Effect of Nitrogen and Boron Localization on the Electrical Properties of Porous Graphene

Mahmoud Jafari,Shima Nazifi,Mohamad Asadpour 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.9

The electrical properties of porous graphene (PG) are investigated by using the density functional theory (DFT) with the generalized gradient approximation (GGA). The addition of Boron and nitrogen impurities could change the semiconductor into the n or p-type. Results showed that PG had pseudo-metal properties and a direct band gap. Furthermore, adding two impurities resulted in a greater decrease in the energy of the band gap as compared to the other states. In particular, when two impurities were of the boron type, the reduction was more tangible. Moreover, the addition of impurity could also increase the conductivity and pushed the electrical properties toward being a metal.

An Efficient Plant Regeneration System via Direct Organogenesis with in Vitro Flavonoid Accumulation and Analysis of Genetic Fidelity among Regenerants of Teucrium polium L.

Faraz Arash Rad,Morad Jafari,Nabi Khezrinejad,Mahmoud Pouryousef Miandoab 한국원예학회 2014 Horticulture, Environment, and Biotechnology Vol.55 No.6

An efficient and rapid plant regeneration system via direct organogenesis was established for felty germander(Teucrium polium L.), an endangered and valuable medicinal plant. Induction of shoot organogenesis was obtainedusing nodal explants and preconditioned intact seedlings on the MS medium supplemented with various concentrationsand combinations of plant growth regulators. The highest number of shoots (7.14/explants) was obtained from nodalexplants cultured on MS containing 2.0 mg·L-1 BAP and 0.5 mg·L-1 NAA. For preconditioning, Best response in termsof number of adventitious shoots per explant (6.85) and greatest shoot length (5.43 cm) was obtained with seedlingsperpetrated in 0.5 mg·L-1 TDZ. The rooted plantlets were acclimatized successfully in the greenhouse with a survivalrate of 100%. Significant differences (p < 0.05) were found between the greenhouse-grown tissue culture raised plantsin total flavonoid contents. Methanolic extracts of plants raised on TDZ (0.5 mg·L-1) containing medium showed thehighest amount of flavonoid contents (1.67 mg Ru·g-1 DW) and a higher antioxidant activity (52.31%) in comparisonwith the field-grown mother plant. Randomly amplified polymorphic DNA (RAPD) analysis of plants raised preconditioningprocedure revealed there were no somaclonal variations among them. Our results indicated that thecytokinin-preconditioning mediated micropropagation protocol could be used for the production of a large number oftrue-to-type plants of T. polium, which may contain higher quantities of valuable phytochemicals than those of wildplants.

Measurement of the electrolyte flow velocity and bubbles characterization during electrochemical reactions in lead-acid batteries using the PIV system

Saeed Nahidi,Iraj Jafari Gavzan,Seyfolah Saedodin,Mahmoud Salari 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-

Thefluidflow of electrolyte within the cells of the electrochemical batteries has a vital role on theperformance of batteries. Many numerically and experimentally investigations have been carried out onthis subject. Inflooded electrolyte batteries during high rates charging and discharging process, due tothe electrochemical reactions, insoluble gas bubbles are produced on the surface of electrodes anddispersed in the electrolyte. Despite the importance of the presence of bubbles on the electrolyte velocityand concentrationfield, in all studies, the presence of bubbles have been ignored. In this study, anexperimental setup has been developed for measuring the electrolyte velocity in theflooded lead-acidbatteries based on utilizing the Particle Image Velocimetry system. The results for different states ofcharge (SOCs) showed that by increasing the number of bubbles which occurs at high SOCs, the velocity ofelectrolyteflow increases. Also in the SOCs 40%, 60% and 100% compared to the SOC 0%, the averagedvelocity of the electrolyte has increased about 16.8%, 29%, and 79%, respectively. The obtained resultsshow that at higher SOCs, the effect of stratification phenomenon on the electrolyte velocity with respectto the effect of the presence of bubbles in the electrolyte is negligible.

Comparative Study of Poly(L-Lactic Acid) Scaffolds Coated with Chitosan Nanoparticles Prepared via Ultrasonication and Ionic Gelation Techniques

Majid Salehi,Mahdi Naseri-Nosar,Mahmoud Azami,Saeedeh Jafari Nodooshan,Javad Arish 한국조직공학과 재생의학회 2016 조직공학과 재생의학 Vol.13 No.5

In this study, an attempt was made to develop bi-functional constructs serving both as scaffolds and potential delivery systems for application in neural tissue engineering. The constructs were prepared in two steps. In the first step, the bulks of poly (L-lactic acid) (PLLA) in 1, 4-dioxane/water (87:13) were fabricated using liquid-liquid thermally induced phase separation technique. In the next step, the prepared bulks were coated with chitosan nanoparticles produced by two different techniques of ultrasonication and ionic gelation by grafting-coating technique. In ultrasonication technique, the chitosan solution (2 mg/mL) in acetic acid/sodium acetate buffer (90:10) was irradiated by an ultrasound generator at 20 kHz and power output of 750 W for 100 s. In ionic gelation technique, the tripolyphosphate in water solution (1 mg/mL) was added to the same chitosan solution. The physicochemical properties of the products were characterized by Scanning Electron Microscopy, Attenuated Total Reflection Fourier Transform-Infrared, liquid displacement technique, contact angle measurement, compressive and tensile tests, as well as zeta potential and particle size analysis using dynamic light scattering. Moreover, the cell proliferation and attachment on the scaffolds were evaluated through human glioblastoma cell line (U-87 MG) and human neuroblastoma cell line [BE (2)-C] culture respectively. The results showed that the samples coated with chitosan nanoparticles prepared by ultrasonication possessed enhanced hydrophilicity, biodegradation and cytocompatibility compared with pure PLLA and PLLA coated with chitosan nanoparticles prepared by ionic gelation. This study suggests successful nanoparticles-scaffold systems which can act simultaneously as potential delivery systems and tissue engineering scaffolds.

Evaluation of Response to Preoperative Chemotherapy Versus Surgery Alone in Gastroesophageal Cancer: Tumor Resectability, Pathologic Results and Post-Operative Complications

Marandi, Aref Kashefi,Shojaiefard, Abolfazl,Soroush, Ahmadreza,Abdegah, Ali Ghorbani,Jafari, Mehdi,Khodadost, Mahmoud,Mahmoudzade, Hossein Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup3

Gastroesophageal cancer is one of the most common types of cancer worldwide. Despite significant developments in management, 5-year survival in the developing world is less than 20 percent. Due to restricted research about the impact of preoperative chemotherapy (POC) on tumor resection, pathological response and postoperative complications in Iran, we designed and implemented the present retrospective cross- sectional study on 156 patients with gastroesophageal cancer (GEc) between 2013 and 2015 at Shariati Hospital of Tehran. Two groups were included, the first group had previously received preoperative chemotherapy and the second group had only undergone surgery. All patients were followed for at least one year after the operation in terms of tumor recurrence, relapse free survival and one-year survival. The two groups were eventually compared regarding tumor resection, pathological response, postoperative complications, recurrence rate and survival. The mean age was $66.5{\pm}7.3years$ and 78 percent were male. The tumor resectability, pathological response and postoperative complications in the group which received POC were 93.5%, 21.8% and 12.8%, respectively, and in the surgery alone group figures for tumor resection and postoperative complications were 76% and 29.5%, respectively. Also based on our study the 5-year survival in the POC group was better (79.5% vs. 66.5%). Using standard neoadjuvant regimens (preoperative chemotherapy/chemoradiotherapy) beforesurgery could increase tumor resectability, pathological response, and improve the general status of the patients. Therefore using POC may be recommended over surgery alone.