GRADIENT YAMABE SOLITONS WITH CONFORMAL VECTOR FIELD

Fasihi-Ramandi, Ghodratallah,Ghahremani-Gol, Hajar Korean Mathematical Society 2021 대한수학회논문집 Vol.36 No.1

The purpose of this paper is to investigate the geometry of complete gradient Yamabe soliton (Mn, g, f, λ) with constant scalar curvature admitting a non-homothetic conformal vector field V leaving the potential vector field invariant. We show that in such manifolds the potential function f is constant and the scalar curvature of g is determined by its soliton scalar. Considering the locally conformally flat case and conformal vector field V, without constant scalar curvature assumption, we show that g has constant curvature and determines the potential function f explicitly.

Harnack Estimate for Positive Solutions to a Nonlinear Equation Under Geometric Flow

Fasihi-Ramandi, Ghodratallah,Azami, Shahroud Department of Mathematics 2021 Kyungpook mathematical journal Vol.61 No.3

In the present paper, we obtain gradient estimates for positive solutions to the following nonlinear parabolic equation under general geometric flow on complete noncompact manifolds $$\frac{{\partial}u}{{\partial}t}={\Delta}u+a(x,t)u^p+b(x,t)u^q$$ where, 0 < p, q < 1 are real constants and a(x, t) and b(x, t) are functions which are C² in the x-variable and C¹ in the t-variable. We shall get an interesting Harnack inequality as an application.

Effect of Alkaline Drinking Water on Bone Density of Postmenopausal Women with Osteoporosis

( Sanaz Fasihi ),( Siavash Fazelian ),( Farinaz Farahbod ),( Fateme Moradi ),( Morteza Dehghan ) 대한폐경학회 2021 대한폐경학회지 Vol.27 No.2

Objectives: Postmenopausal women are predisposed to osteoporosis, and those on acidic diets are at a higher risk, because it has been demonstrated that such diets have adverse effects on bone health. In this study, the effect of alkaline drinking water on bone mineral density was evaluated in postmenopausal women with osteoporosis. Methods: One hundred postmenopausal women with osteoporosis (T-score ≤ -2.5) were equally divided into an intervention group and a control group (n = 50 each). The intervention group received calcium D (daily), alkaline drinking water (1.5 L daily with pH 8.6 ± 0.3), and Osteofos tablet (70 mg weekly), whereas the control group received only calcium D and Osteofos tablet for 3 months. T-scores of the femur and spine bones were obtained using bone densitometry before and 3 months after the intervention. Results: After the intervention, the mean T-scores of the femur and spine bones significantly increased in both the control and intervention groups (P < 0.05). However, the mean changes in the spine T-score were significantly higher in the intervention group (0.39 ± 0.07) than in the control group (0.08 ± 0.01) (P < 0.05). No significant differences were observed in the mean changes in the femur T-score between the two groups. Conclusions: Our findings demonstrate that drinking alkaline water improves spine T-scores in postmenopausal women with osteoporosis. Hence, alkaline water can be used to treat osteoporosis due to increased bone density in postmenopausal women. Longterm interventions are necessary to confirm the effects of alkaline water on femur density.

THE SET OF ZOLL METRICS IS NOT PRESERVED BY SOME GEOMETRIC FLOWS

Azami, Shahroud,Fasihi-Ramandi, Ghodratallah Korean Mathematical Society 2019 대한수학회논문집 Vol.34 No.3

The geodesics on the round 2-sphere $S^2$ are all simple closed curves of equal length. In 1903 Otto Zoll introduced other Riemannian surfaces with the same property. After that, his name is attached to the Riemannian manifolds whose geodesics are all simple closed curves of the same length. The question that "whether or not the set of Zoll metrics on 2-sphere $S^2$ is connected?" is still an outstanding open problem in the theory of Zoll manifolds. In the present paper, continuing the work of D. Jane for the case of the Ricci flow, we show that a naive application of some famous geometric flows does not work to answer this problem. In fact, we identify an attribute of Zoll manifolds and prove that along the geometric flows this quantity no longer reflects a Zoll metric. At the end, we will establish an alternative proof of this fact.

RICCI 𝜌-SOLITONS ON 3-DIMENSIONAL 𝜂-EINSTEIN ALMOST KENMOTSU MANIFOLDS

Azami, Shahroud,Fasihi-Ramandi, Ghodratallah Korean Mathematical Society 2020 대한수학회논문집 Vol.35 No.2

The notion of quasi-Einstein metric in theoretical physics and in relation with string theory is equivalent to the notion of Ricci soliton in differential geometry. Quasi-Einstein metrics or Ricci solitons serve also as solution to Ricci flow equation, which is an evolution equation for Riemannian metrics on a Riemannian manifold. Quasi-Einstein metrics are subject of great interest in both mathematics and theoretical physics. In this paper the notion of Ricci 𝜌-soliton as a generalization of Ricci soliton is defined. We are motivated by the Ricci-Bourguignon flow to define this concept. We show that if a 3-dimensional almost Kenmotsu Einstein manifold M is a 𝜌-soliton, then M is a Kenmotsu manifold of constant sectional curvature -1 and the 𝜌-soliton is expanding with λ = 2.

Efficiency of stress transfer between polymer matrix and nanoplatelets in clay/polymer nanocomposites

Zare, Yasser,Fasihi, Mohammad,Rhee, Kyong Yop Elsevier 2017 Applied clay science Vol.143 No.-

<P><B>Abstract</B></P> <P>The Hui-Shia model, which considers the complete stress transfer between polymer matrix and particles (perfect interfacial adhesion), overpredicts the Young's modulus of clay/polymer nanocomposites (CPN). In this work, the effective aspect ratio and volume fraction of nanoclay are expressed assuming the imperfect load transfer, the minimum length of platelets required for efficient stress transfer (<I>L</I> <SUB> <I>c</I> </SUB>) and the interfacial shear strength (<I>τ</I>). Additionally, “<I>I</I>” parameter as the level of stress transfer in CPN is defined and determined using the effective parameters. The large nanoclay platelets with low “<I>L</I> <SUB> <I>c</I> </SUB>” give a high level of “<I>I</I>”. Also, high “<I>L</I> <SUB> <I>c</I> </SUB>” and slight “<I>τ</I>” observe the poor levels of effective parameters and Young's modulus of CPN. The “<I>I</I>” values are calculated for some samples which indicate the different levels of stress transfer in CPN. It is possible to analyze the levels of interfacial properties and stress transfer in CPN using the developed model.</P> <P><B>Highlight</B></P> <P> <UL> <LI> The Hui-Shia model is developed for Young's modulus of clay/polymer nanocomposites. </LI> <LI> The effective aspect ratio and volume fraction of nanoclay are expressed. </LI> <LI> The critical length of platelets and interfacial shear strength are assumed. </LI> <LI> “<I>I</I>” parameter is defined as the level of stress transfer and determined. </LI> </UL> </P>

Generalized hyperbolic geometric flow

Shahroud Azami,Ghodratallah Fasihi-Ramandi,Vahid Pirhadi 대한수학회 2023 대한수학회논문집 Vol.38 No.2

In the present paper, we consider a kind of generalized hyperbolic geometric flow which has a gradient form. Firstly, we establish the existence and uniqueness for the solution of this flow on an $n$-dimensional closed Riemannian manifold. Then, we give the evolution of some geometric structures of the manifold along this flow.

Immunization of mice with chimeric protein-loaded aluminum hydroxide and selenium nanoparticles induces reduction of Brucella melitensis infection in mice

Goudarzi Tahereh,Abkar Morteza,Zamanzadeh Zahra,Fasihi-Ramandi Mahdi 대한백신학회 2023 Clinical and Experimental Vaccine Research Vol.12 No.4

Purpose: Due to the many problems with commercially available vaccines, the production of effective vaccines against brucellosis is a necessity. The aim of this study was to evaluate the immune responses caused by the chimeric protein consisting of trigger factor, Bp26, and Omp31 (TBO) along with aluminum hydroxide (AH/TBO) and selenium (Se/TBO) nanoparticles (NPs) as adjuvants in mouse model. Materials and Methods: Recombinant antigen expression was induced in Escherichia coli BL21 (DE3) bacteria using IPTG (isopropyl-d-1-thiogalactopyranoside). Purification and characterization of recombinant protein was conducted through NiFe3O4 NPs, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blot. NP characteristics, including morphology and particle size, were measured in vitro. The recombinant TBO was loaded on to AH and Se NPs and were administered subcutaneously. After mice immunization, measurement of antibody titter and protection assay was performed. Results: The average sizes of AH and Se NPs were about 60 nm and 150 nm, respectively. The enzyme-linked immunosorbent assay results showed that the serum of mice immunized by subcutaneous injection with both nanovaccines produced significant immunoglobulin G (IgG) responses against the chimeric antigen. The results of TBO-specific IgG isotype (IgG2a/IgG1) analysis showed that both AH and Se NPs induced a type to T-helper immune response. In addition, the results of the challenge with the pathogenic strain of Brucella melitensis 16M showed that vaccinated mice with AH/TBO NPs indicated a higher reduction of bacterial culture than immunized mice with Se/TBO NPs and TBO alone. Conclusion: The results showed that AH NPs carrying chimeric antigen can be a promising vaccine candidate against brucellosis by producing protective immunity.

Damage identification in laminated composite plates using a new multi-step approach

Narges Fallah,Seyed Rohollah Hoseini Vaez,Hossein Fasihi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.1

In this paper a new multi-step damage detection approach is provided. In the first step, condensed modal residual vector based indicator (CMRVBI) has been proposed to locate the suspected damaged elements of structures that have rotational degrees of freedom (DOFs). The CMRVBI is a new indicator that uses only translational DOFs of the structures to localize damaged elements. In the next step, salp swarm algorithm is applied to quantify damage severity of the suspected damaged elements. In order to assess the performance of the proposed approach, a numerical example including a three-layer square laminated composite plate is studied. The numerical results demonstrated that the proposed CMRVBI is effective for locating damage, regardless of the effect of noise. The efficiency of proposed approach is also compared during both steps. The results demonstrate that in noisy condition, the damage identification approach is capable for the studied structure.

Corrigendum: Marginal bone loss around crestal or subcrestal dental implants: prospective clinical study

Sargolzaie, Naser,Zarch, Hosein Hoseini,Arab, Hamidreza,Koohestani, Tahereh,Ramandi, Mahdiye Fasihi The Korean Association of Oral and Maxillofacial S 2022 대한구강악안면외과학회지 Vol.48 No.4