142 research outputs found

    Gold nanoparticle and mean inactivation dose of human intestinal colon cancer HT-29 cells

    Get PDF
    Background: Mean inactivation dose is a useful radiobiological parameter for the comparison of human cell survival curves. Objectives: Given the importance and accuracy of these parameters, in the present study, the radio sensitivity enhancement of colon cancer (HT-29) cells in the presence of gold nanoparticles (GNPs) were studied using the mean inactivation dose (MID). Materials and Methods: Naked-GNPs with 50 nm diameters were incubated with HT-29 cells. The cytotoxicity and uptake of these particles on HT-29 cells were assessed. After determining the optimum GNPs concentration, the cells were incubated with gold nanoparticle for 24 hours. The change in the MID value as well as the radio sensitization enhancement under irradiation with 9 MV X-ray beams in the presence of GNPs were evaluated by multiple (3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium)MTS assay. Results: Cell survival in the presence of GNPs was more than 90% and the maximum uptake of GNPs was observed at 60 μM of gold nanoparticles. In contrast, in the presence of GNPs combined with radiation, cell survival and MID value significantly decreased, so that the radio sensitization enhancement was 1.4. Conclusions: Due to the significant reduction in the mean inactivation dose of colon cancer cells in the presence of gold nanoparticles, it seems that GNPs are suitable options to achieve a new approach in order to improve radiotherapy efficiency without increasing the prescribed radiation dose

    Examining the Role of RFID Technology on SCM Effectiveness, Case: Food industry of Iran

    Get PDF
    Taking advantage of the new technology, supply chain has already created a chain of cooperation among its own Companies, and, in a larger scale, within a universal environment. Superior to these technologies is RFID which is an abbreviation for Radio Frequency Identification. RFID is one of the most advanced technologies in the contemporary world. Perishable products and hose with short time expiry particularly food products bring about many challenges and problems for the supply chain managers. Such challenges are mostly due to variety in the number of products, especial need for keeping track of the products during the supply chain process, their short term expiry; need to control their temperature during the supply chain process, and their high quantity. Using RFID is one of the best possible ways that can help managers deal with logistical problems of perishable products. In food industry, storage level is generally low because of a high possibility of expiry. Today, changes in methods of production, distribution, maintenance and sale of food products have led to some changes in the demand of consumers for higher quality as well as greater longevity of food products. In order for more confidence in desirable packing in supply chain of food products, such innovations as smart packaging or active packaging have achieved popularity

    Energy optimisation in residential apartments through the passive design strategies by evaluating the local construction materials and designs in semi-arid climate condition of Tehran

    Get PDF
    Low energy building design methods, and the corresponding environmental constraints, are widely explored in many developed countries. Tehran characterized by its semi-arid climates and geographical location in a global region is renowned for its high energy consumption and carbon emission rates. This research aims to evaluate the energy performances of low energy housing in multi residential buildings in Tehran and provide design guidance in improving their energy and thermal performances using passive design measures. The research considers the building envelope as the back bone of its energy optimisation. It takes into account the local climatic conditions context and local construction practices as well as the most often used construction materials. In order to fulfil the above stated aim, this research uses annual KWh/m2 as a design selection metric to evaluate various design considerations in Tehran. A comprehensive, three phase studies have been carried out for the research in order to achieve following objectives: (a) identify building construction factors resulting in high energy consumption in domestic buildings in Tehran; (b) assess the local efficient design and materials contributing to reduction of energy consumption in Tehran (c) evaluate passive domestic design with regards to free running buildings where is applicable (d) propose guidance on better energy performance residential buildings in Tehran through passive design principles. The finding of this research proves that a systematically selection of various designs and materials within the local practices and market, coupled with considerations of local standard thermal comfort requirements, up to 70% of energy savings can be achieved in Tehran without imposing much change against the cost and design to the existing practices

    Revisiting the magnetic and crystal structure of multiferroic KNiPO4_4

    Full text link
    The magnetic, dielectric and structural properties of type-I multiferroic KNiPO4_4 have been investigated by neutron powder diffraction, magnetization, dielectric and high temperature synchrotron-XRD measurements. Below the N\'{e}el transition of TNT_\mathrm{N} = 25 K, KNiPO4_4 displays a weakly non-collinear antiferromagnetic (AFM) structure with the orientation of the Ni2+^{2+} magnetic moments mainly along aa axis. The compound crystallizes in the polar orthorhombic Pna21Pna2_1 space group at room temperature. A second-order structural phase transition corresponding to the onset ferroelectricity is observed at around TCT_\mathrm{C}\sim 594(3)^\circC, above which the crystal structure of KNiPO4_4 adopts the centrosymmetric PnmaPnma space group. The compound also displays another structural phase transition at T0T_\mathrm{0}\sim 469 -- 488^\circC, with a first-order character, which is attributed to the rearrangement of oxygen ligands, resulting in a change in the nickel ion co-ordination from four to five

    The psychometric properties of the Persian version of the contamination cognition scale (CCS)

    Get PDF
    Objective: In recent years, many researchers have been searching for effective cognitive factors in the development of obsessive-compulsive disorder (OCD). One of the scales designed to measure this characteristic is the contamination cognition scale (CCS) that evaluates 2 dimensions: overestimating the likelihood and severity of contamination. The aim of the present study was to evaluate the psychometric properties of the Persian version of CCS. Method: The study population of this descriptive psychometric study included students of Shahed University. A total of 490 students were selected via cluster sampling and completed the CCS. CCS was translated and back- translated before given to the students. The Obsessive Beliefs Questionnaire (OBQ) and the Padua Inventory (PI) were used. To assess the evidence for the validity of the scale, the exploratory and confirmatory factor analyses were used. The gathered data were analyzed by SPSS-22 and Amos-22 software. Results: The results of the confirmatory factor analysis (CFA) showed that one-factor model did not have adequate fitness (RMSEA > .05). Therefore, to explore the factors of this scale, exploratory factor analysis (EFA) was used, and it revealed 3 factors (public equipment, food, and restroom) for each of the dimensions (likelihood and severity). CFA by AMOS-22 confirmed the three-factor model (GFI, CFI, and NFI > .95; RMSEA < .05). Furthermore, the results supported criteria validity of CCS with the PI total score (0.56- 0.47, p < 0.001) and PI-contamination subscale (0.71-0.75, p < 0.001). Also, the correlation between CCS and responsibility/threat subscale of the OBQ was significant (0.47- 0.49, p < 0.001) The Cronbach's alpha for likelihood dimensions total was 0.93 and it was 0.94 for severity dimension total. The composite reliability was 0.95 for the likelihood dimension and 0.96 for severity dimension of CCS. Also, the test-retest reliability after a 4-week interval was confirmed (likelihood: r = 0.78; severity: r = 0.81, p < .001). Conclusion: The results indicated that one-factor model of CCS did not have adequate fitness, but three-factor model was confirmed in both dimensions (likelihood and severity). According to the results of the present study, the reliability and validity of the Persian version of CCS were acceptable. © 2018 Tehran University of Medical Sciences

    Electro-magneto-thermo-mechanical Behaviors of a Radially Polarized FGPM Thick Hollow Sphere

    Get PDF
    ABSTRACT In this study an analytical method is developed to obtain the response of electro-magneto-thermoelastic stress and perturbation of a magnetic field vector for a thick-walled spherical functionally graded piezoelectric material (FGPM). The hollow sphere, which is placed in a uniform magnetic field, is subjected to a temperature gradient, inner and outer pressures and a constant electric potential difference between its inner and outer surfaces. The thermal, piezoelectric and mechanical properties except the Poisson&apos;s ratio are assumed to vary with the power law functions through the thickness of the hollow sphere. By solving the heat transfer equation, in the first step, a symmetric distribution of temperature is obtained. Using the infinitesimal electro-magnetothermo-elasticity theory, then, the Navier&apos;s equation is solved and exact solutions for stresses, electric displacement, electric potential and perturbation of magnetic field vector in the FGPM hollow sphere are obtained. Moreover, the effects of magnetic field vector, electric potential and material in-homogeneity on the stresses and displacements distributions are investigated. The presented results indicate that the material in-homogeneity has a significant influence on the electro-magneto-thermo-mechanical behaviors of the FGPM hollow sphere and should therefore be considered in its optimum design

    Factors affecting intensive care units nursing workload

    Get PDF
    Background: The nursing workload has a close and strong association with the quality of services provided for the patients. Therefore, paying careful attention to the factors affecting nursing workload, especially those working in the intensive care units (ICUs), is very important. Objectives: This study aimed to determine the factors affecting nursing workload in the ICUs of the hospitals affiliated to Tehran University of Medical Sciences. Materials and Methods: This was a cross-sectional and analytical-descriptive study that has done in Iran. All nurses (n = 400) who was working in the ICUs of the hospitals affiliated to Tehran University of Medical Sciences in 2014 were selected and studied using census method. The required data were collected using a researcher-made questionnaire which its validity and reliability were confirmed through getting the opinions of experts and using composite reliability and internal consistency (α = 0.89). The collected data were analyzed through exploratory factor analysis (EFA), confirmatory factor analysis (CFA) and using SPSS 18.0 and AMOS 18.0. Results: Twenty-five factors were divided into three major categories through EFA, including structure, process, and activity. The following factors among the structure, process and activity components had the greatest importance: lack of clear responsibilities and authorities and performing unnecessary tasks (by a coefficient of 0.709), mismatch between the capacity of wards and the number of patients (by a coefficient of 0.639), and helping the students and newly employed staff (by a coefficient of 0.589). Conclusions: The nursing workload is influenced by many factors. The clear responsibilities and authorities of nurses, patients' admission according to the capacity of wards, use of the new technologies and equipment, and providing basic training for new nurses can decrease the workload of nurses. © 2014, Iranian Red Crescent Medical Journal; Published by Kowsar Corp

    Anomalous codeposition of cobalt and ruthenium from chloride-sulfate baths

    Get PDF
    Codeposition of Ru and Co was studied at room temperature and at 50oC with various Ru3+ and Co2+ concentrations in the electrolyte. The codeposition of Co and Ru proved to be anomalous since no pure Ru could be obtained in the presence of Co2+ in the electrolyte, but a significant Co incorporation into the deposit was detected at potentials where the deposition of pure Co was not possible. The composition of the deposits varied monotonously with the change of the concentration ratio of Co2+ and Ru3+. The deposition of Ru was much hindered and the current efficiency was a few percent only when the molar fraction of Co in the deposit was low. Continuous deposits could be obtained only when the molar fraction of Co in the deposit was at least 40 at.%. The deposit morphology was related to the molar fraction of Co in the deposit. The X-ray diffractograms are in conformity with a hexagonal close-packed alloy and indicate the formation of nanocrystalline deposits. Two-pulse plating did not lead to a multilayer but to a Co-rich alloy. Magnetoresistance of the samples decreased with increasing Ru content

    The risk factors and related hospitalizations for cases with positive and negative COVID-19 tests: A case-control study

    Get PDF
    Background: The aim of this study was to evaluate the risk factors for hospitalizations of cases with positive and negative COVID-19 tests. Methods: In this case-control study, the case and control groups consisted of 292 COVID-19 patients and 296 non-COVID-19 patients. Patients who referred to a reference laboratory in Tehran (Iran) in March 2020 were selected and interviewed. The patients were contacted by telephone and data were recorded through a questionnaire. Results: The sample of this study consisted of 588 patients (349 59% females, 239 41% males) with a mean age of 42 ± 15. The results of this study showed that comorbidities like diabetes (OR = 7.42), hypertension (OR = 4.85), asthma and respiratory diseases (OR = 5.64) in addition to symptoms including fever (OR = 6.67), chills (OR = 11.2), anorexia (OR = 11.3), dyspnea (OR = 4.8), weakness and lethargy (OR = 5.7) were the most predictive variables for hospitalization of non-COVID-19 cases. Furthermore, demographical variables like male gender (OR = 3.71), high age (>50; OR = 3.12), BMI (>25; OR = 2.37), travel (OR = 2.79), comorbidities including diabetes (OR = 5.26), hypertension (OR = 3.7) and underlying immunosuppressant patients receiving corticosteroid therapy (OR = 3.62) in addition to symptoms like anorexia OR = 2.55 and dyspnea (OR = 6.99) tend to increase the risk of hospital admission in COVID-19 patients, suggesting their predictive values for hospitalization of COVID-19 patients. Conclusion: Our results indicated that different factors tend to increase the odds of hospital admission in patients with positive and negative COVID-19 tests, suggesting their predictive values for hospitalization. © 202
    corecore