The applications of nanotechnology in food industry

Nanotechnology has the potential of application in the food industry and processing as new tools for pathogen detection, disease treatment delivery systems, food packaging, and delivery of bioactive compounds to target sites. The application of nanotechnology in food systems will provide new methods to improve safety and the nutritional value of food products. This article will review the current advances of applications of nanotechnology in food science and technology. Also, it describes new current food laws for nanofood and novel articles in the field of risk assessment of using nanotechnology in the food industry.     

Generalized SDOF system for seismic analysis of concrete rectangular liquid storage tanks

This paper presents a simplified method using the generalized single degree of freedom (SDOF) system for seismic analysis and design of concrete rectangular liquid storage tanks. In most of the current design codes and standards for concrete liquid storage tanks, the response of liquid and tank structures is determined using rigid boundary conditions for the determination of hydrodynamic pressures. Also, the lumped mass approach is used for dynamic analysis. However, it has been shown that the flexibility of a tank wall increases the hydrodynamic pressures as compared to the rigid wall assumption. On the other hand, the consistent mass approach reduces the response of liquid containing structures as compared to the lumped mass approach. In the proposed method, the consistent mass approach and the effect of flexibility of a tank wall on hydrodynamic pressures are considered. The prescribed vibration shape functions representing the first five mode shapes for the cantilever wall boundary condition are studied. The application of the proposed shape functions and their validity are examined using two different case studies including a tall and a shallow tank. The results are then compared with those using the finite element method from a previous investigation and ACI 350.3 commonly used in current practice. The results indicate that the proposed method is fairly accurate which can be used in the structural design of liquid containing structures. It is also concluded that the effect of the second mode should also be considered in the dynamic analysis of liquid containing structures.     

Antioxidant Activities of Free and Liposome-Encapsulated Green tea extracts on canola oil oxidation stability

In the present study, green tea extract was encapsulated in liposomes based on the Mozafari method (with no organic solvents) and characterized for its physicochemical properties (encapsulation efficiency, particle size, and Z-potential). Encapsulation efficiency, particles size, and Z-potential were determined to be 51.34, 419 nm, and -57 mV, respectively. Total polyphenol content of the green tea by Folin-Ciocalteu's phenol reagent was measured as 164.2 mg gallic acid/g extract. Free radical scavenging activities of free and liposomal extracts were 90.6 and 93.4%, respectively, using the DPPH method. Antioxidant activity of the ethanolic extract of green tea in free and liposomal forms with concentrations of 200, 600, and 1000 mg L⁻¹ were assessed on oxidative stability of the canola oil at 60 °C for 0, 4, 8, 12, 16, 20, 24, 28, and 32 days. Results were compared to results of synthetic antioxidant butylated hydroxytoluene at 200 mg L⁻¹. To assess antioxidant activity on canola oil stability, peroxide, thiobarbitoric acid, and anisidine values were assessed as well as the total oxidation value and rancimat test. Results showed that the liposomal green tea extract was more effective than the free extract. Furthermore, a 600 mg L⁻¹ concentration of the green tea extract showed a significant antioxidant activity, compared to other extract concentrations. Increasing storage time and various concentrations of the ethanolic green tea extracts included significant effects on canola oil stability (P ≤ 0.05). Results demonstrated that the green tea extract could be used as an effective antioxidant. Free and liposomal extract (at 600 mg L⁻¹) resulted in stronger functionality than the synthetic antioxidant butylated hydroxytoluene.     

Tuning PI and fractional order PI controllers with an additional fractional order Pole

The PI controller with an additional pole (PI?+?P) already has been proposed to decrease the noise effect on the control signal. In this paper, a fractional order pole is employed to increase the PI?+?P controller performance. The fractional order is obtained by adjusting the Nyquist plot slope in gain crossover frequency. This condition as well as gain crossover frequency and phase margin specifications are utilized to design the PI controller augmented with an additional fractional order pole (PI?+?FO[P]). To design these two controllers, a first-order plus delay time (FOPDT) model is utilized. For plants that could not be described by this model, its fractional order version (FFOPDT) could be utilized. In this case, a FOPI?+?FO[P] controller is obtained that could improve the transient response of the closed-loop system. The numerical simulations accomplished on various plant models (including chemical plants) demonstrate the effectiveness of the proposed controller comparing with the PI?+?P, PID, FOPI, and fractional order proportional-integral-derivative controllers.     

碳纤维布加固钢筋混凝土梁的弯曲性能

对采用碳纤维布加固的钢筋混凝土梁的弯曲性能进行研究。考察了配筋率ρ对加固梁弯曲强度的影响。对12个混凝土梁试件(截面尺寸为宽150mm,高200mm,长2000mm)进行了试验。梁截面具有三种不同的纵向钢筋配筋率,9个试件在受弯区域采用碳纤维布加固,另外3个试件作为对比试件。不同试件中,碳纤维布的宽度、长度和层数是变化的。与对比试件相比,加固梁的弯曲强度和刚度增加了。从研究结果可得出,与最大配筋率的梁相比,ACI440·2R-02的设计指南和加拿大的I-SIS高估了碳纤维布在小配筋率梁的弯曲强度方面的增加作用。随着梁的配筋率ρ的增长,试验荷载与按照ACI440·2R-02指南和加拿大ISIS计算荷载的比值是增长的。因此,由两个设计指南提出的方程更适合于高配筋率的梁,接近最大配筋率ρmax的梁试件的破坏具有足够的延性。     

Seismic soil–structure interaction analysis of wind turbines in frequency domain

In this paper, the seismic behavior of wind turbines sitting on a finite flexible soil layer is investigated in three‐dimensional space. A numerical algorithm formulated in frequency domain is proposed in order to simulate the dynamic soil–structure interaction (SSI). The wind turbine is discretized using finite element method (FEM) while, the underlying soil is represented by complex dynamic stiffness functions based on cone models. A parametric study consisting of 24 ground motions and three soil profiles is carried out, and different response quantities of the wind tower model are calculated and presented in the paper. The free‐field ground motions are estimated based on an equivalent linear approach using SHAKE2000 computer software. Transfer functions for total acceleration of the wind tower are obtained under the considered soil profiles and the modal frequencies of the coupled wind turbine–soil foundation are estimated. It is shown that the response quantities such as displacement, rotation, acceleration, base shear and moment are significantly affected by SSI, although the effect of SSI on the fundamental frequencies of the wind tower is insignificant. The moment and shear force distribution along the height of the tower is highly influenced as the soil stiffness decreases. The change in seismic demand distribution along the tower height because of SSI is not addressed by simplified design approached and should be carefully considered in seismic design of wind towers. Copyright © 2016 John Wiley & Sons, Ltd.     

Production of propionic acid in a fermented dairy beverage

A dairy beverage containing propionic acid was produced using the adjunct starter cultures with Lactobacillus acidophilus and Propionibacterium freudenreichii ssp. shermanii. The impacts of temperature (30, 35 and 40 °C) and inoculation ratio (1:2, 1:4 and 1:8) on propionic acid production and viability of micro‐organisms were studied. The incubation temperature had a significant adverse (P < 0.05) effect on the viability of P. freudenreichii and propionic acid production. Maximum amount of produced propionic acid (in 1:4–30 °C treatment) was 0.77%w/w. P. freudenreichii and L. acidophilus counts remained high (9 × 10⁶ and 1.5 × 10⁶ cfu/mL, respectively) after cold storage.     

Experimental Study of RC Rectangular Liquid Containing Structures Retrofitted with GFRP Composites

The continual functioning of Liquid Containing Structures “LCS” is necessary for the well being of a society. These structures are designed based on serviceability criteria such as cracking that leads to leakage. Cracks form in liquid containing structures (LCS) for different reasons such as restrained thermal and shrinkage deformations, applied external loads such as earthquake loads, etc. These cracks can create exposure condition to initiate the corrosion process in reinforcement. The effectiveness of glass fiber reinforced polymer (GFRP) composites in recovering the structural strength of damaged members is widely recognized by engineers. However, the effectiveness on the use of GFRP composites as a protecting layer to prevent the passage of liquid through the cracks has not yet been reported in the literature. This concept inspires the main purpose of the investigation in this experimental study. Cracked reinforced concrete specimens subjected to different conditions of loading such as direct tension and cyclic flexure are repaired externally using GFRP sheets. The specimens are then subjected to hydrostatic pressure using a water pressure chamber at the crack location. This study shows that the application of GFRP composites for crack remediation in liquid containing structures could be very effective under monotonic loading. However, the effectiveness under cyclic flexure especially under higher load levels is questionable.