bluuebunny/crossref_metadata_2025 huggingface dataset:
Masked O‐Benzoquinone Strategy in Organic Synthesis: Short and Efficient Construction of cis‐Decalins and Linear Triquinanes from 2‐Methoxyphenols
Authors: Liao Chun‐Chen
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Development of Methods Suitable for Natural Product Synthesis: The Azadirachtin Story
Authors: Ley Steven V.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Seleno‐ and Telluroaldehydes and ‐ketones
Authors: Guziec L. J. , Guziec, F. S. Jr.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Hetera(cyclo)phanes
Authors: Voegtle Fritz , Pawlitzki Gregor , Hahn Uwe
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Selenophenes
Authors: Sommen Geoffroy L.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Nucleoside 5′‐Triphosphates: Self‐Association, Acid—Base, and Metal Ion‐Binding Properties in Solution
Authors: Sigel Helmut , Griesser Rolf
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Electrophilicity Scales for Carbocations
Authors: Mayr Herbert , Ofial Armin R.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Chemistry and Structural Biology of Androgen Receptor
Authors: Gao Wenqing , Bohl Casey E. , Dalton James T.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Collagen: The Next Generation of Resorbable Biodevices in Surgery
Authors: de Lustro Frank , Sehl Louis , Estridge Trudy , Wallace Donald
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Computational Modeling Approaches to Structure—Function Analysis of G Protein‐Coupled Receptors
Authors: Fanelli Francesca , De Benedetti Pier G.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Variable Temperature Infrared Spectroscopy: A Convenient Tool for Studying the Thermodynamics of Weak Solid—Gas Interactions
Authors: Garrone Edoardo , Otero Arean Carlos
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Asymmetric epoxidation of cinnamyl alcohol with optically active titanium complexes
Authors: Pérez Yolanda , Morante‐Zarcero Sonia , del Hierro Isabel , Sierra Isabel , Fajardo Mariano , Otero Antonio
Published: November 2005

A family of titanium(IV) alkoxo compounds [{Ti(O‐i‐Pr)2(OR)2}2] 1–4 prepared by alcohol exchange of Ti(O‐i‐Pr)4 and a chiral higher‐boiling alcohol [ROH = 1,2:3,4‐di‐O‐isopropylidene‐α‐d‐galactopyranose, 1,2:5,6‐di‐O‐isopropylidene‐α‐d‐glucofuranose, (1R,2S,5R)‐(−)‐menthol, (1S‐endo)‐(−)‐borneol, (1S,2R,5S)‐(+)‐menthol, and (+)‐borneol] has been tested to evaluate their catalytic activity and stereoselectivity in the asymmetric epoxidation of cinnamyl alcohol. © 2005 Wiley‐Liss, Inc. Chirality
Determination of the stereoselectivity of chiral drug transport across Caco‐2 cell monolayers
Authors: He Ying , Zeng Su
Published: November 2005

This study aimed to determine the transport characteristics of chiral drug enantiomers across Caco‐2 cell monolayers as a model of human intestinal epithelial membrane. Esmolol was chosen as a model drug, and the study focused on the transepithelial transport of esmolol enantiomers in this in vitro model system. Separation and quantitation of (S)‐ and (R)‐esmolol were performed by RP‐HPLC with the use of GITC as a precolumn derivatizing agent. Bidirectional transport studies of 5.0–400.0 μmol/l esmolol demonstrated that the two enantiomers were transported mainly by a passive, transcellular mechanism. At concentrations of 5.0–100.0 μmol/l, enantioselective permeability of esmolol was observed. In the absorptive transport, Papp of (S)‐esmolol was smaller than (R)‐esmolol and vice versa for secretory transport. The enantioselectivity disappeared when the drug concentration was increased to 200.0 μmol/l. In conclusion, the transport characteristics of (S)‐ and (R)‐esmolol were distinctly different. An enantioselective carrier‐mediated mechanism in addition to passive diffusion was involved in the transport process of esmolol across Caco‐2 cell monolayers. © 2005 Wiley‐Liss, Inc. Chirality
Combining the enantioselectivity of a cyclodextrin and a diamide selector in a mixed binary gas‐chromatographic chiral stationary phase
Authors: Levkin Pavel A. , Ruderisch Alexander , Schurig Volker
Published: November 2005

The present work reports on the investigation of a mixed binary chiral stationary phase (CSP) prepared by simultaneous attachment of permethylated‐β‐cyclodextrin (D selector) and resorcinarene with pendant l‐ or d‐valine diamide groups (L′ and D′ selectors, respectively) to a polysiloxane matrix via platinum‐catalyzed hydrosilylation. The gas‐chromatographic investigation of a number of racemates on the four different CSPs (D, D′, DD′, and DL′) showed that the enantioselectivity of the individual chiral selectors was retained in the mixed binary CSPs. As a consequence, hydrocarbons, underivatized alcohols, ketones, and almost all proteinogenic amino acid derivatives could be separated simultaneously on each of the mixed CSPs. Matched and mismatched cases of enantioseparation on the mixed binary CSPs were observed but turned out to be of minor importance for enantiomeric separation. In general, more racemates were separated with α ≥ 1.02 on the mixed phases as compared to the single phases. In order to analyze the influence of the presence of the diamide selector on the enantioselectivity of the cyclodextrin selector, a mixed ternary CSP containing the selector D and a racemic mixture of the selectors D′ and L′ [D(D′L′)] was prepared and investigated. Merits and limitations of the approach of mixed binary CSPs are discussed. © 2005 Wiley‐Liss, Inc. Chirality
Elderly subgroup analysis of a randomized phase III study of docetaxel plus platinum combinations versus vinorelbine plus cisplatin for first‐line treatment of advanced nonsmall cell lung carcinoma (TAX 326)
Authors: Belani Chandra P. , Fossella Frank
Published: November 2005

BACKGROUND

Controversy continues over whether elderly patients with advanced nonsmall cell lung carcinoma (NSCLC) should receive platinum‐based chemotherapy. TAX 326 reported improved survival with docetaxel–cisplatin (DC) versus vinorelbine–cisplatin (VC) for advanced NSCLC. DC and docetaxel–carboplatin (DCb) were better tolerated than VC. We analyzed the efficacy and toxicity in patients ages < 65 and ≥ 65 years.

METHODS

Chemotherapy‐naive, TNM Stage IIIB–IV NSCLC patients were randomized to DC (docetaxel 75 mg/m2 and cisplatin 75 mg/m2, d1 q3w), DCb (docetaxel 75 mg/m2 and carboplatin area under the concentration–time curve 6 mg/mL.min, d1 q3w), or VC (vinorelbine 25 mg/m2, d1, 8, 15, and 22 and cisplatin 100 mg/m2, d1 q4w).

RESULTS

Of 1218 patients, 401 were age ≥ 65 years (149/118/134 DC/DCb/VC arms). In the elderly, median survival was 12.6 versus 9.9 months, 1‐year survival was 52% versus 41%, 2‐year survival was 24% versus 17% for DC versus VC, respectively. DCb survival results were similar to those for VC: median, 9.0 months; 1‐year, 38%; 2‐year, 19%. Survival outcomes were similar between elderly and younger patients across treatment arms. Compared with younger patients, elderly patients reported moderately higher incidences of NCI CTC (version 1.0) Grade 3–4 asthenia, infection, and pulmonary toxicities across treatment arms, and diarrhea and sensory neurotoxicity for cisplatin‐containing arms. Most hematologic toxicities occurred with similar incidences between elderly and younger patients, although neutropenia was slightly increased in elderly patients.

CONCLUSION

First‐line docetaxel–cisplatin chemotherapy showed similar activity in elderly and younger patients with advanced/metastatic NSCLC; elderly patients tolerated docetaxel–platinum well despite experiencing slightly more toxicity than younger patients. Cancer 2005. © 2005 American Cancer Society.
Angiosarcoma of the breast
Authors: Vorburger Stephan A. , Xing Yan , Hunt Kelly K. , Lakin Gregory E. , Benjamin Robert S. , Feig Barry W. , Pisters Peter W. T. , Ballo Matthew T. , Chen Lei , Trent Jonathan , Burgess Michael , Patel Shreyaskumar , Pollock Raphael E. , Cormier Janice N.
Published: November 2005

BACKGROUND

Angiosarcoma of the breast is a rare entity. The objectives of this study were to evaluate prognostic factors and determine outcomes in a large contemporary series of patients.

METHODS

Clinical and pathologic factors were analyzed in all patients with angiosarcoma of the breast treated between 1990 and 2003. Overall survival (OS) and disease‐free survival (DFS) were estimated using the methods of Kaplan and Meier. Multivariate analyses were performed to evaluate prognostic factors.

RESULTS

Fifty‐five women with angiosarcoma of the breast were identified. The median age was 49.1 years, and the median follow‐up time was 3.7 years. The median OS and DFS were 2.96 years and 2.26 years, respectively. For the 32 patients withprimaryangiosarcoma of the breast 5‐year OS was 59%. Twenty‐three (42%) patients had received prior radiation therapy for the treatment of breast cancer. These patients with radiation therapy‐associated angiosarcoma were on average 30 years older and less likely to present with distant metastatic disease than patients presenting with radiation‐naive angiosarcoma of the breast. Although radiation‐naive patients appeared to have had better early DFS and OS, the Kaplan–Meier curves were not statistically different between patients with radiation therapy‐associated disease and radiation therapy‐naive patients. On multivariate analysis, tumor recurrence (P= 0.006) was the only significant adverse prognostic factor noted for OS.

CONCLUSIONS

In this series of 55 patients with angiosarcoma of the breast, radiation therapy‐naive angiosarcomas occurred in younger patients, but they behaved similarly to radiation therapy‐associated angiosarcomas. Cancer 2005. © 2005 American Cancer Society.
A population‐based description of glioblastoma multiforme in Los Angeles County, 1974–1999
Authors: Chakrabarti Indro , Cockburn Myles , Cozen Wendy , Wang Ya‐Ping , Preston‐Martin Susan
Published: November 2005

BACKGROUND

There have been reports that the incidence rates of brain tumors have increased over the past few decades, but most have considered all brain tumors together. The authors analyzed the pattern of glioblastoma multiforme (GBM) occurrence in Los Angeles County, California to shed light on the incidence and descriptive epidemiology of this type of brain tumor.

METHODS

Data were obtained from the Los Angeles County Cancer Surveillance Program. Incidence rates were analyzed by gender, race, age at diagnosis, period of diagnosis (1974–1981, 1982–1988, or 1989–1999), and socioeconomic status (SES). In addition, data were stratified according to anatomic subsite. A multivariate model describing changes in rates by each of these variables was constructed.

RESULTS

Age‐specific incidence rates (ASIR) rose sharply after age 30 years. The peak ASIR was at age 70–74 years in males and at age 75–79 years in females. The age‐adjusted incidence rate (AAIR) of GBM increased from 1974 to 1999 by an estimated 2.4% per year among males and 2.8% per year among females. Overall, males had a 60% increased risk of brain tumors compared with females. Males had a higher incidence of GBM compared with females at each anatomic subsite except the posterior fossa. The largest male:female ratio occurred in the occipital lobes. Non‐Latino whites had the highest incidence rates (2.5 per 100,000) followed by Latino whites (1.8 per 100,000), and blacks (1.5 per 100,000). After 1989, compared with the period before magnetic resonance imaging (MRI) was available, there was an increase in GBM incidence rates among those with of higher SES that was most pronounced in females. The incidence of GBM was highest for frontal lobe tumors and for tumors that involved two or more lobes (overlapping tumors), followed by tumors in the temporal and parietal lobes. In the multivariate analysis, year of diagnosis, SES, gender, race (Latino but not black), site, and age at diagnosis all were important predictors of incidence rate.

CONCLUSIONS

GBM incidence increased in Los Angeles County over the last 30 years and especially after 1989, suggesting that the introduction of MRI may have contributed to the increase. Individuals older than age 65 years experienced the greatest increase in incidence over time. Older age, male gender, higher SES, and non‐Latino white race increased the risk of GBM. Previously unreported incidence rates for GBM among Latino whites were significantly lower than among non‐Latino whites but were intermediate between non‐Latino whites and blacks. Cancer 2005. © 2005 American Cancer Society.
Long‐term survivors after gamma knife radiosurgery for brain metastases
Authors: Kondziolka Douglas , Martin Juan J. , Flickinger John C. , Friedland David M. , Brufsky Adam M. , Baar Joseph , Agarwala Sanjiv , Kirkwood John M. , Lunsford L. Dade
Published: November 2005

BACKGROUND

Stereotactic radiosurgery, with or without whole‐brain radiation therapy, has become a valued management choice for patients with brain metastases, although their median survival remains limited. In patients who receive successful extracranial cancer care, patients who have controlled intracranial disease are living longer. The authors evaluated all brain metastasis in patients who lived for ≥ 4 years after radiosurgery to determine clinical and treatment patterns potentially responsible for their outcome.

METHODS

Six hundred seventy‐seven patients with brain metastases underwent 781 radiosurgery procedures between 1988 and 2000. Data from the entire series were reviewed; and, if patients had ≥ 4 years of survival, then they were evaluated for information on brain and extracranial treatment, symptoms, imaging responses, need for further care, and management morbidity. These long‐term survivors were compared with a cohort who lived for < 3 months after radiosurgery (n = 100 patients).

RESULTS

Forty‐four patients (6.5%) survived for > 4 years after radiosurgery (mean, 69 mos with 16 patients still alive). The mean age at radiosurgery was 53 years (maximum age, 72 yrs), and the median Karnofsky performance score (KPS) was 90. The lung (n = 15 patients), breast (n = 9 patients), kidney (n = 7 patients), and skin (melanoma; n = 6 patients) were the most frequent primary sites. Two or more organ sites outside the brain were involved in 18 patients (41%), the primary tumor plus lymph nodes were involved in 10 patients (23%), only the primary tumor was involved in 9 patients (20%), and only brain disease was involved in 7 patients (16%), indicating that extended survival was possible even in patients with multiorgan disease. Serial imaging of 133 tumors showed that 99 tumors were smaller (74%), 22 tumors were unchanged (17%), and 12 tumors were larger (9%). Four patients had a permanent neurologic deficit after brain tumor management, and six patients underwent a resection after radiosurgery. Compared with the patients who had limited survival (< 3 mos), long‐term survivors had a higher initial KPS (P = 0.01), fewer brain metastases (P = 0.04), and less extracranial disease (P < 0.00005).

CONCLUSIONS

Although the expected survival of patients with brain metastases may be limited, selected patients with effective intracranial and extracranial care for malignant disease can have prolonged, good‐quality survival. The extent of extracranial disease at the time of radiosurgery was predictive of outcome, but this does not necessarily mean that patients cannot live for years if treatment is effective. Cancer 2005. © 2005 American Cancer Society.
Diagnostic mammography performance and race
Authors: Yankaskas Bonnie C. , Gill Karminder S.
Published: November 2005

BACKGROUND

A previous study compared the performance (sensitivity, specificity, positive predictive value, and cancer detection rate) of screening mammography in Black and White women. No study, to the authors' knowledge, has evaluated the difference in the performance of diagnostic mammography between Black and White women.

METHODS

Univariate analysis was used to evaluate differences in characteristics and cancers between Black and White women. Stratified and adjusted logistic regression analyses were used to test the association of Black and White race with performance measures of diagnostic mammography.

RESULTS

The sensitivity of diagnostic mammography was higher (91% vs. 84%) and specificity was lower (86% vs. 90%) among Black women compared with White women. After controlling for age, density, self‐reported breast problems, and previous mammography, sensitivity was significantly higher (odds ratio [OR] = 1.82, 95% confidence interval [CI] = 1.22–2.80) and specificity was significantly lower (OR = 0.75, 95% CI = 0.70–0.81) among Black women. The crude cancer detection rate of mammography was higher for Black women (42.6/1000) than for White women (31.0/1000) and Black women had a higher proportion of cancers that were > 2.0 cm (57.4% vs. 46.2%) that were more often poorly differentiated (61.7% vs. 49.3%) and were more often estrogen‐receptor and progesterone‐receptor negative.

CONCLUSIONS

Black women have lower specificity of diagnostic mammography and, consequently, more unnecessary workups than White women. Black women have higher sensitivity of diagnostic mammography, with cancers that are larger and more advanced than White women. Delay in responding to signs and symptoms would explain the size and later stage. However, more research is needed to understand the biologic differences of breast cancer characteristics between Black and White women. Cancer 2005. © 2005 American Cancer Society.
Reduced cancer incidence among patients with schizophrenia
Authors: Barak Yoram , Achiron Anat , Mandel Matilda , Mirecki Ilona , Aizenberg Dov
Published: November 2005

BACKGROUND

The incidence of cancer in patients with schizophrenia has been conversely reported to be higher, lower, or similar to that in the general population. The effects of lifestyle factors such as excess smoking, exposure to neuroleptic medications, and genetic factors that may influence the incidence of cancer in this group are not clear. The current study was performed to evaluate the frequency of cancer in a large cohort of patients with schizophrenia and to determine the standardized incidence ratios (SIRs) of any malignancy in this group.

METHODS

Data regarding the design, setting, and participants of the current study were analyzed from a cohort of 3226 patients with schizophrenia who were enrolled in the computerized health registry of the Abarbanel Mental Health Center between1993–2003. The mean age of the patients at the time of the diagnosis of cancer was 49 ± 14.7 years, with the majority of patients (61%) being male. All patients with schizophrenia records in the database were combined with the records of the Israeli National Cancer Registry to identify pathologically confirmed cancer comorbidity. The cancer incidence rates among patients with schizophrenia were compared with the expected incidence in an age‐matched and gender‐matched general population sample for the same time interval.

RESULTS

Among 1247 female patients with schizophrenia, 22 (1.8%) developed breast cancer and 68 (5.5%) developed cancers of any type. Fifty‐two of the 1979 male schizophrenic patients (2.6%) developed cancer. The SIRs were 0.58 (95% confidence interval [95% CI], 0.48–0.69) with a P value of < 0.05 for all cancers in the cohort, and 0.60 (95% CI, 0.37–0.90) for female breast cancer.

CONCLUSIONS

The results of the current study demonstrate a reduced risk of cancer in patients with schizophrenia. The mechanisms responsible for the lower risk need be investigated further. Cancer 2005. © 2005 American Cancer Society.
Dynamic Grid tasks composition and distribution through agents
Authors: Negri A. , Poggi A. , Tomaiuolo M. , Turci P.
Published: November 2005

This paper presents a multi‐agent system called GAIN (Grid Agent Infrastructure), which can be used for the development of flexible agent‐based Grid systems. The system supports users both in the development and execution of Grid applications. In particular, GAIN allows the definition of workflow applications by composing different tasks made available by the Grid nodes. Furthermore, it follows the different phases of the execution of the workflow providing transparent allocation and re‐allocation of the tasks on the different nodes of the Grid. A first prototype of the system has been realized by using the JADE agent development software and it has been tested in lab trials involving a network of different JADE platforms. In these trials, tasks provided both by the agents of the system and by external legacy software systems have been composed. Copyright © 2005 John Wiley & Sons, Ltd.
Using the Grid paradigm for multimedia applications
Authors: Zaia Angelo , Bruneo Dario , Puliafito Antonio
Published: November 2005

Very popular mobile devices such as cellular phones, laptops, and handheld and tablet PCs are becoming more and more powerful. One of today's trends is to access multimedia services from this sort of device. Their low capacity in terms of storage, and their high inclination to wireless connection, suggest the use of streaming techniques instead of media download. Mobile devices are, at present, dramatically unhomogeneous for visualization and audio reproduction characteristics. Consequently, today multimedia delivery systems are very customized for some device profiles or for wireless connection types. Transcoding techniques are used in order to adapt the same media source to the multiple hardware profiles. Client‐based transcoding techniques show their weakness in high energy consumption, and server‐based transcoding techniques suffer from scalability problems. In this paper we propose a scalable distributed multimedia server based on the Grid computing paradigm, which can adapt media content to the device profile and/or to the connection link. Copyright © 2005 John Wiley & Sons, Ltd.
Designing Grid services for multimedia streaming in an e‐learning environment
Authors: Amoretti M. , Bertolazzi R. , Reggiani M. , Zanichelli F. , Conte G.
Published: November 2005

Next generation e‐learning platforms will support cooperative use of geographically distributed educational resources as an aggregated environment, thus enabling a more effective knowledge exchange. Sharing this goal, our research activity addresses the definition and implementation of a service‐based infrastructure for content distribution and multimedia streaming. The proposed architecture provides enough flexibility, extensibility, and scalability to cope with the ever‐increasing heterogeneity and mobility of edge devices. In this paper, we initially illustrate the general objectives and requirements in the development of an e‐learning oriented application for multimedia content discovery, access, and distribution in a virtual community. Architectural considerations have motivated the use of Grid technologies as they provide access to resources and services of different administrative domains in a transparent, seamless, and secure way. The Grid‐based architecture has been endowed with a number of services including discovery and streaming of multimedia objects, multimedia content update, quality of service (QoS) management, and support for user authentication and authorization. A multimedia application based on the architecture is described and evaluated on a multi‐domain network. Copyright © 2005 John Wiley & Sons, Ltd.
Optimized green fluorescent protein variants provide improved single cell resolution of transgene expression in ascidian embryos
Authors: Zeller Robert W. , Weldon Don S. , Pellatiro Mark A. , Cone Angela C.
Published: November 2005

The green fluorescent protein (GFP) is used extensively to monitor gene expression and protein localization in living cells, particularly in developing embryos from a variety of species. Several GFP mutations have been characterized that improve protein expression and alter the emission spectra to produce proteins that emit green, blue, cyan, and yellow wavelengths. DsRed and its variants encode proteins that emit in the orange to red wavelengths. Many of these commercially available fluorescent proteins have been “codon optimized” for maximal levels of expression in mammalian cells. We have generated several fluorescent protein color variants that have been codon optimized for maximal expression in the ascidian Ciona intestinalis. By analyzing quantitative time‐lapse recordings of transgenic embryos, we demonstrate that, in general, our Ciona optimized variants are detected and expressed at higher levels than commercially available fluorescent proteins. We show that three of these proteins, expressed simultaneously in different spatial domains within the same transgenic embryo are easily detectable using optimized fluorescent filter sets for epifluorescent microscopy. Coupled with recently developed quantitative imaging techniques, our GFP variants should provide useful reagents for monitoring the simultaneous expression of multiple genes in transgenic ascidian embryos. Developmental Dynamics 235:456–467, 2006. © 2005 Wiley‐Liss, Inc.
The design and implementation of session‐based IDS
Authors: Mizutani Masayoshi , Shirahata Shin , Minami Masaki , Murai Jun
Published: November 2005

One of the techniques for detecting malicious communications from network traffic is to use a network‐based intrusion detection system (IDS). However, since an existing IDS handles a low‐risk alert for which an attack failed and a high‐risk alert for which an attack succeeded in a similar manner, malicious communications cannot be detected properly unless a risk analysis is performed for each alert. This means that as the number of detection targets of the IDS increases, the cost of the risk analysis for every alert also increases proportionally. In other words, as the number of detection targets continues to increase, it becomes difficult to effectively deal with network incidents by using the IDS. In this paper, the authors focus on the fact that by continuously monitoring communications after an attack, the success or failure of the attack can be determined from the responses. They define these continuous communications as a session and design and implement a session‐based IDS that enables the risk to be evaluated immediately and automatically. They also evaluate the effectiveness of the session‐based IDS in an actual operating network. The results showed that this research lowered the operational cost of the IDS and enabled network incidents to be dealt with effectively. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(3): 46–58, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20251
A VoIP packet loss concealment technique taking account of pitch variation in pitch waveform replication
Authors: Aoki Naofumi
Published: November 2005

In order to realize speech communication by means of best‐effort packet communications, which is inherently unsuitable for real‐time processing, VoIP addresses the fundamental problem of degradation of communications quality by errors such as packet loss and delay. In the present research, based on the two‐sided PWR method, an error concealment technique based on waveform replication, a method of performing error concealment more effectively by taking account of the pitch variations of the speech data in the loss frame is proposed. Evaluation experiments with SNR, PESQ, and DMOS as the metrics suggest the effectiveness of the proposed method. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(3): 1–9, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20268
On the Usefulness of Bond Orders and Overlap Populations to Chalcogen–Nitrogen Systems
Authors: Oláh Julianna , Blockhuys Frank , Veszprémi Tamás , Van Alsenoy Christian
Published: November 2005

Bond orders calculated using the Mayer, Wiberg or NAO methodologies are incompatible with the observed bond lengths in chalcogen–nitrogen systems. To study this discrepancy four types of bond orders and three types of (scaled) overlap populations have been used to determine the bonding in these systems. A new overlap population based on the Hirshfeld partitioning of the electron density is compared to the Mayer, Wiberg, NAO and Fuzzy bond order schemes and the Mulliken and Fuzzy overlap population schemes. The correlation between the investigated bond orders and overlap populations is excellent for common organic molecules, but the (scaled) Hirshfeld and Fuzzy overlap population schemes produce the best results for a series of chalcogen‐nitrogen systems. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Preparation of Semiconductor/Polymer Coaxial Nanocables by a Facile Solution Process
Authors: Xiong Shenglin , Fei Linfeng , Wang Zhenghua , Zhou Hong Yang , Wang Weizhi , Qian Yitai
Published: November 2005

We report on the preparation of ultralong semiconductor tellurium/cross‐linked PVA coaxial nanocables with a core 20–30 nm in diameter and a surrounding sheath about 5–20 nm in thickness by a simple hydrothermal process. The length of these nanocables can be up to 500–800 μm. In the present synthesis PVA was used as the reducing agent to react with Na2TeO3, and it also serves as the capping reagent and the source of the sheaths. The synergistic effects of the interaction of cross‐linked PVA with the tellurium nanowires could play an important role in the formation of the morphology of the resulting products.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Mu‐34: a New Porous Layered Fluorogallophosphate Material Obtained by in Situ Generation of Ethylamine
Authors: Lakiss Louwanda , Simon‐Masseron Angélique , Porcher Florence , Patarin Joël
Published: November 2005

A new two‐dimensional microporous fluorogallophosphate with porous layers, named Mu‐34, has been synthesized by in situ generation of ethylamine as the structure‐directing agent, the latter arising from the decomposition of ethylformamide. The fluorogallophosphate Mu‐34, Ga6P8O32FC14N7H56 (Z = 2), crystallizes in the triclinic space group P$\bar {1}$ with the following unit cell parameters: a = 11.0832(6), b = 11.393(6), c = 21.335(1) Å, α = 100.62(4), β = 99.66(5), γ = 108.34(5)°. The structure was solved from single crystal XRD data. This new fluorogallophosphate displays porous layers with apertures delimited by 12‐membered rings intercalated by protonated ethylamine molecules. Mu‐34 was also characterized by powder XRD, SEM, elemental and thermal analyses, and 13C, 19F, and 31P MAS solid state NMR spectroscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Ruthenium Metallodendrimers Based on Nitrile‐Functionalized Poly(alkylidene imine)s
Authors: Ornelas Cátia , Vertlib Viatcheslav , Rodrigues João , Rissanen Kari
Published: November 2005

The preparation of the first‐ and second‐generation of nitrile‐functionalized poly(alkylidene imine) dendrimers with the organometallic ruthenium complex [Ru(η5‐C5H5)(PPh3)2Cl] peripherally attached is described. The reaction of N,N′‐bis(cyanomethyl)piperazine (1), N,N′‐bis[N′′,N′′′‐bis(cyanoethyl)aminoethyl]piperazine (2), or N,N,N′,N′‐tetrakis(cyanoethyl)ethylenediamine (3) with [Ru(η5‐C5H5)(PPh3)2Cl] (4) in the presence of TlPF6 gives the new air‐stable ruthenium metallodendrimers 5, 6, and 7, respectively. These stable metallodendrimers are easily prepared and represent a novel quantitative method to solidify and chromatographically purify the otherwise semi‐liquid nitrile‐functionalized poly(alkylidene imine) dendrimers. The compounds were fully characterized by IR and 1H, 13C, and 31P NMR spectroscopy, and mass spectrometry. These dendrimers represent the first example of the utilization of nitrile‐functionalized poly(alkylidene imine)s as cores in the preparation of metallodendrimers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Photoreactions of Tricyclic α‐Cyclopropyl Ketones and Unsaturated Enones – Synthesis of Polyquinanes and Analogous Ring Systems
Authors: Tzvetkov Nikolay T. , Neumann Beate , Stammler Hans‐Georg , Mattay Jochen
Published: November 2005

Polycyclic systems of both angular and propellane type have been synthesized through intramolecular radical cyclization reactions, by photochemically induced electron transfer of tricyclic α‐cyclopropyl ketones or by photolysis of unsaturated enones. In general, tricyclic α‐cyclopropyl ketones, each bearing an alkynyl or alkenyl side chain at the position γ to the carbonyl group, were used as starting materials. The reactions resulted in regioselective cleavage of one cyclopropyl bond with formation of tri‐ to tetracyclic ring systems by a tandem fragmentation‐radical/radical anionic reaction pathway. The regioselectivity of the cyclization (exo/endo) depends on the length of the unsaturated side chain. In cases involving α‐cyclopropane derivatives with alkoxymethyl side chains, various non‐cyclization processes were observed. In addition, the photoinduced cyclization of the corresponding bicyclic enone derivatives with the same unsaturated side chains afforded tetra‐ and tricyclic products of propellane type in good yields and with high stereoselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Reconfiguration of the Symmetry and Charge‐Transfer Characteristics of a Triply Crowned 1,3,5‐Tris(arylalkynyl)mesitylene by Successive Metal Ion Complexation
Authors: Hennrich Gunther , Rurack Knut , Spieles Monika
Published: November 2005

A triply benzocrown‐ether‐functionalized trialkynylmesitylene derivative with C3 symmetry as well as its linear analogue have been synthesized and their optical properties have been studied by UV/Vis absorption, steady‐state and time‐resolved fluorescencece spectroscopy. The spectroscopic investigation of the uncomplexed compounds revealed the nature of the electronic and excitonic communication pathway in the ground and excited states of the all‐meta‐substituted chromophore system. Upon cation complexation, the octopolar character of the free trialkynyl compound becomes dipolar and finally returns to octopolar in the fully complexed species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Enantioselective Diamination of Alkenes by Use of a Bisimidoosmium Reagent with the Aid of Chiral Catalysts
Authors: Almodovar Iriux , Hövelmann Claas H. , Streuff Jan , Nieger Martin , Muñiz Kilian
Published: November 2005

The development of a new method for the diamination of alkenes is reported. It is based on a reaction in the presence of stoichiometric or catalytic amounts of chiral auxiliaries, which permits the direct synthesis of enantiomerically enriched osmaimidazolidines. The combined application of a catalyst‐directing oxazolidinone group and a titanium catalyst results in enantioselective alkene diamination with enantiomer ratios of up to 95:5. Absolute configurations of representative osmaimidazolidine products were established unambiguously by solid‐state structure analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Generalized Procedure for the One‐Pot Preparation of Glycosyl Azides and Thioglycosides Directly from Unprotected Reducing Sugars under Phase‐Transfer Reaction Conditions
Authors: Kumar Rishi , Tiwari Pallavi , Maulik Prakas R. , Misra Anup K.
Published: November 2005

Per‐O‐acetylated glycosyl azides and thioglycosides were prepared in excellent yield directly from unprotected reducing sugars through in situ generation of per‐O‐acetylated glycosyl bromides by a generalized one‐pot procedure under phase‐transfer conditions. Stereoselective products were formed with complete inversion at the anomeric centers of the glycosyl bromides to provide a general high‐yielding procedure for the preparation of 1,2‐trans‐glycosyl azides and thioglycosides.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Postsynthesis modification of a cellulose acetate ultrafiltration membrane for applications in water and wastewater treatment
Authors: Morão A. , Escobar I. C. , Pessoa de Amorim M. T. , Lopes A. , Gonçalves I. C.
Published: November 2005

A technique for postsynthesis modification of a cellulose acetate ultrafiltration membrane with possible application in water and wastewater treatment is studied. The technique used an oxidizing agent (persulfate) to develop free radicals on the membrane surface, and that was expected to promote grafting of hydrophilic macromolecules (polyethylene glycol). A chain‐transfer agent (2‐mercaptoethanol) was tested to control the grafting process, avoiding the formation of long chains that usually lead to high permeability losses in other graft techniques. The modifications aimed at the decrease of the fouling susceptibility of the membrane studied. The possibility of an increase in rejection was also investigated. The membrane was characterized before and after modification, by attenuated total reflectance–Fourier transform‐infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and in terms of the rejection of neutral reference solutes. The information given by the different techniques of characterization provided strong evidences of the occurrence of modification, although permeation of (real) foulants was the decisive test. To obtain information about the fouling tendency of the nonmodified and modified membranes, two different kinds of foulants were used: a humic acid (usually found in surface waters) and textile auxiliaries (representing one of the most important industries in Portugal). The results showed an increase in the rejections of the humic acid, and significant improvements in the performance of the membrane with respect to fouling tendency in the case of the textile auxiliaries. © 2005 American Institute of Chemical Engineers Environ Prog, 2005
Representing the bed roughness of coarse‐grained streams in computational fluid dynamics
Authors: Carney Shaun K. , Bledsoe Brian P. , Gessler Daniel
Published: November 2005

Computational fluid dynamics (CFD) applications are increasingly utilized for modelling complex flow patterns in natural streams and rivers. Although CFD has been successfully implemented to model many complex flow situations in natural stream settings, adequately characterizing the effects of gravel and cobble beds on flow hydraulics in CFD is a difficult challenge due to the scale of roughness lengths and the inadequacy of traditional roughness representations to characterize flow profiles in situations with large roughness elements. An alternative method of representing gravel and cobble beds is presented. Appropriate drag forces associated with different grain sizes are computed and included in the momentum equations to account for the influence of a hydraulically rough bed. Comparisons with field measurements reveal reasonable agreement between measured and modelled profiles of spatially averaged velocity and turbulent kinetic energy, and model fidelity to the non‐logarithmic behaviour of the velocity profiles. The novel method of representing coarse beds expands the utility of CFD for investigating physical processes in natural channels with large bed roughness. Copyright © 2005 John Wiley & Sons, Ltd.
On the interplay between inertial and viscoelastic effects for the flow in weakly modulated channels
Authors: Abu‐Ramadan Ehab , Khayat Roger E.
Published: November 2005

The flow inside a spatially modulated channel is examined for viscoelastic fluids of the Oldroyd‐B type. The lower wall is flat and the upper wall is sinusoidally modulated. The modulation amplitude is assumed to be small. Thus, a regular perturbation expansion of the flow field coupled to a variable‐step finite‐difference scheme is used to solve the problem. Convergence and accuracy assessment against earlier experimental results indicate that there is a significant range of validity of the perturbation approach. The influences of wall geometry, inertia and viscoelasticity on the flow kinematics and stresses are investigated systematically. In particular, the interplay between the flow and fluid parameters effects on the conditions for the onset of backflow, number of vortices, their size and location is revealed. The distance between the flow separation and reattachment locations identifies the vortex size. Non‐monotonic dependence of the vortex size on elasticity is reported. The critical conditions for the onset of negative elasticity effects on vortex size are identified. The critical Reynolds number for the onset of backflow initially decreases then levels off or even increases as elasticity increases. For highly elastic fluid and large enough Reynolds number, more than one vortex appear near the lower wall. Copyright © 2005 John Wiley & Sons, Ltd.
A grid‐free upwind relaxation scheme for inviscid compressible flows
Authors: Balasubramanyam S. , Raghurama Rao S. V.
Published: November 2005

A new grid‐free upwind relaxation scheme for simulating inviscid compressible flows is presented in this paper. The non‐linear conservation equations are converted to linear convection equations with non‐linear source terms by using a relaxation system and its interpretation as a discrete Boltzmann equation. A splitting method is used to separate the convection and relaxation parts. Least squares upwinding is used for discretizing the convection equations, thus developing a grid‐free scheme which can operate on any arbitrary distribution of points. The scheme is grid free in the sense that it works on any arbitrary distribution of points and it does not require any topological information like elements, faces, edges, etc. This method is tested on some standard test cases. To explore the power of the grid‐free scheme, solution‐based adaptation of points is done and the results are presented, which demonstrate the efficiency of the new grid‐free scheme. Copyright © 2005 John Wiley & Sons, Ltd.
Second‐order entropy diminishing scheme for the Euler equations
Authors: Coquel F. , Helluy P. , Schneider J.
Published: November 2005

In several papers of Bouchut et al., Coquel and Le Floch (Math. Comput. 1996; 65(216):1439–1461; Numer. Math. 1996; 74(01):1–34), a general methodology has been developed to construct second‐order finite volume schemes for hyperbolic systems of conservation laws satisfying the entire family of entropy inequalities. This approach is mainly based on the construction of an entropy diminishing projection. Unfortunately, the explicit computation of this projection is not always easy. In the first part of this paper, we carry out this computation in the important case of the Euler equations of gas dynamics. In the second part, we present several numerical applications of the projection in the context of finite volume schemes. Copyright © 2005 John Wiley & Sons, Ltd.
On steady state computation of turbulent flows using k–ε models approximated by the time splitting method
Authors: Du Tao , Wu Zi‐Niu , Wang Bing
Published: November 2005

The time splitting method is frequently used in numerical integration of flow equations with source terms since it allows almost independent programming for the source part. In this paper we will consider the question of convergence to steady state of the time splitting method applied to k–ε turbulence models. This analysis is derived from a properly defined scalar study and is carried out with success for the coupled k–ε equations. It is found that the time splitting method does not allow convergence to steady state for any choice of finite values of the time step. Numerical experiments for some typical turbulent compressible flow problems support the fact that the time splitting method is always nonconvergent, while its nonsplitting counterpart is convergent. Copyright © 2005 John Wiley & Sons, Ltd.
Spectral element benchmark simulations of natural convection in two‐dimensional cavities
Authors: Gjesdal Thor , Wasberg Carl Erik , Reif Bjørn Anders Pettersson
Published: November 2005

This paper reports the results of spectral element simulations of natural convection in two‐dimensional cavities. In particular, a detailed comparison is performed with the reference data for the 8:1 cavity at Ra=3.4 × 105 recently described by Christon et al. [Int. J. Numer. Methods Fluids 2002; 40:953–980]. The Navier–Stokes equations augmented by the Boussinesq approximation to represent buoyancy effects are solved by a numerical method based on a spectral element discretization and operator splitting. The computed solutions agree closely with the reference data for both the square and the rectangular cavity configurations. Copyright © 2005 John Wiley & Sons, Ltd.
Third‐order‐accurate semi‐implicit Runge–Kutta scheme for incompressible Navier–Stokes equations
Authors: Nikitin Nikolay
Published: November 2005

A semi‐implicit three‐step Runge–Kutta scheme for the unsteady incompressible Navier–Stokes equations with third‐order accuracy in time is presented. The higher order of accuracy as compared to the existing semi‐implicit Runge–Kutta schemes is achieved due to one additional inversion of the implicit operator I‐τγL, which requires inversion of tridiagonal matrices when using approximate factorization method. No additional solution of the pressure‐Poisson equation or evaluation of Navier–Stokes operator is needed. The scheme is supplied with a local error estimation and time‐step control algorithm. The temporal third‐order accuracy of the scheme is proved analytically and ascertained by analysing both local and global errors in a numerical example. Copyright © 2005 John Wiley & Sons, Ltd.
PEM Fuel Cell Stack Cold Start Thermal Model
Authors: Sundaresan M. , Moore R. M.
Published: November 2005

For passenger fuel cell vehicles (FCVs), customers will expect to start the vehicle and drive almost immediately, implying a very short system warmup to full power. While hybridization strategies may fulfill this expectation, the extent of hybridization will be dictated by the time required for the fuel cell system to reach normal operating temperatures. Quick‐starting fuel cell systems are impeded by two problems: (i) the freezing of residual water or water generated by starting the stack at below freezing temperatures and (ii) temperature‐dependent fuel cell performance, improving as the temperature reaches the normal range. Cold start models exist in the literature; however, there does not appear to be a model that fully captures the thermal characteristics of the stack during sub‐freezing startup conditions. Existing models lack the following features: (i) modeling of stack internal heating methods (other than stack reactions) and their impact on the stack temperature distribution and (ii) modeling of endplate thermal mass effect on end cells and its impact on the stack temperature distribution. Unlike a lumped model, which may use a single temperature as an indicator of the stack's thermal condition, a model considering individual cell layers can reveal the effect of the endplate thermal mass on the end cells, and accommodate the evaluation of internal heating methods that may mitigate this effect. This paper presents and discusses results from simulations performed with a new, layered model.