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- 저자 : Ahmad Akbari (검색결과 23 건)
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Ahmad Akbari,Maryam Homayoonfal 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.8
The aim of this research is synthesis of high performance loose nanofiltration membranes for separation of direct dyes from textile wastewater. This involved sulfonation of polysulfone with the aim of increasing hydrophilicity and permeability; synthesis of a sulfonated polysulfone and polysulfone (SPSf/PSf) blended membrane for developing the mechanical resistance and stability of the filtration behavior; and synthesis of TiO2/SPSf/PSf nanocomposite membrane for magnifying selectivity. FTIR analysis confirmed the sulfonated groups and the TiO2 nanoparticles presence. AFM and SEM analysis proved the highest surface roughness and the smallest pore size of TiO2/SPSf/PSf nanocomposite membrane, respectively. The results of water absorption test revealed that the highest level of hydrophilicity belonged to the SPSf/PSf followed by TiO2/SPSf/PSf membrane. The nanofiltration tests showed that the SPSf/PSf membranes enjoy the highest permeability, while the TiO2/SPSf/PSf nanocomposite not only had an acceptable permeability but also presented the highest dye separation efficiency.
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Ahmad Akbari,Zahra Derikvandi,Sayed Majid Mojallali Rostami 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.28 No.-
Chitosan was coated into polyamide membranes by in situ reaction of amine and hydroxyl groups ofchitosan and un-reacted of acylchloride of polyamide active layer. Effect of chitosan concentration andcoagulation time on the membrane chemical structure, morphology, separation performances and antifoulingproperties were characterized by FT-IR, SEM, AFM, cross-flow membrane module device andcetyltrimethylammonium bromide experiment. Water flux of the polyamide membranes enhanced from32.9 to 59.6 L/m2 h and anti-fouling results proved that excellent fouling resistance. Thus, chitosan as asecondary modifier has special potential to improve the performance of polyamide membranes.
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Ahmad Shanei,Hadi Akbari-Zadeh 대한의학회 2019 Journal of Korean medical science Vol.34 No.37
Background: In this article, we estimated the combined effect of radiotherapy (RT) with ultrasound (US) wave and the ability of gold nanoparticles (GNPs) to improve their combined therapeutic effects. Methods: At first, HeLa cells received the various treatment modalities: RT (6 MV; 0.5, 1, and 2 Gy), US irradiation (1 MHz; 0.5, 1, and 1.5 W/cm2 , 1 minute), and RT+US. Afterwards, the enhanced effect of US on RT was evaluated. Then, the effect of the synthesized GNPs at different concentrations (0.2, 1, and 5 µg/mL, 24 hours) was evaluated to assess the effect on HeLa cells combined with RT+US. Cell survival rates in the different treatment groups at 24, 48, and 72 hours post-treatment were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide and trypan blue assays. Results: Our results show US irradiation could enhance the effect of RT at the same radiation dose and could be utilized as a sensitizer agent for RT. Moreover, our findings indicate RT+US in combination with different nanoparticle concentrations could enhance the effect of RT+US so that they can improve the treatment results up to 9.93 times and act as sonodynamic- radiosensitivity. These results also indicate that the combination of RT with US along with GNPs has synergistic effects compared to RT or US alone. Cell survival results show that combining the low US waves (1.5 W/cm2 ), GNPs (5 μg/mL), and X-rays (2 Gy) increase the cytotoxicity on HeLa cell up to 95.8%. Conclusion: We concluded that GNPs could act as a good sensitizing agent in RT+US irradiation and could result in the synergistic effects.
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Fitting Cure Rate Model to Breast Cancer Data of Cancer Research Center
Baghestani, Ahmad Reza,Zayeri, Farid,Akbari, Mohammad Esmaeil,Shojaee, Leyla,Khadembashi, Naghmeh,Shahmirzalou, Parviz Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.17
Background: The Cox PH model is one of the most significant statistical models in studying survival of patients. But, in the case of patients with long-term survival, it may not be the most appropriate. In such cases, a cure rate model seems more suitable. The purpose of this study was to determine clinical factors associated with cure rate of patients with breast cancer. Materials and Methods: In order to find factors affecting cure rate (response), a non-mixed cure rate model with negative binomial distribution for latent variable was used. Variables selected were recurrence cancer, status for HER2, estrogen receptor (ER) and progesterone receptor (PR), size of tumor, grade of cancer, stage of cancer, type of surgery, age at the diagnosis time and number of removed positive lymph nodes. All analyses were performed using PROC MCMC processes in the SAS 9.2 program. Results: The mean (SD) age of patients was equal to 48.9 (11.1) months. For these patients, 1, 5 and 10-year survival rates were 95, 79 and 50 percent respectively. All of the mentioned variables were effective in cure fraction. Kaplan-Meier curve showed cure model's use competence. Conclusions: Unlike other variables, existence of ER and PR positivity will increase probability of cure in patients. In the present study, Weibull distribution was used for the purpose of analysing survival times. Model fitness with other distributions such as log-N and log-logistic and other distributions for latent variable is recommended.
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Survival Analysis of Patients with Breast Cancer using Weibull Parametric Model
Baghestani, Ahmad Reza,Moghaddam, Sahar Saeedi,Majd, Hamid Alavi,Akbari, Mohammad Esmaeil,Nafissi, Nahid,Gohari, Kimiya Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.18
Background: The Cox model is known as one of the most frequently-used methods for analyzing survival data. However, in some situations parametric methods may provide better estimates. In this study, a Weibull parametric model was employed to assess possible prognostic factors that may affect the survival of patients with breast cancer. Materials and Methods: We studied 438 patients with breast cancer who visited and were treated at the Cancer Research Center in Shahid Beheshti University of Medical Sciences during 1992 to 2012; the patients were followed up until October 2014. Patients or family members were contacted via telephone calls to confirm whether they were still alive. Clinical, pathological, and biological variables as potential prognostic factors were entered in univariate and multivariate analyses. The log-rank test and the Weibull parametric model with a forward approach, respectively, were used for univariate and multivariate analyses. All analyses were performed using STATA version 11. A P-value lower than 0.05 was defined as significant. Results: On univariate analysis, age at diagnosis, level of education, type of surgery, lymph node status, tumor size, stage, histologic grade, estrogen receptor, progesterone receptor, and lymphovascular invasion had a statistically significant effect on survival time. On multivariate analysis, lymph node status, stage, histologic grade, and lymphovascular invasion were statistically significant. The one-year overall survival rate was 98%. Conclusions: Based on these data and using Weibull parametric model with a forward approach, we found out that patients with lymphovascular invasion were at 2.13 times greater risk of death due to breast cancer.
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Maryam Akbari,Ahmad Molaeirad,Ramazan Ali Khavari-Nej 한국고분자학회 2017 Macromolecular Research Vol.25 No.10
Bacteriorhodopsin (BR) has emerged as an important material for constructing data storage devices due to its unique properties. In this study, BR has been immobilized on modified polycarbonate (PC) surface of compact disk (CD) by using of Langmuir-Blodgett (LB) method. UV/Ozone treatment was used to amplify the immobilization of BR on PC surface. ATR-FTIR and UV-Visible spectroscopy analyses were carried out to study the structure properties of the monolayer. Our results show that an efficient bio surface of PC was fabricated by the Langmuir-Blodgett deposition which is an appropriate candidate to immobilization of BR and formation 0 and 1 bite that relate to bR and P, Q intermediate states in order to construct biomemory.
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Baghestani, Ahmad Reza,Shahmirzalou, Parviz,Zayeri, Farid,Akbari, Mohammad Esmaeil,Hadizadeh, Mohammad Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.12
Background: Breast cancer is a malignant tumor that starts from cells of the breast and is seen mainly in women. It's the most common cancer in women worldwide and is a major threat to health. The purpose of this study was to fit a Cox proportional hazards model for prediction and determination of years of survival in Iranian patients. Materials and Methods: A total of 366 patients with breast cancer in the Cancer Research Center were included in the study. A Cox proportional hazard model was used with variables such as tumor grade, number of removed positive lymph nodes, human epidermal growth factor receptor 2 (HER2) expression and several other variables. Kaplan-Meier curves were plotted and multi-years of survival were evaluated. Results: The mean age of patients was 48.1 years. Consumption of fatty foods (p=0.033), recurrence (p<0.001), tumor grade (p=0.046) and age (p=0.017) were significant variables. The overall 1- year, 3-year and 5-year survival rates were found to be 93%, 75% and 52%. Conclusions: Use of covariates and the Cox proportional hazard model are effective in predicting the survival of individuals and this model distinguished 4 effective factors in the survival of patients.
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Application of a Non-Mixture Cure Rate Model for Analyzing Survival of Patients with Breast Cancer
Baghestani, Ahmad Reza,Moghaddam, Sahar Saeedi,Majd, Hamid Alavi,Akbari, Mohammad Esmaeil,Nafissi, Nahid,Gohari, Kimiya Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16
Background: As a result of significant progress made in treatment of many types of cancers during the last few decades, there have been an increased number of patients who do not experience mortality. We refer to these observations as cure or immune and models for survival data which include cure fraction are known as cure rate models or long-term survival models. Materials and Methods: In this study we used the data collected from 438 female patients with breast cancer registered in the Cancer Research Center in Shahid Beheshti University of Medical Sciences, Tehran, Iran. The patients had been diagnosed from 1992 to 2012 and were followed up until October 2014. We had to exclude some because of incomplete information. Phone calls were made to confirm whether the patients were still alive or not. Deaths due to breast cancer were regarded as failure. To identify clinical, pathological, and biological characteristics of patients that might have had an effect on survival of the patients we used a non-mixture cure rate model; in addition, a Weibull distribution was proposed for the survival time. Analyses were performed using STATA version 14. The significance level was set at $P{\leq}0.05$. Results: A total of 75 patients (17.1%) died due to breast cancer during the study, up to the last follow-up. Numbers of metastatic lymph nodes and histologic grade were significant factors. The cure fraction was estimated to be 58%. Conclusions: When a cure fraction is not available, the analysis will be changed to standard approaches of survival analysis; however when the data indicate that the cure fraction is available, we suggest analysis of survival data via cure models.
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Two-Microphone Binary Mask Speech Enhancement in Diffuse and Directional Noise Fields
Roohollah Abdipour,Ahmad Akbari,Mohsen Rahmani 한국전자통신연구원 2014 ETRI Journal Vol.36 No.5
Two-microphone binary mask speech enhancement(2mBMSE) has been of particular interest in recentliterature and has shown promising results. Current2mBMSE systems rely on spatial cues of speech and noisesources. Although these cues are helpful for directionalnoise sources, they lose their efficiency in diffuse noisefields. We propose a new system that is effective in bothdirectional and diffuse noise conditions. The systemexploits two features. The first determines whether a giventime–frequency (T–F) unit of the input spectrum isdominated by a diffuse or directional source. A diffusesignal is certainly a noise signal, but a directional signalcould correspond to a noise or speech source. The secondfeature discriminates between T–F units dominated byspeech or directional noise signals. Speech enhancement isperformed using a binary mask, calculated based on theproposed features. In both directional and diffuse noisefields, the proposed system segregates speech T–F unitswith hit rates above 85%. It outperforms previoussolutions in terms of signal-to-noise ratio and perceptualevaluation of speech quality improvement, especially indiffuse noise conditions.
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