bluuebunny/crossref_metadata_2025_split huggingface dataset:
o‐(Pentafluorobenzyloxycarbonyl)benzoyl chloride: a novel electrophoric derivatisation reagent for amino compounds designed for negative ion chemical ionisation mass spectrometry
Authors: Leis Hans J. , Windischhofer Werner 
Published: December 2010

AbstractThe synthesis of a novel electrophoric derivatisation reagent, o‐(pentafluorobenzyloxycarbonyl)benzoyl chloride, is described. The reagent was tested against selected primary and secondary amino compounds as analytical targets. The derivatives exhibit excellent mass spectral properties under negative ion chemical ionisation (NICI), i.e. reduced fragmentation and thus high ion current for the targeted m/z during analysis. Since the reagent bears a pentafluorobenzyl ester group, resulting mass NICI mass spectra were expectedly dominated by dissociative resonance electron capture typically observed with these compounds. The reagent is suitable for detecting volatile primary and secondary amines with high sensitivity. Background is reduced by a shift in detected m/z and retention time, as demonstrated for the analysis of the drug methylphenidate from human plasma. Copyright © 2010 John Wiley & Sons, Ltd.
Mass spectrometric characterization of black tea thearubigins leading to an oxidative cascade hypothesis for thearubigin formation
Authors: Kuhnert Nikolai , Drynan J. Warren , Obuchowicz Jaczek , Clifford Michael N. , Witt Matthias 
Published: December 2010

AbstractThearubigins are the most abundant group of phenolic pigments found in black tea, accounting for an estimated 60–70% of the solids in a typical black tea infusion. Fifty years ago the term thearubigins was first introduced and to date the chemical nature of the thearubigins remains largely unresolved, if not mysterious, despite numerous attempts made to clarify their structure. Thearubigins isolated from 15 commercial black teas have been analyzed using a strategy combining standard chemical characterization along with a series of modern complementary mass spectrometry techniques, including MALDI‐TOF‐MS, FTICR‐MS, LC/TOF‐MS and LC/MS/MS. Fifteen molecular formulas have been matched to constituents of fresh tea leaf that have survived processing and 21 to dimeric transformation products such as theasinensins, theaflavins, theaflavates, theanaphthoquinones, theacitrins and oolongtheanins, which were further confirmed by ESI MS/MS. MALDI‐TOF‐MS data revealed an average of 5000 additional thearubigin components in the mass range between m/z 1000 to 2100 clearly defining the molecular weight range of the thearubigin fraction. Six selected samples have for the first time been analyzed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). FT‐ICR‐MS data revealed the presence of a maximum of 9428 peaks in the mass range 300 to 1000 m/z and molecular formulas were assigned to 1517 of them. Data interpretation strategies developed for petrolomics studies (van Krevelen and Kendrick analyses) have for the first time been applied to black tea thearubigins and a novel interpretation protocol has been developed to refine these procedures for the investigation of complex mixtures, leading to a novel hypothesis for the formation and structure of the black tea thearubigins named oxidative cascade hypothesis. Copyright © 2010 John Wiley & Sons, Ltd.
Azo‐group reduction during the matrix‐assisted laser desorption/ionization process in the presence of 2,5‐dihydroxybenzoic acid
Authors: Svoboda Martin , Kodíček Milan 
Published: December 2010

AbstractSome time ago, we published an announcement that the azo group that closes model cyclic peptides is often reduced in matrix‐assisted laser desorption/ionization mass spectrometry (MALDI MS) in the presence of 2,5‐dihydroxybenzoic acid (2,5‐DHB) as the matrix. In this work, we demonstrate that these peptides are ionized in all DHB matrix isomers, although threshold ionization laser energies as well as the reduction ratios differ in each matrix. Using a NALDI plate, we confirmed that their reduction depends on the presence of DHB matrix and that the hydrogen atoms participating in the reaction come from the DHB matrix hydroxyl group. We show that the reduction ratio is affected by the overall covalent structure of the peptide, by the presence of a free carboxyl group in DHB matrix, by the mutual position of the hydroxyl and carboxyl groups, as well as the laser beam intensity. Based on these results, it can be concluded that the azo‐group reduction in cyclic peptides is a very complex process and we are far from fully understanding its nature. We hope that our experimental results will help to shed some light on the MALDI process that still remains mysterious in some of its aspects. Copyright © 2010 John Wiley & Sons, Ltd.
Multiple levels of PKR inhibition during HIV‐1 replication
Authors: Clerzius Guerline , Gélinas Jean‐François , Gatignol Anne 
Published: December 2010

AbstractRecent therapeutic approaches against HIV‐1 include IFN in combination therapy for patients with coinfections or as an alternative strategy against the virus. These treatment options require a better understanding of the weak efficacy of the IFN‐stimulated genes, such as the protein kinase RNA‐activated (PKR), which results in viral progression. Activated PKR has a strong antiviral activity on HIV‐1 expression and production in cell culture. However, PKR is not activated upon HIV‐1 infection when the virus reaches high levels of replication, due to viral and cellular controls. PKR is activated by low levels of the HIV‐1 trans‐activation response (TAR) RNA element, but is inhibited by high levels of this double‐stranded RNA. The viral Tat protein also counteracts PKR activation by several mechanisms. In addition, HIV‐1 replicates only in cells that have a high level of the TAR RNA binding protein (TRBP), a strong inhibitor of PKR activation. Furthermore, increased levels of adenosine deaminase acting on RNA (ADAR1) are observed when HIV‐1 replicates at high levels and the protein binds to PKR and inhibits its activation. Finally, the PKR activator (PACT) also binds to PKR during HIV‐1 replication with no subsequent kinase activation. The combination of all the inhibiting pathways that prevent PKR phosphorylation contributes to a high HIV‐1 production in permissive cells. Enhancing PKR activation by counteracting its inhibitory partners could establish an increased innate immune antiviral pathway against HIV‐1 and could enhance the efficacy of the IFN treatment. Copyright © 2010 John Wiley & Sons, Ltd.
Modelling reach‐scale variability in sediment mobility: An approach for within‐reach prioritization of river rehabilitation works
Authors: Hoyle J. , Brooks A. , Spencer J. 
Published: December 2010

ABSTRACTMany Australian river ecosystems have been, and continue to be, adversely affected by increased channel dimensions and sediment supplies occurring in the period since European settlement. One of the key aims of river rehabilitation in these rivers is to help reduce sediment yield by preventing ongoing bank erosion and remobilization of instream bed material stores. While various tools have been developed to help identify sediment sources at the catchment scale, this is often at a resolution that is too coarse to be translated directly to on‐ground rehabilitation works, as most riverworks programs are designed and implemented at the reach or within‐reach scale. This paper provides a method of prioritizing rehabilitation at the within‐reach scale by using a high‐resolution reach‐scale modelling approach to examine the relative entrainment potential of sediment stores. The method has been developed for a 10 km reach of the upper Hunter River, NSW, Australia. Shear stress distribution is examined using the widely available model HEC‐RAS, and incorporating a detailed, LiDAR‐derived, representation of the in‐channel vegetation into a spatially distributed Manning's roughness layer. At the geomorphic unit scale, the results highlight that the elevated ‘bench’ units, which represent significant stores of sand and silt, are much more vulnerable to remobilization than the lower elevation gravel bar units. At the sub‐reach scale (500–2000 m) shear stresses are greatest in the most confined sections. While instream geomorphic heterogeneity has been significantly reduced in these locations, ongoing erosion is limited by bedrock and buried coarse gravel terrace material in the bed and banks. These results highlight the need for targeted rehabilitation strategies that account for within‐reach variability in entrainment potential as well as on‐the‐ground knowledge of sediment supply and geological controls. Copyright © 2010 John Wiley & Sons, Ltd.
Cryptosystems based on continued fractions
Authors: Kanso Ali 
Published: December 2010

AbstractIn this paper, we propose three secret‐key cryptosystems based on the theory of continued fractions for possible use in cryptographic applications. We present and analyze a sequence of rational numbers, whose randomness properties are demonstrated using well‐know statistical packages. Accordingly, we propose a cryptosystem that acts on a group of characters at a time. Then, a binary keystream generator, generating keystreams with good randomness properties, is suggested for possible use in stream cipher applications. Finally, we propose a cryptosystem related to the well‐known Baptista's cryptosystem that is based on a chaotic logistic map. However, our cryptosystem is based on the theory of continued fractions, and is shown to exhibit better properties and decrypts information much faster than Baptista's cryptosystem. Copyright © 2010 John Wiley & Sons, Ltd.
Network specific false alarm reduction in intrusion detection system
Authors: Hubballi Neminath , Biswas Santosh , Nandi Sukumar 
Published: December 2010

ABSTRACTIntrusion Detection Systems (IDSs) are used to find the security violations in computer networks. Usually IDSs produce a vast number of alarms that include a large percentage of false alarms. One of the main reason for such false alarm generation is that, in most cases IDSs are run with default set of signatures. In this paper, a scheme for network specific false alarm reduction in IDS is proposed. A threat profile of the network is created and IDS generated alarms are correlated using neural network. Experiments conducted in a test bed have successfully filtered out most of the false alarms for a range of attacks yet maintaining theDetection Rate. Copyright © 2010 John Wiley & Sons, Ltd.
Optimized packet formation in multi‐level security wireless data acquisition networks
Authors: Younis Mohamed , Farrag Osama , Lee Sookyoung , D'Amico William 
Published: December 2010

AbstractThe limited channel capacity and the varying propagation conditions of radio signals have motivated research for boosting the achievable throughput in wireless networks. Among the effective optimization strategies is to dynamically adjust the packet size either to better suit the channel conditions or to minimize the number of overhead bits in the individual packets. However, multi‐levels of security requirements impose constraints on the data mix in the packet payload and may diminish the gains achievable by contemporary packet‐size optimization schemes. This paper presents a novel bandwidth optimization algorithm for wireless data acquisition networks where strict confidentiality requirements and access restriction policies have to be observed. The algorithm exploits the classification of data in minimizing the number of packet transmissions as well as the overhead within the individual packets. The idea is to combine the transmission of packets based on the time sensitivity and security attributes of the data in the payload. The performance of the proposed algorithm is validated through mathematical analysis and through simulation. The simulation results confirm the effectiveness of the algorithm in boosting data throughput in the network. Copyright © 2010 John Wiley & Sons, Ltd.
Repair of post‐tensioned precast beam to column connections
Authors: Kaya Mustafa , Arslan A. Samet 
Published: December 2010

SUMMARYEarthquakes can cause immense damage to precast structures, rendering them inhabitable. After the 1999 Marmara earthquake in Turkey, research by the Turkish Precast Union stated that 24.50% of the precast structures were damaged with some of this damage being observed in the beam‐to‐column connections of the structures. Since it is essential to provide those rendered homeless by the earthquake with safe habitable accommodation, repairing medium and slight levels of damage at the connection parts should be undertaken. In order to prove that a repaired connection was sufficiently strong, a precast beam‐to‐column post‐tensioned connection was tested in three phases. In phase one, middle level damage was observed at 6% drift at these connections. In phase two, 1.2, 2.4 and 4.8% drifts were applied three times to the test specimens. As a result of the extra loads applied, little damage was observed. In the last phase, the four connections tested in the first phase were repaired using epoxy resin and then retested. The results from the tests on the repaired precast and the reference undamaged specimens showed that the repaired specimens were sufficiently strong, thus proving that repair to damaged precast beam‐to‐column post‐tensioned connections can be undertaken. Copyright © 2010 John Wiley & Sons, Ltd.
Theoretical design of high‐performance microstrip ultra‐wideband bandpass filters with controllable transmission zeros
Authors: Chen Chun‐Ping , Ma Zhewang , Anada Tetsuo , Hsu Jui‐Pang 
Published: December 2010

AbstractThis paper presents an efficient design of high‐performance microstrip ultra‐wideband (UWB) bandpass filters (BPFs) consisting of stepped‐impedance resonators (SIRs) and two‐section open‐ended SIR stubs. An analytical study is conducted on the proposed filter prototype to show its theoretical mechanism when an exact elliptical function synthesis technique is not available. Instead, a pseudo‐elliptical filter design scheme is successfully proposed for filter. As an example, a UWB BPF with a fractional bandwidth (FBW) of 110% (BW: 3.1–10.6 GHz) is then synthesized, simulated, fabricated, and measured. The measured frequency responses of the UWB filter compare very well with the predicted ones and successfully satisfy the outdoor specifications of the Federal Communications Commission (FCC). The fabricated filter also exhibits an easily fabricated structure (no via holes and a minimum gap size of 0.16 mm), a compact size, low insertion loss, a flat group delay, and good stopband characteristics as well. It should be noted that, in terms of the proposed design scheme, the proposed filter prototype can also be used to realize a UWB filter with a given FBW of even greater than 110%. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
One‐dimensional Salen‐type Chain‐like Lanthanide(III) Coordination Polymers: Syntheses, Crystal Structures, and Fluorescence Properties
Authors: Wang Gui‐Ling , Tian Yong‐Mei , Cao Dian‐Xue , Yu Yan‐Shuang , Sun Wen‐Bin 
Published: December 2010

AbstractFour salen‐type lanthanide(III) coordination polymers [LnH2L(NO3)3(MeOH)x]n [Ln = La (1), Ce (2), Sm (3), Gd (4)] were prepared by reaction of Ln(NO3)3·6H2O with H2L [H2L = N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine]. Single‐crystal X‐ray diffraction analysis revealed that H2L effectively functions as a bridging ligand forming a series of 1D chain‐like polymers. The solid‐state fluorescence spectra of polymers 1 and 2 emit single ligand‐centered green fluorescence, whereas 3 exhibits typical red fluorescence of SmIII ions. The lowest triplet level of ligand H2L was calculated on the basis of the phosphorescence spectrum of GdIII complex 4. The energy transfer mechanisms in the lanthanide polymers were described and discussed.
Therapeutic role of direct peroral cholangioscopy using an ultra‐slim upper endoscope
Authors: Moon Jong Ho , Choi Hyun Jong , Ko Bong Min 
Published: December 2010

AbstractIntroductionPeroral cholangioscopy provides direct visualization of the bile duct and facilitates diagnostic procedures and therapeutic intervention. The currently available mother–baby scope system is not widely used because of its disadvantages. Direct peroral cholangioscopy (POC) with a regular, ultra‐slim, upper endoscope can provide a valuable and economic solution for evaluating bile duct lesions, although its therapeutic role in biliary tract disease is uncertain. We assessed the usefulness of direct POC with an ultra‐slim endoscope for therapeutic application in patients with biliary diseases.MethodsSeveral new techniques and accessories allow therapeutic intervention under direct POC using an ultra‐slim upper endoscope with a larger, 2‐mm working channel. Intracorporeal laser or electrohydraulic lithotripsy under direct POC is a main therapeutic intervention for patients with bile duct stones resistant to conventional endoscopic procedures. Tumor ablation therapy such as photodynamic therapy and argon plasma coagulation may be performed under direct POC. Direct POC can be applied to guide biliary interventions such as guidewire placement, stone removal, and migrated stent retrieval, using diverse accessories.ConclusionDirect POC with an ultra‐slim upper endoscope allows therapeutic intervention for patients with biliary diseases. Enhancements of the endoscope and specialized accessories are expected to expand the therapeutic role of direct POC.
Increasing DHA and EPA Concentrations Prolong Action Potential Durations and Reduce Transient Outward Potassium Currents in Rat Ventricular Myocytes
Authors: Li Hong‐Xia , Wang Ru‐Xing , Li Xiao‐Rong , Guo Tao , Wu Ying , Guo Su‐Xia , Sun Li‐Ping , Yang Zhen‐Yu , Yang Xiang‐Jun , Jiang Wen‐Ping 
Published: December 2010

AbstractThe goal of this study was to determine the mechanisms of n‐3 polyunsaturated fatty acids (n‐3 PUFA) on anti‐arrhythmias and prevention of sudden death. The calcium‐tolerant Sprague–Dawley rat ventricular myocytes were isolated by enzyme digestion. Effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on action potentials and transient outward potassium currents (Ito) of epicardial ventricular myocytes were investigated using whole‐cell patch clamp techniques. Action potential durations (APDs) andItowere observed in different concentrations of DHA and EPA. APD25, APD50, and APD90with 0.1 μmol/L DHA and EPA were prolonged less than 15% and 10%. However, APDs were prolonged in concentration‐dependent manners when DHA and EPA were more than 1 μmol/L. APD25, APD50, and APD90were 7.7 ± 2.0, 21.2 ± 3.5, and 100.1 ± 9.8 ms respectively with 10 μmol/L DHA, and 7.2 ± 2.5, 12.8 ± 4.2, and 70.5 ± 10.7 ms respectively with 10 μmol/L EPA.Itocurrents were gradually reduced with the increased concentrations of DHA and EPA from 1 to 100 μmol/L, and their half‐inhibited concentrations were 2.3 ± 0.2 and 3.8 ± 0.6 μmol/L. The results showed APDs were prolonged andItocurrent densities were gradually reduced with the increased concentrations of DHA and EPA. The anti‐arrhythmia mechanisms of n‐3 PUFA are complex, however, the effects of n‐3 PUFA on action potentials andItomay be one of the important mechanisms.
A New Mechanism for Photo‐ and Radiation‐Induced Decomposition of Sphingolipids
Authors: Lisovskaya Alexandra G. , Shadyro Oleg I. , Edimecheva Irina P. 
Published: December 2010

AbstractData have been obtained showing regularities in product formation following radiolysis of serinol, lysosphingomyelin and photolysis of N‐(2‐hydroxypropyl)hexanamide, sphingomyelin, which point to the possibility of photo‐ and radiation‐induced destruction of the named substrates via a C–C bond rupture. The key stage of this process is the formation and decomposition of N‐centered radicals generated from the starting compounds.
Antioxidative and hepatoprotective effects of fructo-oligosaccharide ind-galactose-treated Balb/cJ mice
Authors: Chen Hsiao-Ling , Wang Cheng-Hsin , Kuo Yi-Wen , Tsai Chung-Hung 
Published: December 2010

Chronic subcutaneous (s.c.) administration ofd-galactose (DG) to BL/6J mice has been shown to induce oxidative stress and is considered a model to mimic accelerated ageing. Fructo-oligosaccharide (FO) is a well-defined prebiotic and its fermentation by lactic acid bacteria has been shown to exert antioxidative capacity. The present study was aimed to determine whether FO attenuated DG-induced oxidative stress and hepatopathy in Balb/cJ mice. Mice (12 weeks of age,n40) were divided into control (s.c. saline), DG (s.c. 1·2 g/kg body weight), DG+FO (5 %, w/w) and DG+vitamin E (0·2 %, w/w) groups and were killed after 52 d of treatment. Results indicated that DG significantly decreased the hepatic superoxide dismutase and glutathione peroxidase activities. These alterations were ameliorated both by FO and vitamin E. DG increased the hepatic TAG content approximately by 7·2 % compared with the vehicle control, which was in agreement with the histological alteration. FO, similar to vitamin E, almost normalised the hepatic TAG content and ameliorated the histological characteristics of fatty liver. Similarly, the increased plasma alanine aminotransferase activity induced by DG was normalised by FO and vitamin E, respectively. Faecal bifidobacteria counts were greater in the DG+FO and DG+vitamin E groups compared with the DG group, respectively. In conclusion, the present study indicated that FO diminished the altered hepatic antioxidative enzyme activities and morphology caused by chronic DG administration in Balb/cJ mice, partially associated with its prebiotic role in the colon.
Family Strategies: Fluidities of Gender, Community and Mobility in Rural West China
Authors: Judd Ellen R. 
Published: December 2010

AbstractThis article queries the current mobility of China's rural population by inverting the usual urban perspective and looking at this mobility through exploring the lives of those who do not move. It departs from a micro-analysis of who remains in the countryside in three west China agricultural communities between 2003 and 2005 and links this with an exploration of emergent structural features of rural communities as they are remade in the early 21st century in the wake of the abolition of agricultural taxes and levies. The ethnographic approach adopted highlights the agency, choices and practices of local people in charting their courses in a rural social world being drained of people. It proposes the utility for analysis of family strategies, identifying a repertoire of resourceful and diverse practices through which people strive to recreate and repopulate their social worlds. The argument links the study of historical directions in polity and economy with local and gendered practices in everyday life.