Computational aspects of the expected differential probability of 4-round AES and AES-like ciphers

In this paper we study the security of the Advanced Encryption Standard (AES) and AES-like block ciphers against differential cryptanalysis. Differential cryptanalysis is one of the most powerful methods for analyzing the security of block ciphers. Even though no formal proofs for the security of AES against differential cryptanalysis have been provided to date, some attempts to compute the maximum expected differential probability (MEDP) for two and four rounds of AES have been presented recently. In this paper, we will improve upon existing approaches in order to derive better bounds on the EDP for two and four rounds of AES based on a slightly simplified S-box. More precisely, we are able to provide the complete distribution of the EDP for two rounds of this AES variant with five active S-boxes and methods to improve the estimates for the EDP in the case of six active S-boxes.     

Gyroscopic and mode interaction effects on micro-end mill dynamics and chatter stability

This paper investigates the gyroscopic and mode interaction effects on the micro-end mill dynamics and the stability behavior due to regenerative chatter. A high-speed spindle system for micro-milling is modeled using finite elements. The transfer functions and the mode shapes are studied to gain a deep insight into the dynamic characteristics. The experimentally identified chatter states and operational vibration modes are given to verify the analytical results. It is shown that, due to the small rotary inertia of the micro-end mill, the gyroscopic effect considered in the inertial frame is less significant despite high rotational speeds. The mode interaction strongly affects the dynamics and the chatter stability. Moreover, piezoelectric elements are applied to in-process excitation in order to identify the transfer behavior of the micro-end mill in the operating state.     

Infrared Heating as a Disinfestation Method Against <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> and Its Effect on Textural and Cooking Properties of Milled Rice

Infrared (IR) heating method against rice weevils (Sitophilus oryzae) in an egg stage was investigated. A kinetic model was developed to describe insect mortality in a temperature range of 40–60 °C. Effects of IR heating temperature (50–60 °C) and exposure time (1–3 min) on insect mortality and quality attributes of the treated rice were evaluated. The optimized condition obtained by means of the response surface method was used to analyze rice quality before and after IR treatment with storage. The results showed that the 0.5th-order thermal death kinetic equation was the most suitable model, and the S. oryzae eggs had less heat tolerance than the adults and some other species. Mortality achieved 100 % after 2 min for all temperatures. Both IR heating parameters significantly affected the treated milled rice qualities. The minimal changes in rice quality before and after storage could be obtained using optimized temperature and exposure time of 53.6 °C and 1.2 min, respectively.     

The development of a glove-box/Vitrobot combination: air-water interface events visualized by cryo-TEM

Aqueous interfaces are of paramount importance in the study of biological systems as well as in the biomedical sciences. To study these interfaces at the nanometer level it is of interest to develop methods that allow their observation with cryogenic transmission electron microscopy (cryo-TEM). Prevention of dehydration to preserve the "native" state during sample preparation prior to vitrification is often one of the most important parameters to control in cryo-TEM experiments. For the preparation of these types of samples, we felt the need for an extended workspace with temperature and humidity control; a 'glove-box' that seamlessly connects to the vitrification instrument, the Vitrobot. In this paper we describe the use of the glove-box in the 2D and 3D cryo-TEM study of DNA adsorption and calcium carbonate mineralization to Langmuir films. The data presented illustrates the necessity of a humidity-controlled environment to preserve the original "native" state of the monolayer system.     

A high-density multi-point LAPS set-up using a VCSEL array and FPGA control

A new LAPS (light-addressable potentiometric sensor) set-up will be introduced, in which the light sources are miniaturised by the utilisation of a VCSEL (vertical-cavity surface-emitting laser) array to increase the measurement spot density. An FPGA (field-programmable gate array) is used to generate modulation signals for individual illumination of each measurement spot of the LAPS. The new set-up can operate a large number of measurement spots simultaneously by reading out the sum photocurrent and separate the signals of the individual measurement spots by an FFT analysis. The frequency, amplitude and offset of the modulation signal can be configured for each measurement spot by software. The new system can be combined with a positioning stage allowing the parallel read out of a single line of measurement spots and a scan perpendicular to that line in a similar manner, like for an optical scanner set-up. First measurements demonstrate the functionality of the new LAPS set-up as a chemical imaging system.     

Fatigue crack growth in TRIP steel under positive R-ratios

Load-controlled fatigue tests are conducted for four positive R values on a low-alloy TRIP steel for two different heat treatments: an optimal treatment leading to a multiphase microstructure containing retained austenite, ferrite, bainite and martensite, and a non-optimal treatment leading to a ferritic–martensitic dual-phase microstructure. A significantly increased resistance to fatigue crack growth is found for the optimal case with respect to the non-optimal case. The amount of crack closure is found to be larger in case of the non-optimally treated (ferritic–martensitic) steel. Close to the crack tip, an increased hardness suggests martensite formation. An EBSD technique is used to quantify the volume of retained austenite ahead of the crack tip, within the plastic zone. It is found that martensite formation only occurs within the monotonic plastic zone during fatigue. By evaluation of the retained austenite fraction during straining in static tensile tests, the plastic strain levels within the plastic zone are assessed. Additionally, the effect of martensite formation on fracture toughness is estimated.     

Electrochemical reduction of nickel ions from diluteartificial solutions in a GBC reactor

The electrochemical reduction of nickel ions from a dilute solution has been carried out in a gas diffusion electrode packed bed electrode cell (GBC). Particle size and electrode configuration have been found to have a significant influence on the reduction process. Electrodes with a high porosity and large pores have been found to be the best for nickel deposition. The nickel current efficiency, Ni, is reported to be dependent on the current density, volumetric flow rate, nickel and boric acid concentration, and the pH. The fall in the nickel current efficiency is caused by an increase in electrode surface pH above a certain level, caused by either high bulk solution pH or high current density, leading to possibly formation of Ni(OH)2. It has been found that under conditions of exclusively metallic nickel deposition Ni/(1–Ni) is proportional to i0.69,Q10.52,CNi0.67,CBA–0.19 and pH1.0.     

Physical degradation of genomic DNA of soybean flours does not impair relative quantification of its transgenic content

In this paper, four different physical treatments (microwaves, heating by conduction, sonication and pressure autoclaving) were performed to degrade a pure DNA extract, and their influence on GMO quantification was studied. The aim was to check the hypothesis that processing of agrofood products results in a similar degradation rate for both the transgenic target and the specific target. Indeed we could observe that even if the used physical treatments could lead to a significant increase of C _t values for both transgenic and specific targets, the resulting ΔC _t remained stable. So, the main conclusion of the study is that the aforementioned hypothesis seems valid and thus a physical degradation of DNA will not affect the relative quantitation of the GMO content, provided that both the specific and transgenic targets have very similar size. A second important issue of the experiments performed was that DNA is a very robust molecule as it is extremely difficult to reach a mean size below 100 bp. The study also gives evidence of the importance of using small targets.