Microwave distillation followed by headspace single drop microextraction coupled to gas chromatography-mass spectrometry (GC–MS) for fast analysis of volatile components of Echinophora platyloba DC

To avoid the traditional and time consuming hydrodistillation, the analyses of volatile components in aerial parts of Echinophora platyloba DC was carried out by a simple microwave distillation followed by headspace single drop microextraction (MD–HS–SDME) coupled to gas chromatography–mass spectrometry (GC–MS). The headspace volatile compounds were collected after irradiation using a single drop of n-heptadecan. The extraction conditions were optimised using the relative peak areas as index. The chemical composition of the MD–HS–SDME extracts was confirmed according to their retention indexes and mass spectra. Fifty-three components were extracted and identified by using the MD–HS–SDME method. E-β-ocimene (53.81%), R-d-decalactone (12.75%), α-pinene (6.43%), n-heptanol (6.27%), β-phellanderne (2.70%) and linalool (1.89%) were the major constituents.     

Miller Compensation: Optimal Design for Operational Amplifiers with a Required Settling Time

Optimizing the settling response of an operational amplifier can be a serious design issue in today’s low-power CMOS technologies. Several design challenges emerge when improving the linear and nonlinear responses of an amplifier. In this paper, we developed a settling model for use in design and optimization of two-stage Miller-compensated amplifiers. Using this model, the closed-form relations between settling time/settling error, gain-bandwidth product, noise, power and stability have been obtained. These relations are employed to form a settling-based design routine for Miller-compensated amplifiers. Simulation results in 0.18- \(\upmu \) m CMOS validate the effectiveness of the proposed routine. In a design prototype, it predicts the settling time with an error less than 3 %. In another design example, the relationship between settling time and gain-bandwidth has been evaluated with an accuracy higher than 95 %. The proposed design routine is used to implement a 40 MS/s sample-and-hold amplifier. It achieves a settling time and signal-to-noise-plus-distortion ratio equal to 12.5 ns and 82 dB, respectively.     

The Effect of Barium Doping on the Selective Structure of Bi-2223 Phase

The partial substitution of Sr by Ba in the two nominal compositions of Bi_1.8Pb_0.4Sr_2−x Ba _x Ca_2.2Cu₃O _y [x=0.0, 0.1, 0.2, and 0.3 (A group)] and Bi_1.66Pb_0.34Sr_2−x Ba _x Ca₂Cu₃O _y [x=0.0, 0.1, 0.2, 0.3, 0.4, and 0.5 (B group)] have been investigated by resistivity, ac susceptibility measurements and by XRD and SEM analysis. In general, the nature of the temperature dependence of resistivity and susceptibility measurements indicate the presence of a superconducting transition between grains coupled by weak links. However, the XRD and SEM analyses show that the relative composition of initial elements used in Bi-(2223) is essential to the site that is selected by the Ba ions. In the A group, Ba doping up to x=0.1 will improve the phase formation of Bi-2223, and improve the superconductivity properties of the samples. In the B group, although Ba doping up to x=0.1 will enhance the phase formation of Bi-2223, it will decrease the coupling between the grain and the superconductivity properties of these systems. The presence of lower Tc phases will begin to appear for x>0.1, in both of these systems. The superconductivity properties and the phase formation of Bi-(2223) will decrease as the Ba concentration increases.     

Synthesis of TiO2 nanoparticles by a combined sol-gel ball milling method and investigation of nanoparticle size effect on their photocatalytic activities

TiO₂ nanoparticles were synthesized by a sol-gel method and the effect of ball milling of dried gel on the particle size has been investigated. The results show that the ball milling has a crucial role in preparation of nanosized TiO₂ powder. Also thermal treatment at different temperatures can control the size of prepared nanoparticles. The photocatalytic activities of TiO₂ nanoparticles with different sizes were studied by photocatalytic degradation of Congo red dye using a homemade photoreactor. The photo degradation of Congo red dye was monitored by UV-Vis absorption measurements. It was found that the nanopowders which were synthesized at 550 °C with average particle size of 55 nm show the maximum photocatalytic activities. These nanopowders which were a mixture of anatase and rutile phases did not show the same photocatalytic effect on Eriochrome black, Bromocresol green, Methyl orange and Rose Bengal dyes.     

Reduction of formaldehyde emission from plywood

The aim of this work is to evaluate performances of tannin-based resins designed as adhesive in the plywood production. For this purpose, a part of phenol formaldehyde (PF) and melamine formaldehyde (MF) in the classic adhesive formulation was replaced by tannin. The physical properties of the formulated resins (rheological characterization, etc.) were measured. In order to analyze the mechanical performance of tannin-based resins, plywood panels were produced and the mechanical properties including tensile strength wood failure and three-point bending strength were investigated. The performance of these panels is comparable to those of plywood panels made by commercial PF and MF. The results showed that the plywood panels bonded with tannin–PF (PFT) and tannin–MF (MFT) resins exhibited better mechanical properties in comparison to the plywood panels made of commercials PF and MF. The introduction of small properties of tannin in PF and MF resins contribute to the improvement of the water performance of these adhesives. The formaldehyde emission levels obtained from panels bonded with tannin-based resins were lower than those obtained from panels bonded with control PF and MF. Although there are no actual reaction at all between PF, MF, and tannin, addition of tannin significantly improves the water resistance of PF and MF resins. This is a novel finding that manifests the possibility of replacing a convention PF and MF resins by tannin. Modified adhesive is one of the goals in the plywood production without changing any of their production conditions with improvement to their overall properties.     

Oleogel Fabrication Based on Sodium Caseinate,Hydroxypropyl Methylcellulose,and Beeswax: Effect of Concentration,Oleogelation Method,and Their Optimization

In the present study, the oleogel preparation with hydroxypropyl methylcellulose (HPMC) (0–2 g/100 g), sodium caseinate (CN) (0–4 g/100 g), beeswax (0–5 g/100 g), and oleogelation method (foam and emulsion template) was optimized using response surface methodology (RSM) to attain the desirable oil retaining ability, rheological, and textural characteristics. For all the chosen responses, the quadratic model was the best-fitting model with a determination coefficient of R² > 0.91. Results exhibited that the HPMC and CN concentrations were the most influential tested factors on the oil binding capacity, textural, and rheological characteristics of the oleogels due to the formation of more complex and strong network. There was a significant improvement in oil binding capacity and structure recovery of samples by beeswax addition. To produce oleogel similar to industrial shortening, the optimization method was done based on maximum oil binding capacity and thixotropic recovery and other responses were chosen equal to those of shortening values (ɳ_a = 330 Pa.s, G′ = 276,543 Pa, A value = 164,308 Pa s rad⁻¹, and firmness = 44.99 g). As regards the optimized level of structuring agents and responses (ɳ_a = 317 and 329 Pa.s, G′ = 249,782 and 260,997 Pa, A value = 180,022 and 180,373 Pa s rad⁻¹, and firmness = 44.37 and 36.98 g corresponding to Optimization 1 and Optimization 2, respectively), fabrication of oleogels with at least 90 g/100 g trans-free and low saturated oil and attributes close to industrial shortening is possible.     

Non-classical plate model for FGMs

Engineering with Computers - In this work, we developed a non-classical plate model for the analysis of the behavior of microplates prepared from functionally graded materials (FGMs). It was...     

Comparison of functional properties and SDS-PAGE patterns between fish protein isolate and surimi produced from silver carp

The purpose of this study was to investigate and compare the physicochemical properties of fish protein isolate (FPI) produced from silver carp (Hypophthalmichthys molitrix), which is a relatively cheap fish with low consumption in Fars (a state of Iran). In this research, proteins were isolated using pH shifts method. Results showed that in terms of production efficiency, protein recovery, lipid reduction and functional properties such as water-holding capacity, emulsifying capacity, foaming capacity and water absorption, FPI was better than conventional surimi. The treated samples at pH?=?2.5 represented better functional properties relative to other samples. The electrophoretic patterns demonstrated that acidic pH led to vanish high molecular weight protein bands because these proteins were converted to low molecular weight proteins, whereas basic pH caused the formation of high molecular weight proteins relative to myosin heavy chain. It seems that in basic pH, the proteins were linked together after denaturation and then aggregated. Overall, the results showed that physicochemical qualitative properties of FPI were better than those of conventional surimi.     

Enhanced biosurfactant production with low-quality date syrup by Lactobacillus rhamnosus using a fed-batch fermentation

Food Science and Biotechnology - Novel strategies toward the use of low-cost media to produce food-grade microbial products have been considerably attended in recent years. In this study, date...