Qinghai Gao

Atactic polymerization of propylene catalyzed by mono(η5‐cyclopentadienyl)titanium tribenzyloxide combined with methylaluminoxane

Propylene has been polymerized with mono(η 5 -cyclopentadienyl)titanium tribenzyloxide activated with methylaluminoxane(MAO). It was found that the content of residual trimethylaluminium (TMA) in MAO has a determinative effect on the polymerization. An excess of TMA in the catalyst system reduces the Ti species to inactive lower valent states. The catalyst system gives medium molecular-weight atactic polypropylene (M, = 2-7 × 10 4 ) with narrow molecular weight distribution (M w / M n = 1.4-1.8). The polymer has a stereoirregular structure described by Bernoullian statistics. Statistical analysis of the regiotriad distribution of the polypropylene chains indicates a regioblock microstructure.

A few DNA-based security techniques

Biological systems have been a rich source of inspiration for computer security professionals. In this paper we briefly review some of the security proposals inspired by DNA. By looking at the procedures of genetic information processing we propose a few techniques that can be applied to protect information, including a secure communication protocol inspired by primer-based gene recognition, DNA-based key distribution inspired by DNA base sequence complementarities, DNA-based steganography with the chemical information of the bases co-inspired by the LSB-based image steganography, and steganography with intronization inspired by the intron removal process in the central dogma of biology. The security of the proposed techniques is briefly analyzed.

Ethylene/styrene copolymerization in the presence of cyclopentadienyltitanium tribenzyl oxide and various methylaluminoxanes

Copolymerizations of ethylene and styrene in the presence of CpTi(OBz) 3 and various MAOs have been investigated. It was found that the composition and structure of the copolymerization products are strongly dependent on the amount of free alkylaluminium, involving the residual trimethylaluminium (TMA) in MAO and external alkylaluminium (TIBA), in the systems. The catalyst system containing less free alkylaluminium affords an ethylene/styrene copolymer. while that containing plenty of free alkylaluminium affords a mixture of the corresponding homopolymers. This seems to be due to the existence of different Ti species caused by the free alkylaluminium content in the systems.

Looking at a class of RFID APs through GNY logic

Radio Frequency Identification Authentication Protocols (RFID APs) are an active research topic and many protocols have been proposed. In this paper, we consider a class of recently proposed lightweight RFID authentication protocols: CRAP, LCAP, OHLCAP, O-TRAP, YA-TRAP, and YA-TRAP+, which are claimed to be resistant to conventional attacks and suitable for low cost RFID device scenarios. We examine them using GNY logic to determine whether they can be proved to have achieved their protocol goals. We show that most of them meet their goals, though some do not. Furthermore this approach enables us to identify similarities and subtle differences among these protocols. Finally, we offer guidelines on when it is necessary to use encryption rather than hash functions in the design of RFID authentication protocols.

Biometric authentication in Smart Grid

The Smart Grid being developed nationwide aims at bringing modern IT network into the industrial control system (ICS) network to more effectively generate, transmission, and distribute electricity. These networks have their unique vulnerabilities and face all types of threats. Interconnecting them will undoubtedly increase complexity, introduce new vulnerabilities and the combined network will become more attractive to hackers. How successful the Smart Grid project can be largely depends on how well it defends against remote network-based attacks. User authentication for accessing the Smart Grid is the first and strongest line of defense against these types of attacks. Modern password based authentication mechanism has been proven inadequate. It is believed that biometric authentication will significantly improve the security of the Smart Grid network. In this paper we propose using biometrics to authenticate users accessing the Smart Grid. Firstly we look at a few biometric traits that have been proposed for user authentication in modern IT network and physical access control. Then we propose privacy-enhanced methods of applying fingerprint for user authentication. The proposed approaches can help relieve users privacy concern for their fingerprint data, mainly due to its traditional usage for crime and background investigation. Since our methods improve the secrecy of biometric data, they make it possible to include biometrics as a factor in the desired multifactor user authentication for the Smart Grid.

Effects of residual and external alkylaluminum on the synthesis of syndiotactic polystyrene with cyclopentadienyltitanium tribenzyloxide-methylaluminoxane catalyst

The effects of residual trimethylaluminum (TMA) in methylaluminoxane (MAO) and external alkylaluminum (AIR 3 ) on styrene syndiotactic polymerization with CpTi(OBz) 3 as a catalyst precursor have been investigated by comparison of the polymerizations using a series of MAOs containing various amounts of residual TMA. The results indicated that the residual TMA plays a deciding role in the reduction of Ti and promotes formation of the active centers for styrene polymerization. The variations in the catalytic activity and molecular weight of the polymer caused by additions of external AIR 3 , AlMe 3 , AlEt 3 , Al(i-Bu) 3 , and AlEt 2 Cl, into the catalyst systems are quite different, depending the properties of MAO used and the type of the external AlR 3 . It was found that there is an optimum range of concentration ratio of the free AlR 3 , including the residual TMA and external AlR 3 , to the total Al compounds, 25-35 mol %, for maximum catalytic activities. The catalytic activities decrease at the ratios either above or below the range.

d -Glucose mitigates the agglomeration of the hollow graphitic carbon nanospheres

Hollow graphitized porous carbon nanosphere (CNS) materials were synthesized from the polymerization of resorcinol (R) and formaldehyde (F) in the presence of a well-characterized iron polymeric complex. However, CNS formed large aggregates, which limit the full utilization of the nanostructures of CNS in applications. In order to mitigate the agglomeration of primary CNS, we conducted step-by-step investigation of the CNS synthetic process to identify the origin of the aggregate formation and explored methods to minimize the agglomeration of the formed CNS. It was found that when d-glucose, a crystalline compound, was added in the resorcinol–formaldehyde polymerization process, CNS aggregation was alleviated. The resulted CNS was studied for its surface and structure properties by transmission electron microscope, Brunauer–Emmett–Teller surface area bulk conductivity measurement, and Raman spectroscopy. The role of d-glucose in reducing aggregation of CNS seems to be related to its influence on the polymerization process.

Some challenges in forensic fingerprint classification and interpretation

The usage of fingerprints is no longer limited to crime investigation. And automated fingerprint identification systems have been developed for a variety of applications. However, in law enforcement agency manual categorization and analysis are still an indispensible part of fingerprint operation mainly for the following two reasons: (1) Automated fingerprint classification and identification systems are far from perfection. They can help to expedite the identification process, but cannot completely replace human fingerprint experts in terms of identification accuracy; (2) Fingerprint classification can help speed up the automated searching process as fingerprint databases become overwhelmingly large. In this paper, we review existing classification systems, including Henry, Vucetich, Battley, and NCIC classification systems, and look into the challenges of classifying certain ambiguous fingerprints and interpreting latent prints. By reviewing literature and a representative case of fingerprint misidentification, we analyze the objective and subjective factors contributing to erroneous and inconsistent identification.

Recent Developments on Applying Biometrics in Cryptography

Biometrics is an identification technology widely used in physical access control and forensics. Cryptography is the science for information security. People generally agreed that biometric information needs to be protected with cryptography. Many researchers also believe that biometrics can enhance the security of cryptography. In this article I have surveyed recent developments on applying biometrics in cryptography, focusing on binding and generating a cryptographic key. The security of these proposals is briefly analyzed. Additionally I have reviewed some other developments, such as matching without removing chaff points, encrypted templates matching, symmetric hashing, and biometric random number generation.

Effectiveness of authenticating users with randomly constructed fingerprint templates

In recent years, using fingerprints to authenticate users in physical and logical access control has been gaining popularity. Thus protecting fingerprint data becomes an important issue. One of the ideas proposed in literature to safeguard fingerprint data is to construct secure fingerprint template from fingerprint image(s). One requirement for this proposal is that the template can be utilized to authenticate its owner but an impostor cannot use it to reconstruct the original fingerprints. How to satisfy this requirement is still an ongoing research problem. Partial fingerprints are more readily available than full fingerprints. Application of 3D finger scanner renders fast capturing of multiple partial fingerprints without any distortion. Recognition based on partial fingerprints from different fingers can significantly increase the number of available fingerprint templates. A secret-key based randomized selection of multiple partial fingerprints from multiple fingers can protect the privacy of fingerprint data. In this paper we propose a novel approach to constructing fingerprint templates from multiple partial fingerprint images. The randomized construction process makes reverse engineering more resource consuming. Our testing results show that individual partial fingerprints from different parts of a finger do not match with each other. By enrolling a combined template from multiple partial fingerprints, authentication can be done successfully. The matching score exponentially increase with the number of minutiae in a fingerprint. The randomly constructed template from multiple original templates does not cause an increase in false recognition rate (FRR), compared with the matching results of the original template.