A voltage-controlled ring oscillator using InP full enhancement-mode HEMT logic

A voltage-controlled ring oscillator (VCO) based on a full enhancement-mode InAIAs/InGaAs/InP high electron mobility transistor (HEMT) logic is proposed. An enhancement-mode HEMT (E-HEMT) is fabricated, whose threshold is demonstrated to be 10 mV. The model of the E-HEMT is established and used in the SPICE simulation of the VCO. The result proves that the full E-HEMT logic technology can be applied to the VCO. And compared with the HEMT DCFL technology, the complexity of our fabrication process is reduced and the reliability is improved.

Micro Insert: A Prototype Full-Ring PET Device for Improving the Image Resolution of a Small-Animal PET Scanner

A full-ring PET insert device should be able to enhance the image resolution of existing small-animal PET scanners. Methods: The device consists of 18 high-resolution PET detectors in a cylindric enclosure. Each detector contains a cerium-doped lutetium oxyorthosilicate array (12 x 12 crystals, 0.72 x 1.51 x 3.75 mm each) coupled to a position-sensitive photomultiplier tube via an optical fiber bundle made of 8 x 16 square multiclad fibers. Signals from the insert detectors are connected to the scanner through the electronics of the disabled first ring of detectors, which permits coincidence detection between the 2 systems. Energy resolution of a detector was measured using a Ge-68 point source, and a calibrated 68Ge point source stepped across the axial field of view (FOV) provided the sensitivity profile of the system. A Na-22 point source imaged at different offsets from the center characterized the in-plane resolution of the insert system. Imaging was then performed with a Derenzo phantom filled with 19.5 MBq of F-18-fluoride and imaged for 2 h; a 24.3-g mouse injected with 129.5 MBq of F-18-fluoride and imaged in 5 bed positions at 3.5 h after injection; and a 22.8-g mouse injected with 14.3 MBq of F-18-FDG and imaged for 2 h with electrocardiogram gating. Results: The energy resolution of a typical detector module at 511 keV is 19.0% +/- 3.1 %. The peak sensitivity of the system is approximately 2.67%. The image resolution of the system ranges from 1.0- to 1.8-mm full width at half maximum near the center of the FOV, depending on the type of coincidence events used for image reconstruction. Derenzo phantom and mouse bone images showed significant improvement in transaxial image resolution using the insert device. Mouse heart images demonstrated the gated imaging capability of the device. Conclusion: We have built a prototype full-ring insert device for a small-animal PET scanner to provide higher-resolution PET images within a reduced imaging FOV. Development of additional correction techniques are needed to achieve quantitative imaging with such an insert.

bridge the gap between software test process and business value: a case study

Chinese Academy of Sciences (ISCAS)

Biophysical studies on the full-length human cyclin A(2): Protein stability and folding/unfolding thermodynamics

Human cyclin A(2) participates in cell cycle regulation, DNA replication, and transcription. Its overexpression has been implicated in the development and progression of a variety of human cancers. However, cyclin A(2) or its truncated form is very unstable in the absence of binding partner, which makes it difficult to get a deep insight of structural basis of the interactions. Therefore, biophysical studies of the full-length human cyclin A, would provide important information regarding protein stability and folding/unfolding process.

Improved Melting Strength of Polypropylene by Reactive Compounding With Ultrafine Full-Vulcanized Polybutadiene Rubber (UFBR) Particles

Ultrafine full-vulcanized polybutadiene rubber (UFBR) in particle sizes of ca. 50-100 nm has been used for modifying mechanical and processing performances of polypropylene (PP), and PP-g-maleic anhydride (PP-MA) has been used as a compatibilizer for enhancing the interfacial adhesion between the two components. The results show that PP/UFBR possesses rheological behaviors such as highly branched PP when UFBR content in blends reaches 10 wt%, while in contrast, the much low content of UFBR combining small amount of PP-MA endows the material with rheological characteristics of high melt strength materials like highly branched PP.

Nanocrystalline LaOCl:Tb3+/Sm3+ as promising phosphors for full-color field-emission displays

Nanocrystalline LaOCl:Tb3+/Sm3+ phosphors were synthesized by a Pechini-type sol-gel process. Under UV and electron-beam excitation, LaOCl:Tb3+/Sm3+ show the characteristic emission of Tb3+ (D-5(3,4) -> F-7(6), ... (2)) and Sm3+ ((4)G(5/2) -> H-6(5/2),(7/2),(9/2)), respectively. In particular, the cathodoluminescence (CL) color of LaOCl:Tb3+ can be tuned from blue to green by changing Tb3+-doped concentration, and their CL intensities (brightness) are higher than those of commercial products Y2SiO5:Ce3+ and ZnO:Zn, respectively. White CL can be realized by codoping with Tb3+ and Sm3+ in a single-phase LaOCl host. The obtained white light is very close to the standard white light. These phosphors are promising for application in field-emission displays.

Formation of low surface energy separators with undercut structures via a full-solution process and its application in inkjet printed matrix of polymer light-emitting diodes

In this paper, low surface energy separators With undercut structures were fabricated through a full solution process, These low Surface energy separators are more suitable for application in inkjet printed passive-matrix displays of polymer light-emitting diodes. A patterned PS film was formed on the P4VP/photoresist film by microtransfer printing firstly. Patterned Au-coated Ni film was formed on the uncovered P4VP/photoresist film by electroless deposition. This metal film was used as mask to pattern the photoresist layer and form undercut structures with the patterned photoresist layer. The surface energy of the metal film also decreased dramatically from 84.6 mj/m(2) to 21.1 mJ/m(2) by modification of fluorinated mercaptan self-assemble monolayer on Au surface. The low surface energy separators were used to confine the flow of inkjet printed PFO solution and improve the patterning resolution of inkjet printing successfully. Separated PFO stripes, complement with the pattern of the separators, formed through inkjet printing.

Novel Oligo-9,9 '-spirobifluorenes through ortho-Linkage as Full Hydrocarbon Host for Highly Efficient Phosphorescent OLEDs

4-Bromo-9,9'-spirobifluorene is facilely synthesized, and from this precursor, two ortho-linked oligo-9,9'-spirobifluorenes, 44BSF and 24TSF, are constructed. Devices with 24TSF as the full-hydrocarbon host material and Ir(ppy)(3) or (ppq)(2)Ir(acac) as the triplet emitter show maximum external quantum efficiencies of 12.6 and 10.5% for green and red electrophosphorescence, respectively.

Full View of Single-Molecule Force Spectroscopy of Polyaniline in Oxidized, Reduced, and Doped States

The macroscopic mechanical properties of polyaniline (PANI) lie mainly on two factors, the structure of molecular aggregations of polymers and the mechanical properties of a single polymer chain. The former factor is swell revealed; however, the latter is rarely studied. In this article, we have employed atomic force microscopy-based single-molecule force spectroscopy to investigate the mechanical properties of a kind of water-soluble PANI at a single-molecular level. We have carried out the study comparatively on single-chain-stretching experiments of oxidized, reduced, and doped PANI and obtained a full view of the single-chain elasticity of PANI in all these states. It is found that oxidized and reduced PANI chains are rigid, and the oxidized PANI is more rigid than the reduced PANI. Such a difference in single-chain elasticity can be rationalized by the molecular structures that are composed of benzenoid diamine and quinoid diimine its different proportions. The doped PANI has been found to be more flexible than the oxidized and reduced PANI, and the modified freely jointed chain parameters of doped PANI are similar with those of a common flexible-chain polymer.

Effects of bridge ions, DNA species, and developing temperature on flat-lying DNA monolayers

Recently, we have successfully constructed flat-lying DNA monolayers on a mica surface (J. Phys. Chem. B 2006, 110, 10792-10798). In this work, the effects of various factors including bridge ions, DNA species, and developing temperature on the configuration of DNA monolayers have been investigated by atomic force microscopy (AFM) in detail. AFM results show that the species of bridge ions and developing temperature play a crucial role during the formation process. For example, the divalent cation Zn2+ resulted in many DNA chains stuck side by side in the monolayers due to the strong interactions between it and DNA's bases or the mica surface. Most DNA chain's conglutinations disappeared when the developing temperature was higher than 40 degrees C. Cd2+ and Ca2+ produced more compact DNA monolayers with some obvious aggregations, especially for the DNA monolayers constructed by using Ca2+ as the bridge ion. Co2+ produced well-ordered, flat-lying DNA monolayers similar to that of Mg2+. Furthermore, it was found that the flat-lying DNA monolayers could still form on a mica surface when plasmid DNA pBR 322 and linear DNA pBR 322/Pst I were used as the DNA source. Whereas, it was hard to form DNA monolayers on a (3-aminopropyl)triethoxysilane-mica surface because the strong interactions between DNA and substrate prevented the lateral movement of DNA molecules.

Synthesis of new bis-BINOLs linked by a 2,2 '-bipyridine bridge

A series of new G-symmetric chiral ligands 8, 9, 11 and 12, consisting of two binaphthyl units linked by a 2,2'-bipyridine bridge, has been synthesized via Suzuki cross-coupling reactions.