Gelatin-based functional films integrated with grapefruit seed extract and TiO2 for active food packaging applications

, Article Food Hydrocolloids ; Volume 112 , 2021 ; 0268005X (ISSN) Riahi, Z ; Priyadarshi, R ; Rhim, J. W ; Bagheri, R ; Sharif University of Technology

Elsevier B.V 2021

Abstract

Gelatin-based functional films were prepared by the addition of grapefruit seed extract (GSE, 5 wt% based on gelatin) and various amounts of TiO2 (0.5, 1.0, 3.0, and 5.0 wt% based on gelatin). TiO2 was evenly dispersed in the gelatin film, but the film surface roughness was increased as the concentration of TiO2 increased. The mechanical strength and water contact angle (WCA) of the composite film were the highest, while the water vapor permeability (WVP) was the lowest when 0.5 wt% TiO2 was used. The addition of GSE slightly reduced the UV light transmittance, but the addition of TiO2 almost completely prevented the UV light transmission. The addition of GSE and TiO2 did not significantly...

The effect of mixing molar ratios and sand particles on microstructure and mechanical properties of metakaolin-based geopolymers

, Article Materials Chemistry and Physics ; Volume 240 , 2020 Riahi, S ; Nemati, A ; Khodabandeh, A. R ; Baghshahi, S ; Sharif University of Technology

Elsevier Ltd 2020

Abstract

In this study the influence of the molar ratios such as SiO2:Al2O3:Na2O:H2O, as well as the sand particles on the mechanical performance, shrinkage and microstructure of metakaolin based geopolymers was studied. Considering different content of the reactive silica and alumina in metakaolin, forty eight different compositions were prepared. The proper condition for achieving the highest mechanical performance as well as less structural defects by tailoring the curing condition, molar ratios and addition of sand particles are presented. Special attention was paid to the incorporation of sand particles up to 70 wt% on the microstructure, shrinkage and mechanical properties of metakaolin based...

Investigation of interfacial and mechanical properties of alumina-coated steel fiber reinforced geopolymer composites

, Article Construction and Building Materials ; Volume 288 , 2021 ; 09500618 (ISSN) Riahi, S ; Nemati, A ; Khodabandeh, A. R ; Baghshahi, S ; Sharif University of Technology

Elsevier Ltd 2021

Abstract

In this study, alumina coated steel reinforced geopolymer composites were successfully fabricated and their interfacial and mechanical properties were investigated. The fiber–matrix interface characteristics were assessed using single-fiber push-out and water contact angle experiments as well as SEM-EDS analysis. Finally, the role of alumina coating on the compressive, flexural and toughness of the geopolymer composites was investigated. The morphological studies revealed that alumina coating on steel can chemically bonded and microstructurally integrated with the surrounding matrix. The push-out test showed that the interfacial shear strength was increased approximately 150% in composites...

Alginate-based multifunctional films incorporated with sulfur quantum dots for active packaging applications

, Article Colloids and Surfaces B: Biointerfaces ; Volume 215 , 2022 ; 09277765 (ISSN) Riahi, Z ; Priyadarshi, R ; Rhim, J. W ; Lotfali, E ; Bagheri, R ; Pircheraghi, G ; Sharif University of Technology

Elsevier B.V 2022

Abstract

Sulfur quantum dots (SQDs) were fabricated using a facile hydrothermal method and used for the preparation of functional food packaging film and compared the properties with other sulfur-based fillers like elemental sulfur (ES) and sulfur nanoparticles (SNP). The SQDs have an average size of 5.3 nm and were very stable in aqueous suspension. Unlike other sulfur-based fillers, the SQD showed high antioxidant, antibacterial and antifungal activity, but no cytotoxicity was found for L929 mouse fibroblasts even after long-term exposure of 48 h. When sulfur-based fillers were added to the alginate film, SQD was more evenly dispersed in the polymer matrix than SNP and ES. The addition of SQD to...

Experimental investigation of inorganic scale deposition during smart water injection - A formation damage point of view

, Article IOR NORWAY 2017 - 19th European Symposium on Improved Oil Recovery: Sustainable IOR in a Low Oil Price World, 24 April 2017 through 27 April 2017 ; 2017 ; 9789462822092 (ISBN) Ghasemian, J ; Mokhtari, R ; Ayatollahi, S ; Riahi, S ; Malekzade, E ; Sharif University of Technology

2017

Abstract

Smart water injection is determined as an effective EOR process to change the wettability and interfacial tension for better micro/macro sweep efficiencies. This water contains reactive ions such as Mg ∧(2+), Ca ∧(2+) and SO-4 ∧(2-) which can act as potential determining ions and change the surface charge of calcite rocks. One of the major concerns in the execution of an effective waterflood, especially in tight carbonate reservoirs, is the incompatibility between the formation brine and the injecting water. This research work aims to investigate the most important challenge of waterflooding process related to the possible formation damage because of inorganic scale deposition during...

Titania nanotubes decorated with cu(I) and cu(II) oxides: antibacterial and ethylene scavenging functions to extend the shelf life of bananas

, Article ACS Sustainable Chemistry and Engineering ; Volume 9, Issue 19 , 2021 , Pages 6832-6840 ; 21680485 (ISSN) Riahi, Z ; Priyadarshi, R ; Rhim, J. W ; Hong, S. I ; Bagheri, R ; Pircheraghi, G ; Sharif University of Technology

American Chemical Society 2021

Abstract

Titanium nanotubes (TNTs) were prepared using TiO2 and decorated with CuO and Cu2O to have photocatalytic efficiency under visible light. TNTs decorated with copper oxides (TNT-CuO and TNT-Cu2O) were confirmed by the elemental mapping and XPS results. Unlike TNT and TiO2, TNT-CuO and TNT-Cu2O showed higher photocatalytic activity, such as antimicrobial and ethylene scavenging activities under visible light. Between the two types of copper oxide-decorated TNTs, TNT-Cu2O showed photocatalytic activity higher than that of TNT-CuO. The ethylene scavenging activity of TNT-Cu2O was about 40% higher than that of TNTs and TNT-CuO. The photocatalytic activity of titanium-based nanoparticles was...

Error estimation, adaptivity and data transfer in enriched plasticity continua to analysis of shear band localization

, Article Applied Mathematical Modelling ; Volume 31, Issue 6 , 2007 , Pages 983-1000 ; 0307904X (ISSN) Khoei, A. R ; Asil Gharebaghi, S ; Tabarraie, A. R ; Riahi, A ; Sharif University of Technology

2007

Abstract

In this paper, an adaptive FE analysis is presented based on error estimation, adaptive mesh refinement and data transfer for enriched plasticity continua in the modelling of strain localization. As the classical continuum models suffer from pathological mesh-dependence in the strain softening models, the governing equations are regularized by adding rotational degrees-of-freedom to the conventional degrees-of-freedom. Adaptive strategy using element elongation is applied to compute the distribution of required element size using the estimated error distribution. Once a new mesh is generated, state variables and history-dependent variables are mapped from the old finite element mesh to the...

Cellulose nanofiber-based ethylene scavenging antimicrobial films incorporated with various types of titanium dioxide nanoparticles to extend the shelf life of fruits

, Article ACS Applied Polymer Materials ; Volume 4, Issue 7 , 2022 , Pages 4765-4773 ; 26376105 (ISSN) Riahi, Z ; Ezati, P ; Rhim, J. W ; Bagheri, R ; Pircheraghi, G ; Sharif University of Technology

American Chemical Society 2022

Abstract

TiO2 nanotubes (TNTs) were synthesized hydrothermally and modified by Cu2O using a sol-gel method to provide photocatalytic activity in visible light. Cellulose nanofiber (CNF)-based films were prepared by adding TiO2, TNTs, and Cu2O-modified TNT (TNT-Cu2O). The TiO2-based nanoparticles (TiO2, TNTs, and TNT-Cu2O) were uniformly distributed in the base polymer to make compatible and flexible films. The incorporation of nanoparticles significantly enhanced the UV-shielding properties of the film while slightly decreasing the transparency. Incorporating nanofillers improved the film's mechanical and water resistance properties depending on the nanoparticle type. The TNT-Cu2O-added CNF film...

Carboxymethyl cellulose-based functional film integrated with chitosan-based carbon quantum dots for active food packaging applications

, Article Progress in Organic Coatings ; Volume 166 , 2022 ; 03009440 (ISSN) Riahi, Z ; Rhim, J. W ; Bagheri, R ; Pircheraghi, G ; Lotfali, E ; Sharif University of Technology

Elsevier B.V 2022

Abstract

A chitosan-based carbon quantum dots (CQDs) with multifunctional properties were synthesized using a hydrothermal process. The CQDs were spherical with an average size of 7.8 ± 2.4 nm. The CQD showed strong antioxidant activity, potent antibacterial activity against E. coli and L. monocytogenes, and antifungal activity against A. niger and P. chrysogenum. In addition, the prepared CQD showed negligible cytotoxicity against L929 cells even at a concentration of 500 μg/mL. Carboxymethyl cellulose (CMC)-based functional films were fabricated by adding various amounts of CQD. The CQDs were evenly dispersed in the polymer matrix to form a highly transparent UV-blocking film. The addition of CQD...

Effects of geometric imperfections on the performance of Sahand cooling tower

, Article 10th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2010, Bangkok, 3 August 2006 through 5 August 2006 ; Volume 5 , 2006 , Pages 331-338 ; 9748257207 (ISBN); 9789748257204 (ISBN) Riahi, H. T ; Haghighi, B ; Sharif University of Technology

School of Engineering and Technology 2006

Abstract

During construction of one of the Sahand cooling towers due to slip forming performance some imperfections were raised mostly between elevation of +30 and +40 meter. It was evaluated that some points of the shell should be repaired. In constructing the cooling tower from elevation +40 to +60 meter these imperfections were removed and the cooling tower was constructed with no problem until the elevation +130 meter. In this paper reasons of generation of geometric imperfections in Sahand cooling tower are clearly shown and possible ways for preventing them are discussed. Applied repairing method for Sahand cooling tower is explained in detail. Geometrical imperfections of the constructed...

Parametric study of a vapor compression refrigeration system integrated with a PCM storage tank for increasing condenser sub-cooled temperature

, Article Case Studies in Thermal Engineering ; Volume 47 , 2023 ; 2214157X (ISSN) Riahi, A ; Shafii, M. B ; Sharif University of Technology

Elsevier Ltd 2023

Abstract

In this work, the parametric study of a vapor compression refrigeration system integrated with a PCM storage tank for increasing the condenser sub-cooled temperature has been conducted based on the hottest day in Tehran city. The effects of various parameters such as comfort zone temperature, condenser and evaporator temperatures, and changes in heat transfer coefficient relative to the thickness of the ice formation in the PCM tank have been considered for simulating the desired system in the EES software. The focus of this study is to figure out the system's performance according to the changes in the effective parameters of the PCM storage tank. The results indicate that adding the PCM...

Experimental evaluation of a vapor compression cycle integrated with a phase change material storage tank for peak load shaving

, Article Engineered Science ; Volume 23 , 2023 ; 2576988X (ISSN) Riahi, A ; Shafii, M. B ; Sharif University of Technology

Engineered Science Publisher 2023

Abstract

In this study, the combination of a vapor compression cycle with a phase change material (PCM) storage tank has been assessed experimentally during the hottest day based on Tehran city climatic conditions. The temperature conditions for outdoor (condenser, compressor, etc.) and indoor (evaporator) air conditioning (AC) units are provided with the help of two separate test chambers and a controller system. The desired system has been surveyed based on two scenarios. In each scenario, the system is evaluated for the conventional AC system (with no PCM involved) and the AC plus PCM unit (conventional AC + PCM storage tank). Based on scenario 1 operating strategy, the results show that adding...

Surface Modification of Metallic Implants and Improvement of their Biological Properties in Presence of Bioactive Ceramic Nanoparticles

, M.Sc. Thesis Sharif University of Technology Riahi, Zohreh (Author) ; Sadrnezhad, Khatiboleslam (Supervisor)

Abstract

By consideration of increasing demands to use implants and efforts to get technical knowledge and localization of this implants, considerable research in this field is needed. Therefore, presentation of a coating which is able to provide parameters needed for an acceptable implant is the aim of this study. In this direction, modification of surface of metallic implants in order to achieve nanotubes of titanium oxide, with the purpose of providing biocompatibility was done. On the other hand, because chronic infection of the implant’s surrounding is one of the main important reasons in rejection of implants, 〖TiO〗_2 nanotubes as a drug carrier were used in order to solve this problem. So,...

Design and construction of a charge controller for stand-alone PV/battery hybrid system by using a new control strategy and power management

, Article Solar Energy ; Volume 149 , 2017 , Pages 132-144 ; 0038092X (ISSN) Mirzaei, A ; Forooghi, M ; Ghadimi, A. A ; Abolmasoumi, A. H ; Riahi, M. R ; Sharif University of Technology

Elsevier Ltd 2017

Abstract

In this paper, a new control strategy and power management for a stand-alone PV/battery hybrid power system has been suggested. The solar cell arrays provide energy in the steady-state and the battery provides energy in transient states. Here, a charge controller system based on the MPP tracking technology, suitable for using in the islanded micro grid that contains a solar panel and a battery is designed. The charge controller includes a unidirectional DC-DC converter as an interface circuit between the solar panel and the DC bus, a bidirectional DC-DC converter as an interface circuit between the battery and the DC bus with a control system and power management in different states of...

The study of prepration of blue V zircon pigment by using zircon and sulphuric acid

, Article Innovative Processing and Manufacturing of Advanced Ceramics and Composites - 8th Pacific Rim Conference on Ceramic and Glass Technology, PACRIM 8, Vancouver, BC, 31 May 2009 through 5 June 2009 ; Volume 212 , JUL , 2010 , Pages 197-206 ; 10421122 (ISSN); 9780470876466 (ISBN) Riahi, M ; Faghihi Sani, M. A ; Sharif University of Technology

2010

Abstract

Depending on the type of dopant metal, many kinds of zircon based pigments are produced and blue vanadium pigment is the most important one of them. In this study, blue zircon ceramic pigments were synthesized from intermediate product, resulting from decomposition of zircon sand with NaOH. In this regard, various amounts of sulfuric acid, water, NH4VO3 as colorant, NaF as mineralizer and extra quartz were added to the prepared Na 2ZrSiO5. Role of quartz was to omit the repercussions of presence of free zirconia in the composition. The main objective of this work is to assess various reactions at different temperatures during blue pigment synthesis. Phase analysis was done by X ray...

Seismic assessment of steel frames with the endurance time method

, Article Journal of Constructional Steel Research ; Volume 66, Issue 6 , 2010 , Pages 780-792 ; 0143974X (ISSN) Riahi, H. T ; Estekanchi, H. E ; Sharif University of Technology

2010

Abstract

In the endurance time (ET) method, structures are subjected to a specially designed intensifying ground acceleration function and their performance is judged based on their response at various excitation levels. A range of equivalent intensities can be covered in a single numerical or experimental simulation, thus significantly reducing the computational demand as compared to full nonlinear response-history analyses. The applied excitation intensity at various times has been correlated with those of the scaled ground motions. Response spectra of seven ground motions on stiff soil were used to produce intensifying acceleration functions that at each time window produce a response spectrum...

Experimental and numerical investigation of fluid dynamics of the bounded and unbounded triangular jets

, Article Proceedings of the ASME Turbo Expo, 9 June 2008 through 13 June 2008, Berlin ; Volume 5, Issue PART A , 2008 , Pages 41-47 ; 9780791843154 (ISBN) Riahi, R ; Bagheri, F ; Farhanieh, B ; Sharif University of Technology

2008

Abstract

In the present study, the fluid characteristics of triangular turbulent jet flow are considered experimentally and numericafly. The results of spatially developed three- dimensional jet, issued from an equilateral triangular nozzle are presented. The jet is discharged to both bounded and unbounded domains. Because of the wind tunnel set up restrictions, the experimental study has done just for the bounded domain. The hot-wire anemometry is used for experimental study. A numerical method employing control volume approach with collocated grid arrangement which couples the velocity and pressure fields with SIMPLEC algorithm is introduced to discrete the governing equations of fluid flow. The...

Speed Control of Permanent Magnet Synchronous Motor with Flexible Coupling Using Load Torque Observer

, M.Sc. Thesis Sharif University of Technology Riahi, Mohammad Reza (Author) ; Tahami, Farzad (Supervisor)

Abstract

Elastic joints in 2-mass drive systems, because of their limited stiffness, can decrease the performance of the control system and lead to motor and load speed oscillation. Shaft torque ignoring can also stress both mechanical and electrical drive components. Because of low degree of freedom, conventional controllers, such as the PI controllers, cannot improve the performance of the system and keep the system stable at the same time. In this thesis, the dynamic response and stability of the 2-mass systems is improved using state controller. State estimation of 2-mass system is required for state space controller . In the thesis, different state observer is analyzed and compared with each...

Nano Ethics: Reviewing and Criticizing the Approaches to Solve the Ethical Problems in Nanotechnology

, M.Sc. Thesis Sharif University of Technology Tajmir Riahi, Hossein (Author) ; Taghavi, Mostafa (Supervisor)

Abstract

Nanotechnology is an emerging field in technology that exploits the chemical and physical properties created by careful manipulation of materials at atomic and molecular levels. These properties lead to abilities created by this technology, which many scientists regard as the next industrial revolution. Although Nanotechnology promises bright future, today, researchers having learned from the history of technology are trying to predict its unwanted aspects and negative effects to decrease its potential issues. Researchers of Nano-ethics are trying to enable us to encounter Nanotechnology’s achievements in a reasonable way, by studying its ethical and social obligations. Since in our country,...

The Study of the Behaviour and Performance of a New Elevated Tank

, M.Sc. Thesis Sharif University of Technology Tajmir Riahi, Hossein (Author) ; Khansari, Vahid (Supervisor)

Abstract

Various types of tanks are used to store a variety of liquids, drinking water, chemicals, petrochemicals, and liquefied natural gas. Of these, one type is ‘elevated tank’ which is used to provide the required pressure for the water distribution systems rather than satisfying the water demand. Satisfactory performance of tanks during strong ground motions is crucial for modern facilities. Theoritical and experimental investigations of the dynamic behaviour of liquid storage tanks are conducted to seek possible improvments in the design of such tanks to resist earthquakes. The behaviour and performance of a new elevated tank was studied in this work. It was carried out through finite elements...