Toward a systematic design methodology for large multigigahertzrapid single flux quantum circuits

Rapid single flux quantum (RSFQ) digital circuits have reached the level of medium- to large-scale of integration. At this level, existing design methodologies, developed specifically for RSFQ circuits, have become computationally inefficient. Applying mature semiconductor methodologies to the design of RSFQ circuits, one encounters substantial difficulties originating from the differences between both technologies. In this paper, a new design methodology aimed at large-scale RSFQ circuits is proposed. This methodology is based on a semiconductor semicustom design approach. An established design methodology for small-stale RSFQ digital circuits, based on circuit (junction-level) simulation and device parameter optimization, is used for the design of basic RSFQ cells. A library composed of about 20 basic RSFQ cells has been developed based on this approach. A novel design methodology for large-scale circuits, presented in this paper, is based on logic (gate-level) simulation and timing optimization. This methodology has been implemented around the Cadence integrated design environment and used successfully at the University of Rochester for the design of two large-scale digital circuits     

Interfacial Connections between Organic Perovskite/n+ Silicon/Catalyst that Allow Integration of Solar Cell and Catalyst for Hydrogen Evolution from Water

The rapidly increasing solar conversion efficiency (PCE) of hybrid organic–inorganic perovskite (HOIP) thin-film semiconductors has triggered interest in their use for direct solar-driven water splitting to produce hydrogen. However, application of these low-cost, electronic-structure-tunable HOIP tandem photoabsorbers has been hindered by the instability of the photovoltaic-catalyst-electrolyte (PV+E) interfaces. Here, photolytic water splitting is demonstrated using an integrated configuration consisting of an HOIP/n⁺silicon single junction photoabsorber and a platinum (Pt) thin film catalyst. An extended electrochemical (EC) lifetime in alkaline media is achieved using titanium nitride on both sides of the Si support to eliminate formation of insulating silicon oxide, and as an effective diffusion barrier to allow high-temperature annealing of the catalyst/TiO₂-protected-n⁺silicon interface necessary to retard electrolytic corrosion. Halide composition is examined in the (FA_1-xCs_x)PbI₃ system with a bandgap suitable for tandem operation. A fill factor of 72.5% is achieved using a Spiro-OMeTAD-hole-transport-layer (HTL)-based HOIP/n⁺Si solar cell, and a high photocurrent density of −15.9 mA cm⁻² (at 0 V vs reversible hydrogen electrode) is attained for the HOIP/n⁺Si/Pt photocathode in 1 m NaOH under simulated 1-sun illumination. While this thin-film design creates stable interfaces, the intrinsic photo- and electro-degradation of the HOIP photoabsorber remains the main obstacle for future HOIP/Si tandem PEC devices.     

Adhesion and Surface Interactions of a Self‐Healing Polymer with Multiple Hydrogen‐Bonding Groups

The surface properties and self‐adhesion mechanism of self‐healing poly(butyl acrylate) (PBA) copolymers containing comonomers with 2‐ureido‐4[1H]‐pyrimidinone quadruple hydrogen bonding groups (UPy) are investigated using a surface forces apparatus (SFA) coupled with a top‐view optical microscope. The surface energies of PBA–UPy4.0 and PBA–UPy7.2 (with mole percentages of UPy 4.0% and 7.2%, respectively) are estimated to be 45–56 mJ m^?2 under dry condition by contact angle measurements using a three probe liquid method and also by contact and adhesion mechanics tests, as compared to the reported literature value of 31–34 mJ m^?2 for PBA, an increase that is attributed to the strong UPy–UPy H‐bonding interactions. The adhesion strengths of PBA–UPy polymers depend on the UPy content, contact time, temperature and humidity level. Fractured PBA–UPy films can fully recover their self‐adhesion strength to 40, 81, and 100% in 10 s, 3 h, and 50 h, respectively, under almost zero external load. The fracture patterns (i.e., viscous fingers and highly “self‐organized” parallel stripe patterns) have implications for fabricating patterned surfaces in materials science and nanotechnology. These results provide new insights into the fundamental understanding of adhesive mechanisms of multiple hydrogen‐bonding polymers and development of novel self‐healing and stimuli‐responsive materials.     

Evolution of multiprotocol label switching

Multiprotocol label switching (MPLS) is rapidly emerging as an Internet Engineering Task Force (IETF) standard intended to enhance the speed, scalability, and service provisioning capabilities in the Internet. MPLS uses the technique of packet forwarding based on labels, to enable the implementation of a simpler high-performance packet forwarding engine. This also decouples packet forwarding from routing, facilitating the provision of varied routing services independent of the packet forwarding paradigm. The authors track the evolution of this technology in relation to other existing technologies. Then an overview of the MPLS architecture and design is provided. In addition, some of the work that was a precursor to MPLS is discussed, as well as related issues and debates     

Radiative and multiphonon relaxation of the mid-IR transitions ofPr3+ in LaCl3

Electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission coefficients, fluorescence efficiencies, and fluorescence lifetimes are determined for the lower lying states of Pr:LaCl₃ using the Judd-Ofelt theory and calculated multiphonon emission probabilities. The results are used to characterize demonstrated mid-IR laser transitions and predict new potential mid-IR laser transitions in Pr:LaCl₃     

Nitrogen Plasma Processing of SiO2/4H-SiC Interfaces

A nitrogen plasma annealing process for gate dielectric applications in 4H-SiC metal oxide semiconductor (MOS) technology has been investigated. This process results in substantially greater interfacial N coverage at the SiO₂/4H-SiC interface and lower interface trap densities than the state-of-the-art nitric oxide (NO) annealing process. Despite these exciting results, the field-effect mobility of MOS field-effect transistors (MOSFETs) fabricated by use of this process is very similar to that of NO-annealed MOSFETs. These results emphasize the importance of understanding mobility-limiting mechanisms in addition to charge trapping in next-generation 4H-SiC MOSFETs.     

High-temperature quasi-continuous operation of optically pumpedCdZnTe/ZnTe multiple-quantum-well lasers at 620 nm

Low-lasing-threshold quasi-continuous optically pumped II-VI quantum-well lasers were operated well above room temperature at 620 nm. This result shows promise for high-repetition-rate, short-pulse generation by direct modulation of the injection current and also CW operation of future wide-gap II-VI diode lasers above room temperature     

Specific cytotoxicity in vitro of lymphocytes sensitized in culture against tumor cells

The production of tumor-specific cell-mediated cytotoxicity following in vitro sensitization of C57BL spleen cells against a syngeneic 3LL Lewis lung carcinoma was studied. Lymphocytes were sensitized on monolayers of the tumor cells for 4-5 days. The cytotoxicity was assayed by measuring the reduction in 3H-leucine and 3H-thymidine incorporation by target cells after interaction with the sensitized lymphocytes. Spleen lymphocytes sensitized on monolayers of 3LL tumor cells caused a high extent of lysis; such cells tested on C57BL or C3H fibroblast targets evoked only a low level of cytotoxicity. C57BL spleen cells sensitized on C57BL fibroblasts caused a low level of cytotoxicity when tested on a 3LL target. Thus cytotoxicity appeared to be tumor specific. The reduced incorporation into protein and DNA of target tumor cells caused by the sensitized lymphocytes was a measure of cell injury, which was more sensitive than direct cell count or uptake of 51CR. Lymphocytes from syngeneic tumor-bearing mice, tested 13-25 days after tumor inoculation, did not manifest in vitro cytotoxicity. On the contrary, such lymphocytes sometimes appeared to have a promoting effect on the tumor cells.     

Morphology of polyurethane modified by plasticizing,blending, or reinforcing

The morphology of modified thermoplastic PU has been studied by SEM and DSC. The PU was modified by addition of various amounts of dibutyl phthalate (DBP) plasticizer, vinyl polymers (PVA, PVAc, PVC, VAc–VC copolymer), polysiloxane or fiber reinforcement (glass or cotton) to diolpolyether, followed by mixing and vigorous stirring with dephenylmethane diisocyanate. SEM observations indicated that PU and its modifications have a cellular (foam) structure. A homogeneous matrix was observed in binary blends of PU and DBP in ratios of 20:1 down to 6.6:1; PVA, PVAc, VAc–VC copolymer with a weight ratio of 40:1, PU containing glass fiber (20:1) or cotton fiber (40:1). Blends of PU—with PVA at a weight ratio of 20:1, with PVC in ratios from 20:1 down to 5:1, or with polysiloxane polymer—were heterogeneous and thus not miscible, as evidenced by SEM observations. With the exception of the PU—PSO mixtures, the thermal behavior of the heterogeneous blends did not permit any conclusion regarding miscibility.     

Evaluation of patient improvement in a token economy treatment program.

Investigated various indices of improvement in 20 female chronic mental patients (mean age = 36 yrs) who were randomly assigned to a token economy treatment ward as compared with 20 control patients who received typical custodial treatment. All Ss were given standardized interviews consisting of 5 experimental tasks. Segments of the interviews were video-recorded and rated by naive raters on a 20-item questionnaire. Results indicate that the token-economy Ss were better oriented, had more skill in making business purchases and discriminations, and were better able to follow commands. Token economy Ss were rated as being more cooperative and communicative, more socially desirable, more appropriate in mood, and as exhibiting less psychotic behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)