Extraction of Bioactive Compounds from Milled Grape Canes (Vitis vinifera) Using a Pressurized Low-Polarity Water Extractor

Trans-resveratrol and trans-ε-viniferin were extracted from milled grape canes using pressurized low-polarity water. The effects of temperature were significant for both compounds (p ≤ 0.05): extraction at 160 °C resulted in a 40% loss of trans-resveratrol compared to 95 °C while reduction of trans-ε-viniferin at both temperatures remained at 30%. Increasing ethanol concentration from 0% to 25% increased the extraction of total phenolics and trans-ε-viniferin by 44% and 489%, respectively. Solvent flow rate also influenced trans-ε-viniferin extraction. Antioxidant activity showed a strong correlation with total phenolic content of the extracts, and the two target phenolic compounds. Except for the modifier concentration, the extraction parameters studied were not statistically significant with respect to the antioxidant activity of extracts (p > 0.05). Effective diffusivities of trans-resveratrol multiplied from 3.3 × 10⁻¹¹ to 10.4 × 10⁻¹¹ m²/s by three times with increasing temperature. The modified Gompertz equation satisfactorily explained the extraction of the stilbenes investigated.     

Derivation of low-power first-order low-pass,high-pass and all-pass filters

In this letter, a new voltage-mode (VM) configuration for providing low-power and simultaneous realization of first-order low-pass, high-pass and all-pass filters is presented. The output of the all-pass filter is taken differentially. The proposed circuit contains low number of components, i.e., only two NMOS transistors, a floating battery, a grounded capacitor and a floating resistor. Adding two NMOS transistors to the proposed circuit it is modified as an all-pass filter with a single-ended output. The main advantage of the presented circuits in comparison with other counterparts is their extremely low power dissipation. Moreover, the floating resistor can be replaced with an additional NMOS transistor in triode region to provide electronic tunability. Simulation results using SPICE program are given to demonstrate the performance of the proposed circuit.     

Velocity and temperature field characteristics of water and air during natural convection heating in cans

Presence of headspace during canning is required since an adequate amount allows forming vacuum during the process. Sealing technology may not totally eliminate all entrapped gases, and headspace might affect heat transfer. Not much attention has been given to solve this problem in computational studies, and cans, for example, were mostly assumed to be fully filled with product. Therefore, the objective of this study was to determine velocity and temperature evolution of water and air in cans during heating to evaluate the relevance of headspace in the transport mechanism. For this purpose, canned water samples with a certain headspace were used, and required governing continuity, energy, and momentum equations were solved using a finite volume approach coupled with a volume of fluid element model. Simulation results correlated well with experimental results validating faster heating effects of headspace rather than insulation effects as reported in the literature. The organized velocity motions along the air-water interface were also shown. Practical Application: Canning is a universal and economic method for processing of food products, and presence of adequate headspace is required to form vacuum during sealing of the cans. Since sealing technology may not totally eliminate the entrapped gases, mainly air, headspace might affect heating rates in cans. This study demonstrated the increased heating rates in the presence of headspace in contrast with some studies in the literature. By applying the effect of headspace, required processing time for thermally processed foods can be reduced leading to more rapid processes and lower energy consumptions.     

New resistorless and electronically tunable realization of dual-output VM all-pass filter using VDIBA

In this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal transconductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel second-order APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 μm level-7 CMOS process parameters with ±0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments.     

Understanding the Chena Hot Springs,Alaska, geothermal system using temperature and pressure data from exploration boreholes

Chena Hot Springs is a small, moderate temperature, deep circulating geothermal system, apparently typical of those associated to hot springs of interior Alaska. Multi-stage drilling was used in some exploration boreholes and was found to be useful for understanding subsurface flow characteristics and developing a conceptual model of the system. The results illustrate how temperature profiles illuminate varying pressure versus depth characteristics and can be used alone in cases where staged drilling is not practical. The extensive exploration activities helped define optimal fluid production and injection areas, and showed that the system could provide sufficient hot fluids (∼57 °C) to run a 400-kWe binary power plant, which came on line in 2006.     

Numerical simulation of various cross sectional workpieces using conventional deep drawing and hydroforming technologies

This study focuses on the determination of optimum sheet metal forming process and process parameters for various cross sectional workpieces by comparing the numerical results of high-pressure sheet metal forming, hydro-mechanical deep drawing (DD) and conventional DD simulations. Within the range of each cross section, depth, characteristic dimensions ratio and fillet radius have been altered systematically. Steel of types St14 and DC04 have been used as the specimen material in the numerical analyses and the experimental verification throughout the study. All numerical simulations have been carried out by using a dynamic–explicit commercial finite element code and an elasto-plastic material model. During the analyses each workpiece was simulated by the three competing processes. The results of analyses, such as sheet thickness distribution, necking, forming of radii etc., are used for assessing the success of each forming process alternative. The analyses revealed that depending on the workpiece geometry and dimensional properties certain processes are preferable for obtaining more satisfactory products. Working windows for each process have been established based on the analyzed parameters of the circular, elliptic, rectangular and square cross sectional product geometries. This data is expected to be useful for selecting the appropriate production process for a given workpiece geometry and understand the limits of each sheet metal forming processes.     

Numerical treatment of a quasilinear initial value problem with boundary layer

The paper deals with the singularly perturbed quasilinear initial value problem exhibiting initial layer. First the nature of solution of differential problem before presenting method for its numerical solution is discussed. The numerical solution of the problem is performed with the use of a finite-fitted difference scheme on an appropriate piecewise uniform mesh (Shishkin-type mesh). An error analysis shows that the method is first-order convergent except for a logarithmic factor, in the discrete maximum norm, independently of the perturbation parameter. Finally, numerical results supporting the theory are presented.     

江西相山矿田鹏姑山地区铀成矿条件及资源潜力分析

鹏姑山地区位于相山矿田西部的居隆庵菱形断块与芙竹坪菱形断块所夹持的"锐角"部位,东邻邹家山、船坑及平顶山矿床,西靠书塘、李家岭及居隆庵矿床,是书塘的北东段与邹家山4号带西南延伸段。区内断裂构造发育,主要有贯穿整个鹏姑山地区的北东向邹家山-石洞和北西向济河口两个主断裂,其次是主断裂派生的近南北向断裂,以及包含火山塌陷构造。通过近几年的勘查工作,在区内西端初步发现一条受近南北向济河口断裂控制的铀成矿带。矿体受构造、岩性组间界面以及蚀变复合控制。现有的资料显示,该区铀成矿地质条件优越,铀资源潜力大。