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Enhanced viability and improved in situ antibacterial activity of the probiotic LAB microencapsulated layer-by-layer in alginate beads coated with nisin

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FOOD BIOSCIENCE 2023年第3期53卷 1025-1033页

作者： Zarali, maryam Sadeghi, Alireza Jafari, Seid Mahdi ebrahimi, maryam Mahoonak, Alireza Sadeghi Gorgan Univ Agr Sci & Nat Resources Dept Food Sci & Technol Gorgan Iran Gorgan Univ Agr Sci & Nat Resources Dept Food Mat & Proc Design Engn Gorgan Iran Golestan Univ Med Sci Food Drug & Nat Prod Hlth Res Ctr Gorgan Iran

In the present study, a layer-by-layer technique was used to prepare alginate-nisin (Alg-N) as coating layer to encapsulate a potential probiotic-protective lactic acid bacteria (LAB) isolate in order to improve its both survival and antibacterial activities in situ. The isolate was identified as Pediococcus acidilactici according to the sequencing results of the PCR products. The mean size of Alg and Alg-N microcapsules was also equal to 762.63 and 501.77 mu m, respectively based on the results of field emission scanning electron microscopy. In accordance with the zeta potential data, the Alg-N surrounding layer was confirmed. Furthermore, the Fourier transform infrared findings revealed the adsorption of nisin on the Alg beads. The antibacterial activity of the produced microcapsule on Staphylococcus aureus (100% inhibition) was significantly (P < 0.05) higher than that of the other foodborne bacteria studied. In addition, enhanced viability of the microencapsulated LAB in simulated gastrointestinal conditions and flavored milk, as well as its improved in situ inhibitory effect on S. aureus were verified.

关键词： Layer-by-layer Alginate-nisin coating Enhanced survival In situ antibacterial

Role of nanomaterials in improving the functionality of probiotics; integration of nanotechnology onto micro-structured platforms

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FOOD BIOSCIENCE 2023年第3期53卷 3154-3167页

作者： Sadeghi, Alireza ebrahimi, maryam Kharazmi, Mohammad Saeed Jafari, Seid Mahdi Gorgan Univ Agr Sci & Nat Resources Dept Food Sci & Technol Gorgan Iran Golestan Univ Med Sci Food Drug & Nat Prod Hlth Res Ctr Gorgan Iran Univ Calif Riverside Fac Med Riverside CA 92679 USA Gorgan Univ Agr Sci & Nat Resources Dept Food Mat & Proc Design Engn Gorgan Iran

There is a growing interest in the production of probiotics (PRO) enriched food and pharmaceutical products as personalized nutrition and/or medicines. Due to the limitations associated with PRO such as their survival and targeted delivery in food/gastrointestinal matrices, it is necessary to introduce the next-generation PRO (NGPs). Combined formulation of PRO and nanomaterials (NMs) as a promising progress in nano-biotechnology has interesting potential applications. These NMs as proper carrier or coating agents have pivotal importance in food/drug applications of NGPs. There are several case studies related to the unique and promising capabilities of NMs for targeted delivery, long-term viability and stability of PRO, as well as potent infection control by these essential microorganisms and engineering of the smart constructs with enhanced functionalities using these innovative valuable platforms. Furthermore, surface to volume ratio of the produced constructs and adhesion of the PRO onto the intestinal epithelial mucus can be improved using novel NMs. Although integration of PRO with nanostructured platforms has promising beneficial effects, there are some limitations such as potential inhibitory effect of NMs on metabolic activity of PRO that needs to be considered. Furthermore, potential interactions between NMs and food components, their potential side effects on gut hemostasis, as well as concerns about their toxicity and biosafety are important issues in this context. This review sought to present and discuss the most recent cutting-edge publications associated with capabilities of NMs to improve crucial functionalities of the NGPs for their essential and innovative applications.

关键词： Next -generation probiotics Nanostructured platforms Efficiency Smart constructs Biosafety

Compensatory growth response of rainbow trout Oncorhynchus mykiss Walbaum following short starvation periods

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Chinese Journal of Oceanology and Limnology 2015年第4期33卷 928-933页

作者： maryam AZODI Eisa ebrahimi Omidvar FARHADIAN Nasrollah MAHBOOBI-SOOFIANI Vahid MORSHEDI Department of Fisheries Faculty of Natural Resources Isfahan University of Technology Young Researchers Club of Ilam Azad University

This sixty-day study was performed to determine the effects of short-term starvation and refeeding cycles on growth, feeding performances and body composition of rainbow trout （Oncorhynchus mykiss）. Three hundred trout fingerlings with an average initial weight of 17.54-0.06 g were randomly distributed in 15 circular fiberglass tanks. The fish were exposed to 5 different feeding regimes; control： continuously fed twice daily to apparent satiation; T1： starved for 1 day and re-fed for 2 days; T2： starved for 1 day and re-fed for 4 days; T3： starved for 3 days and re-fed for 12 days; T4： starved for 4 days and re-fed for 16 days. At the end of the experiment, growth performance, feed utilization, whole body ash and moisture contents were not significantly （P〉0.05） different among the treatments. However, whole body protein content in T3 was significantly higher than other treatments （P〈0.05）. A significant difference in whole body fat content was observed between T3 and the control group at the end of the experiment （P〈0.05）. In conclusion this experiment suggests that feeding schedules involving starvation （1-4 days） and re-feeding cycles are a promising feed management tool for rainbow trout culture.

关键词： Oncorhynchus mykiss compensatory growth growth performance body composition

Porosity parameters in biomaterial science: Definition, impact, and challenges in tissue engineering

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Frontiers of Materials Science 2021年第3期15卷 352-373页

作者： Mehdi ebrahimi Biomedical and Tissue Engineering Prince Philip Dental HospitalThe University of Hong KongHong KongChina

Porosity parameters are one of the structural properties of the extracellular microenvironment that have been shown to have a great impact on the cellular phenotype and various biological activities such as diffusion of fluid,initial protein adsorption,permeability,cell penetration and migration,ECM deposition,angiogenesis,and rate and pattern of new tissue *** heterogeneity of the study protocols and research methodologies do not allow reliable meta-analysis for definite *** such,despite the huge available literature,no generally accepted consensus is defined for the porosity requirements of specific tissue engineering ***,based on the biomimetic approach,the biological substitutes should replicate the 3D local microenvironment of the recipient site with matching porosity parameters to best support local cells during tissue ***,the porosity of biomaterials should mimic the porosity of the substituting natural tissue and match the clinical *** analysis of the impact of architectures(i.e.,porosity)on biophysical,biochemical,and biological behaviors will support designing smart biomaterials with customized architectural and functional properties that are patient and defect site-specific.

关键词： porosity pore size pore geometry topography tissue engineering

Nonlinear phenomena in vibrations of embedded carbon nanotubes conveying viscous fluid

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Nanotechnology and Precision Engineering 2024年第1期7卷 44-54页

作者： Reza ebrahimi Mechanical Engineering Faculty of EngineeringYasouj UniversityYasouj 75918-74831Iran

Various nonlinear phenomena such as bifurcations and chaos in the responses of carbon nanotubes(CNTs)are recognized as being major contributors to the inaccuracy and instability of nanoscale mechanical ***,the main purpose of this paper is to predict the nonlinear dynamic behavior of a CNT conveying viscousﬂuid and supported on a nonlinear elastic *** proposed model is based on nonlocal Euler–Bernoulli beam *** Galerkin method and perturbation analysis are used to discretize the partial differential equation of motion and obtain the frequency-response equation,respectively.A detailed parametric study is reported into how the nonlocal parameter,foundation coefﬁcients,ﬂuid viscosity,and amplitude and frequency of the external force inﬂuence the nonlinear dynamics of the ***,quasi-periodic,and chaotic behaviors and hardening nonlinearity are revealed by means of the vibration time histories,frequency-response curves,bifurcation diagrams,phase portraits,power spectra,and Poincaré***,the results show that it is possible to eliminate irregular motion in the whole range of external force amplitude by selecting appropriate parameters.

关键词： Nonlinear vibration Carbon nanotubes Nonlocal effect Viscousﬂuid Nonlinear elastic medium

Vibration analysis of fluid-conveying multi-scale hybrid nanocomposite shells with respect to agglomeration of nanofillers

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Defence Technology（防务技术） 2021年第1期17卷 212-225页

作者： Farzad ebrahimi Ali Dabbagh Department of Mechanical Engineering Faculty of EngineeringImam Khomeini International UniversityQazvinIran School of Mechanical Engineering College of EngineeringUniversity of TehranTehranIran

The vibration problem of a fluid conveying cylindrical shell consisted of newly developed multi-scale hybrid nanocomposites is solved in the present manuscript within the framework of an analytical *** consistent material is considered to be made from an initial matrix strengthened via both macro-and nano-scale *** influence of nanofillers’agglomeration,generated due to the high surface to volume ratio in nanostructures,is included by implementing Eshelby-Mori-Tanaka homogenization ***,the equivalent material properties of the carbon nanotube reinforced(CNTR)nanocomposite are coupled with those of CFs within the framework of a modified rule of *** the other hand,the influences of viscous flow are covered by extending the Navier-Stokes equation for cylinders.A cylindrical coordinate system is chosen and mixed with the infinitesimal strains of first-order shear deformation theory of shells to obtain the motion equations on the basis of the dynamic form of principle of virtual ***,the achieved governing equations will be solved by Galerkin’s method to reach the natural frequency of the structure for both simply supported and clamped boundary *** a set of illustrations,effects of each parameter on the dimensionless frequency of nanocomposite shells will be shown graphically.

关键词： Vibration Agglomeration effect Multi-scale hybrid nanocomposites Galerkin’s solution Viscous fluid flow

Experimental investigation and numerical simulation of plastic flow behavior during forward-backward-radial extrusion process

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Progress in Natural Science:Materials International 2016年第6期26卷 650-656页

作者： A.Farhoumand R.ebrahimi Department of Materials Science and Engineering School of Engineering Shiraz University

Finite element method was employed to investigate the effect of process parameters of plastic deformation behavior in Forward-Backward-Radial Extrusion(FBRE) process. The result of an axisymmetric model shows that the friction between die components and the sample has a substantial effect on the material flow *** strain heterogeneity index(SHI) slightly decreases with an increase in friction, large portion of the sample experiences significant strain heterogeneity. Increasing the friction factor also localizes the strain heterogeneity effect in the backward section, and spread the effect in the forward section. Decreasing the friction in the FBRE process can reduce the amount of the strain heterogeneity in the product while decreases the required punch force substantially. Furthermore, an increase in gap thickness increases the deformation in the area close to the lower punch at the expense of the area in the vicinity of the upper punch. The numerical simulation has a good agreement with the experimental results which confirms the accuracy of the proposed finite element model.

关键词： Finite element analysis Extrusion Forming Plastic deformation Strain heterogeneity

Wave propagation analysis of rotating thermoelastically-actuated nanobeams based on nonlocal strain gradient theory

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Acta Mechanica Solida Sinica 2017年第6期30卷 647-657页

作者： Farzad ebrahimi Parisa Haghi Department of Mechanical Engineering Faculty of Engineering Imam Khomeini International University Qazvin Iran

This paper is concerned with the wave propagation behavior of rotating functionally graded（FG）temperature-dependent nanoscale beams subjected to thermal loading based on nonlocal strain gradient stress ***,linear and nonlinear temperature distributions across the thickness are ***-elastic properties of FG beam change gradually according to the Mori–Tanaka distribution model in the spatial *** nanobeam is modeled via a higher-order shear deformable refined beam theory which has a trigonometric shear stress *** governing equations are derived by Hamilton’s principle as a function of axial force due to centrifugal stiffening and *** solution of these equations is provided employing a Galerkin-based approach which has the potential to capture various boundary *** applying an analytical solution and solving an eigenvalue problem,the dispersion relations of rotating FG nanobeam are *** results illustrate that various parameters including temperature change,angular velocity,nonlocality parameter,wave number and gradient index have significant effects on the wave dispersion characteristics of the nanobeam under *** outcome of this study can provide beneficial information for the next-generation research and the exact design of nano-machines including nanoscale molecular bearings,nanogears,etc.

关键词： Wave propagation FGMS Nonlocal strain gradient theory Rotating nanobeam Refined beam theory

CFD-DEM simulation of turbulence modulation in horizontal pneumatic conveying

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Particuology 2017年第2期15卷 15-24页

作者： Mohammadreza ebrahimi Martin Crapper Institute for Infrastructure and Environment School of Engineering The University of Edinburgh The King's Buildings Edinburgh EH9 3JL UK Department of Mechanical and Construction Engineering Northumbria University Ellison Place Newcastle-upon-Tyne NE1 8ST UK

A study is presented to evaluate the capabilities of the standard k–ε turbulence model and the k–ε turbulence model with added source terms in predicting the experimentally measured turbulence modulation due to the presence of particles in horizontal pneumatic conveying, in the context of a CFD–DEM Eulerian–Lagrangian simulation. Experiments were performed using a 6.5-m long, 0.075-m diameter horizontal pipe in conjunction with a laser Doppler anemometry （LDA） system. Spherical glass beads with two sizes, 1.5 and 2 mm, were used. Simulations were performed using the commercial discrete element method software EDEM, coupled with the computational fluid dynamics package FLUENT. Hybrid source terms were added to the conventional k–ε turbulence model to take into account the influence of the dispersed phase on the carrier phase turbulence intensity. The simulation results showed that the turbulence modulation depends strongly on the model parameter Cε3. Both the standard k–ε turbulence model and the k–ε turbulence model with the hybrid source terms could predict the gas phase turbulence intensity trend only generally. A noticeable discrepancy in all cases between simulation and experimental results was observed, particularly for the regions close to the pipe wall. It was also observed that in some cases the addition of the source terms to the k–ε turbulence model did not improve the simulation results when compared with those of the standard k–ε turbulence model. Nonetheless, in the lower part of the pipe where particle loading was greater due to gravitational effects, the model with added source terms performed somewhat better.

关键词： Turbulence modulation Pneumatic conveying Eulerian-Lagrangian approach Laser Doppler anemometry