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GENERALIZED CAYLEY GRAPH OF UPPER TRIANGULAR MATRIX RINGS
Afkhami, Mojgan,Hashemifar, Seyed Hosein,Khashyarmanesh, Kazem Korean Mathematical Society 2016 대한수학회보 Vol.53 No.4
Let R be a commutative ring with the non-zero identity and n be a natural number. ${\Gamma}^n_R$ is a simple graph with $R^n{\setminus}\{0\}$ as the vertex set and two distinct vertices X and Y in $R^n$ are adjacent if and only if there exists an $n{\times}n$ lower triangular matrix A over R whose entries on the main diagonal are non-zero such that $AX^t=Y^t$ or $AY^t=X^t$, where, for a matrix B, $B^t$ is the matrix transpose of B. ${\Gamma}^n_R$ is a generalization of Cayley graph. Let $T_n(R)$ denote the $n{\times}n$ upper triangular matrix ring over R. In this paper, for an arbitrary ring R, we investigate the properties of the graph ${\Gamma}^n_{T_n(R)}$.
Discoloration of teeth due to different intracanal medicaments
Afkhami, Farzaneh,Elahy, Sadaf,Nahavandi, Alireza Mahmoudi,Kharazifard, Mohamad Javad,Sooratgar, Aidin The Korean Academy of Conservative Dentistry 2019 Restorative Dentistry & Endodontics Vol.44 No.1
Objectives: The objective of this study was to assess coronal discoloration induced by the following intracanal medicaments: calcium hydroxide (CH), a mixture of CH paste and chlorhexidine gel (CH/CHX), and triple antibiotic paste (3Mix). Materials and Methods: Seventy extracted single-canal teeth were selected. Access cavities were prepared and each canal was instrumented with a rotary ProTaper system. The specimens were randomly assigned to CH, CH/CHX, and 3Mix paste experimental groups (n = 20 each) or a control group (n = 10). Each experimental group was randomly divided into 2 subgroups (A and B). In subgroup A, medicaments were only applied to the root canals, while in subgroup B, the root canals were completely filled with medicaments and a cotton pellet dipped in medicament was also placed in the pulp chamber. Spectrophotometric readings were obtained from the mid-buccal surface of the tooth crowns immediately after placing the medicaments (T1) and at 1 week (T2), 1 month (T3), and 3 months (T4) after filling. The ${\Delta}E$ was then calculated. Data were analyzed using 2-way analysis of variance (ANOVA), 3-way ANOVA, and the $Scheff{\acute{e}}$ post hoc test. Results: The greatest color change (${\Delta}E$) was observed at 3 months (p < 0.0001) and in 3Mix subgroup B (p = 0.0057). No significant color change occurred in the CH (p = 0.7865) or CH/CHX (p = 0.1367) groups over time, but the 3Mix group showed a significant ${\Delta}E$ (p = 0.0164). Conclusion: Intracanal medicaments may induce tooth discoloration. Use of 3Mix must be short and it must be carefully applied only to the root canals; the access cavity should be thoroughly cleaned afterwards.
Afkhami, Abbas,Sarlak, Nahid,Zarei, Ali Reza,Madrakian, Tayyebeh Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.6
The partial least squares (PLS-1) calibration model based on spectrophotometric measurement, for the simultaneous determination of sulfite and sulfide is described. This method is based on the difference between the rate of the reaction of sulfide and sulfite with Malachite Green in pH 7.0 buffer solution and at 25 ${^{\circ}C}$. The absorption kinetic profiles of the solutions were monitored by measuring the decrease in the absorbance of Malachite Green at 617 nm in the time range 10-180 s after initiation of the reactions with 2 s intervals. The experimental calibration matrix for partial least squares (PLS-1) calibration was designed with 24 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.030-1.5 and 0.030-1.2 $\mu$g m$L ^{-1}$ for sulfite and sulfide, respectively. The proposed method was successfully applied to simultaneous determination of sulfite and sulfide in water samples and whole human blood.
When the Comaximal Graph of a Lattice is Toroidal
Afkhami, Mojgan,Javaheri, Khadijeh Ahmad,Khashyarmanesh, Kazem Department of Mathematics 2016 Kyungpook mathematical journal Vol.56 No.3
In this paper we investigate the toroidality of the comaximal graph of a finite lattice.
Afkhami, Abbas,Masahi, Shokofeh,Bahram, Morteza Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.7
In the present work a very simple, sensitive and selective spectrophotometric method for the determination of nitrite in micellar media is described. The method is based on the color reaction of nitrite with p-nitroaniline in the presence of diphenylamine in acid media. In order to remove the extraction step, Triton X-100, a non-ionic surfactant was used as micellar media. The optimum reaction conditions such as acid concentration, reagents concentration and effect of time have been studied and the analytical characteristics of the method such as limit of detection, linear range and molar absorptivity have been obtained. The interference of some anions and cations was also tested. The method was applied to the determination of nitrite in real samples.
ON THE ANNIHILATOR GRAPH OF GROUP RINGS
Afkhami, Mojgan,Khashyarmanesh, Kazem,Salehifar, Sepideh Korean Mathematical Society 2017 대한수학회보 Vol.54 No.1
Let R be a commutative ring with nonzero identity and G be a nontrivial finite group. Also, let Z(R) be the set of zero-divisors of R and, for $a{\in}Z(R)$, let $ann(a)=\{r{\in}R{\mid}ra=0\}$. The annihilator graph of the group ring RG is defined as the graph AG(RG), whose vertex set consists of the set of nonzero zero-divisors, and two distinct vertices x and y are adjacent if and only if $ann(xy){\neq}ann(x){\cup}ann(y)$. In this paper, we study the annihilator graph associated to a group ring RG.
Wideband Gain Flattened Hybrid Erbium-doped Fiber Amplifier/Fiber Raman Amplifier
Hossein Afkhami,Alireza Mowla,Nosrat Granpayeh,Azadeh Rastegari Hormozi 한국광학회 2010 Current Optics and Photonics Vol.14 No.4
An optimal wideband gain flattened hybrid erbium-doped fiber amplifier/fiber Raman amplifier (EDFA/FRA) has been introduced. A new and effective optimization method called particle swarm optimization (PSO) is employed to find the optimized parameters of the EDFA/FRA. Numerous parameters which are the parameters of the erbium-doped fiber amplifier (EDFA) and the fiber Raman amplifier (FRA)define the gain spectrum of a hybrid EDFA/FRA. Here, we optimize the length, Er3+ concentration, and pump power and wavelength of the EDFA and also pump powers and wavelengths of the FRA to obtain the flattest operating gain spectrum. Hybrid EDFA/FRA with 6-pumped- and 10-pumped-FRAs have been studied. Gain spectrum variations are 1.392 and 1.043 dB for the 6-pumped- and 10-pumped-FRAs,respectively, in the 108.5 km hybrid EDFA/FRAs, with 1 mW of input signal powers. Dense wavelength division multiplexing (DWDM) system with 60 signal channels in the wavelength range of 1529.2-1627.1nm, i.e. the wide bandwidth of 98 nm, is studied. In this work, we have added FRA’s pump wavelengths to the optimization parameters to obtain better results in comparison with the results presented in our previous works.
Abbas Afkhami,Shadieh Sayari,Razieh Moosavi,Tayyebeh Madrakian 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Nickel zinc ferrite nanocomposite was synthesized and characterized by X-ray diffraction (XRD) analysisand scanning electron microscopy (SEM). The XRD patterns confirmed the synthesis of a singlecrystalline Ni0.5Zn0.5Fe2O4 magnetic nanocomposite. Size of the nanocomposite according to SEM wasobtained around 27 nm. Various anionic and cationic dyes were removed from water solutions using thesynthesized sorbent. The Langmuir adsorption capacities (qmax) was found to be 250.0 mg g 1 forAlizarin, 333.3 mg g 1 for reactive blue and Janus green B, 500 mg g 1 for Congo red, crystal violet andmethyl violet.
Generalized Cayley graph of upper triangular matrix rings
Mojgan Afkhami,Seyed Hosein Hashemifar,Kanzem Khashyarmanesh 대한수학회 2016 대한수학회보 Vol.53 No.4
Let $R$ be a commutative ring with the non-zero identity and $n$ be a natural number. $\Gamma ^n_R$ is a simple graph with $R^n \setminus \{0\}$ as the vertex set and two distinct vertices $X$ and $Y$ in $R^{n}$ are adjacent if and only if there exists an $n \times n$ lower triangular matrix $A$ over $R$ whose entries on the main diagonal are non-zero such that $AX^{t}=Y^{t}$ or $AY^{t}=X^{t}$, where, for a matrix $B$, $B^{t}$ is the matrix transpose of $B$. $\Gamma ^n_R$ is a generalization of Cayley graph. Let $T_n (R)$ denote the $n \times n$ upper triangular matrix ring over $R$. In this paper, for an arbitrary ring $R$, we investigate the properties of the graph $\Gamma ^n_{T_n(R)}$.