Charge transfer through DNA: A selective electrochemical DNA biosensor

The charge-transfer properties of DNA duplexes are exploited to produce a fast, simple, sensitive, and selective DNA biosensor by exposing the DNA recognition interface to a sample containing target DNA and the redox-active intercalator, anthraquinonemonosulfonic acid (AQMS). Electrochemistry from electron transfer through the DNA to AQMS intercalated into DNA duplexes can be differentiated from electrochemistry due to direct access of the AQMS to the electrode surface due to the difference in the environment of the AQMS giving a shift in the potential at which the molecule is reduced. The ability to distinguish between the two electrochemical signals enables DNA hybridization to be monitored in real time. This in situ detection scheme has good selectivity, being able to differentiate between a complementary target DNA sequence and one containing either C-A or G-A single-base mismatches. The concentration detection limit of the biosensor is 0.5 nM (1 pmol) with an assay time of 1 h. The fact that the end user is only required to simultaneously add the sample containing the target DNA and AQMS gives a DNA biosensor that is highly compatible with PCR on chip technologies.     

RF CMOS technology for MMIC

This paper presents a high performance RF CMOS technology with a complete portfolio of RF and base band components for single-chip systems. Using an optimized 0.13 μm CMOS topology, f_T of 86 GHz and f_max of 73 GHz are obtained, in addition to a NF_min of 1.5 dB without ground-shielded signal pad. The high-Q accumulation-mode and diode varactors are optimized to perform a high tuning range of 47% and 25%, respectively. Inductors with a quality factor of 18 at 1.7 nH are obtained using copper interconnect, while capacitors with high unit capacitance and quality factor are fabricated with metal-insulator-metal structures. Finally, a deep n-well isolation is adopted to suppress the interblock coupling noise penetrating through substrate by 40 and 25 dB at 0.1 and 2.4 GHz, respectively. These results clearly demonstrate that CMOS technology can provide a complete solution for single-chip wireless systems.     

Simulation of Nitrogen and Oxygen Spectra Emitted from High Density Hot Plasma

The expected emission spectra of nitrogen and oxygen high density plasma have been studied for different conditions. Expected nitrogen and oxygen plasma spectra at certain electron temperature range have been plotted. Suitable electron temperature ranges for nitrogen and oxygen plasma soft X-ray emission and extreme ultraviolet emission have been investigated. Numerical experiments confirm the possibility of developing nitrogen and oxygen plasma focus as a powerful X-ray radiation source for water-window X-ray microscopy, by selecting the working gas pressure, choosing corresponding design and operating parameters of the device. We have illustrated that the results obtained from XRAYFIL simulation could be used to provide spectroscopic information of the plasma focus simulated by Lee model.     

Blind detection of vascular sources and territories using random vessel encoded arterial spin labeling

Object  

The goal of this work is to use vessel encoded arterial spin labeling (VEASL) methods to detect feeding arteries without prior knowledge of their positions, and map the vascular territory of each.     

磁控共溅射GaAs/SiO2细小纳米颗粒镶嵌材料的结构和非线性光学性质

应用磁控共溅射技术和后退火方法制备了GaAs/SiO2纳米颗粒镶嵌薄膜,并分别应用原子力显微镜、X射线衍射和卢瑟福背散射实验来观测薄膜的形貌、相结构和化学组分.结果表明GaAs纳米颗粒的平均直径很小(约为1.5～3.2nm),且均匀地分布于SiO2之中,薄膜中的GaAs和SiO2组分都符合化学计量关系.应用脉冲激光高斯光束对薄膜的光学非线性进行了Z扫描测试和分析.结果表明,薄膜的三阶光学非线性折射率系数和非线性吸收系数都由于量子限制效应而大大地增强,在非共振条件下,它们分别约为4×10-12m2/W和2×10-5m/W,在准共振的条件下,它们分别约为2×10-11m2/W和-1×10-4m/W.     

Development of a pressure control system for brace treatment of scoliosis

Bracing is a common nonsurgical treatment for scoliosis, but its effectiveness has been debated. Some clinical studies have shown efficacy of brace treatment is correlated to how the brace has been worn. The more often the patients wear their braces to the prescribed tightness as well as the prescribed length of wear each day, the better the treatment outcome. A system of four wireless pressure control devices was developed to understand brace wear-time and regulate a target pressure range at the brace-body interface. Each pressure control device could function independently and be embedded in the brace at key pressure areas. Such a system could improve the quality of brace wear-making the treatment more effective and refining our understanding of the three-pressure-point brace treatment concept during daily activities. This paper reports the system development and validation. The system was tested on four healthy subjects for 2 h without pressure regulation and 2 h with regulation. The results show that the pressure regulation doubled the time spent in a desired pressure range on average (from 31% to 62%). Brace-wear time was logged correctly. The system was also validated through a seven-day continuous test, and a fully charged battery could run for 30 days without requiring recharge.     

A Multifunctional Iridium‐Carbazolyl Orange Phosphor for High‐Performance Two‐Element WOLED Exploiting Exciton‐Managed Fluorescence/Phosphorescence

By attaching a bulky, inductively electron‐withdrawing trifluoromethyl (CF₃) group on the pyridyl ring of the rigid 2‐[3‐ (N‐phenylcarbazolyl)]pyridine cyclometalated ligand, we successfully synthesized a new heteroleptic orange‐emitting phosphorescent iridium(III) complex [Ir( L ₁ )₂(acac)] 1 ( HL ₁ = 5‐trifluoromethyl‐2‐[3‐(N‐phenylcarbazolyl)]pyridine, Hacac = acetylacetone) in good yield. The structural and electronic properties of 1 were examined by X‐ray crystallography and time‐dependent DFT calculations. The influence of CF₃ substituents on the optical, electrochemical and electroluminescence (EL) properties of 1 were studied. We note that incorporation of the carbazolyl unit facilitates the hole‐transporting ability of the complex, and more importantly, attachment of CF₃ group provides an access to a highly efficient electrophosphor for the fabrication of orange phosphorescent organic light‐emitting diodes (OLEDs) with outstanding device performance. These orange OLEDs can produce a maximum current efficiency of ～40 cd A^?1, corresponding to an external quantum efficiency of ～12% ph/el (photons per electron) and a power efficiency of ～24 lm W^?1. Remarkably, high‐performance simple two‐element white OLEDs (WOLEDs) with excellent color stability can be fabricated using an orange triplet‐harvesting emitter 1 in conjunction with a blue singlet‐harvesting emitter. By using such a new system where the host singlet is resonant with the blue fluorophore singlet state and the host triplet is resonant with the orange phosphor triplet level, this white light‐emitting structure can achieve peak EL efficiencies of 26.6 cd A^?1 and 13.5 lm W^?1 that are generally superior to other two‐element all‐fluorophore or all‐phosphor OLED counterparts in terms of both color stability and emission efficiency.     

Effect of Oligothienyl Chain Length on Tuning the Solar Cell Performance in Fluorene‐Based Polyplatinynes

A series of solution‐processable and strongly visible‐light absorbing polyplatinynes containing oligothienyl–fluorene ring hybrids were synthesized and characterized. These rigid‐rod organometallic materials are soluble in polar organic solvents and show intense absorptions in the visible spectral region, rendering them excellent candidates for bulk heterojunction polymer solar cells. The photovoltaic behavior depends significantly on the number of thienyl rings along the polymer chain, and some of these polymer solar cells show high power conversion efficiencies (PCEs) of up to 2.9% and a peak external quantum efficiency to 83% under AM1.5 simulated solar illumination. The effect of oligothienyl chain length on improving the polymer solar cell efficiency and on their optical and charge transport properties is elucidated in detail. At the same blend ratio of 1:5, the light‐harvesting capability and PCE increase markedly with increasing number of thienyl rings. The power dependencies of the solar cell parameters (including the short‐circuit current density, open‐circuit voltage, fill‐factor, and PCE) were also examined. The present work opens up an attractive avenue to developing conjugated metallopolymers with broad and strong solar energy absorptions and tunable solar cell efficiency and supports the potential of metalated conjugated polymers for efficient power generation.     

A Paradigm of Carbon Nanotube Interconnects in Microelectronic Packaging

Carbon nanotube (CNT) arrays/films were transferred onto copper substrates via eutectic tin/lead (SnPb) solder pastes. The morphologies, thermal stabilities, adhesion to substrates, and electrical properties of the as-transferred CNT arrays were studied. The CNT arrays generated negligible expansion or contraction below 250°C. The adhesion of CNT arrays to the substrate was significantly improved by the transfer process. An ohmic contact was formed between the transferred CNT arrays and the Sn-Pb solder. Four-probe electrical measurements yielded the resistance of the as-transferred CNT films under the electrode to be around 0.0056 Ω, from which the resistivity of each individual CNT tube was calculated to be 2.44 × 10⁻⁴ Ω cm.     

The influence of solder volume and pad area on Sn–3.8Ag–0.7Cu and Ni UBM reaction in reflow soldering and isothermal aging

This paper examines various aspects of SAC (Sn–3.8Ag–0.7Cu wt.%) solder and UBM interactions which may impact interconnection reliability as it scales down. With different solder joint sizes, the dissolution rate of UBM and IMC growth kinetics will be different. Solder bumps on 250, 80 and 40 μm diameter UBM pads were investigated. The effect of solder volume/pad metallization area (V/A) ratio on IMC growth and Ni dissolution was investigated during reflow soldering and solid state isothermal aging. Higher V/A ratio produced thinner and more fragmented IMC morphology in SAC solder/Ni UBM reflow soldering interfacial reaction. Lower V/A ratio produced better defined IMC layer at the Ni UBM interface. When the ratio of V/A is constant, the IMC morphology and growth trend was found to be similar. After 250 h of isothermal aging, the IMC growth rate of the different bump sizes leveled off. No degradation in shear strength was observed in these solder bump after 500 h of isothermal aging.