Field modulated microwave absorption in YBa2Cu3O7/PrBa2Cu3O7 multilayers

We describe field modulated microwave absorption measurements on YBa₂Cu₃0₇ / PrBa₂Cu₃O₇ multilayers with PrBa₂Cu₃O₇ thickness in the range 2.5 to 10 nm and with a fixed YBa₂Cu₃O₇ thickness of 10 nm. The Fourier spectrum of the reflected microwave power reveals one fundamental frequency which appears at T_c and even harmonics of the modulation field frequency at lower temperatures. The determination of the irreversibility line near T_c for different values of the PrBa₂Cu₃O₇ thickness and inferred from the vanishing of the nonlinear response signal at 2 in the presence of superimposed dc and modulation fields is reportedit.     

A decentralized optimal LQ state observer based on an augmented Lagrangian approach

This paper is devoted to the design of a decentralized optimal batch LQ state observer for state estimation of large-scale interconnected systems, well suited for implementation on a sensor network. The here-proposed approach relies on both the use of an augmented Lagrangian formulation and a price-decomposition–coordination algorithm. The state estimation of an open-channel hydraulic system illustrates the effectiveness of this approach and is used to provide a comparison with alternative methods.     

Design of Marx generators as a structured eigenvalue assignment

We consider the design problem for a Marx generator electrical network, a pulsed power generator. We show that the components design can be conveniently cast as a structured real eigenvalue assignment with significantly lower dimension than the state size of the Marx circuit. Then we present two possible approaches to determine its solutions. A first symbolic approach consists in the use of Gröbner basis representations, which allows us to compute all the (finitely many) solutions. A second approach is based on convexification of a nonconvex optimization problem with polynomial constraints. We also comment on the conjecture that for any number of stages the problem has finitely many solutions, which is a necessary assumption for the proposed methods to converge. We regard the proof of this conjecture as an interesting challenge of general interest in the real algebraic geometry field.     

Effect of PUFA at sn‐2 position in dietary triacylglycerols on the fatty acid composition of adipose tissues in non‐ruminant farm animals

The influence of the distribution of polyunsaturated fatty acids on the glycerol backbone of dietary triacylglycerols on the fatty acid profile of adipose tissue and muscle phospholipids was investigated in growing‐finishing pigs (48) and broiler chicken (84). The animals were fattened on barley/soybean meal diets supplemented with a blend of soybean oil and beef tallow, either in the ratio 3:1 w/w (high‐PUFA) or 1:3 w/w (low‐ PUFA). Part of the high‐ and low‐PUFA blends was chemically interesterified to randomly distribute all fatty acids over the three positions of the glycerol. Thus, two sets of diets of identical overall fatty acid composition, but differing in the distribution of fatty acids in the triacylglycerols, were fed. Growth performance and carcass composition were neither affected by fatty acid composition nor by randomisation of dietary fats in either animal species. Apparent digestibility of energy was slightly lower in pigs fed the low‐PUFA blends. Fatty acid profile of subcutaneous fat of pigs and broilers as well as of internal body fat (lamina subserosa) and muscle phospholipids of pigs varied according to the dietary fatty acid composition but was not affected by randomisation of dietary fats. These findings are explained in terms of the hydrolysis of TAG during transport of lipids from enterocytes to adipose tissue cells and the continuous lipolysis and re‐esterification of fatty acids that take place in adipose tissue cells.     

Gas-liquid and liquid-solid mass transfers in two types of stationary catalytic basket laboratory reactor

Measurements of gas-liquid and liquid-solid mass transfer coefficients were performed in two types of three-phase laboratory reactor equipped with stationary catalytic basket and multiple impeller. Those reactors are called Robinson-Mahoney reactors. Local liquid-solid mass transfer coefficients were measured using naphtol particle dissolution in n-heptane at several agitation speeds. Experiments had shown that local coefficients depended on the particle locations in the basket and agitation speeds. The local coefficient values and profiles were quite similar for both studied reactors even though the reactor designs were different. Similar values of RM basket thicknesses might account for this phenomenon because the liquid-solid mass transfers could be correlated with the ones in packed beds with forced liquid circulation. Gas-liquid mass transfer coefficients were measured using standard dynamic absorption methods in air-water or hydrogen-gas oil system. As in stirred tanks, the gas-liquid mass transfers were linked to the impeller designs and characteristics (gas-inducing or classical impeller) and to the operating conditions such as agitation speeds and fluid properties. However, correlations applicable to stirred tank reactors can be used with Robinson-Mahoney reactors, the baskets behaving like additional baffles or reduction of tank diameters.     

Liquid–solid mass transfer in a three-phase stationary catalytic basket reactor

Measurements of the liquid–solid mass transfer coefficient k_S were performed in a three-phase multiple impeller and stationary catalytic basket reactor, called a Robinson–Mahoney reactor. Local coefficients were determined using naphtol particle dissolution in water and n-heptane with or without gas flow. Experiments have shown that local coefficients k_{S loc} depend on the particle position in the basket, agitation speed, and liquid properties. A correlation linking k_S to liquid velocity was established in a reactor simulating hydrodynamics in a piece of catalytic basket. Liquid velocity values were validated using a particle image velocimetry technique in a Robinson–Mahoney reactor, using water. © 2005 American Institute of Chemical Engineers AIChE J, 2005     

Identification of Pheromone Synergists in American Palm Weevil, Rhynchophorus Palmarum, and Attraction of Related Dynamis Borassi

Thirteen host-plant kairomone blends, including 28 compounds, were tested and showed moderate to high synergy with rhynchophorol. The blends plus rhynchophorol also attracted the related Dynamis borassi. Ethanol–ethyl acetate blends in various ratios showed moderate synergy. Two blends, including "characteristic coconut" odor molecules, were as efficient as sugarcane in synergizing rhynchophorol and field luring American Palm weevils (APWs). Preliminary olfactometer tests of natural host-plant volatiles demonstrated the role of fermentation in primary APW attraction. The synergists were chosen from a comparative study of the odors emitted by four plant materials attractive to the APW: sugarcane, coconut, Jacaratia digitata tree and Elaeis guineensis (Oil palm). The volatiles were isolated during 6 days of sequential trappings onto Supelpak-2 adsorbent. The highly volatile fraction of sugarcane volatiles was sampled by solid-phase microextraction (SPME). Odors were analyzed and identified by gas chromatography and mass spectrometry. Electroantennogram responses to the plant odors were recorded to help in screening for bioactivity. The odor compositions between plants prior to and during fermentation were compared using a principal component analysis (PCA) to determine common odor features of the plants and to design simplified blends for field activity screening. About 100 components were identified in the >4-carbon fraction of the odors, among which 65% were fermentation volatiles. Fermentation generated a strong increase in the amount and variety of the volatiles emitted. The palm materials emitted two- to threefold greater odor amounts than the other plants. The odors from each plant were distinct according to PCA, with few common abundant components: isopentanol, 2-methylbutanol, their acetates, acetoin, isobutyl acetate, 2,3-butanediol, and 2-phenylethanol. Ethanol and ethyl acetate accounted for 80–90% in the highly volatile fraction of sugarcane odors. Coconut odor was mainly characterized by phenol, guaiacol, 1,2-dimethoxybenzene, ethyl esters of tiglic and 3,3-dimethylacrylic acids, 2-hexanone, 2-nonanone; and, to a lesser extent, by 2-heptanone, menthone, -phellandrene, ethyl octanoate and decanoate, which were also present in other plants.     

Crystal growth of high doped Nd:YAG

For years, neodymium-doped yttrium aluminum Garnet (Nd:YAG) crystals of dopant levels of up to 1.1% concentration have been produced for military, industrial, medical, and scientific applications. More and more however, a need exists for crystals doped with higher neodymium concentrations. Nd:YAG crystals with dopant levels of 1.3% and 1.4% can produce greater efficiency in Q-switch operations, thus smaller crystals can be used to achieve the desired output power. Additionally, smaller crystals are easier to cool and therefore deleterious thermal effects can be minimized. It is difficult to incorporate the large diameter Nd³⁺ ion into the relatively small Y³⁺ sites of the YAG crystal lattice, which limits the achievable dopant concentration. In this paper, we will present the growth of highly doped Nd:YAG crystals with excellent optical quality achieved by modifying the growth parameters. Spectroscopy results and laser results obtained from our 1.3% and 1.4% Nd:YAG crystals will also be presented.     

Controllable Fabrication of Inhomogeneous Microcapsules for Triggered Release by Osmotic Pressure

Inhomogeneous microcapsules that can encapsulate various cargo for controlled release triggered by osmotic shock are designed and reported. The microcapsules are fabricated using a microfluidic approach and the inhomogeneity of shell thickness in the microcapsules can be controlled by tuning the flow rate ratio of the middle phase to the inner phase. This study demonstrates the swelling of these inhomogeneous microcapsules begins at the thinnest part of shell and eventually leads to rupture at the weak spot with a low osmotic pressure. Systematic studies indicate the rupture fraction of these microcapsules increases with increasing inhomogeneity, while the rupture osmotic pressure decreases linearly with increasing inhomogeneity. The inhomogeneous microcapsules are demonstrated to be impermeable to small probe molecules, which enables long‐term storage. Thus, these microcapsules can be used for long‐term storage of enzymes, which can be controllably released through osmotic shock without impairing their biological activity. The study provides a new approach to design effective carriers to encapsulate biomolecules and release them on‐demand upon applying osmotic shock.     

CMOS stacked folded differential structure power amplifier for high power RF application

This article describes the feasibility of a Power Amplifier (PA) in 0.13 μm CMOS technology from STMicroelectronics for high power applications. To obtain a high output power with a good linearity, a new topology called Stacked Folded Differential Structure (SFDS) is proposed. It allows obtaining similar power performances to a PA with DAT in a lower die area. This PA provides 23 dBm of maximum output power (P_max) with 20% of power added efficiency (PAE) at 1.95 GHz. The linear gain is equal to 11 dB and the output power at 1 dB compression point (OCP₁) achieves 21 dBm. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.