Thermal stability behaviors of Cr(N,O)/CrN double-layered coatings by TGA/DTA analysis

In this study, Cr(N,O)/CrN double-layered coatings were synthesized using the cathodic arc deposition (CAD) process. CrN film was first deposited onto a substrate as an interlayer to ensure better adhesion, and Cr(N,O) film was subsequently deposited on top of the CrN layer as the surface layer. Variation in the Cr(N,O) coating composition was achieved through changing the O₂/N₂ flow ratio during the last stage of processing. Phase structure, chemical composition, and morphology of the resulting coatings were analyzed and observed using the X-ray diffractometer, Auger electron spectrometer and SEM. In addition, oxidation behavior of the coatings was investigated using TGA/DTA methods. The tests were carried out by increasing temperature up to 1000 °C in ambient air. With the introduction of oxygen gas during the CAD process, a superficial layer was produced in the Cr(N,O) constituent containing CrN and Cr₂O₃ phases. The formation of the oxide phase attributed to the reaction of chromium and oxygen was more favorable than that of chromium and nitrogen. The results also showed that Cr(N,O)/CrN double-layered coatings exhibited superior oxidation resistance at elevated temperature than that of CrN single-layer coated specimen (870 °C vs. 750 °C).     

An Efficient Systolic Algorithm for the Longest Common Subsequence Problem

A longest common subsequence (LCS) of two strings is a common subsequence of the two strings of maximal length. The LCS problem is to find an LCS of two given strings and the length of the LCS (LLCS). In this paper, a fast linear systolic algorithm that improves on previous systolic algorithms for solving the LCS problem is presented. For two given strings of length m and n, where m n, the LLCS and an LCS can be found in m + 2n – 1 time steps. This algorithm achieves the tight lower bound of the time complexity under the situation where symbols are input sequentially to a linear array of n processors. The systolic algorithm can be modified to take only m + n steps on multicomputers by using the scatter operation.     

Fast problem-size-independent parallel prefix circuits

A family of parallel algorithms solving the prefix problem on the combinational circuit model is presented. These prefix circuits are waist-size optimal with waist 1 (WSO-1). They are not only building blocks for constructing fast depth-size optimal prefix circuits, but also themselves fast problem-size-independent prefix circuits. When the problem size is greater than the circuit width, the presented prefix circuits may very much faster than any other prefix circuits of the same width, especially when the problem size is greater than or equal to twice the circuit width. The new prefix circuits are compared analytically with other representative prefix circuits to show how fast they are. They have the minimum depth and are the fastest among all WSO-1 prefix circuits of the same width and fan-out. Thus, they are better building blocks than other WSO-1 circuits for constructing fast depth-size optimal prefix circuits with the same fan-out.     

Identification of a new sildenafil analogue adulterant,desethylcarbodenafil, in a herbal supplement

In a maca-containing herbal supplement claimed to remedy erectile dysfunction, a new sildenafil analogue was found using adulterant screening with TLC, GC-MS and LC-MS/MS. This compound was isolated by column chromatography and HPLC, and identified by extensive 1D- and 2D-NMR and mass spectral analyses. The structure of this new compound was established as 5-[2-ethoxy-5-(piperazine-1-carbonyl) phenyl]-1-methyl-3-propyl-1,6-dihydro-pyrazolo[4,3-d]pyrimidin-7-one, and was named desethylcarbodenafil.     

Growth Hormone Releasing Peptide-2 Attenuation of Protein Kinase C-Induced Inflammation in Human Ovarian Granulosa Cells

Cyclooxygenase-2 (COX-2) and interleukin-8 (IL-8) are two important inflammatory mediators in ovulation. Ghrelin may modulate inflammatory signaling via growth hormone secretagogue receptors. We investigated the role of ghrelin in KGN human ovarian granulosa cells using protein kinase C (PKC) activator phorbol 12, 13-didecanoate (PDD) and synthetic ghrelin analog growth hormone releasing peptide-2 (GHRP-2). GHRP-2 attenuated PDD-induced expression of protein and mRNA, the promoter activity of COX-2 and IL-8 genes, and the secretion of prostaglandin E2 (PGE₂) and IL-8. GHRP-2 promoted the degradation of PDD-induced COX-2 and IL-8 proteins with the involvement of proteasomal and lysosomal pathways. PDD-mediated COX-2 production acts via the p38, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways; PDD-mediated IL-8 production acts via the p38, JNK and ERK pathways. GHRP-2 reduced the PDD-induced phosphorylation of p38 and JNK and activator protein 1 (AP-1) reporter activation and PDD-induced NF-κB nuclear translocation and reporter activation. The inhibitors of mitogen-activated protein kinase phosphatase-1 (MKP-1) and protein phosphatase 2 (PP2A) reduced the inhibitory effect of GHRP-2 on PDD-induced COX-2 and IL-8 expression. Our findings demonstrate an anti-inflammatory role for ghrelin (GHRP-2) in PKC-mediated inflammation of granulosa cells, at least in part, due to its inhibitory effect on PKC-induced activation of p38, JNK and NF-κB, possibly by targeting to MKP-1 and PP2A.     

Synthesis, characterization and hydrolysis of aromatic polyazomethines containing non-coplanar biphenyl structures

New polyazomethines containing electron-withdrawing trifluoromethyl group and non-coplanar biphenyl structures were prepared at room temperature under reduced pressure. It was found that these polyazomethines would undergo hydrolysis in DMSO solution at temperature higher than 50 °C. The hydrolysis, evidenced by ¹H NMR spectra and GPC chromatograms, was resulted from the reverse reaction of azomethine formation and was facilitated at higher temperature. The GPC results also suggested that post-polymerization would be possible if polyazomethine films were heated at elevated temperature (200 °C) under reduced pressure (0.27 torr). The HOMO (−5.69 to −5.96 eV) and LUMO (−3.04 to −3.18 eV) energy levels of the new polyazomethines are much lower than those of other polyazomethines. Combined with the excellent solubility and good thermal stability, non-coplanar biphenyl structure containing electron-withdrawing trifluoromethyl group could be a new candidate as electron acceptor for the structure design of new conjugated polymers.     

A New Class of Depth-Size Optimal Parallel Prefix Circuits

Given n values x₁, x₂, ... ,x_n and an associative binary operation o, the prefix problem is to compute x₁ox₂o··· ox_i, 1in. Many combinational circuits for solving the prefix problem, called prefix circuits, have been designed. It has been proved that the size s(D(n)) and the depth d(D(n)) of an n-input prefix circuit D(n) satisfy the inequality d(D(n))+s(D(n))2n–2; thus, a prefix circuit is depth-size optimal if d(D(n))+s(D(n))=2n–2. In this paper, we construct a new depth-size optimal prefix circuit SL(n). In addition, we can build depth-size optimal prefix circuits whose depth can be any integer between d(SL(n)) and n–1. SL(n) has the same maximum fan-out lgn+1 as Snir's SN(n), but the depth of SL(n) is smaller; thus, SL(n) is faster. Compared with another optimal prefix circuit LYD(n), d(LYD(n))+2d(SL(n))d(LYD(n)). However, LYD(n) may have a fan-out of at most 2 lgn–2, and the fan-out of LYD(n) is greater than that of SL(n) for almost all n12. Because an operation node with greater fan-out occupies more chip area and is slower in VLSI implementation, in most cases, SL(n) needs less area and may be faster than LYD(n). Moreover, it is much easier to design SL(n) than LYD(n).     

Making on-line logistics training sustainable through e-learning

The purpose of this study is to investigate the possibility of using an online logistics certification learning environment as a training tool to equip future logisticians with required logistics skills. This study incorporates an online logistics certification website that was constructed for college students to familiarize themselves with the certification. In addition, this study also performed comparison tests on students before and after their interaction with the web-based learning environment system to ascertain the system’s effectiveness. Our findings suggest that such a system might motivate students to familiarize themselves with logistics-related certification information and can enhance students’ professional capabilities. In addition, the web-based learning environment might possibly motivate students to join logistics related industries in the future.     

An organic hydrogel film with micron-sized pillar array for real-time and indicator-free detection of Zn

A hydrogel sensing film for a real-time and indicator-free detection of Zn²⁺ is developed by embedding a fluorescent indicator 11,16-bis(phenyl)-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimethene in a hydrogel host poly(2-hydroxyethyl methacrylate). The sensing film shows high stability and selectivity to Zn²⁺. The sensitivity of the sensing film is increased by fabricating a micron-sized pillar array on the surface of the sensing film to increase the surface area. For Zn²⁺ concentrations of 10⁻⁴ and 10⁻³ M, the response time is 30 and 3 s, respectively.