Inhibition of acid corrosion of steel using cetylpyridinium chloride

The cationic surfactant cetylpyridinium chloride (CPC) showed high inhibition efficiency for the corrosion of low carbon steel in 1 M H₂SO₄. Electrochemical measurements were dedicated to test the performance of CPC at different concentrations and temperatures. CPC has a significant inhibiting effect on the corrosion of steel and protection efficiencies up to 97% were measured. The inhibitor shifted the corrosion potential in the cathodic direction. It was found that adsorption is consistent with the Bockris–Swinkels isotherm in the studied temperature range (30–60 °C). The negative values of the free energy of adsorption and the decrease in apparent activation energy in the presence of the inhibitor suggest chemisorption of the CPC molecule on the steel surface.     

City Compactness: Assessing the Influence of the Growth of Residential Land Use

In the urban sprawl paradigm, residential land use exhibits a more significant growth than other categories. Consequently, large proportions of the natural environment are converted to residential areas, particularly in tropical countries. Compact urban development is one of the most sustainable urban forms with environmental perspectives, such as rural development containment and natural environment preservation. However, no proper investigation of the relationship and influence of residential growth and city compactness is available. This study evaluated and forecasted the residential development of Kajang City in Malaysia based on compact development. First, the relationship between residential land use change and city compactness was evaluated. Second, residential growth was projected by utilizing the land transformation model (LTM) and the statistical-based weight of evidence (WoE) using various spatial parameters. Both models were evaluated with respect to observed land use and compactness maps. Results indicated that most of the newly developed residential areas were in zones where the degrees of compactness increase during certain periods. In addition, LTM performed better and provided a more accurate modeling of residential growth than the WoE. However, WoE provided clearer and more informative results than LTM in terms of functional relationships between dependent and independent variables related to city compactness.     

Synergistic Behavior of a Triblock Copolymer with Anionic and Cationic Surfactants in Aqueous Solution

The synergistic behavior of poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymer in aqueous solution with the synthesized anionic surfactants [decyl sulfonate (A10), myristyl sulfonate (A14) and cetyl sulfonate (A16)] and cationic surfactants [decyl pyridinium bromide (C10), myristyl peridinium bromide (C14) and cetyl pyridinium bromide (C16)] was investigated using a surface tension technique at 25 °C. The results show that the CMC values of binary mixtures for anionic and cationic surfactants with the triblock copolymer are lower than that of single surfactants. The synergistic interaction between surfactant molecules and copolymer molecules in binary mixed solution enhance the adsorption of surfactant molecules at the interface. The micellar mole fractions (X _m) and the interaction parameter (β) of these surfactants in mixed micelles were determined.

加劲不锈钢管混凝土柱的非线性性能

该文考察了加劲的细柔高强不锈方钢管及矩形钢管混凝土柱的非线性性能。加劲的细柔钢管的整体高厚比（D/t）都介于60～160之间。混凝土的强度介于普通混凝土和高强混凝土之间。考察的对象主要是轴向受压的短柱。建立了非线性有限元模型来研究加劲的钢管混凝土柱的受力性能。进行了参数分析来考察横截面几何尺寸、混凝土强度等参数对柱子性能及承载力的影响。还将加劲钢管混凝土柱的结果与无加劲钢管混凝土柱的结果进行了对比。     

The influence of sampling duration on recovery of culturable fungi using the Andersen N6 and RCS bioaerosol samplers

The influence of sampling duration on recovery of culturable fungi was compared using the Andersen N6 and the Reuter Centrifugal Sampler (RCS). Samplers were operated side-by-side, collecting 15 samples each of incrementally increasing duration (1-15 min). From 270 samples collected, 26 fungal genera were recovered. Species of Alternaria, Aspergillus, Cladosporium, Epicoccum, Penicillium and Ulocladium were most frequent. Data adjusted to CFU/m3 were fitted to a Poisson regression model with a logarithmic link function and evaluated for the impact of sampling time on qualitative and quantitative recovery of fungi, both as individual taxa and in aggregate according to xerotolerance. Significant differences between the two samplers were observed for xerotolerant and normotolerant moulds, as well as Aspergillus spp. and Cladosporium spp. With the exception of Cladosporium spp., overall recoveries were higher with the RCS. When the Andersen N6 was used, the recovered levels of Cladosporium spp. and unidentified yeasts were reduced significantly at sampling times over 6 min. Similarly, when the RCS was used, recovery of Aspergillus spp., Penicillium spp., Ulocladium spp., unidentified yeasts, and low water activity fungi declined significantly at sampling times over 6 min. PRACTICAL IMPLICATIONS: Currently, the industry-wide trend for viable air sampling in indoor environmental investigations is to use sampling times between 2 and 4 min in duration. Our results support the routine use of a 6-min sampling time where low spore loads are expected, resulting in improved limits of detection.     

Pulse anodic stripping voltammetric determination of copper with an amoxicillin–nafion modified glassy carbon electrode

The analysis of Cu²⁺ by pulse anodic stripping voltammetry using a Nafion-modified glassy Carbon electrode incorporated with Amoxicillin is described. A significant increase in the voltammetric response was achieved at the modified electrode compared to a bare glassy carbon electrode. Cu²⁺ was accumulated in HAc–NaAc buffer (pH 3.6) at a potential of −0.7 V (vs. Ag/AgCl) for a certain time and then determined by pulse anodic stripping voltammetry. Parameters and conditions, such as the mass of Nafion, the concentration of Amoxicillin, the pH of medium, the accumulation potential, and the accumulation time were optimized. Under the optimum conditions, the calibration curve was linear in the range 8 × 10⁻¹⁰–2 × 10⁻⁸ M with a correlation coefficient of 0.9998 and relative standard deviation 4.87% (n = 5). The detection limit was 1.3 × 10⁻¹⁰ M. A study of interfering substances was also performed and the analytical utility of the method was demonstrated by applying to various pharmaceutical products.     

One-step, nanoparticle-mediated bacterial detection with magnetic relaxation

Acknowledging the need for the development of fast and sensitive bacterial detection methods, we functionalized superparamagnetic iron oxide nanoparticles to identify Mycobacterium avium spp. paratuberculosis (MAP), through magnetic relaxation. Our results indicate that the MAP nanoprobes (1) bind specifically to MAP, (2) can quantify the bacterial target quickly in milk and blood with high sensitivity, and (3) are not susceptible to interferences caused by other bacteria. The use of the described magnetic nanosensors in the identification and quantification of bacteria in clinical and environmental samples is anticipated.     

On the Applicability of the Magnetic Susceptibility Models for the Magnetic Superconductor Ru-1212

The applicability of theoretical models for the ac susceptibility measurements of polycrystalline RuSr₂GdCu₂O₈ superconductor has been examined within the temperature range between 8–50 K, ac magnetic field 0.5–25 G, and frequency 20–12500 Hz. In general, a reasonable qualitative agreement between theory and experiment was attained. An evident and detectable asymmetry was observed within the Cole–Cole polar plots with a peak enhancement for both theoretical and experimental data. The modified critical state models are found to generate much better explanation of the ac susceptibility measured data than Bean’s model. For fields above 20 G, the results are agreed roughly with the Bean critical state model, while below 20 G, the Kim–Anderson model is more suitable to account of the magnetic performance. The temperature and field amplitude dependencies of the flux-creep exponent, n, were extracted from the real part of susceptibility, χ′, dependence on frequency. The flux-creep exponent was found to decrease with both temperature and ac field amplitude in accordance to a power-law of the form: n(T,H)=n ₀(H)T ^−s(H). Such dependence might be an indication of a crossover to flux-creep bundles regime.     

New strategies in model order reduction of trajectory piecewise‐linear models

Model order reduction based on trajectory piecewise linearization (TPWL) is a beneficial technique for approximating nonlinear models. One efficient method for building projection matrix in TPWL reduction is by aggregation of projection matrices of linearization points (LPs). However, in this method, the size of projection matrix will also grow up by increasing the number of LPs, which yield the increment of the size of reduced model. In other words, the size of reduced model will depend on the number of LPs. In this paper, we will address this issue and propose two new strategies for obviating this problem. Contrarily to former works in TPWL modeling, we established a model via TWPL based on output weighting of parallel linear models. Then, we proposed two reduction strategies for suggested TPWL model. The first algorithm inspires from former works in this field but in a parallel structure that enable segregation of projection matrices whereas the second algorithm remedies the problem by considering the high‐order TPWL model as a unit linear model and reduces this model like a linear model but uses back projection method for constructing different outputs. The efficiency of methods is shown by comparison with former TPWL methods through vast simulations. Copyright © 2015 John Wiley & Sons, Ltd.