Publications

Illicium verum extract is investigated as a corrosion inhibitor of aluminium in the presence of an acid medium using gravimetric and impedance techniques. The gravimetric results reveal that the adsorption of inhibitor on the metal surface is physisorption. The impedance measurements are used to interpret the electrochemical process occurring at the interface of aluminium and corrosive medium. The surface characteristics of aluminium are evaluated using scanning electron microscopy‐energy dispersive X‐ray spectroscopy. The percentage composition of chemical constituents present in the extract is obtained using gas chromatography‐mass spectrometry and E‐anethole is found to be the main chemical component. The interaction between the chemical constituents or inhibitor molecules and the metal surface are evaluated using Monte Carlo simulation. The determination of electron density on the inhibitor molecules is performed using density functional theory. The results from this respective study demonstrate good inhibitive properties of the illicium verum extract towards the corrosion of aluminium in concentrated hydrochloric acid solution.

Modern networks achieve robustness and scalability by maintaining states on their nodes. These nodes are referred to as middleboxes and are essential for network functionality. However, the presence of middleboxes drastically complicates the task of network verification. Previous work showed that the problem is undecidable in general and EXPSPACE-complete when abstracting away the order of packet arrival. We describe a new algorithm for conservatively checking isolation properties of stateful networks. The asymptotic complexity of the algorithm is polynomial in the size of the network, albeit being exponential in the maximal number of queries of the local state that a middlebox can do, which is often small. Our algorithm is sound, i.e., it can never miss a violation of safety but may fail to verify some properties. The algorithm performs on-the fly abstract interpretation by (1) abstracting away the order of packet processing and the number of times each packet arrives, (2) abstracting away correlations between states of different middleboxes and channel contents, and (3) representing middlebox states by their effect on each packet separately, rather than taking into account the entire state space. We show that the abstractions do not lose precision when middleboxes may reset in any state. This is encouraging since many real middleboxes reset, e.g., after some session timeout is reached or due to hardware failure.

The point of zero charge (pH pzc ) is one of the most important properties in determining the nature of the surface charge on oxide films in contact with aqueous solutions. Contact angle titration is a simple, rapid and direct surface titration approach to determine the pH pzc of oxide films, compared with mass titration, potentiometric titration and batch equilibration method. Although contact angle titration has been an effective method to estimate the pH pzc in the past, there are some limitations in previous methodologies for the correlation between the contact angle and the surface charge density, due to the consideration of only the negative charged OH − at surface or the absence of a vital part of solution potential for the electrochemical potential of H + in electrolyte. Based on the work of many previous contributors, two general thermodynamic methods for determining the pH pzc of oxide films by contact angle titration are developed here. The methods provide precise, fundamental understandings of the variation of the contact angle with surface charge density, which is of great significance for interfacial science.

A diblock copolymer containing a fullerene(C60)-rich block and a poly(3-hexylthiophene) block functions as a compatibilizer in poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) blends. The copolymer is used to probe the impact of morphology and phase-segregation kinetics on the performance of P3HT:PCBM-based solar cells. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2006/c1787_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Weaving organic threads Woven fabrics are inherently flexible. Liu et al. created a molecular fabric analog using metal-organic frameworks (see the Perspective by Gutierrez-Puebla). Phenanthroline ligands on a copper metal complex directed the addition of organic linkers via imine bonds to create helical organic threads with woven texture. Removing the copper allowed the strands to slide against each other and increased the elasticity of the material 10-fold. Science , this issue p. 365 ; see also p. 336

A thick sequence of Late Miocene to Pleistocene sediments thought to represent deposition in a Neogene forearc basin are preserved in the structural basin referred to as the Eel River basin' located offshore of NW California and SE Oregon. The southern portion of this structural basin comes on land in the vicinity of Eureka where the marine and fluvial Wildcat Group is exposed. Basal Wildcat Group sediments are fluvial and littorial. Marine sandstones of the Wildcat Group contain K-spar concentrations of 5.5% and are believed to represent a fresh source. [sup 40]Ar/[sup 39]Ar laser probe analyses of Wildcat Group micas yield dates of 52--57, 66--75, 128.5 and 299--303 Ma. The presence of Idaho detritus throughout the Neogene Wildcat Group indicates that the Klamath Mountains remained low during the Pliocene and early Pleistocene. Younger fluvial sediments in this region contain primarily locally derived detritus indicating local uplift of the Klamath Mountains. To the north, at Crescent City, thin remnants of the near-shore Saint George Formation and the eastern estuarine and fluvial Wimer Formation are lowermost Pliocene in age (5 ma). The presence of the highly erodible Wilmer Formation on uplifted plateaus in an area of extreme rainfall suggest that these sedimentsmore » represent only the lowermost portion of an originally much thicker sequence. Consequently, the sediments confined to the present day Eel River basin do not represent the lateral extent of the original forearc basin. Sandstones and conglomerates of the Saint George and Wimer Formation indicate a local Klamath provenance derivation.« less

Following the long-held belief that the Internet is hierarchical, the network topology generators most widely used by the Internet research community, Transit-Stub and Tiers, create networks with a deliberately hierarchical structure. However, in 1999 a seminal paper by Faloutsos et al. revealed that the Internet's degree distribution is a power-law. Because the degree distributions produced by the Transit-Stub and Tiers generators are not power-laws, the research community has largely dismissed them as inadequate and proposed new network generators that attempt to generate graphs with power-law degree distributions.Contrary to much of the current literature on network topology generators, this paper starts with the assumption that it is more important for network generators to accurately model the large-scale structure of the Internet (such as its hierarchical structure) than to faithfully imitate its local properties (such as the degree distribution). The purpose of this paper is to determine, using various topology metrics, which network generators better represent this large-scale structure. We find, much to our surprise, that network generators based on the degree distribution more accurately capture the large-scale structure of measured topologies. We then seek an explanation for this result by examining the nature of hierarchy in the Internet more closely; we find that degree-based generators produce a form of hierarchy that closely resembles the loosely hierarchical nature of the Internet.