29 research outputs found
DEVELOPMENT OF FLY ASH-BASED GEOPOLYMER MEMBRANE FOR METHYLENE BLUE DYE REMOVAL
No full textFly ash-based geopolymer synthesized by reacting fly ash with an alkaline activator has a potential for membrane application due to its high mechanical strength, easy synthesis and low cost. In this research, a new fly ash-based geopolymer (FAGP) membrane was successfully synthesized and the effects of the forming agent, alkaline activator and Si/Al ratio on its membrane application were investigated. The morphology, pore structure and functional groups FAGPs were characterized using field-emission scanning electron microscopy (FESEM), Brunauer- Emmett-Teller (BET) analysis and Fourier Transform Infrared spectroscopy (FTIR) respectively. Based on the FESEM results, the membrane with 5.0 wt% egg white and 0.6 wt% of H2O2 (GE5) showed homogenous and interconnected porosity, and based on the BET result, the pore sizes of the membrane increased from 11.49 nm (GE0) to 19.60 nm (GE5). Performance analysis on methylene blue dye removal in an aqueous solution revealed that GE0-GE5 gave a significantly high removal R>90% with the highest permeation rate of 15 L/m2. h. for GE5. At the best removal condition, the final concentration of dye was recorded at 30 ppm which is below the Standard B discharge limit. Meanwhile, the mechanical properties of the modified FAGP membrane was studied through flexural strength test by varying the concentrations of sodium hydroxide (NaOH) which are 4M-12M, and Si/Al ratios at 1.86/1, 2.2/1 and 2.3/1. The optimum NaOH concentration was found to be at 10M, meanwhile Si/Al ratio of 2.3/1 resulted in a significant increase to the strength of the geopolymer membrane. Thus, geopolymer membranes derived from fly ash was proven effective for dye removal. Future works are still needed to obtain optimal FAGP to achieve targeted industrial applications
Threshold for blowup for the supercritical cubic wave equation
No full textIn this paper, we discuss singularity formation for the focusing cubic wave equation in the energy supercritical regime. For this equation an explicit nontrivial self-similar blowup solution was recently found by the first and third author in [27]. In the seven dimensional case it was proven to be stable along a co-dimension one manifold of initial data. Here, we provide numerical evidence that this solution is in fact a critical solution at the threshold between finite-time blowup and dispersion. Furthermore, we discuss the spectral problem arising in the stability analysis in general dimensions
Existence of nontrivial solutions for critical biharmonic equations with logarithmic term
No full textIn this paper, we consider the existence of nontrivial solutions to the
following critical biharmonic problem with a logarithmic term \begin{equation*}
\begin{cases} \Delta^2 u=\mu \Delta u+\lambda u+|u|^{2^{**}-2}u+\tau u\log u^2,
\ \ x\in\Omega, u|_{\partial \Omega }=\frac{\partial u}{\partial
n}|_{\partial\Omega}=0, \end{cases} \end{equation*} where , , denotes the
iterated N-dimensional Laplacian, is a bounded
domain with smooth boundary ,
is the critical Sobolev exponent for the embedding
and is
the closure of under the norm . The uncertainty of the sign of
in has some interest in itself. To know which of the
three terms , and has a greater
influence on the existence of nontrivial weak solutions, we prove the existence
of nontrivial weak solutions to the above problem for under some
assumptions of and
Characterization of R2M3X5 intermetallics and the structure determination of Fe3GaTe2.
No full textIntermetallic compounds are solid-state materials that include at least two metals,
a crystal structure that is different from its constituents, and a definite chemical formula.
The complex structures and varying physical properties separate intermetallics from
metallic alloys allowing for the study of interesting bonding and structure-property
relationships. This work investigates the R2 M3 X5 family of compounds, with attention
placed on Co3 Ga2 Ge5 and Sm 2 Ru3Sn5 for their relationship to the Ru3Sn7 binary structure
type. Herein, I present the synthesis, structure determination, and physical properties
measurement of Co3 Ga2 Ge5 , highlighting the need for multiple structural characterization
methods to distinguish Ga and Ge from each other due to their similar X-ray and neutron
scattering factors. By using 71 Ga nuclear magnetic resonance spectroscopy and an analysis
of the X-ray absorption fine structure, the degree of Ga/Ge site mixing is revealed,
enhancing the understanding of Co 3 Ga2 Ge5 as a doped analogue of the Ru3 Sn7 binary
structure type. I characterize Sm2 Ru 3 Sn5 and report the magnetism and transport properties.
An antiferromagnetic transition is observed at T N = 3.8 K, marking the first example of a
Ru3 Sn7 -related compound that contains a lanthanide and further highlighting a structure
that has potential to introduce magnetic moments to a topologically relevant band structure.
Resistivity measurements indicate metallic behavior, and analysis of the magnetic entropy
from the heat capacity revealed a doublet ground state due to crystal electric field splitting.
Our experimental and computational results highlight localized Sm3+ moments and suggest
a possible interplay between Ruddelman-Kitel-Kasuya-Yosida (RKKY) and Kondo
interactions, positioning Sm 2 Ru 3 Sn5 as a promising material for studying topology and
complex physical phenomena. The crystal structure of Fe3-xGaTe2 is investigated via X-
ray crystallography in the context of its physical properties as a candidate for spintronic
devices. From conflicting reports from different research groups, ambiguity remains
around which space group is the best to classify Fe3 GaTe2 . Lorentz transmission electron
microscopy (L-TEM) indicates the presence of hybrid skyrmions. If these skyrmions are
stabilized by the Dzaloshinskii-Moriya interaction, Fe3-xGaTe2 should adopt a non-
centrosymmetric environment. Our findings reflect a centrosymmetric crystal structure
(P63 /mmc) for the bulk material; however, other groups report non-centrosymmetric space
groups: P63mc, P31c, and P3m1. This work underscores the importance of effective
structural characterization for its insights into the differences between bulk and local
structure and the implications for the physical properties of a given material
Canonical local algorithms for spin systems: heat bath and Hasting's methods
No full textWe introduce new fast canonical local
algorithms for discrete and continuous spin systems.
We show that for a broad selection of spin systems
they compare favorably to the known ones except for
the Ising ±1 spins.
The new procedures use discretization scheme and the
necessary information have to be stored
in computer memory before the simulation.
The models for testing discrete spins are the
Ising ±1, the general Ising S or Blume-Capel model,
the Potts and the clock models.
The continuous spins we examine are the O(N) models, including
the continuous Ising model (N=1), the Ising model (N=1),
the XY model (N=2), the Heisenberg model (N=3), the Heisenberg model (N=3), the O(4) model with applications
to the SU(2) lattice gauge theory, and the general O(N) vector spins
with
A constraint on existence of torsion free lie modules.
No full textFor any simple Lie algebra L with any maximal toral subalgebra H, the classification of all simple H diagonalizable L modules having a finite dimensional weight space is known to depend on determining the simple torsion free L modules of finite degree. It is further known that the only simple Lie algebras which admit simple torsion free modules of finite degree are those of types A\sb{n-1} and C\sb{m}. For the case of A\sb{n-1} we show that there are no simple torsion free A\sb{n-1} modules of degree k for and We conclude with some examples showing that there exist simple torsion free A\sb{n-1} modules of degrees 1, and whenever Dept. of Mathematics and Statistics. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1992 .T376. Source: Masters Abstracts International, Volume: 31-04, page: 1811. Thesis (M.Sc.)--University of Windsor (Canada), 1992
Finite-time blow-up in a two species chemotaxis-competition model with degenerate diffusion
No full textThis paper is concerned with the two-species chemotaxis-competition model
with degenerate diffusion,
with , , where is a ball with some ; ,
; is the spatial average
of . The purpose of this paper is to show finite-time blow-up in the sense
that there is such that
for the
above model within a concept of weak solutions fulfilling a moment inequality
which leads to blow-up. To this end, we also give a result on finite-time
blow-up in the above model with the terms ,
replaced with the nondegenerate diffusion terms ,
, where
Characterization of indica-type giant embryo mutant rice enriched with nutritional components
No full textFive giant embryo mutants, described as
MH-gel, MH-ge2, MH-ge3, MH-ge4
and
MH-ge5
, which were derived from the same indica rice
cv
. ‘Minghui 86’ and characterized by 2.0, 1.88, 2.08, 1.93 and 1.88 times enlarged embryo than that of wild type, were selected for the current study. The mutated giant embryos were controlled by a single recessive gene, and except mutated locus with
MH-ge1
other four loci were allelic to each other and the previous reported locus
ge
in japonica rice
cv
. ‘Kinmaze’. No obvious differences in physicochemical properties such as apparent amylose content (AAC), alkali spreading value (ASV), gel consistency (GC), and starch paste viscosity were observed between giant embryo mutants and wild type. Significant increases in the contents of crude lipid (LC), crude protein (PC), Vitamin B1 (V
B1
), Vitamin B2 (V
B2
), Vitamin E (V
E
), essential amino acids such as Arginine (Arg), Aspartic acid (Asp), Glutamic acid (Glu), Lysine (Lys), Methionine (Met), and mineral elements such as calcium (Ca), iron (Fe), potassium (K), phosphorus (P) and zinc (Zn) were detected in brown rice (BR) of giant embryo mutants. The amounts of gamma aminobutyric acid (GABA), an inhibitory neurotransmitter, were similar in the BR of giant embryo mutants and wild type, and more GABA content was observed in germinated brown rice (GBR) than BR. Significant enrichments were detected in the GBR of giant embryo mutants, basically corresponding to the enlarged embryo
Validation of a spatial-temporal soil water movement and plant water uptake model
No full textManagement and irrigation of plants increasingly relies on accurate mathematical models for the movement of water within unsaturated soils. Current models often use values for water content and soil parameters that are averaged over the soil profile. However, many applications require models to more accurately represent the soil–plant–atmosphere continuum, in particular, water movement and saturation within specific parts of the soil profile. In this paper a mathematical model for water uptake by a plant root system from unsaturated soil is presented. The model provides an estimate of the water content level within the soil at different depths, and the uptake of water by the root system. The model was validated using field data, which include hourly water content values at five different soil depths under a grass/herb cover over 1 year, to obtain a fully calibrated system for plant water uptake with respect to climate conditions. When compared quantitatively to a simple water balance model, the proposed model achieves a better fit to the experimental data due to its ability to vary water content with depth. To accurately model the water content in the soil profile, the soil water retention curve and saturated hydraulic conductivity needed to vary with depth
On finite field analogues of determinants involving the Beta function
No full textMotivated by the works of L. Carlitz, R. Chapman and Z.-W. Sun on cyclotomic
matrices, in this paper, we investigate certain cyclotomic matrices concerning
the Jacobi sums over finite fields, which can be viewed as finite field
analogues of certain matrices involving the Beta function. For example, let
be a prime power and let be a generator of the group of all
multiplicative characters of . Then we prove that
where
is the Jacobi sum over . This is a finite
analogue of where
is the Beta function. Also, if is an odd prime, then we show that
Comment: 16 pages. Comments are welcom
