Second-order stresses and strains in heterogeneous steels: Self-consistent modeling and X-ray diffraction analysis

Theoretical and experimetal methods have been developed to characterize the effect of mechanical loading on the mesoscopic and macroscopic mechanical state of polycrystalline materials. Ferritic and austenitic single-phase materials were first analyzed, then phase interaction was studied in a multiductile phase material (austeno-ferritic duplex steel) and a natural reinforced composite (pearlitic steel). The theoretical method is based on the self-consistent approach in which elastic and plastic characteristics of the phases have been applied through the micromechanical behavior of single-crystal-using slip systems and microscopic hardening. The effects of a crystallographic texture and phase interaction during loading and after unloading were studied. The elastic and plastic anisotropy of the grains having the same crystallographic orientation were assessed by diffraction strain analysis. The simulation was compared with the experiments performed using the X-ray diffraction technique. In the considered duplex and pearlitic steels, it was observed that the ferrite stress state is much lower than the austenite and cementite ones. The results of diffraction strain distribution have showed the pertinence of the models and give valuable information, for example, for the yield stress and the hardening parameters of each phase in a two-phase material.     

Chemotherapy and immunotherapy in adult malignant gliomas

This review summarizes papers published during 1991 and 1992. The poor results obtained in the postneurosurgical treatment of gliomas led researchers to pursue attempts to try to overcome glioma cell resistance. The intra-arterial route was explored in several phase II studies with new drugs and even immunoconjugates; rates of response between 30% to 60% were obtained. New drugs (fotemustine, eflornithine, and estramustine) or combined protocols planned to circumvent chemoresistance were tested and showed some efficiency with moderate toxicity, enlarging the number of drugs available against malignant gliomas. On the contrary, two retrospective analyses warned about the risk of reduction of median time to survival due to adjuvant chemotherapy in anaplastic astrocytomas; this finding, if confirmed, would suggest to defer chemotherapy at the time of recurrence in this type of glial tumor. Immunobiologic therapies as immunomodifiers, immunoconjugates, or cytotoxic lymphocyte-activated killer cells and tumor-infiltrating lymphocytes were tested and allowed some responses to be obtained. In young children, chemotherapy regimens were found to be efficient in malignant plexus choroid carcinomas and low-grade gliomas, allowing radiation therapy to be deferred. Many studies were methodologically unsatisfactory because of uncertain pathology grouping, noncompliance to initial protocols, or too small populations of patients.     

Differential time course of angiotensin-induced AP-1 and Krox proteins in the rat lamina terminalis and hypothalamus

Binding to olfactory receptors is the first step in odorant and pheromonal recognition and discrimination. These receptors constitute one of the most important, although poorly known, families of neuronal receptors. In this study we used degenerated oligonucleotides and a RT-PCR approach to selectively amplify olfactory receptors in the nasal epithelium of the domestic pig Sus scrofa. Several combinations of oligonucleotide were tested and allowed the isolation of eleven different partial sequences belonging to the seven transmembrane olfactory receptor family. These receptors formed a separate family within the seven transmembrane receptor superfamily in pigs. Using the criteria of Ben Arie et al. [Ben-Arie N., Lancet D., Taylor C., Khen M., Walker N., Ledbetter DH., Carrozzo R., Patel K., Sheer D., Lehrah H. and North M., Hum. Mol. Genet., 3 (1994) 229-235], the 11 receptors described here can be classified into three known families and seven subfamilies (one known and six new).     

Robust self-stabilizing weight-based clustering algorithm

Ad hoc networks consist of wireless hosts that communicate with each other in the absence of a fixed infrastructure. Such networks cannot rely on centralized and organized network management. The clustering problem consists of partitioning network nodes into non-overlapping groups called clusters. Clusters give a hierarchical organization to the network that facilitates network management and that increases its scalability.In a weight-based clustering algorithm, the clusterheads are selected according to their weight (a node’s parameter). The higher the weight of a node, the more suitable this node is for the role of clusterhead. In ad hoc networks, the amount of bandwidth, memory space or battery power of a node could be used to determine weight values.A self-stabilizing algorithm, regardless of the initial system configuration, converges to legitimate configurations without external intervention. Due to this property, self-stabilizing algorithms tolerate transient faults and they are adaptive to any topology change.In this paper, we present a robust self-stabilizing weight-based clustering algorithm for ad hoc networks. The robustness property guarantees that, starting from an arbitrary configuration, after one asynchronous round, the network is partitioned into clusters. After that, the network stays partitioned during the convergence phase toward a legitimate configuration where the clusters verify the “ad hoc clustering properties”.     

Improving security and performance of an Ad Hoc network through a multipath routing strategy

Privacy and security solutions require today the protection of personal information so that it may not be disclosed to unauthorized participant for illegal purposes. It is a challenge to address these issues in networks with strong constraints such as Ad Hoc network. The security increase is often obtained with a quality of service (QoS) decrease. We propose in this paper a solution that provides at the anonymity, security to Ad Hoc network with a limited impact on QoS. This method could be efficient against some viral attacks. We also give some security proofs of our solution for Ad Hoc networks. The work of Hervé Aiache and Cédric Tavernier was supported by DISCREET, IST project no. 027679, funded in part by the European Commission’s Information Society Technology 6th Framework Programme.     

A 2 MV Van de Graaff accelerator as a tool for planetary and impact physics research

Investigating the dynamical and physical properties of cosmic dust can reveal a great deal of information about both the dust and its many sources. Over recent years, several spacecraft (e.g., Cassini, Stardust, Galileo, and Ulysses) have successfully characterised interstellar, interplanetary, and circumplanetary dust using a variety of techniques, including in situ analyses and sample return. Charge, mass, and velocity measurements of the dust are performed either directly (induced charge signals) or indirectly (mass and velocity from impact ionisation signals or crater morphology) and constrain the dynamical parameters of the dust grains. Dust compositional information may be obtained via either time-of-flight mass spectrometry of the impact plasma or direct sample return. The accurate and reliable interpretation of collected spacecraft data requires a comprehensive programme of terrestrial instrument calibration. This process involves accelerating suitable solar system analogue dust particles to hypervelocity speeds in the laboratory, an activity performed at the Max Planck Institut fu?r Kernphysik in Heidelberg, Germany. Here, a 2 MV Van de Graaff accelerator electrostatically accelerates charged micron and submicron-sized dust particles to speeds up to 80 km s(-1). Recent advances in dust production and processing have allowed solar system analogue dust particles (silicates and other minerals) to be coated with a thin conductive shell, enabling them to be charged and accelerated. Refinements and upgrades to the beam line instrumentation and electronics now allow for the reliable selection of particles at velocities of 1-80 km s(-1) and with diameters of between 0.05 μm and 5 μm. This ability to select particles for subsequent impact studies based on their charges, masses, or velocities is provided by a particle selection unit (PSU). The PSU contains a field programmable gate array, capable of monitoring in real time the particles' speeds and charges, and is controlled remotely by a custom, platform independent, software package. The new control instrumentation and electronics, together with the wide range of accelerable particle types, allow the controlled investigation of hypervelocity impact phenomena across a hitherto unobtainable range of impact parameters.     

Mechanical properties of continuous bamboo fiber-reinforced biobased polyamide 11 composites

This study is devoted to the analysis of the properties of continuous bamboo fiber (BF)-reinforced polyamide 11 (PA 11) composites. The SEM observations highlighted continuity between BFs and the polymeric matrix showing a high density of hydrogen bonds. The comparative calorimetric study of the matrix and its composites showed that the crystallinity of PA 11 was not modified by the presence of bamboo fibers. The physical aging observed in PA 11 is no more observed in composites due to physical interactions between PA 11 and BFs. The mechanical properties were investigated by tensile strength and dynamic mechanical analysis. The introduction of BFs enhanced Young's modulus of the matrix by a factor of 10. The presence of BFs also improved the storage shear modulus G′ over the whole temperature range. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47623.     

A First Report of Photoemission in Experiments Related to Flash Sintering

A highly nonlinear increase in electrical conductivity and concomitant photoemission occurs not only during “flash sintering” but also in presintered, dense specimens. We report results from experiments with dense specimens that show a strong correspondence between the intensity of photoemission and electrical conductivity of specimens under a variety of conditions of the electrical parameters. It is proposed that both properties are related to the concentration of electron–hole pairs generated in such experiments.