Comparison of the cuscore, GLRT and cusum control charts for detecting a dynamic mean change

Although statistical process control (SPC) techniques have been focused mostly on detecting constant mean shifts, dynamic and time-varying process changes frequently occur in the monitoring of feedback-controlled and autocorrelated processes. In this research, the performances of cumulative score (Cuscore), generalized likelihood ratio test (GLRT), and cumulative sum (CUSUM) charts in detecting a dynamic mean change that finally approaches a steady-state value are compared. Theoretical results in average run length (ARL) comparison are provided. From the theretical study we find that, when the steady-state value is greater or less than a critical value,Rδ/2+δ/2, the Cuscore and CUSUM charts have a different performance in detecting the mean change. We prove also that the GLRT has the best performance among the three charts in detecting any mean change for which the steady-state value is not equal to δ or δR, when the in-control ARL is large.     

Effect of Electrostatic Interaction on Electrodeposition of Nickel Hexacyanoferrate with Functional MWCNTs and Their Application for the Determination of Persulfate and Tannic Acid

A nanocomposite film of NiHCF electrodeposited onto AFCNT was modified on GCE by the electrostatic interaction of multiple scan cyclic voltammetry. Amino groups have been introduced with a positive charge onto the surface of MWCNTs. The presence of NiHCF‐AFCNT/GCE was characterized by using FE‐SEM, EDS, EIS, and XRD studies. The nanocomposite film of NiHCF‐AFCNT was further utilized to determine persulfate and tannic acid, respectively. The nanocomposite film modified electrode displays linear response from 0.1 to 19 mM and 10 to 170 µM for persulfate and tannic acid with a correlation coefficient of 0.9921 and 0.9869. The detection limits were found to be 0.1 mM and 1 µM, respectively. As results, the electrostatic interaction between positively charged metal ions, amino functionalized CNT and negatively charged hexacyanoferrate can be a new subject for many interesting applications.     

Ligand Modification Transforms a Catalase Mimic into a Water Oxidation Catalyst

The catalytic reactivity of the high‐spin Mn^II pyridinophane complexes [(Py₂NR₂)Mn(H₂O)₂]²⁺ (R=H, Me, tBu) toward O₂ formation is reported. With small macrocycle N‐substituents (R=H, Me), the complexes catalytically disproportionate H₂O₂ in aqueous solution; with a bulky substituent (R=tBu), this catalytic reaction is shut down, but the complex becomes active for aqueous electrocatalytic H₂O oxidation. Control experiments are in support of a homogeneous molecular catalyst and preliminary mechanistic studies suggest that the catalyst is mononuclear. This ligand‐controlled switch in catalytic reactivity has implications for the design of new manganese‐based water oxidation catalysts.     

Direct Growth of Cobalt Hydroxide Rods on Nickel Foam and Its Application for Energy Storage

The present work reports synthesis of cobalt hydroxide (Co(OH)₂) rods on nickel foam and its supercapacitor application. Hierarchical Co(OH)₂ rods with length of approximately 3.5 μm and diameter of approximately 400 nm were prepared by one‐step, simple, and inexpensive chemical‐bath‐deposition method. The direct growth of Co(OH)₂ rods on the Ni foam gave three dimensional (3D) structure for easy access of electrolyte throughout material surface. Also, well‐adhered interface between Co(OH)₂ rods and Ni‐foam surface gave better conduction channels. Detailed electrochemical study was performed by using cyclic voltammetry and galvanostatic charge/discharge measurements. The results demonstrate that Co(OH)₂ rods on Ni foam are efficient electrodes for supercapacitor application.     

Styrene Aziridination by Iron(IV) Nitrides

Thermolysis of the iron(IV) nitride complex [PhB(tBuIm)₃Fe?N] with styrene leads to formation of the high‐spin iron(II) aziridino complex [PhB(tBuIm)₃Fe‐N(CH₂CHPh)]. Similar aziridination occurs with both electron‐rich and electron‐poor styrenes, while bulky styrenes hinder the reaction. The aziridino complex [PhB(tBuIm)₃Fe‐N(CH₂CHPh)] acts as a nitride synthon, reacting with electron‐poor styrenes to generate their corresponding aziridino complexes, that is, aziridine cross‐metathesis. Reaction of [PhB(tBuIm)₃Fe‐N(CH₂CHPh)] with Me₃SiCl releases the N‐functionalized aziridine Me₃SiN(CH₂CHPh) while simultaneously generating [PhB(tBuIm)₃FeCl]. This closes a synthetic cycle for styrene azirdination by a nitride complex. While the less hindered iron(IV) nitride complex [PhB(MesIm)₃Fe?N] reacts with styrenes below room temperature, only bulky styrenes lead to tractable aziridino products.     

Exploring the interactions between gold nanoparticles and analytes through surface‐assisted laser desorption/ionization mass spectrometry

Surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) is applied to provide strong evidence for the chemical reactions of functionalized gold nanoparticles (Au NPs) with analytes – Hg²⁺ ions induced MPA?Au NPs aggregation in the presence of 2,6‐pyridinedicarboxylic acid (PDCA) and H₂O₂ induced fluorescence quenching of 11‐MUA?Au NDs. PDCA‐Hg²⁺‐MPA coordination is responsible for Au NPs aggregation, while the formation of 11‐MUA disulfide compounds that release into the bulk solution is responsible for H₂O₂‐induced fluorescence quenching. In addition to providing information about the chemical structures, SALDI‐MS is also selective and sensitive for the detection of Hg²⁺ ions and H₂O₂. The limits of detection (LODs) for Hg²⁺ ions and H₂O₂ by SALDI‐MS were 300 nM and 250 µM, respectively. The spot‐to‐spot variations in the two studies were both less than 18% (50 sample spots). Our results reveal that SALDI‐MS can be used to study analyte‐induced changes in the surface properties of nanoparticles. Copyright © 2010 John Wiley & Sons, Ltd.     

Average case analysis of the Boyer‐Moore algorithm

Limit theorems (including a Berry‐Esseen bound) are derived for the number of comparisons taken by the Boyer‐Moore algorithm for finding the occurrences of a given pattern in a random text. Previously, only special variants of this algorithm have been analyzed. We also propose a means of computing the limiting constants for the mean and the variance. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006.     

Detection of melamine in infant formula and grain powder by surface‐assisted laser desorption/ionization mass spectrometry

We have developed a method for the determination of melamine (MEL), ammeline (AMN), and ammelide (AMD) by surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) using gold nanoparticles (Au NPs). The major peaks for MEL, AMN, and AMD at m/z 127.07, 128.05, and 129.04 are assigned to the [MEL + H]⁺, [AMN + H]⁺, and [AMD + H]⁺ ions. Because the three tested compounds adsorb weakly onto the surfaces of the Au NPs through Au–N bonding, they can be easily concentrated from complex samples by applying a simple trapping/centrifugation process. The SALDI‐MS method provides limits of detection of 5, 10, and 300 nM for MEL, AMN, and AMD, respectively, at a signal‐to‐noise ratio of 3. The signal variation for 150‐shot average spectra of the three analytes within the same spot was 15%, and the batch‐to‐batch variation was 20%. We have validated the practicality of this approach by the analysis of these three analytes in infant formula and grain powder. This simple and rapid SALDI‐MS approach holds great potential for screening of MEL in foods. Copyright © 2012 John Wiley & Sons, Ltd.