A Complete Separation of Hexane Isomers by a Functionalized Flexible Metal Organic Framework

The separation ability of branched alkane isomers (nHEX, 3MP, 22DMB) of the flexible and functionalized microporous iron(III) dicarboxylate MIL‐53(Fe)‐(CF₃)₂ solid is evaluated through a combination of breakthrough experiments (binary or ternary mixtures), adsorption isotherms, X‐ray diffraction temperature analysis, quasi‐elastic neutron scattering measurements and molecular dynamics simulations. A kinetically controlled molecular sieve separation between the di‐branched isomer of hexane 22DMB from a mixture of paraffins is achieved. The reported total separation between mono‐ and di‐branched alkanes which was neither predicted nor observed so far in any class of porous solids is spectacular and paves the way towards a potential unprecedented upgrading of the RON of gasoline.     

Microwave active resonator band-pass filters in various mmic technologies

In this article, two topologies of L-C parallel active resonators are presented. These circuits are realized in MMIC technology, using three transistors which could be MESFET, hemt or HBT. The survey of these resonators shows the possibility, by controling the values of a resistor and/or a capacitor, on the one hand, to tune the resonance frequency of these circuits, and on the other hand, to cancel out their losses so as to obtain negative conductance. Compact, lossless and narrow-band filters are then implemented using previous active resonators. To date, the use of mesfet technology has reduced the synthesis of such active filters in S-band and at X-band low frequencies. Now, however, hemt and HBT technologies allow the extension of their implementation to the whole X-band. This survey is illustrated by the simulated response of a 10 GHz filter with a 500 MHz 3 dB bandwidth. The mmic technology is a 0.2 μm hemt one. The simulated performances of this filter achieve a mean transmission gain of 0. 5 dB, with a reflection loss higher than 10 dB at 10 GHz,     

Spreading Codes Generator for Wireless CDMA Networks

The prime characteristic of spread spectrum modulated signals is that their bandwidth is greater than the information rate. In this way a redundancy is introduced that allows the severe levels of inteference inherent in the transmission of digital information over radio and satellite links to be overcome. Current spread spectrum applications are primarily in military communications; nevertheless, there is growing interest in this technique for third generation mobile radio networks (UMTS, FPLTS, etc.) with open discussion regarding the practicality of using a multiple access system based on spread spectrum techniques (CDMA). However, in order to support as many users in the same bandwidth as other multiple access techniques such as TDMA or FDMA, it is important how to generate large families of sequences that present low cross-correlation. The aim of this paper is to describe a spreading codes generator that can produce a large number of PN sequences with good properties of auto- and cross-correlation. Moreover, the codes generated shows high unpredictability and good statistical behaviour. This also allows the implementation of some features that are common on military networks such as message privacy (increasingly important in commercial networks) without additional cost. The structure presented shows itself to be advantageous for high speed generation of codes at a low cost, low power consumption (allowing longer life for batteries), small size and simplicity of implementation, essential ingredients for commercial equipment. Another attractive feature is its structural parallelism, useful in VLSI implementations. All of these features render it potentially suitable for the implementation of channel bandwidth sharing systems in future wireless personal communications networks.     

A High Voltage Line Driver for Subscriber Loop Interfaces in a Low Voltage Submicron BiCMOS Technology

This paper presents a 30 V line driver for short loop subscriber line interface circuit applications. The high voltage line drivers was implemented in a low-voltage 0.8 m BiCMOS process using 30 V extended-drain MOS transistors, fully compatible with the low voltage technology. Using a Quasi-Current Mirror architecture for the output stage, the line driver is capable of delivering more than 30 mA current into the lines with an idle current as low as 1 mA, satisfying the short loop requirements. With less than 0.24 mm² area, the circuit can be easily integrated with low-voltage circuitry on a single chip.     

Life cycle assessment of MSF,MED and RO desalination technologies

In this work, a comparison of the commonly deployed commercial desalination technologies worldwide—multistage flash (MSF), multieffect evaporation and reverse osmosis (RO)—is assessed by applying life cycle analysis (LCA). LCA, a powerful, and internationally accepted tool used to examine environmental cradle-to-grave consequences of making and using products and services, identifies and quantifies energy and material usage and waste discharges. The International Standard Organization (ISO) 14000 impact factors, which are internationally accepted standard indicators for environmental impact assessment, have been evaluated, and different evaluation methods (Centre for Environmental Studies (CML) 2 baseline 2000, Eco-Points 97 and Eco-Indicator 99) have been applied to different scenarios. The assessment includes the entire life cycle of each desalination process, encompassing extraction and processing raw materials, manufacturing, transportation and distribution, plant operation and final reject disposal.     

Modeling of transient natural convection heat transfer in electric ovens

Prediction of transient natural convection heat transfer in vented enclosures has multiple applications such as understanding of cooking environment in ovens and heat sink performance in electronic packaging industry. The thermal field within an oven has significant impact on quality of cooked food and reliable predictions are important for robust design and performance evaluation of an oven. The CFD modeling of electric oven involves three-dimensional, unsteady, natural convective flow-thermal field coupled with radiative heat transfer. However, numerical solution of natural convection in enclosures with openings at top and bottom (ovens) can often lead to non-physical solutions such as reverse flow at the top vent, partly a function of initialization and sometimes dependent on boundary conditions. In this paper, development of a physics based robust CFD methodology is discussed. This model has been developed with rigorous experimental support and transient validation of this model with experiments show less than 3% discrepancy for a bake cycle. There is greater challenge in simulating a broil cycle, where the fluid inside the cavity is stably stratified and is also highlighted. A comparative analyses of bake and broil cycle thermal fields inside the oven are also presented.     

Kinetics and thermodynamic behavior of WO3 and WO3:P thin films

 There is a considerable interest in the research and development of materials and devices, that can be used for optical switching of large-scale glazings. Several potential switching technologies are available for glazings, including those based on electrochromic, thermochromic and photochromic phenomena. One of the most promising technologies for optical switching devices is electrochromism (EC). In order to improve the electrochromic properties of tungsten oxide, we have investigated the effect of phosphorous insertion on the electrochromic behavior of oxide films prepared by the sol–gel process.The kinetics and thermodynamics of electrochemical intercalation of lithium into Li_xWO₃ and Li_xWO₃:P films prepared by the sol–gel process were investigated. The standard Gibbs energy for lithium intercalation was calculated. The chemical diffusion coefficients, D, of lithium intercalation into oxide, were measured by galvanostatic intermittent titration technique (GITT), as functions of the depth of lithium intercalation.     

Optical and electrochemical properties of V2O5:Ta Sol–Gel thin films

Vanadium and tantalum-doped vanadium pentoxide, V₂O₅ and V₂O₅:Ta thin films (2.5 and 5 mol% of Ta) were prepared using sol–gel dip-coating technique.The coating solutions were prepared by reacting vanadium (V) oxytripropoxide and tantalum ethoxide (V) as precursors using anhydrous isopropyl alcohol as solvent.The films were deposited on a transparent glass substrate with ITO conducting film by dip-coating technique, with a withdrawal of 20 cm/min from the vanadium–tantalum solution and heat treated at 300 °C for 1 h. The resulting films were characterized by cyclic voltammetry, optical spectroscopy and by X-ray diffraction analysis (XRD). XRD data show that the films thermally treated at 300 °C were crystalline.A charge density of 70 mC/cm² was obtained for the film with 5 mol% of Ta, with an excellent stability up to 1500 cycles.     

Effects of double-muscling on carcass quality, beef tenderness and myofibrillar protein degradation in Belgian Blue White bulls

Carcass properties and meat quality characteristics of 32 Belgian Blue White double-muscled bulls (DM) were compared with those of 59 bulls of the same breed with normal conformation (N). DM showed superior carcass quality as revealed in increased dressing percentage, meat production yield, conformation grade, muscle/fat and muscle/bone ratios (all P < 0·001). Longissimus dorsi (LD) shear force values, drip and cooking losses at 8 days post mortem (pm) were significantly higher (P < 0·001) for DM, whereas sarcomere lengths were not different. Calpain 1 and calpastatin levels at 1 h and 24 h pm were tremendously decreased in DM as were also cathepsin B and L levels at 1 and 8 days pm (P < 0·001). As evident from semi-quantitative SDS-PAGE, these differences were accompanied by higher titin and lower 30 kDa levels (P < 0·001) in DM. Troponin-t levels were not different, but very low. Intramuscular collagen content was significantly lower in DM (P < 0·001). This suggests that lower background toughness in DM was compensated for by reduced post-mortem proteolytic tenderization. Discrepancy with literature reports regarding tenderness of DM might be related to the extreme muscularity of the Belgian Blue White breed, compared to other DM breeds. The results also suggest that reduced protein turnover might be involved in the muscle hypertrophy phenomenon within this breed, because of likely reduced levels of calpains and cathepsins in living DM animals.     

Study of the glucide fraction in ropy wines

Gas chromatography was used to study the polysaccharides present in samples that exhibited significant microbially induced viscosity values. Alterations in the media considered were related to the percentage glucose content and the total polysaccharide content.