Hemicellulose, the second, most common polysaccharide in nature constitutes approximately 20-35% of lignocellulosic biomass. Effective utilization of biomass, hitherto underutilized, is gaining tremendous importance for the production of energy, fuels, and chemicals. Amongst the vast array of chemicals derived from lignocellulosics, furfural is the key chemical that fi nds wide applications in oil refi ning, plastics, pharmaceutical and agrochemical industries. There is no synthetic route for the production of furfural. A few conventional technologies currently in practice for its separation and subsequent isolation are appropriately reviewed. Major disadvantages associated with processes currently used for the production of furfural based on acid-catalyzed hydrolysis have been discussed. A need to develop a process which is devoid of all the shortcomings associated with conventional process is emphasized. Several important aspects of chemistry underlying the acid hydrolysis of xylose are discussed. The importance of myriad pre-treatment steps involved to surmount the physical and chemical barriers and to liberate xylose from the confi nes of acid-resistant layer of lignin has been emphasized. New developments in the production of furfural from cyclodehydration of xylose using solid acid catalysts in the recent past have been reviewed appropriately in present communication. Finally, the production of furfural and furfuryl alcohol, their domestic market and export in China deserve some coverage and therefore have appropriately been discussed as well.

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Copper/silica nanocomposite catalysts prove efficient for the direct hydrocyclization of biomass‐derived levulinic acid to cyclic 2‐methyltetrahydrofuran in the vapor phase, at moderate hydrogen pressures. A nickel‐promoted copper/silica catalyst with a high copper loading (72 wt %) is particularly effective for the direct hydrocyclization (89 % selectivity). The catalysts are stable during long‐term experiments, showing little sign of leaching or sintering.

Abstract-In this paper, we propose a ranking based locality sensitive hashing inspired two-factor cancelable biometrics, dubbed "Index-of-Max" (IoM) hashing for biometric template protection. With externally generated random parameters, IoM hashing transforms a real-valued biometric feature vector into discrete index (max ranked) hashed code. We demonstrate two realizations from IoM hashing notion, namely Gaussian Random Projection based and Uniformly Random Permutation based hashing schemes. The discrete indices representation nature of IoM hashed codes enjoy several merits. Firstly, IoM hashing empowers strong concealment to the biometric information. This contributes to the solid ground of non-invertibility guarantee. Secondly, IoM hashing is insensitive to the features magnitude, hence is more robust against biometric features variation. Thirdly, the magnitude-independence trait of IoM hashing makes the hash codes being scale-invariant, which is critical for matching and feature alignment. The experimental results demonstrate favorable accuracy performance on benchmark FVC2002 and FVC2004 fingerprint databases. The analyses justify its resilience to the existing and newly introduced security and privacy attacks as well as satisfy the revocability and unlinkability criteria of cancelable biometrics.Index Terms-Fingerprint, cancelable template, Index-of-Max hashing, security and privacy I. INTRODUCTIONATELY, rapid proliferation of biometric applications leads to massive amount of biometric templates. Public worries about the security and privacy of the biometric templates if stolen or compromised. Such concerns are attributed to the strong binding of individuals and privacy, and further complicated by the fact that biometric traits are irrevocable. Given the above threats, a number of proposals have been reported to protect the biometric templates. Generally, the proposals available in the literature can be broadly divided into two categories: feature transformation (or cancelable biometrics) and biometric cryptosystems (biometric encryption). Biometric cryptosystem serves the purpose of either securing the secret using biometric feature (key binding) or generating the secret directly from the biometric feature (key generation). On the other hand, cancelable biometrics [1] is truly meant for biometric template protection. It refers to the irreversible transform that can alter the biometric templates such that security and privacy of the templates can be assured. If a cancelable template is compromised, a new template can be re-generated from the same biometrics.The cancelable biometric schemes in the literature vary according to different biometric modalities. However, the operation of a general cancelable biometrics system is similar to the conventional biometric system where the system composes of sensor, feature extractor and matcher except the former includes a parameterized transformation function right after feature extractor, and the matching is done in the transformed domain, rather in the feature doma...

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Abstract. In modern collaborative and distributed applications, authenticated group key agreement (GKA) is one of important issues. Recently identity (ID)-based authenticated GKA has been increasingly researched because of the simplicity of a public key management. In this paper, we present a formal treatment on ID-based authenticated GKA, which extends the standard GKA model. We present two GKA protocols which use a bilinear-based cryptography: one is a bilinear variant of Burmester and Desmedt protocol [13] and the other is ID-based authenticated protocol based on the former protocol. Our protocols are scalable and 2-round protocols with forward secrecy. In particular, the ID-based authenticated GKA protocol provides a batch verification technique, which verifies the validity of transcripts from other group players simultaneously and improves computational efficiency. We then prove their securities under the decisional bilinear DH and computational DH assumptions. IntoductionBackground. In many modern collaborative and distributed applications such as multicast communication, audio-video conference and collaborative tools, scalable and reliable group communication is one of the critical problems. A group key agreement (GKA) protocol allows a group of users to share a key which may later be used to achieve some cryptographic goals. In addition to this basic tool an authentication mechanism provides an assurance of key-sharing with intended users. A protocol achieving these two goals is called an authenticated group key agreement (AGKA) protocol.Among various authentication flavors, asymmetric techniques such as certificate based PKI (public key infrastructure) or ID-based system are commonly used to provide authentication. In a typical PKI deployed system, a user should obtain a certificate of a long-lived public key from the certifying authority and this certificate be given to a partner to authenticate the user. Whereas in a IDbased system, the partner just has to know the public identity of the user such as e-mail address. Thus, compared to certificate-based PKI system, ID-based authenticated systems simplify the key agreement (management) procedures.

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An efficient synthesis of 4-arylcoumarins has been accomplished via Kostanecki reactions of 2-hydroxybenzophenones with acetic anhydride employing DBU at ambient temperature. Using the same strategy, several 2-acyloxybenzophenone derivatives were readily converted to 3,4-difunctionalized coumarins. This protocol offers a notable improvement in reaction conditions for coumarin synthesis and takes advantage of its synthetic capability, especially for highly functionalized 4-arylcoumarins with structural diversity.