The use of charging effects in Al/Al2O3 metal-matrix composites as a contrast mechanism in the SEM

A technique is described to image two phases (alumina and spinel) within a metal-matrix composite which takes advantage of charging effects that occur during examination in an SEM. Microscope and specimen parameters which affect the amount of contrast generated via charging are discussed, and imaging strategies are introduced to optimize the effect. “Model” metal-matrix composite specimens were developed to verify the degree of charging in each phase.     

In-vitro iron dialysability from legumes: Influence of phytate and extrusion cooking

In-vitro iron dialysability from five Italian legumes (mottled bean, white bean, faba bean, chickpea, lentil) and the influence of phytate and extrusion cooking on it were evaluated. Iron dialysability was 2·3 and 2·4% in mottled and white bean respectively, 1·2% infaba bean, 2·7% in chickpea and 1·1% in lentil. After extrusion cooking the flours showed a marked iron contamination and a decrease in iron dialysability, but these changes were significant only for mottled bean. Enzymic phytate removal induced an increase in iron dialysability > 100% in all the raw legumes except mottled bean which showed an increase of only 57%. This finding indicates that, although phytate consistently modifies iron dialysability, it is difficult to identify a quantitative relationship between phytate content and iron dialysability.     

Fourier-transform infrared conformational study of bovine insulin in surfactant solutions

BACKGROUND: bcl-2 protein is an oncoprotein encoded by a protooncogene bcl-2 which is thought to be a key gene for the regulation of cell life and death. bcl-2 protein has been reported to be expressed in a subset of prostate cancers, and its biological role in this disease has not yet been elucidated. This present study focused on the cell cycle analysis of bcl-2 immunoreactivity in prostate tumor samples and correlated findings with the prognosis of the patients. METHODS: Archival tissues from 37 prostate cancers were submitted for immunohistochemistry and DNA analysis via flow cytometry. All tissues were obtained before the patients received any treatment. Immunohistochemistry was performed using streptavidin biotin procedures, and DNA flow cytometry was done by a combination of two methods. RESULTS: Fourteen of 37 prostate cancers (38%) exhibited bcl-2 immunoreactivity. bcl-2 positive prostate cancers significantly correlated with DNA aneuploidy and higher proliferation indices, but not with histological differentiation. Clinically, there was a poorer prognosis for patients with bcl-2 positive prostate cancer. CONCLUSIONS: Our data indicates that bcl-2 protein expression in prostate cancer is associated with cell proliferation and may serve as a predictive factor for the prognosis of prostate cancer.     

Irreversible refrigerators with isothermal heat exchanges: Réfrigérateurs irréversibles avecéchanges thermiques isotherms

A maximum for the coefficient of performance (COP_f) is verified for a temperature difference between reservoirs and the hot isotherm of a closed irreversible cyclical refrigerator working at steady-state conditions. A maximum also exists when the COP_f is considered as a function only of a parameter depending on the thermal characteristics of the heat exchangers. The influence of the parameter and entropy generation on the COP_f maxima is described.     

Designing Templates for Mining Association Rules

Current approaches to data mining usually address specific userrequests, while no general design criteria for the extraction of associationrules are available for the end-user. In this paper, we propose aclassification of association rule types, which provides a general frameworkfor the design of association rule mining applications. Based on theidentified association rule types, we introduce predefined templates as ameans to capture the user specification of mining applications. Furthermore,we propose a general language to design templates for the extraction ofarbitrary association rule types.     

Saw and digital technologies in mutlicarrier demodulators

One key technology, for the implementation of future on-board processing payloads, is the multicarrier demodulator (MCD). The MCD is instrumental in allowing FDMA/TDM access schemes which optimize the use of on-board and ground resources in VSAT networks. This paper deals with the analogue and digital implementations of MCD, trying to assess the fields of application of each of the two technologies.     

Variable-gain up-converter with current reuse for 5-GHz WLAN applications

A variable-gain up-conversion mixer for 5-GHz WLAN applications is presented, whose input stage is based on a novel variable gain transconductor. The proposed topology features reduced power consumption by exploiting dc current reuse for mixer biasing. Moreover, a new low-consumption control circuit is introduced, which achieves a temperature-stable and linear-in-dB characteristic, providing a 40-dB dynamic range within ±1 dB gain error.     

Dynamic Effects in Hopkinson Bar Four-Point Bend Fracture

Hopkinson bar techniques have played an important role in the study of high-rate deformation and fracture behavior of materials. In the current work, a split Hopkinson pressure bar was developed for dynamic four-point bend fracture testing, referred to as a “two-bar (incident and transmitted bars)/four-point” (2-bar/4-pt) bend test. To further understand some fundamental issues regarding stress wave propagation in this 2-bar/4-pt bend testing system, dynamic fracture tests were performed in pulse-shaped and unshaped pulse testing conditions. The effect of the pulse shaper on the incident pulse characteristics (rise time and duration), specimen’s dynamic response (load and loading point displacement), crack initiation time and stress-state equilibrium were investigated experimentally in the current work. The present results show that stress state equilibrium can be achieved prior to fracture initiation in notched and precracked specimens. In the pulse-shaped bending test, the specimen is more likely to attain stress-state equilibrium than in an unshaped incident pulse test. The crack initiation time was extended and the time required for attaining stress equilibrium was reduced by pulse shaping due to the tailored incident pulse having a longer rise time, which ensures that stress equilibrium is achieved prior to crack initiation. This article is based on a presentation made in the symposium entitled “Dynamic Behavior of Materials,” which occurred during the TMS Annual Meeting and Exhibition, February 25–March 1, 2007 in Orlando, Florida, under the auspices of The Minerals, Metals and Materials Society, TMS Structural Materials Division, and TMS/ASM Mechanical Behavior of Materials Committee.     

Two-Way Protocol with Imperfect Devices

The security of a deterministic quantum scheme for communication, namely the LM05 [1], is studied in presence of a lossy channel under the assumption of imperfect generation and detection of single photons. It is shown that the scheme allows for a rate of distillable secure bits higher than that pertaining to BB84 [2]. We report on a first implementation of LM05 with weak pulses.