Modelling of proteolysis in Iranian brined cheese using proteinase‐loaded nanoliposome

In this study, Flavourzyme was encapsulated in liposomes to accelerate the ripening of Iranian white cheese. Liposomal enzyme was prepared using a modified heating method. The influence of enzyme content, ripening time and curd retention in saturated brine on proteolysis indices and sensory perception was investigated using response surface methodology. The most influential factor on proteolysis indices was ripening time, while the content of liposomal enzyme and retention time were also significant (P < 0.05). The maximum proteolysis indices and highest sensory characteristic scores were achieved by applying 0.3% w/w enzyme, ripening for 30 days and 8‐h curd retention in saturated brine.     

Removal of the eye-blink artifacts from EEGs via STF-TS modeling and robust minimum variance beamforming

A novel scheme for the removal of eye-blink (EB) artifacts from electroencephalogram (EEG) signals based on a novel space-time-frequency (STF) model of EEGs and robust minimum variance beamformer (RMVB) is proposed. In this method, in order to remove the artifact, the RMVB is provided with a priori information, namely, an estimation of the steering vector corresponding to the point source EB artifact. The artifact-removed EEGs are subsequently reconstructed by deflation. The a priori knowledge, the vector corresponding to the spatial distribution of the EB factor, is identified using the STF model of EEGs, provided by the parallel factor analysis (PARAFAC) method. In order to reduce the computational complexity present in the estimation of the STF model using the three-way PARAFAC, the time domain is subdivided into a number of segments, and a four-way array is then set to estimate the STF-time/segment (TS) model of the data using the four-way PARAFAC. The correct number of the factors of the STF model is effectively estimated by using a novel core consistency diagnostic- (CORCONDIA-) based measure. Subsequently, the STF-TS model is shown to closely approximate the classic STF model, with significantly lower computational cost. The results confirm that the proposed algorithm effectively identifies and removes the EB artifact from raw EEG measurements.     

Investigation of flexural cracking and leakage in RC liquid containing structures

This paper reports the results of an experimental study conducted using full-scale reinforced concrete specimens under monotonic loadings. A variety of loading configurations is arranged to enable various combinations of flexural stresses with tensile and shear stresses across the reinforced concrete section similar to what may exist in the actual liquid containing structures (LCS). The cracking behavior of the specimens is closely monitored and the results are reported. The water-tightness of the cracked specimens are examined by subjecting them to pressurized water at a crack location. It is found that the compression zone created in the section by the bending moment can effectively prevent leakage. This would suggest a new perspective for the crack control criteria in design codes. A comparison is made between experimental results and several crack prediction models, through which their advantages and disadvantages are revealed and discussed. It is observed that commonly used flexural crack prediction models may not efficiently predict the widths of cracks developed under combination of tensile and flexural stresses, which are more representative of the stresses in the actual LCS. Also, large discrepancies are observed in the current crack prediction models when they are compared with each other, which is an indication of the lack of consistency in the current approaches used in various design codes.     

钢筋混凝土框架的抗震性能

纯框架被分类为典型的韧性、名义韧性和GLD(重力荷载设计)。根据侧向抗力、层间位移的分布和构件屈服的次序,可对这些结构的抗震性能进行评估。在研究中,对一个典型的5层框架按照(a)韧性;(b)名义韧性;(c)GLD;(d)改进的GLD方法进行设计,采用非线性时间序列分析和推覆分析,提出了混凝土框架抗震评估的分析方法。通过有效的试验结果验证了分析模型。采用分析模型评估了5层框架的抗震性能。可推断出,在所考虑的地震荷载下,韧性和名义韧性的框架性能良好,而GLD结构的抗震性能不令人满意。损坏的GLD框架被加固后,抗震性能有所提高。     

Punching shear strength of interior slab–column connections strengthened with carbon fiber reinforced polymer sheets

In this paper, punching shear strengthening of flat slabs using Carbon Fiber Reinforced Polymer (CFRP) sheets is studied. Fifteen specimens of reinforced concrete slabs were tested. Thirteen of them were strengthened by CFRP sheets and two specimens were kept as control specimens. Four of these strengthened specimens were tested under cyclic vertical loading. The width of CFRP sheets varied in different specimens. The CFRP sheets were located at the tension side of the slabs in two perpendicular directions. Vertical load was applied downward through a column stub using a hydraulic Jack. In all specimens, no rupture of CFRP sheets was observed. The test results showed that the use of CFRP sheet, in addition to steel reinforcing bars, as flexural reinforcement improves the punching shear strength of slabs. This improvement can be significant for the slabs made of high strength concrete and low steel reinforcement ratio. However, the improvement of punching shear strength due to FRP strengthening reduced under cyclic vertical loading. The test results were compared with the equations proposed by ACI 318 and BS 8110 Codes. The ACI Code underestimates the punching shear strength of slabs and this underestimation becomes more pronounced with the increase in the flexural reinforcement. The BS 8110 Code appropriately accounts for the effect of flexural reinforcement on punching shear strength of slabs. However, for the strengthened slabs, an equivalent reinforcement ratio should be used to include the effect of both steel and CFRP flexural reinforcement.     

Experimental Study on Prefabricated Concrete Bridge Girder-to-Girder Intermittent Bolted Connections System

This paper reports on a new bridge deck slab flange-to-flange connection system for precast deck bulb tee (DBT) girders. In prefabricated bridge system made of DBT girders, the concrete deck slab is cast with the prestressed girder in a controlled environment at the fabrication facility and then shipped to the bridge site. This system requires that the individual prefabricated girders be connected through their flanges to make it continuous for live load distribution. The objectives of this study are to develop an intermittent bolted connection for DBT bridge girders and to provide experimental data on the ultimate strength of the connection system. This includes identifying the crack formation and propagation, failure mode, and ultimate load carrying capacity. In this study, three different types of intermittent bolted connection were developed. Four actual-size bridge panels were fabricated and then tested to collapse. The effects of the size and the level of the fixity of the connecting steel plates, as well as the location of the wheel load were examined. The developed joint was considered successful if the experimental wheel load satisfied the requirements specified in North American bridge codes. It was concluded that location of the wheel load at the deck slab joint affected the ultimate load carrying capacity of the connections developed. Failure of the joint was observed to be due to either excessive deformation and yielding of the connecting steel plates or debonding of the embedded studs in concrete.     

Optimisation of experimental conditions for binding of divalent iron to bioactive casein phosphopeptides

Casein phosphopeptides (CPPs) are mineral‐binding bioactive peptides derived from enzymatic digestion of casein. They have been shown to increase iron bioavailability due to increasing iron solubility at the alkaline pH of the intestine. Thus, they are potentially applicable as an advantageous preparation for iron fortification of food. This study aimed to characterise a commercially available CPP and determines optimum experimental conditions for binding it with ferrous iron. The effect of three variables – pH (5–7.5), mass ratio of iron to CPP (MR) (0.04–0.16) and holding time (40–80 min) – on the CPP's iron content was investigated using the central composite design (CCD) in response surface methodology (RSM), and a quadratic model was developed. The optimisation in this survey was based on the maximum response. Among all the regression's terms, the main and quadratic effects of pH represented the most significant influences on the iron content (P‐value <0.05). The obtained optimum conditions were as follows: pH 6.5, MR 0.14 and holding time 72 min, resulting in binding 68.66 mg iron per gram of the CPP. The quantity of iron bound to the CPP depended considerably on the experimental conditions and proved the importance of optimisation.     

Numerical Modeling of Dynamic Behavior of Annular Tuned Liquid Dampers for Applications in Wind Towers

Abstract: In this study, the performance of annular liquid tanks as a tuned liquid damper (TLD) in mitigating the vibration of wind turbines was investigated using a numerical model. A proposed hybrid wind tower model composed of a concrete shaft and a steel mast with a height of 150 m was simulated using a single‐degree‐of‐freedom system. The structural domain including the tank wall and a rigid mass was modeled using finite element method, while the fluid domain was simulated by finite volume method using CFX software. A parametric study was carried out to investigate the behavior of annular TLD under harmonic loads for different mass and frequency ratios as well as displacement amplitudes. The damping characteristics of the annular TLD model were derived by comparing the numerical results with an equivalent linear model. In addition, the effectiveness of annular TLD was estimated by comparing the numerically calculated damping ratios with those corresponding to the optimum damping ratio values derived for a particular mass ratio based on the concept of tuned mass damper. It was found that that the annular TLD is effective when the amplitude of excitation is small. Moreover, the response of TLD in terms of nonlinear free surface sloshing and the energy dissipated by the system was discussed. Finally, the effectiveness of annular TLD in reducing the structural response of wind turbine towers under random vibrations was evaluated and discussed.     

Simultaneous determination of diclofenac and indomethacin using a sensitive electrochemical sensor based on multiwalled carbon nanotube and ionic liquid nanocomposite

Multiwalled carbon nanotube and ionic liquid-modified carbon ceramic electrode (MWCNT–IL|CCE) was employed for the simultaneous determination of diclofenac and indomethacin (IND). The measurements were carried out by differential pulse voltammetry method in optimal conditions. The prepared electrode showed appropriate voltammetric responses to DCF and IND with 0.225 V difference in the oxidation peak potentials, making fabricated electrode suitable for simultaneous determination of these compounds. The calibration curves were linear over a wide range of concentrations of each species including 0.05–50 μmol L^?1 for DCF and 1–50 μmol L^?1 for IND. Detection limits were found to be 18 and 260 nM for DCF and IND, respectively. The developed method having good stability and sensitivity was successfully applied for DCF and IND in commercial tablet as well as human blood plasma samples.     

Investigation of direct tension cracking and leakage in RC elements

A study is carried out to investigate the cracking characteristics and liquid tightness of a reinforced concrete element under direct tensile loads. The findings are directly applicable to environmental structures such as liquid containing tanks, the design of which is based on serviceability limit states. Cracking plays a significant role in durability and functionality of these types of structures. Contrary to the current practice in some design codes, pure tension cracks are more detrimental to the serviceability of the structure than other types of cracks and must be treated more cautiously. This study targets this issue both experimentally and analytically. Accordingly, a reinforced concrete specimen representing an element of a tank wall is subjected to a monotonic increasing direct tensile load and its cracking behavior is closely monitored. The influence of direct tension cracks on water tightness of the specimen is examined by exposing a major crack to pressurized water and evaluating the water leakage. Additionally, the water leakage flow rate is monitored over a period of 30 h to investigate any probable early self-healing capability of the cracked concrete. In the analytical phase, the load at cracking and the strain of the steel reinforcement are determined and compared with experimental test data. The accuracy of crack prediction models, namely, Broms and Lutz model, and a modified version of Gilbert model are assessed by comparing their results for crack spacing and the maximum crack width against those obtained from the experiment.