Removal of toxic heavy metals from wastewater is an important environmental challenge. In this Study, Zn (II) removal from aqueous solution by chitin extraction from crustaceous shells (shrimp and crab) was investigated. The biosorption studies were determined as a function of contact time, pH, initial metal concentration, and the amount of adsorbent. Adsorption of Zn (II) increased with decrea...

In the first part of this work, we introduce a new type of pseudo-random function for which “aggregate queries” over exponential-sized sets can be efficiently answered. We show how to use algebraic properties of underlying classical pseudo random functions, to construct such “aggregate pseudo-random functions” for a number of classes of aggregation queries under cryptographic hardness assumptio...

In this paper, we present the pseudo-collision, pseudo-second-preimage and pseudo-preimage attacks on the SHA-3 candidate algorithm Luffa. The pseudocollisions and pseudo-second-preimages can be found easily by computing the inverse of the message injection function at the beginning of Luffa. We explain in details the pseudo-preimage attacks. For Luffa-224/256, given the hash value, only 2 iter...

Hamsi is one of the second round candidates of the SHA-3 competition. In this study, we present non-random differential properties for the compression function of the hash function Hamsi-256. Based on these properties, we first demonstrate a distinguishing attack that requires a few evaluations of the compression function and extend the distinguisher to 5 rounds with complexity 2. Then, we pres...

A pseudo-random function is a fundamental cryptographic primitive that is essential for encryp-tion, identiication and authentication. We present a new cryptographic primitive called pseudo-random synthesizer and show how to use it in order to get a parallel construction of a pseudo-random function. We show several NC 1 implementations of synthesizers based on concrete intractability assumption...

Maelstrom-0 is the second member of a family of AES-based hash functions whose designs are pioneered by Paulo Baretto and Vincent Rijmen. According to its designers, the function is designed to be an evolutionary lightweight alternative to the ISO standard Whirlpool. In this paper, we study the preimage resistance of the Maelstrom-0 hash function using its proposed 3CM chaining construction. Mo...

Universit e du Qu ebec a Trois-Rivi eres In practice, it is often necessary to study empirical distribution functions constructed from residuals when estimating the distribution of functions (X) of an observable random variable X. More generally, one can be interested in estimating the distribution function of a non-observable random variable (Q; X) depending on an observable random variable X ...

The removal of Malachite Green (MG) by Cocoa (Theobroma cacao) Shell Activated Carbon (CSAC) was investigated in present study. Adsorption studies were performed by batch experiments as a function of process parameters such as initial pH, contact time, initial concentration and adsorbent dose. A comparison of kinetic models applied to the adsorption of MG on CSAC was evaluated for the pseudo-fi...