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Nishi K. Bhardwaj,Nishi K. Bhardwaj,Surendra P. Singh 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-
Recycled pulp contains large amount of fines having high surface area and amorphous cellulose. Thesefines adsorb water to large extent and dewatering rate is lower compared to virgin pulp. Selectivehydrolysis of these excess ultra fines through cellulase enzymes can be utilized for enhancing thedrainage rate. The concept of monocomponent cellulase treatment of recycled pulp for improvement indrainage and the understanding whether effectiveness depends on a specific type of cellulasecomponent (endoglucanase/cellobiohydrolase) is described. The improvement of 15–23% in pulpdrainability was achieved along with better paper properties.
A Study of Performance and Internal Flow in a New Type of Sewage Pump
Nishi, Yasuyuki,Fukutomi, Junichiro Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.3
Sewage pumps are designed with a wide flow channel by, for example, sacrificing some efficiency and reducing the number of blades, in order to prevent plugging with foreign bodies. However, the behavior of foreign bodies which actually flow into a pump is extremely complex, and there are questions about whether the presumed foreign bodies will actually pass through. This paper proposes a new type of sewage pump impeller designed to further improve pump efficiency and performance in passing foreign bodies. This sewage pump impeller has a structure in which the suction flow channel of a closed type non-clog pump is wound in a helical spiral. The focus of this research was to investigate pump performance and internal flow in this single blade sewage pump impeller. The results clearly indicated the following facts: The developed sewage pump impeller exhibits high efficiency over a wide range of flow rates; internal flow of the pump is very complicated; and the internal flow state varies greatly when the flow rate changes.
A New Blade Profile for Bidirectional Flow Properly Applicable to a Two-stage Jet Fan
Nishi, Michihiro,Liu, Shuhong,Yoshida, Kouichi,Okamoto, Minoru,Nakayama, Hiroyasu Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.4
A reversible axial flow fan called jet fan has been widely used for longitudinal ventilation in road tunnels to secure a safe and comfortable environment cost-effectively. As shifting the flow direction is usually made by only switching the rotational direction of an electric motor due to heavy duty, rotor blades having identical aerodynamic performance for bidirectional flow should be necessary. However, such aerodynamically desirable blades haven't been developed sufficiently, since most of the related studies have been done from the viewpoint of unidirectional flow. In the present paper, we demonstrate a method to profile the blade section suitable for bidirectional flow, which is validated by studying the aerodynamic performances of rotor blades of a two-stage jet fan experimentally and numerically.
Small-Angle Neutron Scattering Study on Defect-Controlled Polymer Networks
Nishi, Kengo,Asai, Hanako,Fujii, Kenta,Han, Young-Soo,Kim, Tae-Hwan,Sakai, Takamasa,Shibayama, Mitsuhiro American Chemical Society 2014 Macromolecules Vol.47 No.5
<P>Tetra-PEG gels are classified to near-“ideal” networks with significantly low inhomogeneities, which were confirmed by small-angle neutron scattering (SANS). In this study, we systematically introduced two types of defects into Tetra-PEG gels and investigated effects of defects on structure. First, we prepared defect-rich networks by simply reducing prepolymer concentration, and observed the evolution of network structure by time-resolved SANS during gelation process. In this case, both the scattering intensity and the correlation length increased with reaction time in the ϕ < ϕ* region, while they scarcely changed in the ϕ > ϕ* region. Here, ϕ and ϕ* are the polymer volume fractions at observation and that at chain-overlap concentration, respectively. Second, we prepared “<I>p</I>-tuned” Tetra-PEG gels by tuning the reaction probability, <I>p</I>, and soaked them in water to expose the inhomogeneities. It was revealed that SANS profiles of as-prepared gels did not change noticeably, while those of swollen gels systematically changed with decreasing <I>p</I>. On the basis of these results, we discuss the relationship between the defects of polymer network and inhomogeneities by using simple schematic pictures of polymer network.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2014/mamobx.2014.47.issue-5/ma402590n/production/images/medium/ma-2013-02590n_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma402590n'>ACS Electronic Supporting Info</A></P>
Radial Thrust of Single-Blade Centrifugal Pump
Nishi, Yasuyuki,Fukutomi, Junichiro,Fujiwara, Ryota Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.4
Single-blade centrifugal pumps are widely used as sewage pumps. However, the impeller of a single-blade pump is subjected to strong radial thrust during pump operation because of the geometrical axial asymmetry of the impeller. Therefore, to improve pump reliability, it is necessary to quantitatively understand radial thrust and elucidate the behavior and mechanism of thrust generating. This study investigates the radial thrust acting up on a single-blade centrifugal impeller by conducting experiments and CFD analysis. The results show that the fluctuating component of radial thrust increases as the flow rate deviates from the design flow rate to low or high value. Radial thrust was modeled by a combination of three components, inertia, momentum, and pressure by applying an unsteady conservation of momentum to the impeller. The sum of these components agrees with the radial thrust calculated by integrating the pressure and the shearing stress on the impeller surface. The behavior of each component was shown, and the effects of each component on radial thrust were clarified. The pressure component has the greatest effect on the time-averaged value and the fluctuating component of radial thrust. The time-averaged value of the inertia component is nearly 0, irrespective of the change in the flow rate. However, its fluctuating component has a magnitude nearly comparable with the pressure component at a low flow rate and slightly decreased with the increase in flow rate.
Structural Analysis of Lipophilic Polyelectrolyte Solutions and Gels in Low-Polar Solvents
Nishi, Kengo,Tochioka, Saki,Hiroi, Takashi,Yamada, Taihei,Kokado, Kenta,Kim, Tae-Hwan,Gilbert, Elliot Paul,Sada, Kazuki,Shibayama, Mitsuhiro American Chemical Society 2015 Macromolecules Vol.48 No.11
<P>Lipophilic polyelectrolyte gels capable of large swelling in low-polar solvents (3 ≤ ε ≤ 10) were developed by Ono et al. (Nature Mater.<x> </x>2007), where ε is the dielectric constant. These gels were prepared by introducing tetraphenylborate as a lipophilic anion (tetrakis(3,5-bis(trifluoromethyl)phenyl)borate; TFPB<SUP>–</SUP>) and tetraalkylammonium with long alkyl chains as a lipophilic cation (tetra(<I>n</I>-butyl)ammonium; TBA<SUP>+</SUP>) into a poly(octadecyl acrylate) (pODA) backbone chain. Here, we investigated the structure of the lipophilic polyelectrolyte gels and corresponding polymer solutions in CH<SUB>2</SUB>Cl<SUB>2</SUB> with small-angle neutron scattering (SANS) and dynamic light scattering (DLS). From SANS, it was revealed that individual pODA chain is regarded as a rod with the cross-section radius of 15 Å and the length of ca. 160 Å and is little changed by introduction of charges or cross-linking. In addition to this, it was revealed from SANS measurements that the second virial coefficient of pODA in CH<SUB>2</SUB>Cl<SUB>2</SUB> was positive. In combination with DLS measurements, we observed several characteristic features similar to polyelectrolyte aqueous systems such as (i) the clear appearance of slow diffusional motion in polymer solutions, (ii) an increase of diffusion coefficient in gels, and (iii) an increase of osmotic modulus in solutions and gels when ionic groups are incorporated in pODA. These experimental findings clearly show that [TBA<SUP>+</SUP>][TFPB<SUP>–</SUP>] dissociates enough and pODA, accompanying these ionic groups, acts as a polyelectrolyte even in a low-polar solvent such as CH<SUB>2</SUB>Cl<SUB>2</SUB> (ε = 8.9). It is concluded that the good compatibility of pODA with CH<SUB>2</SUB>Cl<SUB>2</SUB> and the introduction of dissociable ionic groups into pODA result in high-swelling capability of the lipophilic polyelectrolyte gels.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2015/mamobx.2015.48.issue-11/acs.macromol.5b00753/production/images/medium/ma-2015-00753f_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma5b00753'>ACS Electronic Supporting Info</A></P>
Nishi, Kengo,Hiroi, Takashi,Hashimoto, Kei,Fujii, Kenta,Han, Young-Soo,Kim, Tae-Hwan,Katsumoto, Yukiteru,Shibayama, Mitsuhiro American Chemical Society 2013 Macromolecules Vol.46 No.15
<P>The tacticity effect on phase separation process of poly(<I>N</I>-isopropylacrylamide) (PNiPAM) aqueous solutions was investigated by dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements. SANS measurement revealed that hydrophobicity of PNiPAM consisting of meso- and racemo-isomers increased with increasing the meso-content. This result is in accordance with the result of the previous experimental and simulation study on NiPAM dimers (DNiPAM) and trimers (TNiPAM) [Katsumoto<x>, </x>Y<x>.</x>; <etal></etal> J. Phys. Chem. B<x> </x>2010<x>, </x>114<x>, </x>13312−<lpage>13318</lpage>, and Autieri<x>, </x>E.; <etal></etal> J. Phys. Chem. B<x> </x>2011<x>, </x>115<x>, </x>5827<x>–</x><lpage>5839</lpage>]; i.e., meso-diad is more hydrophobic than racemo-diad. In addition, a series of scattering experiments revealed that the ratio of meso-diad does not affect the static structure or the shrinking behavior of a single chain, but strongly affects the aggregation behavior. The PNiPAMs with low meso-content suddenly associate around the phase separation temperature, while that of the high meso-content gradually aggregate with increasing temperature. We propose that phase transition behavior of PNiPAM aqueous solutions can be controlled by changing the stereoregularity of the polymer chain.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2013/mamobx.2013.46.issue-15/ma401349v/production/images/medium/ma-2013-01349v_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma401349v'>ACS Electronic Supporting Info</A></P>