Molecular Structures and Magnetic Properties of Strongly Antiferromagnetically Coupled Binuclear Copper(II) Complexes [CU2 REP(μ-X)(Y)2]

The molecular structures of binuclear copper(II) complexes [Cu₂REP(μ-OH)(ClO₄)₂] (4) and [Cu₂REP(μ-Cl)Cl₂] (5), in which REP = deprotonated 2,6-bis(1′-(4′-(2″-pyridyl)-2′-thiabutyl))-4-methylphenol, have been characterized by single-crystal X-ray diffraction. The former crystallizes in the triclinic space group Pl? with a = 10.156(3), b = 12.631(3), c = 25.128(10) Å, α = 92.03(3), β = 96.84(3), γ = 108.02(2),° and Z ? 2. Complex 5 crystallizes in the monoclinic space group C2/c with a = 12.166(2), b = 11.825(2), c = 18.240(4) Å, β = 100.97(2)°, and Z =4. All copper ions are pentacoordinated with ligation to a sulfur, a nitrogen, and the bridging phenolato oxygen of the REP ligand, the exogenous bridge, and a counteranion. The coordination geometry of each copper of the binuclear copper sites is square pyramidal in both 4 and 5. Magnetic susceptibility measurements in the temperature range 6–300 K reveal a strong antiferromagnetic spin exchange in 5 (exchange integral 2J = ?460 cm^?1). A diamagnetic behavior is observed for 4 according to a similar cryomagnetic investigation. The diamagnetism of 4 is further confirmed by measurements of magnetic susceptibility through Evan's method at room temperature. Complex 4 has no EPR signal. The powder EPR spectrum of 5 shows the typical triplet state characteristics with Δm = ±1 transitions at g = 2.15 and a weaker Δm = 2 transition at half field with g = 4.24.     

The Self‐Assembly of Anticancer Camptothecin–Dipeptide Nanotubes: A Minimalistic and High Drug Loading Approach to Increased Efficacy

20‐(S)‐Camptothecin (CPT)‐conjugated dipeptides are reported that preassemble into nanotubes with diameters ranging from 80–120 nm. These nanoassemblies maintain a high (～47 %) drug loading and exhibit greater drug stability (i.e., resistance to lactone hydrolysis), and consequently greater efficacy against several human cancer cells (HT‐29, A549, H460, and H23) in vitro compared with the clinically used prodrug irinotecan. A key and defining feature of this system is the use of the CPT‐conjugated dipeptide as both the drug and precursor to the nanostructured carrier, which simplifies the overall fabrication process.     

Decoding permutation arrays with ternary vectors

It is well known that the MacWilliams transform of the weight enumerator of some code having integer coefficients is equivalent to a set of congruences having integer solutions. In this paper, we prove an equivalent condition of Ward’s bound on dimension of divisible codes, which is part of this set of congruences having integer solutions. This new interpretation makes the generalization of Ward’s bound an explicit one.     

MAC-level Forward Error Correction mechanism for minimum error recovery overhead and retransmission

Wireless transmission suffers from poor wireless channel conditions, such as high bit error rate and error bursts resulting from channel fading and radio interference. The MAC-level Forward Error Correction (MFEC) mechanism is proposed to solve these problems. The MFEC mechanism cannot only adaptively adjust Forward Error Correction (FEC) redundancy, depending on the network condition, but can also retransmit whole packets even if the error packet includes several bit errors. In this paper, an Adaptive MAC-level FEC (AMFEC) mechanism is proposed to improve wireless transmission quality. The AMFEC mechanism relies on the effective packet loss rate model to dynamically adjust MFEC redundancy in order to minimize error recovery overhead. The AMFEC mechanism will retransmit the error of sub-packets and increase FEC redundancy to reduce transmission redundancy. The AMFEC mechanism not only enhances the quality of wireless transmission but also reduces the overhead of retransmission. The experimental results show the AMFEC mechanism is better than conventional MFEC mechanisms.     

A comprehensive and non‐prefractionation on the protein level approach for the human urinary proteome: touching phosphorylation in urine

Increasing attention has been paid to the urinary proteome because it holds the promise of discovering various disease biomarkers. However, most of the urine proteomics studies routinely relied on protein pre‐fractionation and so far did not present characterization on phosphorylation status. Two robust approaches, integrated multidimensional liquid chromatography (IMDL) and Yin‐yang multidimensional liquid chromatography (MDLC) tandem mass spectrometry, were recently developed in our laboratory, with high‐coverage identification of peptide mixtures. In this study, we adopted a strategy without pre‐fractionation on the protein level for urinary proteome identification, using both the IMDL and the Yin‐yang MDLC methods for peptide fractionation followed by identification using a linear ion trap‐orbitrap (LTQ‐Orbitrap) mass spectrometer with high resolution and mass accuracy. A total of 1310 non‐redundant proteins were highly confidently identified from two experiments, significantly including 59 phosphorylation sites. More than half the annotated identifications were membrane‐related proteins. In addition, the lysosomal as well as kidney‐associated proteins were detected. Compared with the six largest datasets of urinary proteins published previously, we found our data included most of the reported proteins. Our study developed a robust approach for exploring the human urinary proteome, which would provide a catalogue of urine proteins on a global scale. It is the first report, to our best knowledge, to profile the urinary phosphoproteome. This work significantly extends current comprehension of urinary protein modification and its potential biological significance. Moreover, the strategy could further serve as a reference for biomarker discovery. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of pH on electrocatalytic activity of functionalized carbon nanotubes

In this study, we modified carbon nanotubes (CNTs) by grafting with poly(ethylene glycol) (PEG) using the “grafting to” method. The PEG-grafted CNT (CNT-g-PEG) was cast on indium tin oxide (ITO) electrode to investigate the electrocatalytic activity of CNT to the redox reactions of the Fe(CN)₆^3−/4−as a probe using cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of CNT was correlated with CNT dispersion in the cast film on ITO as a function of pH of aqueous solution from which the film was cast. The CNT dispersions in aqueous solutions of different pH and in the cast films were examined by visual observation and zeta potential, scanning electron microscopy and transmission electron microscopy, respectively. At a pH in the range of 3–11 at which ITO electrode was modified, two functionalized CNT (fCNT and CNT-g-PEG) were both found to electrocatalyze the redox reactions of the Fe(CN)₆^3−/4−probe and the PEG grafts in CNT-g-PEG could help CNT adhere to the electrode to obtain durable modified electrode. The more uniform CNT dispersions in aqueous solutions and in the cast films appeared to have greater electrocatalytic acitivity.     

A low-order active fault-tolerant state space self-tuner for the unknown sampled-data nonlinear singular system using OKID and modified ARMAX model-based system identification

In this paper, we present two control schemes for the unknown sampled-data nonlinear singular system. One is an observer-based digital redesign tracker with the state-feedback gain and the feed-forward gain based on off-line observer/Kalman filter identification (OKID) method. The presented control scheme is able to make the unknown sampled-data nonlinear singular system to well track the desired reference signal. The other is an active fault tolerance state-space self-tuner using the OKID method and modified autoregressive moving average with exogenous inputs (ARMAX) model-based system identification for unknown sampled-data nonlinear singular system with input faults. First, one can apply the off-line OKID method to determine the appropriate (low-) order of the unknown system order and good initial parameters of the modified ARMAX model to improve the convergent speed of recursive extended-least-squares (RELS) method. Then, based on modified ARMAX-based system identification, a corresponding adaptive digital control scheme is presented for the unknown sampled-data nonlinear singular system with immeasurable system state. Moreover, in order to overcome the interference of input fault, one can use a fault-tolerant control scheme for unknown sampled-data nonlinear singular system by modifying the conventional self-tuner control (STC). The presented method can effectively cope with partially abrupt and/or gradual system input faults. Finally, some illustrative examples including a real circuit system are given to demonstrate the effectiveness of the presented design methodologies.     

A continuation BSOR-Lanczos–Galerkin method for positive bound states of a multi-component Bose–Einstein condensate

We develop a continuation block successive over-relaxation (BSOR)-Lanczos–Galerkin method for the computation of positive bound states of time-independent, coupled Gross–Pitaevskii equations (CGPEs) which describe a multi-component Bose–Einstein condensate (BEC). A discretization of the CGPEs leads to a nonlinear algebraic eigenvalue problem (NAEP). The solution curve with respect to some parameter of the NAEP is then followed by the proposed method. For a single-component BEC, we prove that there exists a unique global minimizer (the ground state) which is represented by an ordinary differential equation with the initial value. For a multi-component BEC, we prove that m identical ground/bound states will bifurcate into m different ground/bound states at a finite repulsive inter-component scattering length. Numerical results show that various positive bound states of a two/three-component BEC are solved efficiently and reliably by the continuation BSOR-Lanczos–Galerkin method.     

Investigation of orientation and packing of H8Si8O12 arrays on graphite by scanning tunneling microscopy

The layer structures of H₈Si₈O₁₂ molecules on highly oriented pyrolitic graphite have been investigated by scanning tunneling microscopy. Two kinds of ordered assemblies of H₈Si₈O₁₂ monolayers are observed, with a unit cell of 6.5 Å × 6.5 Å and 7.2 Å × 9.4 Å, respectively. On the basis of the shapes and sizes of the H₈Si₈O₁₂ STM images and the heights of the H₈Si₈O₁₂ monolayers, H₈Si₈O₁₂ can be adsorbed with one face of its cage structure in contact with the substrate surface or with a tilted orientation.