Small size, low power consumption, low phase noise MMIC VCO usingoff-chip packaging resonator for mobile communication

An MMIC VCO with a new type of frequency tunable multilayer ceramic resonator for mobile communication is designed and fabricated for the 2 GHz band. The VCO presents a dramatic size reduction and a C/N performance of -100 dBc/Hz at 100 kHz. Its RF output power is about -3 dBm, the frequency tuning range is 110 MHz, and current consumption is 7mA of DC     

Comparison of constituents, antioxidant potency, and acetylcholinesterase inhibition in Lentinus edodes, Sparassis crispa, and Mycoleptodonoides aitchisonii

This study evaluates three edible mushrooms: Lentinus edodes, Sparassis crispa, and Mycoleptodonoides aitchisonii, in terms of acetylcholinesterase (AChE) inhibition, antioxidant potency and constituents free amino acids and mineral. The concentration of essential amino acids was found to be 34.10 mg/g in M. aitchisonii, 26.25 mg/g in S. crispa, 25.99 mg/g in L. edodes. S. crispa displayed the highest DPPH scavenging activity and phenolic contents. The best results for AChE inhibition were obtained from M. aitchisonii. These results suggest that M. aitchisonii has high potential for cognitive improvement by AChE inhibition and antioxidant potency.     

Steric and electronic effects on mesophase stability of segmented liquid crystalline polymers with arylazomethine pendant groups

Summary The kinetics of DL-lactide polymerization was studied in CH₂Cl₂ at 25°C and in toluene at 70°C with HAPENAlOMe, a new Schiff's base complex derived from 2-hydroxyacetophenone and ethylenediamine. A higher polymerization rate is observed with this initiator as compared to other previously reported Al-alkoxides complexes. The polymerization with HAPENAlOMe is also shown to be a living process in both solvents. Moreover, the polymerization proceeds to quite high conversion without significant occurrence of transesterification reactions as confirmed from ¹³C NMR and SEC analysis. Received: 4 October 1999/Accepted: 6 December 1999     

Electrical conductivity of vapor‐grown carbon nanofiber/polyester textile‐based composites

Polyamide 6/ethylene–propylene–diene metallocene terpolymer/(ethylene–propylene–diene copolymer)‐graft‐(maleic anhydride) blends with clay (3 and 5 wt % depending on the formulation), different clays (montmorillonite and sepiolite) and different surface functionalization (ammonium salts and silanes) were studied to analyze the effect of the shape of clay and type of modifier on their properties. The results have shown that sepiolite has higher influence on the morphology and on the mechanical properties than montmorillonite. In that sense, blends with 3 wt % of sepiolite have reached the best balanced properties, i.e., tensile modulus and impact strength, than their homologous with montmorillonite. Furthermore, the blends with 3 wt % of sepiolite have reached the highest mechanical properties compared with blends with higher montmorillonite content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Strength and fracture analysis of silicon-based components for embedding

Single-crystalline silicon chips are widely employed in printed circuit boards (PCBs) as embedded components. Their design often requires one side patterned with metal contacts, whereas the opposite one is constituted by pure silicon. These components must possess a minimum strength to withstand the loads occurring during both production and operation of the board. In this work, the strength and fracture behaviour of miniaturised Si chips (dimensions: 2 mm × 2 mm × 0.125 mm) has been assessed under biaxial loading on both the pure silicon side and the metal-patterned side by means of a miniaturised ball-on-three-balls (B3B) fixture. Experimental results showed significant difference in the characteristic fracture load between the silicon-side (P₀ = 21.2 N, Weibull modulus m ≈ 2.6) and the metal-patterned side (P₀ = 8.6 N, m ≈ 12.3). Fracture mechanics and fractographic analyses, together with FE simulations of the loading process, helped clarifying the effect of the metal contacts on the overall fracture behaviour of the Si-chips.     

How does carotid artery stenosis increase?

In 25 patients with carotid artery stenosis equal or higher than 40% colour doppler examinations were performed 105 times. The aim of this study was estimate the dynamics of progress of carotid artery stenosis. The mean time of observation was 22.5 months. In 11 (44%) patients there was no progress of stenosis, in 6 (24%) a leap progress over 30% of arterial lumen, and in 8 (32%) patients the progress of carotid artery stenosis were gradual and slow. The leap progress of carotid artery stenosis was usually caused by eruption or dissection of atherosclerotic plaque located in carotid bifurcation and this situation poses especially high risk of stroke.     

Nanostructured copper/porous silicon hybrid systems as efficient sound-emitting devices

In the present work, the photo-acoustic emission from nanostructured copper/porous silicon hybrid systems was studied. Copper nanoparticles were grown by photo-assisted electroless deposition on crystalline silicon and nanostructured porous silicon (nanoPS). Both the optical and photo-acoustic responses from these systems were determined. The experimental results show a remarkable increase in the photo-acoustic intensity when copper nanoparticles are incorporated to the porous structure. The results thus suggest that the Cu/nanoPS hybrid systems are suitable candidates for several applications in the field of thermoplasmonics, including the development of sound-emitting devices of great efficiency.     

Modeling Lightning Impact Thermo-Mechanical Damage on Composite Materials

Carbon fiber-reinforced polymers, used in primary structures for aircraft due to an excellent strength-to-weight ratio when compared with conventional aluminium alloy counterparts, may nowadays be considered as mature structural materials. Their use has been extended in recent decades, with several aircraft manufacturers delivering fuselages entirely manufactured with carbon composites and using advanced processing technologies. However, one of the main drawbacks of using such composites entails their poor electrical conductivity when compared with aluminium alloy competitors that leads to lightning strikes being considered a significant threat during the service life of the aircraft. Traditionally, this problem was overcome with the use of a protective copper/bronze mesh that added additional weight and reduced the effectiveness of use of the material. Moreover, this traditional sizing method is based on vast experimental campaigns carried out by subjecting composite panels to simulated lightning strike events. While this method has proven its validity, and is necessary for certification of the structure, it may be optimized with the aid provided by physically based numerical models. This paper presents a model based on the finite element method that includes the sources of damage observed in a lightning strike, such as thermal damage caused by Joule overheating and electromagnetic/acoustic pressures induced by the arc around the attachment points. The results of the model are compared with lightning strike experiments carried out in a carbon woven composite.