492 research outputs found

    Independent sets of some graphs associated to commutative rings

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    Let G=(V,E)G=(V,E) be a simple graph. A set SVS\subseteq V is independent set of GG, if no two vertices of SS are adjacent. The independence number α(G)\alpha(G) is the size of a maximum independent set in the graph. %An independent set with cardinality Let RR be a commutative ring with nonzero identity and II an ideal of RR. The zero-divisor graph of RR, denoted by Γ(R)\Gamma(R), is an undirected graph whose vertices are the nonzero zero-divisors of RR and two distinct vertices xx and yy are adjacent if and only if xy=0xy = 0. Also the ideal-based zero-divisor graph of RR, denoted by ΓI(R)\Gamma_I(R), is the graph which vertices are the set {x\in R\backslash I | xy\in I \quad for some \quad y\in R\backslash I\} and two distinct vertices xx and yy are adjacent if and only if xyIxy \in I. In this paper we study the independent sets and the independence number of Γ(R)\Gamma(R) and ΓI(R)\Gamma_I(R).Comment: 27 pages. 22 figure

    Lemon Juice as a Natural Catalyse for Synthesis of Shiff’s base: A Green Chemistry Approach

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    The advantages of the use of natural catalysts are eco-friendly, inexpensive, high yields, nonhazardous and short reaction times. The utilization of green chemistry techniques is the elimination of solvents during chemical processes or the replacement of hazardous solvents with environmentally friendly solvents. Green chemistry has used for the synthesis of Schiff bases. Synthesis of Schiff base is carried out the mixture of aldehyde (or ketone) and amine in organic medium with or without an acid catalyst. He presents study Uses Lemon juice as a natural and eco-friendly catalyst in the green chemistry investigated. The synthesized product was characterized by its physical properties, melting point, TLC and then subjected to the in vitro antibacterial activities against gram-positive and gram-negative strains of microbes

    Computation of Gutman Index of Some Cactus Chains

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    Let G be a finite connected graph of order n. The Gutman index Gut(G) of G is defined as {x,y}V(G)deg(x)deg(y)d(x,y)\sum_{\{x,y\}\subseteq V(G)}deg(x)deg(y)d(x, y), where deg(x) is the degree of vertex x in G and d(x, y) is the distance between vertices x and y in G. A cactus graph is a connected graph in which no edge lies in more than one cycle. In this paper we compute the exact value of Gutman index of some cactus chains

    Effects of copper reduction on angiogenesis-related factors in recurrent glioblastoma cases

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    Purpose: To evaluate the therapeutic effects of copper reduction on angiogenesis-related factors in patients with glioblastoma multiforme treated by gamma knife radiosurgery. Materials and Methods: In the present block randomized, placebo-controlled trial, fifty eligible patients with a diagnosis of glioblastoma multiforme who were candidates for gamma knife radiosurgery were randomly assigned into two groups to receive daily either 1gr penicillamine and a low copper diet or placebo for three months. The intervention started on the same day as gamma knife radiosurgery. Serum interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF) and copper levels were measured at baseline and after the intervention. The serum copper level was used as the final index of compliance with the diet. In order to control probable side effects of intervention, laboratory tests were conducted at the beginning, middle and end of the study. Results: The patients had a mean age and Karnofsky Performance Scale of 43.7 years and 75 respectively. Mean serum copper levels were significantly reduced in intervention group. Mean survival time was 18.5 months in intervention group vs. 14.9 in placebo group. VEGF and IL-6 levels in the intervention group were also significantly reduced compared to the placebo group and TNF-α increased less. Conclusions: It seems that reducing the level of copper in the diet and dosing with penicillamine leads to decline of angiogenesis-related factors such as VEGF, IL-6 and TNF-α. Approaches targeting angiogenesis may improve survival and can be used as a future therapeutic strategy

    The correlation between biofilm formation capability and antibiotic resistance pattern in Pseudomonas aeruginosa

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    The infections caused by Pseudomonas aeruginosa are life-threatening, due to high intrinsic antimicrobial resistance of this microorganism. The integrons and biofilm formation of P. aeruginosa have a significant role in antibiotic resistance. Therefore, this study aimed to evaluate antibiotic resistance pattern in Pseudomonas aeruginosa isolates with biofilm formation ability. This cross-sectional study from January 2017 to December 2017 was conducted on 78 isolates (58 clinical and 20 environmental) of P. aeruginosa recovered from the 547 samples (439 of clinical and 108 of environmental samples). The isolates were identified by phenotypic and genotypic tests. Kirby-Bauer disk diffusion method was used for susceptibility testing. The prevalence of class 1, 2 and 3 Integrons, rhlA, and lasB genes were determined using Polymerase Chain Reaction (PCR). Biofilm formation was determined using the microtiter plate method. Data analyzed using Stata 14 software and Chi-Square test. The most prevalent resistance was observed against Ticarcillin/Clavulanic Acid (55). Generally, 56.4 of isolates were producers of strong biofilm in both environmental and clinical isolates. The prevalence of strong biofilm producers in clinical isolates was more than environmental. A significant correlation was observed between Int1, Int2, and rhlA genes with biofilm formation capability (P = 0.02). Regarding >50 of both environmental and clinical isolates were producers of strong biofilm and because the source of clinical isolates may be from the environment, the necessary hygiene measurements should be taken. No significant correlation was observed between lasB gene with biofilm formation capability. © 2019 Elsevier Inc

    Intraoperative angiography should be standard in cerebral aneurysm surgery

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    Intraoperative angiography (IOA) has proven to be a safe and effective adjunct to surgical repair of cerebral aneurysms. Substantial practice variation exists regarding use of this modality in different centers, including use of IOA routinely, selectively, or rarely. In this editorial, we discuss our experience and review the existing literature to develop an argument for routine use of IOA during cerebral aneurysm surgery
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