Book reviews

Abstract

When news of the assassination of Mohandas Gandhi circulated through New Delhi on 30 January 1948, Margaret Bourke-White, one of Life magazine's premier photographers, and Henri Cartier-Bresson, then a comparatively unknown French photojournalist, raced to Birla House, where the event occurred. Both understood the journalistic imperative of photographing Gandhi's body. Because of their different philosophical and technical approaches to photography, they responded to the challenge in different ways and produced very different results. This study compares their ideas, approaches, and results. It also offers a case study of one of Cartier-Bresson' s most important news reportages.¹     

A Study of Twin Variant Selection and Twin Growth in Titanium

An in depth analysis on twin variant selection and twin growth character during compression by means of “interrupted in situ” EBSD orientation measurement was carried out. An experimental verification and geometrical analysis of the use of Schmid's law as a criterion for selecting twin variants was performed, and proved to be conclusive. Twin variants having Schmid factors higher than 0.4 have a good chance to be activated. The twin growth exhibits two modes: {11–22} twins show a tendency to multiple variants system (MVS) and {10–12} twins show predominant variant system (PVS). The Schmid factor plays an important role in MVS and PVS.     

Quantized based image watermarking in an independent domain

This paper presents a performance study for two well known quantized based watermarking schemes Scalar Costa Scheme (SCS), and Trellis Coded Quantization scheme (TCQ) in an independent domain. For our study, the independent domain is obtained by the combination of the cited schemes with Independent Component Analysis (ICA). The Independent Component Analysis is used while inserting and extracting the message. Thus a performance compromise improvement of the original SCS and TCQ schemes in terms of robustness, capacity, and security is shown. Then the obtained schemes performances are compared to the Spread Transform (ST) based scheme well known for its proven good robustness properties. Our results show that, using watermarking with side information in independent domain permits to improve the global SCS and TCQ schemes performances. For example, in the case of SCS, by studying the Bit Error Rate (BER) in function of the watermark to noise ratio (WNR), the robustness has been improved by 20 dB (1 decade) when WNR is equal to 0 dB. Moreover, the capacity study shows for the same WNR=0 dB, the amount of information to be transmitted without error for a given noise level of the proposed SCS combined with ICA scheme (SCS-ICA) is much higher than that of the existing schemes. Finally, the study of the probability density functions (PDF) of the original and marked signals has shown that the Cachin-security level of the TCQ in an independent domain scheme (TCQ-ICA) is the best one compared to the other known schemes.     

Mechanism of formation of urchin-like ZnO

Thin films composed of ZnO nanowires (NWs) hierarchically organized with an urchin-like 3D morphology were obtained by combining the electrochemical deposition and sphere lithography methods. Deposited on a transparent conductive oxide substrate (TCO), a monolayer of carboxylate modified polystyrene spheres organized with a hexagonal closed-packed structure played the role of a template. The spheres were activated in a solution of zinc chloride by the formation of bonds between the carboxylate terminals and the Zn²⁺ ions and were used as a template for the electrodeposition of vertically aligned ZnO NWs around them. Without this treatment, ZnO NWs were deposited only on the TCO substrate between the PS spheres. To reach a density of nanowires high enough to obtain the urchin morphology, the concentration of ZnCl₂ had to be at least equal to 2 M. It was also found, as soon as small grains of ZnO started to be electrodeposited on the polystyrene spheres that the spheres were no longer close packed. The space created between them increased with the increase in the number of small ZnO grains and the increase in their length, allowing the further growth of the nanowires between the spheres. As a result the initial round shape of the spheres was modified and the urchin-like ZnO exhibited an ellipsoidal shape.     

Early development of a biodegradable energetic elastomer

The expected depletion of oil resources and a greater awareness for the environmental impact of plastic products have created a strong interest toward energetic polymers that are not only biodegradable but also obtainable from renewable resources. In this work, a copoly(ester/ether) was synthesized from polyepichlorohydrin and sebacoyl chloride using pyridine as a Lewis‐base catalyst. The chlorinated polymer was azidified with NaN₃ in dimethyl sulfoxide solutions. The success of the reaction was confirmed by ¹H‐NMR, ¹³C‐NMR, and Fourier‐transform infrared spectroscopy. Two types of polyurethane networks were synthesized from the nonenergetic and the energetic copolymers, adding polycaprolactone triol and using L ‐lysine diisocyanate as a nontoxic curing agent. The two resulting polyurethanes were soft thermoset elastomers. The polyurethanes were chemically and mechanically characterized, and their biodegradability was evaluated in compost at 55°C. The nonenergetic and the energetic polyurethanes showed a glass‐transition temperature of −14°C, and −23°C, respectively. The weight loss of the polyurethanes during the composting experiments was monitored. It increased almost linearly with time for both materials. After 20 days, the nonenergetic samples lost about 50% of their mass because of the biodegradation mechanism. Instead, the energetic elastomers lost only about 25% of their initial mass after 25 days. The experimental results revealed that the azide pendant group in the soft segment (the polyether segments) is the main factor that controls the physical, mechanical, and degradation properties of these polyurethane networks. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

How to monitor the modulus of elasticity of concrete,automatically since the earliest age?

Monitoring the evolution of an early age set of parameters on concrete is necessary to predict the early age behaviour of structures. The difficulty lies in the fact that this monitoring must be automatic because the concrete hardening process takes place over a long period after the casting. This paper presents a new methodology and an apparatus, specifically designed at IFSTTAR, to monitor the hardening process of a concrete. Mainly, the Young’s modulus can be monitored in compression. Measurements start soon after having cast the concrete and the sample temperature is completely controlled so that the concrete maturity is well mastered. The performances of this apparatus, obtained on an ordinary concrete, are compared to more classical measurements using an extensometer mounted on the sample just after the setting time and to ultrasonic measurements. In these cases, the temperatures were not controlled and results have to be expressed in equivalent time. A comparison with another method developed and used at ULB by using the same concrete, in the frame of a joined cooperation between our two laboratories is achieved. This test set up is based on the so called Temperature Stress Testing Machine (TSTM). This device has been specifically designed with a control of the concrete maturity by the use of a dummy specimen only submitted to free deformations (thermal, shrinkage). The TSTM allows compressive and tensile testing starting just after the setting time. In addition, concrete properties, such as compressive and tensile strength, have been characterized at early age. These values have been used for the design of the loading histories applied in the automatic tests. The heat released by the cement hydration has also been measured in order to express the results on a maturity scale.     

Genetic analysis of geraniol metabolism during fermentation

Geraniol produced by grape is the main precursor of terpenols which play a key role in the floral aroma of white wines. We investigated the fate of geraniol during wine fermentation by Saccharomyces cerevisiae. The volatile compounds produced during fermentation of a medium enriched with geraniol were extracted by Stir-bar sorptive extraction and analysed by GC–MS. We were able to detect and quantify geranyl acetate but also citronellyl- and neryl-acetate. The presence of these compounds partly explains the disparition of geraniol. The amounts of terpenyl esters are strain dependant. We demonstrated both by gene overexpression and gene-deletion the involvement of ATF1 enzyme but not ATF2 in the acetylation of terpenols. The affinity of ATF1 enzyme for several terpenols and for isoamyl alcohol was compared. We also demonstrated that OYE2 is the enzyme involved in geraniol to citronellol reduction. Fermenting strain deleted from OYE2 gene produces far less citronellol than wild type strain. Moreover lab strain over-expressing OYE2 allows 87% geraniol to citronellol reduction in bioconversion experiment compared to about 50% conversion with control strain.