Magnetism in SiC implanted with high doses of Fe and Mn

High concentrations (0.1–5 at.%) of Mn or Fe were introduced into the near-surface region (≤2000 Å) of 6H-SiC substrates by direct implantation at ～300°C. After annealing at temperatures up to 1000°C, the structural properties were examined by transmission electron microscopy (TEM) and selected-area diffraction pattern (SADP) analysis. The magnetic properties were examined by SQUID magnetometry. While the Mn-implanted samples were paramagnetic over the entire dose range investigated, the Fe-implanted material displayed a ferromagnetic contribution present at <175 K for the highest dose conditions. No secondary phases were detected, at least not to the sensitivity of TEM or SADP.     

Model reduction for optimization of rapid thermal chemical vapordeposition systems

A model of a three-zone rapid thermal chemical vapor deposition (RTCVD) system is developed to study the effects of spatial wafer temperature patterns on polysilicon deposition uniformity. A sequence of simulated runs is performed, varying the lamp power profiles so that different wafer temperature modes are excited. The dominant spatial wafer thermal modes are extracted via proper orthogonal decomposition and subsequently used as a set of trial functions to represent both the wafer temperature and deposition thickness. A collocation formulation of Galerkin's method is used to discretize the original modeling equations, giving a low-order model which loses little of the original, high order model's fidelity. We make use of the excellent predictive capabilities of the reduced model to optimize power inputs to the lamp banks to achieve a desired polysilicon deposition thickness at the end of a run with minimal deposition spatial nonuniformity. Since the results illustrate that the optimization procedure benefits from the use of the reduced-order model, our future goal is to integrate the model reduction methodology into real-time and run-to-run control algorithms. While developed in the context of optimizing a specific RTP process, the model reduction techniques presented in this paper are applicable to other materials processing systems     

Magnetic properties of Co- and Mn-implanted BaTiO3, SrTiO3 and KTaO3

Implantation of Co or Mn into single-crystal BaTiO₃(K), SrTiO₃ or KTaO₃(Ca), followed by annealing at 700 °C, produced ferromagnetic behavior over a broad range of transition metal concentrations. For BaTiO₃, both Co and Mn implantation produced magnetic ordering temperatures near 300 K with coercivities 70 Oe. The M–T plots showed either a near-linear decrease of magnetization with increasing temperature for Co and a non-Brillouin shaped curve for Mn. No secondary phases were detected by high-resolution X-ray diffraction. The same basic trends were observed for both SrTiO₃ and KTaO₃, with the exception that at high Mn concentrations (5 at.%) the SrTiO₃ was no longer ferromagnetic. Our results are consistent with recent reports of room temperature ferromagnetism in other perovskite systems (e.g. LaBaMnO₃) and theoretical predictions for transition metal doping of BaTiO₃ [Nakayama et al., Jap. J. Appl. Phys. 40 (2001) L1355].     

Unresectable pancreatic cancer: is a multi-modality approach a promising therapeutical alternative?

BACKGROUND/AIMS: The aim of this study was to evaluate the combination of immunochemotherapy and stop-flow upper abdominal chemotherapy in the prolongation of survival in patients with unresectable pancreatic cancer. METHODOLOGY: Thirty unresectable pancreatic cancer patients were treated with immuno-chemotherapy in combination with stop-flow upper abdominal chemotherapy, in an attempt to improve survival time. RESULTS: The results obtained in this study indicate that this kind of treatment is feasible, safe and effective for patients suffering from Stage III and IV pancreatic duct carcinoma. Twenty per cent of the patients within this group were able to undergo radical resection and remain alive and free of disease, with a mean survival rate of 16 months. CONCLUSION: The multi-modality approach used in this study achieved promising results for pancreatic cancer patients and is recommended as a promising therapeutic alternative.     

Inverse model-based real-time control for temperature uniformity ofRTCVD

A reduced-order model describing a rapid thermal chemical vapor deposition (RTCVD) process is utilized for real-time model based control for temperature uniformity across the wafer. Feedback is based on temperature measurements at selected points on the wafer surface. The feedback controller is designed using the internal model control (IMC) structure, especially modified to handle systems described by ordinary differential and algebraic equations. The IMC controller is obtained using optimal control theory on singular arcs extended for multi-input systems. Its performance is also compared with one based on the Hirschorn inverse of the model. The proposed scheme is tested with extensive simulations where the full-order model is used to emulate the process. Several cases of significant uncertainty, including model parameter errors, process disturbances, actuator errors, and measurement noise are used to test the robustness of the controller to real life situations. Both controllers succeed in achieving temperature uniformity well within the desirable bounds, even in cases where several sources of uncertainty are simultaneously present with measurement noise     

Thermal characterization of polyamide 11/nanographene platelet nanocomposites

The objective of this study is to evaluate thermal properties of polyamide 11 (PA11)/nanographene platelet (NGP) nanocomposites. Samples were prepared using 1 wt%, 3 wt%, and 5 wt% of NGPs. Isopropyl alcohol (IPA) was used as a solvent to assist in dispersion of the NGPs within the PA11 powder. The NGPs were hand mixed evenly into the PA11 powder using a wooden dowel. Morphological characterization of the PA11/NGP nanocomposite was conducted using scanning electron microscopy. Thermal characterization of nanocomposites includes thermogravimetric analysis, differential scanning calorimetry and thermomechanical analysis. Results indicate that the addition of NGPs shows an initial increase in thermal stability and crystallization temperature (T(c)) along with a decrease in glass transition temperature (T(g)) and no improvement in coefficient of thermal expansion (alpha). These results are attributed to improved interfacial adhesion between NGPs and PA11, restricting polymer chain mobility.     

Properties of Mn-doped Cu2O semiconducting thin films grown by pulsed-laser deposition

Semiconducting oxides offer the potential for exploring and understanding spin-based functionality in a semiconducting host material. Theoretical predictions suggest that carrier-mediated ferromagnetism should be favored for p-type material. Cu₂O is a p-type, direct wide bandgap oxide semiconductor that may hold interest in exploring spin behavior. In this paper, the properties of Mn-doped Cu₂O are described. Activities focused on understanding Mn incorporation during thin-film synthesis, as well as magnetic characterization. The epitaxial films were grown by pulsed-laser deposition. X-ray diffraction was used to determine film crystallinity and to address the formation of secondary phases. SQUID magnetometry was employed to characterize the magnetic properties. Ferromagnetism is observed in selected Mn-doped Cu₂O films, but appears to be associated with Mn₃O₄ secondary phases. In phase-pure Mn-doped Cu₂O films, no evidence for ferromagnetism is observed.     

Macroscopic and microscopic techno-economic analyses highlighting aspects of 5G transport network deployments

Photonic Network Communications - 5G networks will comprise multiple, versatile infrastructures at finest granularity consisting of multiple disaggregated pools of network, compute and storage...     

Structure elucidation and conformational properties of synthetic cannabinoids (-)-2-(6a,7,10,10a-tetrahydro-6,6,9-trimethyl-1-hydroxy-6H-dibe nzo [b,d]pyranyl)-2-hexyl-1,3-dithiolane and its methylated analog

The synthetic cannabinoid (-)-2-(6a,7,10,10a-tetrahydro-6,6,9-trimethyl-1-hydroxy-6H-dibenzo[b,d]+ ++pyranyl)-2-hexyl-1,3-dithiolane (AMG-3) is a cannabimimetic molecular probe with one of the highest binding affinities reported to date. Therefore, due to its potential pharmacological importance, its structure was sought to be elucidated and its conformational properties were studied using a combination of 1D, 2D NMR spectroscopy and molecular modelling. The structure of its methylated analog (-)-2-(6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H dibenzo [b,d]pyranyl-1-methoxy)-2-hexyl-1,3 dithiolane (AMG-18), was also studied and its conformational properties were compared with AMG-3. AMG-18 lacks of the phenolic hydroxyl group a strict requirement for cannabimimetic activity and is almost devoid of any biological activity. The conformational analysis studies showed that 1',1' dithiolane ring restricted the orientation preferences of alkyl chain. This may account for the high binding affinity of AMG-3 to cananbinoid receptors. Grid scan search studies showed different preferences of possible adopting dihedral values of phenolic hydroxyl group and its methyl ether. These observations may account for their differences in biological activity.     

Early experiences and lessons learned from femtocells - [femtocell wireless communications]

There is a continuous pursuit by mobile operators (MOs) to improve indoor coverage in order not only to improve voice quality but also to enable higher data rates in home/office environments. Indoor coverage improvement, in conjunction with inexpensive (voice) offerings, will enable MOs to compete with and take away voice-call-related revenues from fixed network PTTs and/or VoIP operators. Femtocells constitute a promising solution to address all of the above. In this article we present our experience from our extensive study and trials of early (pre-standard) femtocell solutions that were available in the 2007-2008 timeframe.