip ratio have been analysed together with each energy balance; effective input energy, sinkage deformation energy, slippage energy and drawbar pull energy. It is considered that the thrust is developed not only on the main straight part of the bottom track belt but also on parts of the front idler and rear sprocket, and the compaction resistance is calculated from the amount of slip sinkage. For a given vehicle and soil properties, it is determined that the drawbar pull increases directly with the slip ratio and reaches about 70% of the maximum driving force. The compaction resistance reaches about 13% of the maximum driving force. The sinkage of the rear sprocket, the eccentricity, and the trim angle increase with the increment of slip ratio due to the slip sinkage. These analytical results have been verified experimentally. After determining the optimum slip ratio to obtain a maximum effective tractive power, it is found that a larger optimum drawbar pull at optimum contact pressure could be obtained for a smaller eccentricity of vehicle center of gravity and a larger track length-width ratio under the same contact area.     

Unconventional Magnetic and Resistive Hysteresis in an Iodine‐Bonded Molecular Conductor

Simultaneous manipulation of both spin and charge is a crucial issue in magnetic conductors. We report on a strong correlation between magnetism and conductivity in the iodine‐bonded molecular conductor (DIETSe)₂FeBr₂Cl₂ [DIETSe=diiodo(ethylenedithio)tetraselenafulvalene], which is the first molecular conductor showing a large hysteresis in both magnetic moment and magnetoresistance associated with a spin‐flop transition. Utilizing a mixed‐anion approach and iodine bonding interactions, we tailored a molecular conductor with random exchange interactions exhibiting unforeseen physical properties.     

Reversed phase liquid chromatographic determination of organic acids using on-line complexation with copper(II) ion

We describe a simple and sensitive liquid chromatographic method for the analysis of organic acids using on-line complexation with copper(II) ion. Organic acids complexed with copper(II) ion were separated on a reversed-phase C18 column and detected by UV absorption at 240 nm. The copper(II) ion concentration in the mobile phase had a great influence on separation and sensitivity. A mobile phase consisting of 10 mM copper(II) sulfate in 5 mM sulfuric acid (pH 2.3) was used to separate nine organic acids (tartaric, malic, malonic, lactic, acetic, citric, maleic, succinic and fumaric acids). The detection limits of the examined organic acids calculated at S/N = 3 ranged from 0.6 to 100 μM. The detector signal was linear over three orders of magnitude of organic acid concentration. The method successfully measured organic acids in juice and vinegar samples.     

An experimental study of flow-induced fiber orientation and concentration distributions in a concentrated suspension flow through a slit channel containing a cylinder

Flow-induced fiber orientation and concentration distributions were measured in a concentrated fiber suspension (CFS) and a dilute one (DFS). The channel has a thin slit geometry containing a circular cylinder. In the previous work, many researchers have qualitatively studied fiber orientation and concentration distributions in injection-molded products of fiber-reinforced plastics. In the present work, however, they are quantitatively estimated by direct observation of fibers in the concentrated suspension flow. For the CFS, some fibers rotate in an expansion part between the channel wall and the circular cylinder, and the fiber orientation becomes almost random state. On the other hand, fibers are perfectly aligned along the flow direction owing to the elongational flow near the centerline downstream of the cylinder. The fiber concentration has a flat distribution except near the channel wall and the centerline. For the DFS a minimum in the fiber concentration distribution was clearly observed on the centerline, and two peaks beside the centerline and near the channel wall. This characteristic distribution is caused by the fiber-wall and fiber-cylinder interactions. It is found that the obstacle such as the circular cylinder in the channel significantly affects the fiber orientation downstream of the obstacle for the CFD, while it affects the fiber concentration distribution for the DFS.     

Direct detection of nanoparticles and components in smoke by time-of-flight mass spectrometry with soft plasma ionization

A new system combining a soft plasma ionization (SPI) source with a time-of-flight mass spectrometer (TOFMS) has been successfully developed and applied to direct and on-line analysis of nanoparticles in smoke generated during combustion of mosquito coils with no sample preparation. The mass spectra of nanoparticles in smoke were examined in conjunction with the effects of species, pressure and current of the SPI discharge on fragmentation. The results indicated that a maximum mass of m/z 1576 was detectable when the following optima SPI conditions were satisfied: a He gas pressure of 1000 Pa with an air pressure of 1600 Pa and a discharge current of 110 mA. Furthermore, considering the results for emission spectra we suppose an ionization mechanism of SPI in which excitation and ionization of nitrogen molecule is promoted by the presence of He gas, leading to promote the smoke sample ionization. The mass spectrum of nanoparticles showed specific patterns of a peak interval of 74 which were assigned to triacetylene (1,3,5-hexatriyne). The most abundant peak in the mass spectrum, at m/z 452, was assigned to triacontanoic acid.     

Construction of hydrogen-bonded ternary organic crystals derived from L-tartaric acid and their application to enantioseparation of secondary alcohols

Ternary organic crystals consisting of an L-tartaric acid-derived dicarboxylic acid, a commercially available achiral diamine, and a chiral secondary alcohol have been developed and characterized by X-ray crystallography. 1D, 2D, and 3D hydrogen-bonded supramolecular networks were constructed, depending on the structure of the diamine used. Benzylic and aliphatic secondary alcohols were enantioselectively incorporated into the crystal and were successfully enantioseparated with up to 86 and 79% enantiomeric excess (ee), respectively. Selective incorporation of one enantiomer of 2-butanol, which is a small chiral aliphatic alcohol, was achieved by the cooperative effects of hydrogen bonds, CH···π interactions, and van der Waals interactions between the guest and host molecules, with the aid of two water molecules. The high host potential of the binary supramolecular system is mainly attributed to the skewed conformation of two rigid aromatic groups of tartaric acid derivatives, which prevents dense packing of the molecules and enhances the formation of multicomponent inclusion crystals.     

Enantioselective boronate additions to N-acyl quinoliniums catalyzed by tartaric acid

Tartaric acid catalyzes the asymmetric addition of vinylboronates to N-acyl quinoliniums, affording highly enantioenriched dihydroquinolines. The catalyst serves to activate the boronate through a ligand-exchange reaction and generates the N-acyl quinolinium in situ from the stable quinoline-derived N,O-acetal.     

Design, synthesis, and properties of boat-shaped glucopyranosyl nucleic acid

A boat-shaped glucopyranosyl nucleic acid (BsNA) was synthesized to investigate the possibility that the lean of a nucleobase is a factor affecting duplex-forming ability of oligonucleotides. From the crystal structure of a BsNA nucleoside and the thermal stability of duplex oligonucleotides, it was found that not only the lean of the base but also the rotation angle of the glycosidic bond axis were important factors in a stable duplex formation.     

A classification of sharp tridiagonal pairs

Let F denote a field and let V denote a vector space over F with finite positive dimension. We consider a pair of linear transformations A:V→V and A^∗:V→V that satisfy the following conditions: (i) each of A,A^∗ is diagonalizable; (ii) there exists an ordering of the eigenspaces of A such that A^∗V_i⊆V_i-1+V_i+V_i+1 for 0?i?d, where V_-1=0 and V_d+1=0; (iii) there exists an ordering of the eigenspaces of A^∗ such that for 0?i?δ, where and ; (iv) there is no subspace W of V such that AW⊆W, A^∗W⊆W, W≠0, W≠V. We call such a pair a tridiagonal pair on V. It is known that d=δ and for 0?i?d the dimensions of coincide. The pair A,A^∗ is called sharp whenever . It is known that if F is algebraically closed then A,A^∗ is sharp. In this paper we classify up to isomorphism the sharp tridiagonal pairs. As a corollary, we classify up to isomorphism the tridiagonal pairs over an algebraically closed field. We obtain these classifications by proving the μ-conjecture.     

First principles based mean field model for oxygen reduction reaction

A first principles-based mean field model was developed for the oxygen reduction reaction (ORR) taking account of the coverage- and material-dependent reversible potentials of the elementary steps. This model was applied to the simulation of single crystal surfaces of Pt, Pt alloy and Pt core-shell catalysts under Ar and O(2) atmospheres. The results are consistent with those shown by past experimental and theoretical studies on surface coverages under Ar atmosphere, the shape of the current-voltage curve for the ORR on Pt(111) and the material-dependence of the ORR activity. This model suggests that the oxygen associative pathway including HO(2)(ads) formation is the main pathway on Pt(111), and that the rate determining step (RDS) is the removal step of O(ads) on Pt(111). This RDS is accelerated on several highly active Pt alloys and core-shell surfaces, and this acceleration decreases the reaction intermediate O(ads). The increase in the partial pressure of O(2)(g) increases the surface coverage with O(ads) and OH(ads), and this coverage increase reduces the apparent reaction order with respect to the partial pressure to less than unity. This model shows details on how the reaction pathway, RDS, surface coverages, Tafel slope, reaction order and material-dependent activity are interrelated.