Expanding the utility of proteins as platforms for coordination chemistry

Whether for constructing advanced materials and complex biological devices or for building sophisticated coordination complexes with diverse metal-based functions, proteins are nature's favorite building blocks. Yet, our ability to control the assembly of proteins or to use them as ligand platforms for inorganic chemistry has been somewhat limited. In this review, we highlight our work from the past four years, which has aimed to exploit the utility of a protein scaffold in both regards. First, by considering proteins as “simple” ligand platforms and controlling the metal coordination chemistry on their surfaces, we show how their self-assembly can be readily dictated by metal binding. Second, we show how metal-mediated protein self-assembly leads to novel metal centers buried within protein interfaces. While on one hand our studies have pointed out the challenges of using proteins as ligands, they have also revealed how the extensive, chemically-rich protein surfaces can be exploited to form a network of covalent and non-covalent interactions around interfacial metal centers, providing a powerful handle to control their coordination chemistry.     

Synthesis,Crystal Structure and Spectrothermal Analysis of mer–Triaquanicotinamide‐orotato Cobalt(II) Trihydrate

The mixed–ligand orotato (HOr)^2? complex of cobalt(II) with nicotinamide (NA) [Co(HOr)(H₂O)₃(NA)]·3H₂O was synthesized and characterized by elemental analysis, magnetic susceptibility, conductivity, spectral methods (UV–Vis and FT–IR), simultaneous TG, DTG, DTA techniques and X–ray diffraction. The complex crystallizes in the triclinic space group P–1 with unit cell parameters a = 9.320(5), b = 9.493(5), c = 10.381(5) Å, α = 77.003(5), β = 78.852(5), γ = 80.987(5)° and Z = 2. The crystal structure has indicated that the complex has been slightly distorted octahedral geometry and is chelated by the deprotonated N(3) pyrimidine ring and by the carboxylate oxygen atom of the orotate ligand. One nicotinamide molecule is also coordinated to the metal ion by the N atom of the pyridine ring. The crystal structure consists of discrete monomeric units of the complex, which are bridged via hydrogen bonding.     

用于3D WLP和3D SIC的穿透硅通孔技术

数家研究小组和公司已经展示了通过芯片叠层和穿透硅通孔（TSV）互连来实现复杂3D芯片的可行性。     

Instability of FIFO in a simple queueing system with arbitrarily low loads

We show, using a simple example, that the First-In-First-Out (FIFO) policy can be unstable in a system with arbitrarily low load. Our proof is based on the observation that the special structure of the example we use allows us to establish stability using a much simpler queueing system.     

衡量下一代平板显示器的七种方法

随着32英寸720p液晶电视价格降至500美元以下，17英寸PC显示器降至100美元以下，电视、PC显示器和平板显示器制造商必须找到个性化和增值的方法。避免“通用”状态与目前不断增长的视频／图形处理器需求，以及传输急速增长的数据所需更高互连带宽的要求紧密相关。以下介绍的是实现下一代平板显示器个性化差异的七种方法：     

Exact Solutions of the Schrödinger Equation with Position-dependent Effective Mass via General Point Canonical Transformation

Exact solutions of the Schr?dinger equation are obtained for the Rosen–Morse and Scarf potentials with the position-dependent effective mass by appliying a general point canonical transformation. The general form of the point canonical transformation is introduced by using a free parameter. Two different forms of mass distributions are used. A set of the energy eigenvalues of the bound states and corresponding wave functions for target potentials are obtained as a function of the free parameter.     

Electronic-nose for detecting environmental pollutants: signal processing and analog front-end design

Environmental monitoring relies on compact, portable sensor systems capable of detecting pollutants in real-time. An integrated chemical sensor array system is developed for detection and identification of environmental pollutants in diesel and gasoline exhaust fumes. The system consists of a low noise floor analog front-end (AFE) followed by a signal processing stage. In this paper, we present techniques to detect, digitize, denoise and classify a certain set of analytes. The proposed AFE reads out the output of eight conductometric sensors and eight amperometric electrochemical sensors and achieves 91 dB SNR at 23.4 mW quiescent power consumption for all channels. We demonstrate signal denoising using a discrete wavelet transform based technique. Appropriate features are extracted from sensor data, and pattern classification methods are used to identify the analytes. Several existing pattern classification algorithms are used for analyte detection and the comparative results are presented.     

Spectral and electrochemical behavior of 1-[(NO2, COOH)-substituted phenyl]-3,5-diphenylformazans

Abstract  

1-[(NO₂, COOH)-substituted phenyl]-3,5-diphenylformazans were synthesized. The compounds were characterized by infrared (IR), ultraviolet–visible (UV–vis), ¹H nuclear magnetic resonance (NMR), ¹³C NMR spectra, elemental analysis, and cyclic voltammetry. From the UV–vis spectra of substituted formazans it was seen that λ _max values were shorter than the λ _max value of unsubstituted formazan. It was observed that the shift values were dependent on the type and position of the substituents. A correlation between Hammett substituent coefficients and λ _max values was obtained. The oxidation peak potentials of substituted formazans were found more anodic than that of unsubstituted formazan. The oxidation mechanism was a single step for the NO₂-substituted formazans, and two steps for COOH-substituted formazans.     

A 280 mW, 0.07% THD+N class-D audio amplifier using a frequency-domain quantizer

Pulse density modulation (PDM) based class-D amplifiers can reduce non-linearity and tonal content due to carrier signal in pulse width modulation based amplifiers. However, their low-voltage analog implementations also require a linear loop filter and a quantizer. A PDM based class-D audio amplifier using a frequency-domain quantization is presented. The digital intensive frequency-domain approach achieves high linearity under low supply regimes. An analog comparator and a single-bit quantizer are replaced with a current controlled oscillator (ICO) based frequency discriminator. By using the ICO as a phase integrator, a third-order noise shaping is achieved using only two analog integrators. A single-loop, single-bit, class-D audio amplifier is presented with an H-bridge switching power stage, which is designed and fabricated on a 0.18???m CMOS process with 6 layers of metal achieving a total harmonic distortion plus noise (THD+N) of 0.065% and a peak power efficiency of 80% while driving a 4-?? loudspeaker load. The amplifier can deliver the output power of 280 mW.     

Monolithic distributed power management for systems-on-Chip (SoC)

With increasing drive towards higher level of integration, lower cost, and longer battery life in wireless applications, there is a need for efficient monolithicdc-dc power converters. This tutorial paper summarizes the topology tradeoffs that are involved in the implementation of monolithic distributed power management in the future generations of SoCs for portable wireless applications. These circuits have a broad range of requirements including high power density, high energy efficiency, low noise, small size, and low cost. The advantages and disadvantages of each of the competing topologies, namely low-dropout linear, switched-capacitor, and switched-modedc-dc converters are examined in light of these requirements.