A 100-MHz macropipelined VAX microprocessor

A macropipelined CISC microprocessor was implemented in a 0.75-μm CMOS 3.3-V technology. The 1.3-million-transistor custom chip measures 1.62×1.46 cm² and dissipates 16.3 W. The 100-MHz parts were benchmarked at 50 SPEC marks. The on-chip clocking system and several high-performance logic and circuit techniques are described. Macroinstruction handling, micropipeline management, and control store structures highlight the design architecture. The hierarchical array organization and fast tag comparison technique of the primary cache are discussed. Power estimation procedures are outlined, and the results are compared to measurements. Physical design and verification methods, and CAD tools are also described. After extensive functional verification efforts are described, chip and system test results are presented     

A novel skeletal drug delivery system for anti-bacterial drugs using self-setting hydroxyapatite cement

To solve the problem of delivering drugs to skeletal tissue at high enough local concentrations for desirable therapeutic effects, we report a novel approach using a self-setting hydroxyapatite cement, with cephalexin and norfloxacin as model drugs. After setting, the cement was transformed into hydroxyapatite with affinity for hard bone tissue. Continuous in-vitro drug release profiles from loaded cement pellets (0.9-4.8% by weight) in phosphate buffer at pH 7.4 and 37 degrees C followed the Higuchi equation.     

A screening technique useful for testing the effectiveness of novel "self-cleaning" photocatalytic surfaces

We describe a screening methodology that can be used to quickly determine the effectiveness of newly synthesized photocatalysts. We were particularly interested in measuring the destruction of organic molecules painted onto a photocatalytic surface by spraying, with destruction proceeding in ambient air (as a model for airborne toxin destruction). Our method can utilize photocatalysts that are synthesized as powders (such as doped and undoped titanium oxide) and which are then calcined onto a glass substrate disk at 600°C. Herein, we used UV illumination of Aeroxide P-25 TiO(2), but the method is general and can accommodate any region of the light spectrum.     

Reversible, metal-free hydrogen activation by frustrated Lewis pairs

The Lewis acid cyclohexylbis(pentafluorophenyl)boron 1, which exhibits about 15% lower Lewis acidity in comparison with B(C(6)F(5))(3), activates H(2) in the presence of the bulky Lewis bases 2,2,6,6-tetramethylpiperidine (TMP), 1,2,2,6,6-pentamethylpiperidine (PMP), tri-tert-butylphosphine (t-Bu(3)P) leading in facile reactions at room temperature to heterolytic splitting of dihydrogen and formation of the salts [TMPH][CyBH(C(6)F(5))(2)] 2, [PMPH][CyBH(C(6)F(5))(2)] 3 and [t-Bu(3)PH][CyBH(C(6)F(5))(2)] 4, which could be dehydrogenated at higher temperatures. The related Lewis acid 1-phenyl-2-[bis(pentafluorophenyl)boryl]ethane 5 exhibiting about 10% lower Lewis acidity than B(C(6)F(5))(3) is also capable of splitting H(2) in a heterolytic fashion in the presence of TMP, PMP and t-Bu(3)P yielding [TMPH][PhC(2)H(4)BH(C(6)F(5))(2)] 6, [PMPH][PhC(2)H(4)BH(C(6)F(5))(2)] 7 and [t-Bu(3)PH][PhC(2)H(4)BH(C(6)F(5))(2)] 8. Under comparable conditions as for 2-4, the dehydrogenations of 6-8 were much slower. 4b and 6 were characterized by single crystal X-ray diffraction studies.     

Highly Efficient,Solution‐Processed,Single‐Layer,Electrophosphorescent Diodes and the Effect of Molecular Dipole Moment

A new family of highly soluble electrophosphorescent dopants based on a series of tris‐cyclometalated iridium(III) complexes (1–4) of 2‐(carbazol‐3‐yl)‐4/5‐R‐pyridine ligands with varying molecular dipole strengths have been synthesized. Highly efficient, solution‐processed, single‐layer, electrophosphorescent diodes utilizing these complexes have been prepared and characterized. The high triplet energy poly(9‐vinylcarbazole) PVK is used as a host polymer doped with 2‐(4‐biphenylyl)‐5‐(4‐tert‐butyl‐phenyl)‐1,3,4‐oxadiazole (PBD) for electron transport. Devices with a current efficiency of 40 cd A^?1 corresponding to an EQE of 12% can thus be achieved. The effect of the type and position of the substituent (electron‐withdrawing group (CF₃) and electron‐donating group (OMe)) on the molecular dipole moment of the complexes has been investigated. A correlation between the absorption strength of the singlet metal‐to‐ligand charge‐transfer (¹MLCT) transition and the luminance spectral red shift as a function of solvent polarity is observed. The strength of the transition dipole moments for complexes 1–4 has also been obtained from TD‐DFT computations, and is found to be consistent with the observed molecular dipole moments of these complexes. The relatively long lifetime of the excitons of the phosphorescence (microseconds) compared to the charge‐carrier scattering time (less than nanoseconds), allows the transition dipole moment to be considered as a “quasi permanent dipole”. Therefore, the carrier mobility is sufficiently affected by the long‐lived transition dipole moments of the phosphorescent molecules, which are randomly oriented in the medium. The dopant dipoles cause positional and energetic disorder because of the locally modified polarization energy. Furthermore, the electron‐withdrawing group CF₃ induces strong carrier dispersion that enhances the electron mobility. Therefore, the strong transition dipole moment in complexes 3 and 4 perturbs both electron and hole mobilities, yielding a reduction in exciton formation and an increase in the device dark current, thereby decreasing the device efficiency.     

Stable silencing of SNAP-25 in PC12 cells by RNA interference

Background  

SNAP-25 is a synaptic protein known to be involved in exocytosis of synaptic vesicles in neurons and of large dense-core vesicles in neuroendocrine cells. Its role in exocytosis has been studied in SNAP-25 knockout mice, in lysed synaptosomes lacking functional SNAP-25 and in cells after treatment with botulinum toxins A or E that specifically cleave SNAP-25. These studies have shown that SNAP-25 appears to be required for most but not all evoked secretion. In order to further study the role of SNAP-25 in catecholamine secretion from PC12 cells we have used the recently developed technique of RNA interference to generate PC12 cell lines with virtually undetectable levels of SNAP-25. RNA interference is the sequence-specific silencing or knockdown of gene expression triggered by the introduction of double-stranded RNA into a cell. RNA interference can be elicited in mammalian cells in a number of ways, one of which is by the expression of small hairpin RNAs from a transfected plasmid. Selection of stably transfected cell lines expressing a small hairpin RNA allows one-time characterization of the degree and specificity of gene silencing and affords a continuing source of well-characterized knockdown cells for experimentation.     

3G与换机将引爆亚太区手机市场

对于终端厂商而言,亚太区是全球最大的市场,并且潜力最大,因为这一地区拥有全球40%的移动用户。随着欧洲和北美等成熟市场增长趋缓,亚太区的重要性正日渐提升。在那些收入存在较大差距的地区,现阶段运营商面临的挑战是既要鼓励高端用户使用数据业务,又要吸引低收入人群入网而对于设备商而言,则必须在保持现有利润水平的前提下为运营商和消费者提供丰富多彩的终端。无论是运营商、终端提供商还是应用开发商在制定战略时都必须对未来的终端技术有一个清楚的认识。与西欧所有运营商只采用GSM和WCDMA不同的是,亚太地区正在或计划使用的技术…     

Origin of improved RF performance of AlGaN/GaN MOSHFETs compared to HFETs

In this paper, the influence of a 10-nm-thick silicon-dioxide layer, as a passivation or as a gate insulation, on the performance of heterojunction field-effect transistors (HFETs) and metal-oxide-semiconductor HFETs (MOSHFETs), based on an undoped AlGaN/GaN heterostructure on a SiC substrate, was investigated. Channel-conductivity results yield a nearly 50% increase of mobility in the MOSHFET samples compared to the unpassivated HFETs. This increase of the transport properties of the MOSHFET channel is confirmed by a similar 45% increase of the cutoff frequency, from 16.5 to 24 GHz. Hall measurements, however, show a 10% decrease of the mobility in the heterostructure with a SiO/sub 2/ top layer. In this paper, the superior performance of the MOSHFET transistor, in contradiction to the Hall results, is attributed to the screening of the Coulomb scattering of the charged surface defects by the gate-metallization layer.     

Factoring very-high-degree polynomials

In this article, we discuss the current status of polynomial factoring (root finding) algorithms with some historical and mathematical background including size limits, convergence, accuracy and speed. The methods of root approximation versus root refinement are also examined. We then focus on two improved general purpose computational techniques, and in particular the factorization algorithm by Lindsey-Fox (L-F), which makes use of the fast Fourier transform to factor polynomials with random coefficients of degrees as high as 1 million. Computer simulations give insight that result in significant improvements in traditional approaches to an ancient problem.