MYERS' THEOREM FOR COMPLETE RIEMANNIAN HYPERSURFACES

Fatemi, Seyed Hamed Korean Mathematical Society 2019 대한수학회논문집 Vol.34 No.3

In this paper we study the Myers' theorem for orientable Riemannian hypersurfaces under some restrictions on the mean curvature, the second-order mean curvature, or the divergence of the shape operator and give some estimates for the diameter of such hypersurfaces.

Evaluation of Endoscopic Characteristics of Upper Gastrointestinal Polyps in Patients with Familial Adenomatous Polyposis

Fatemi, Seyed Reza,Safaee, Azadeh,Pasha, Sara,Pourhoseingholi, Mohamad Amin,Bahrainei, Rasool,Molaei, Mahsa Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16

Background: Familial adenomatous polyposis (FAP) is a disease inherited in an autosomal dominant fashion. Most FAP patients develop upper gastrointestinal polyps; especially those in the antrum and duodenum are usually neoplastic. The aim of this study was to evaluate the prevalence of gastroduodenal polyps in Iranian FAP patients. Materials and Methods: 28 patients affected by FAP underwent front-view and side-view endoscopy. Papillary biopsies were performed in all patients. Location of polyps, their number and size, pathology study, patient general information (gender, age, family history of FAP or colorectal cancer and gastroduodenal polyps) were analyzed. Results: Gastric polyps were seen in 39.3 % of patients. Some 72.7% of the affected individuals had fundic gland polyps and 36.36% had hyperplastic polyps. Duodenal adenoma was observed in 25% of patients. While 57% of patients had tubular adenoma with low grade dysplasia, 42.8% showed tubulovillous adenoma with low grade dysplasia. Conclusions: Findings of this study indicated that the prevalence of gastroduodenal polyps in FAP patients is high and dysplasia may be evident in duodenal polyps. Therefore, it appears that routine gastroduodenal endoscopy in FAP patients is necessary.

Quantitative Structure Activity Relationship Prediction of Oral Bioavailabilities Using Support Vector Machine

Fatemi, Mohammad Hossein,Fadaei, Fatemeh Korean Chemical Society 2014 대한화학회지 Vol.58 No.6

A quantitative structure activity relationship (QSAR) study is performed for modeling and prediction of oral bioavailabilities of 216 diverse set of drugs. After calculation and screening of molecular descriptors, linear and nonlinear models were developed by using multiple linear regression (MLR), artificial neural network (ANN), support vector machine (SVM) and random forest (RF) techniques. Comparison between statistical parameters of these models indicates the suitability of SVM over other models. The root mean square errors of SVM model were 5.933 and 4.934 for training and test sets, respectively. Robustness and reliability of the developed SVM model was evaluated by performing of leave many out cross validation test, which produces the statistic of $Q^2_{SVM}=0.603$ and SPRESS = 7.902. Moreover, the chemical applicability domains of model were determined via leverage approach. The results of this study revealed the applicability of QSAR approach by using SVM in prediction of oral bioavailability of drugs.

ENHANCED GAMMA RAY FLUX FROM THE GENERAL DIRECTION OF THE VIRGO GALAXY CLUSTER

FATEMI S. J. The Korean Astronomical Society 1996 Journal of The Korean Astronomical Society Vol.29 No.suppl1

There is an excess gamma flux from the general direction of the Galactic North Pole compared with that from the south when allowance is made for the contribution from CR interactions with the HI gas (Osborne et al., 1994). The extent to which it is in accord with the predictions of Wdowczyk and Wolfendale (1990 a,b) for gamma rays secondary to very high energy CR escaping from the VIRGO cluster is examined and it is claimed that the observations may well be of the order of those expected.

Association of vitamin D deficiency with COVID-19 severity and mortality in Iranian people: a prospective observational study

Alireza Fatemi,Seyed Hossein Ardehali,Ghazaleh Eslamian,Morvarid Noormohammadi,Shirin Malek 대한중환자의학회 2021 Acute and Critical Care Vol.36 No.4

Background As the coronavirus disease 2019 (COVID-19) pandemic continues to escalate, it is important to identify the prognostic factors related to increased mortality and disease severity. To assess the possible associations of vitamin D level with disease severity and survival, we studied 248 hospitalized COVID-19 patients in a single center in a prospective observational study from October 2020 to May 2021 in Tehran, Iran. Methods Patients who had a record of their 25-hydroxyvitamin D level measured in the previous year before testing positive with COVID-19 were included. Serum 25-hydroxyvitamin D level was measured upon admission in COVID-19 patients. The associations between clinical outcomes of patients and 25-hydroxyvitamin D level were assessed by adjusting for potential confounders and estimating a multivariate logistic regression model. Results The median (interquartile range) age of patients was 60 years (44–74 years), and 53% were male. The median serum 25-hydroxyvitamin D level prior to admission decreased with increasing COVID-19 severity (P=0.009). Similar findings were obtained when comparing median serum 25-hydroxyvitamin D on admission between moderate and severe patients (P=0.014). A univariate logistic regression model showed that vitamin D deficiency prior to COVID-19 was associated with a significant increase in the odds of mortality (odds ratio, 2.01; P=0.041). The multivariate Cox model showed that vitamin D deficiency on admission was associated with a significant increase in risk for mortality (hazard ratio, 2.35; P=0.019). Conclusions: Based on our results, it is likely that deficient vitamin D status is associated with increased mortality in COVID-19 patients. Thus, evaluating vitamin D level in COVID-19 patients is warranted.

Apple – biomorphic synthesis of porous ZnO nanostructures for glucose direct electrochemical biosensor

Hengameh Fatemi,Abbas Ali Khodadadi,Azam Anaraki Firooz,Yadollah Mortazavi 한국물리학회 2012 Current Applied Physics Vol.12 No.4

Biomorphic porous ZnO nanostructures were successfully synthesized via an aqueous solegel soaking process using pieces of apple flesh and skin as templates and employed for glucose direct electrochemical biosensor. The structure and morphology of ZnO nanostructures were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). By modifying glassy carbon electrode with the biomorphic ZnO nanostructures and Nafion, two glucose biosensors were constructed and their direct electrochemistry of glucose oxidase (GOD) was successfully investigated by cyclic voltammetry (CV). The biomorphic porous ZnO nanostructures using apple skin template (S-ZnO) were more effective in facilitating the electron transfer of immobilized GOD than that of using flesh apple template (F-ZnO). This may be a result of the unique morphology and smaller average crystallite size of the S-ZnO nanostructure. GOD immobilized on Nafion-porous S-ZnO nanostructure composite display direct, reversible,and surface-controlled redox reaction with a detection limit of 10 mM, a response time of 7 s, high sensitivity of 23.4 mA/mM cm2 and a fast heterogeneous electron transfer rate with a rate constant (ks) of 3.9 s-1. It was found that S-ZnO significantly has improved the direct electron transfer between GOD and glassy carbon electrode with good stability and reproducibility. Biomorphic porous ZnO nanostructures were successfully synthesized via an aqueous solegel soaking process using pieces of apple flesh and skin as templates and employed for glucose direct electrochemical biosensor. The structure and morphology of ZnO nanostructures were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). By modifying glassy carbon electrode with the biomorphic ZnO nanostructures and Nafion, two glucose biosensors were constructed and their direct electrochemistry of glucose oxidase (GOD) was successfully investigated by cyclic voltammetry (CV). The biomorphic porous ZnO nanostructures using apple skin template (S-ZnO) were more effective in facilitating the electron transfer of immobilized GOD than that of using flesh apple template (F-ZnO). This may be a result of the unique morphology and smaller average crystallite size of the S-ZnO nanostructure. GOD immobilized on Nafion-porous S-ZnO nanostructure composite display direct, reversible,and surface-controlled redox reaction with a detection limit of 10 mM, a response time of 7 s, high sensitivity of 23.4 mA/mM cm2 and a fast heterogeneous electron transfer rate with a rate constant (ks) of 3.9 s-1. It was found that S-ZnO significantly has improved the direct electron transfer between GOD and glassy carbon electrode with good stability and reproducibility.

Recent Progress in Molecular Simulation of Nanoporous Graphene Membranes for Gas Separation

S. Mahmood Fatemi,Aminreza Baniasadi,Mahrokh Moradi 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.1

If an ideal membrane for gas separation is to be obtained, the following three characteristics should be considered: the membrane should be as thin as possible, be mechanically robust, and have welldefined pore sizes. These features will maximize its solvent flux, preserve it from fracture, and guarantee its selectivity. Graphene is made up of a hexagonal honeycomb lattice of carbon atoms with sp2 hybridization state forming a one-atom-thick sheet of graphite. Following conversion of the honeycomb lattices into nanopores with a specific geometry and size, a nanoporous graphene membrane that offers high efficiency as a separation membrane because of the ultrafast molecular permeation rate as a result of its one-atom thickness is obtained. Applications of nanoporous graphene membranes for gas separation have been receiving remarkably increasing attention because nanoporous graphene membranes show promising results in this area. This review focuses on the recent advances in nanoporous graphene membranes for applications in gas separation, with a major emphasis on theoretical works. The attractive properties of nanoporous graphene membranes introduce make them appropriate candidates for gas separation and gas molecular-sieving processes in nanoscale dimensions.

Deformation Mechanisms and Evolution of Second Phase Particles of Mg–Y–Nd–Gd–Zr Alloy During Plane Strain Compression

S. M. Fatemi,Y. Moradipour,M. Hajian 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

Deformation behavior of a rolled Mg–Y–Nd–Gd magnesium alloy was studied at a temperature range of 240–480 °C underplane strain compression. Two types of samples including different loading-constraining configurations were employed tostudy anisotropy in deformation response. The result showed that plane strain deformation mode extends the temperaturerange for predominance of twinning up to 480 °C. However, yield anisotropy was diminished by increasing temperatureto 480 °C. Moreover, plane strain deformation mode caused the development of dynamic recrystallization to be postponedto high strains. Deformation behavior of the two sample types were explained by calculation of Schmid factor and textureanalysis. Fine dynamically recrystallized grains were traced to form at 420 and 480 °C. Relying on EBSD analysis, the developmentof new grains was explained using continuous dynamic recrystallization mechanism, where pyramidal and prismaticpoles of new grains were rotated relative to their parent grain. The dynamic evolution of metastable β′ and β″ phases was alsoobserved at high temperatures, the fraction of which was remarkably increased with increasing temperature to 420 and 480 °C.

Nanoporous graphene oxide membrane and its application in molecular sieving

S. Mahmood Fatemi,Masoud Arabieh,Hamid Sepehrian 한국탄소학회 2015 Carbon Letters Vol.16 No.3

Gas transport through graphene-derived membranes has gained much interest recently due to its promising potential in filtration and separation applications. In this work, we explore Kr-85 gas radionuclide sequestration from natural air in nanoporous graphene oxide membranes in which different sizes and geometries of pores were modeled on the graphene oxide sheet. This was done using atomistic simulations considering mean-squared displacement, diffusion coefficient, number of crossed species of gases through nanoporous graphene oxide, and flow through interlayer galleries. The results showed that the gas features have the densest adsorbed zone in nanoporous graphene oxide, compared with a graphene membrane, and that graphene oxide was more favorable than graphene for Kr separation. The aim of this paper is to show that for the well-defined pore size called P-7, it is possible to separate Kr-85 from a gas mixture containing Kr-85, O2 and N2. The results would benefit the oil industry among others.

Estimation of the Projections of the Incidence Rates, Mortality and Prevalence Due to Common Cancer Site in Isfahan, Iran

Moradpour, Farhad,Fatemi, Zeinab Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.6

Background: Accurate statistics on the cancer burden are essential, both for purposes of research and for setting priorities in healthcare management. So that in vast countries with partial registration coverage, such as Iran, local data are more useful. We here estimated the incidence, prevalence and mortality time trend of four major cancer site, lung, stomach, breast and prostate, over the period 2001-2010 and provided short-range projections to 2015 in Isfahan. Materials and Methods: Estimates were derived by applying the mortality-incidence analysis method, a back-calculation approach to estimate and project incidence, prevalence and mortality of chronic degenerative disease, starting from knowledge of mortality and relative survival information. Results: Age adjusted incidence, mortality and prevalence rates in Isfahan exhibited a clear upward trend for all four sites during the period 2001-2015, with marked increasees in prostate and breast predicted for the future. Difference in incidence trends between males and females might be attributable to the difference in risk factors specific to certain cancer sites, with smoking being the main risk factor. Conclusions: In this study, males and females displayed an increasing pattern for incidence and mortality rate over the entire study period until 2015. This information can be used as basis for planning healthcare management and allocating recourses in public health.