bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Entry in the NBA Draft
Authors: Groothuis Peter A. , Hill James Richard , Perri Timothy J.
Published: May 2007

In an influential article, “Unraveling in Matching Markets,"Li and Rosen (1998) note that the first 7 picks, and 17 among 29 first-round selections, of the 1997 National Basketball Association (NBA) draft were not college seniors. By 2004, the first pick was a high school senior, and 25 of the first 29 picks were not college seniors. We suggest that recent NBA contract provisions implemented to slow the early entry of talented players have instead provided additional incentives to both players and firms for early entry into the NBA. We explore two competing models that predict why teams choose a talented player sooner in the new rookie contract system: the human capital model and Lazear's option value model. To test why unraveling occurs, we use a panel study of all NBA players for 12 years, from 1989 through 2002.
Molecular mechanisms underlying anti-inflammatory phenotype of neonatal splenic macrophages
Authors: Chelvarajan Lakshman , Popa Diana , Liu Yushu , Getchell Thomas V , Stromberg Arnold J , Bondada Subbarao
Published: May 2007

Neonatal humans and rodents are susceptible to infection with encapsulated bacteria as a result of an inability to make antibodies to capsular polysaccharides. This is partly a result of decreased production of proinflammatory cytokines by splenic macrophages (MΦ) from neonates. In this study, we show that when stimulated with a variety of agonists to TLR2, -4, and -9, neonatal MΦ make less proinflammatory cytokines and more IL-10 than adult MΦ. IL-10 appears to have a role in the decreased proinflammatory cytokine production, as neonatal MΦ treated with anti-IL-10 receptor antibody or from IL-10–/– mice produced levels of proinflammatory cytokines at a level comparable with that produced by adult MΦ. A microarray analysis of RNA from resting and LPS-stimulated MΦ from neonatal and adult mice showed that expression of a large number of genes encoding cytokines, chemokines, and their receptors was decreased dramatically in the neonatal MΦ, although some cytokines, including IL-10 and IL-16, were enhanced. Several genes in the TLR signaling pathway leading to NF-κB activation were down-regulated, which may account for the decreased chemokine and cytokine synthesis. It is surprising that p38α MAPK, known to be required for TLR-induced cytokine secretion, was enhanced in the neonatal MΦ. Our studies with the p38 MAPK inhibitor SB203580 suggested that excess p38 MAPK activity can be inhibitory for TLR2-, -4-, and -9-induced production of proinflammatory cytokines but not IL-10. The anti-inflammatory phenotype of the neonatal Mφ may be unique to the developing organism, although it compromises the neonate’s ability to respond to encapsulated bacteria.
Macroseismic Study of the Zemmouri Earthquake of 21 May 2003 (Mw 6.8, Algeria)
Authors: Harbi A. , Maouche S. , Ousadou F. , Rouchiche Y. , Yelles-Chaouche A. , Merahi M. , Heddar A. , Nouar O. , Kherroubi A. , Beldjoudi H. , Ayadi A. , Benouar D.
Published: May 2007

The 21 May 2003 Zemmouri earthquake ( Mw=6.8), which killed 2,278 people, injured 11,450, made 250,000 homeless, and destroyed or seriously damaged 6,000 buildings and 20,800 housing units, is the most significant earthquake to affect Algeria since the 1980 El Asnam earthquake ( Ms=7.3). This paper presents the report of the macroseismic survey conducted by the Centre of Research in Astronomy, Astrophysics, and Geophysics (CRAAG, Algeria) immediately after the earthquake. The collected data set has led to a comprehensive evaluation of damage and estimation of intensity at about 600 sites, a number never reached in previous earthquake damage surveys. The produced isoseismal map portrays the spatial distribution of intensities from III to X EMS. A map highlighting the damage distribution, where various geological and hydrological phenomena are reported, is also presented. The extent of the socioeconomic impact of this event confirmed that Algerian buildings are highly vulnerable to the recurrence of destructive earthquakes.
Fragility of Hydraulic Elevators for Use in Performance-Based Earthquake Engineering
Authors: Porter Keith
Published: May 2007

New performance-based earthquake engineering methods developed by the Pacific Earthquake Engineering Research Center, the Applied Technology Council, and others include damage analysis at a highly detailed level, requiring the compilation of fragility functions for a large number of damageable generic structural and nonstructural components. This brief paper presents the development of a fragility function for hydraulic elevators. It uses post-earthquake survey data from 91 elevators in nine California locations after two earthquakes. Surveys were used to collect data on facilities and elevators. Ground-motion records from the California Integrated Seismic Network were used to estimate engineering demands at each site. Binary regression analysis was used to fit a fragility function, which takes the form of a lognormal cumulative distribution function with median value of PGA=0.42 g and logarithmic standard deviation of 0.3. The fragility function appears to be reasonable based on four criteria.
A Screening Procedure for Seismic Risk Assessment in Urban Building Stocks
Authors: Sucuoğlu Haluk , Yazgan Ufuk , Yakut Ahmet
Published: May 2007

An effective step for seismic risk mitigation in large urban areas under high seismic risk is to identify the most vulnerable buildings that may sustain significant damage during a future earthquake. Once they are identified properly, existing seismic risks may be reduced either by retrofitting such buildings, or by replacing them with new buildings in view of a particular risk-mitigation planning strategy. A fast and simple seismic risk-assessment procedure for vulnerable urban building stocks is proposed in this study. It is basically a sidewalk survey procedure based on observing selected building parameters from the street side, and calculating a performance score for determining the risk priorities for buildings. Statistical correlations have been obtained for measuring the sensitivity of damage to the assigned performance score by employing a database consisting of 454 damaged buildings surveyed after the 1999 Düzce earthquake in Turkey. The results revealed that the proposed screening procedure provides a simple but effective tool for selecting those buildings that have significant damage risk. These buildings have to be subjected to a more detailed assessment for a final decision on their seismic risk level.
Design Approach Based on UAFR Spectra for Structures with Displacement-Dependent Dissipating Elements
Authors: Rivera J. Luz , Ruiz Sonia E.
Published: May 2007

In the first part of this paper an algorithm is proposed to obtain demand hazard curves and, from them, seismic-response spectra with uniform annual failure rates for single-degree-of-freedom (SDOF) systems with energy-dissipating devices (EDDs). In the second part, a performance-based dual-level approach is proposed for the design of buildings with EDDs. The criterion establishes acceptance conditions (related to serviceability—and to ultimate limit-states) that correspond to the main system and to the dissipating elements. The uncertainties implicit in the transformation between the response of SDOF and MDOF systems with EDDs are taken into account by means of their demand hazard curves. The reliability-based dual-level design criterion proposed is illustrated by means of a ten-story reinforced concrete building rehabilitated with steel energy-dissipating devices.
A Prioritization Scheme for Seismic Intervention in School Buildings in Italy
Authors: Grant Damian N. , Bommer Julian J. , Pinho Rui , Calvi G. Michele , Goretti Agostino , Meroni Fabrizio
Published: May 2007

A seismic rehabilitation program is being implemented to address the vulnerability of a large proportion of Italian building stock. A risk-management framework, initially only for Italian school buildings, has been developed to assign priorities for the rehabilitation, and to give timescales within which retrofit or demolition must take place. Since it is not practical to carry out detailed assessment for around 60,000 Italian schools, the framework is a multiple-level procedure that aims to identify the highest-risk buildings based on filters of increasing detail, and reduces the size of the building inventory at each step. Finally, priorities and timescales are assigned based on vulnerability, seismic hazard, and building occupancy, within a general framework with parameters that must be assigned by the relevant authorities. The methodology is transparent, technically based, and flexible enough to be adapted for other building types or regions.
A Probe into the Seismic History of Athens, Greece from the Current State of a Classical Monument
Authors: Psycharis Ioannis N.
Published: May 2007

Based on the current deformation of a column of the temple of Olympios Zeus (Olympieion) in Athens, Greece, a backward analysis is performed in an effort to investigate the seismic history of the area during the last 2,000 years that the monument has been standing. The analysis inevitably contains many ambiguities, due to the nonlinearity and sensitivity of the seismic response, and the unknown geometry of the structure during each era of its life. In spite of these drawbacks, conclusions can be drawn; these, however, should be verified by similar analyses of other nearby monuments. The results show that the present state of the monument could be the result of: many medium-size, typical, near-field earthquakes with a PGV around 30 cm/s and with an average return period of about 250 years; or a smaller number of stronger earthquakes with a PGV around 50 cm/s and a return period of about 500 years; or a single event with a PGV up to 100 cm/s. It seems unlikely that earthquakes containing pulses of long periods (greater than 1.2 sec) have occurred.
Fragility Functions for Modern Reinforced-Concrete Beam-Column Joints
Authors: Brown Peter C. , Lowes Laura N.
Published: May 2007

Fragility functions are developed to predict the method of repair required for modern reinforced-concrete beam-column building joints subjected to earthquake loading. These fragility functions, in combination with similar fragility functions developed previously for older joints, are used to compare damage progression in older versus modern joints. To develop fragility functions for modern joints, the results of previous experimental investigations are used to generate empirical relationships between damage and earthquake demand, damage states are linked deterministically with commonly employed methods of repair, and the empirical data are modeled using a standard probability distribution. The demand parameters, damage states, methods of repair, and probability distribution used in the current study are chosen to facilitate comparison with results from the previous study. The results of this study are a family of fragility functions that can be used to predict the method of repair required for a modern joint damaged due to earthquake loading and an improved understanding of the relative vulnerability of older versus modern components.
Pharmacological and Physiological Characterization of d[Leu4, Lys8]Vasopressin, the First V1b-Selective Agonist for Rat Vasopressin/Oxytocin Receptors
Authors: Pena Ana , Murat Brigitte , Trueba Miguel , Ventura Maria A. , Bertrand Gyslaine , Cheng Ling Ling , Stoev Stoytcho , Szeto Hazel H. , Wo Nga , Brossard Gabrielle , Serradeil-Le Gal Claudine , Manning Maurice , Guillon Gilles
Published: May 2007

Recently, we synthesized and characterized the first selective V1b vasopressin (VP)/oxytocin receptor agonist, d[Cha4]arginine vasopressin. However, this agonist was only selective for the human receptors. We thus decided to design a selective V1b agonist for the rodent species. We started from previous observations showing that modifying [deamino1,Arg8]VP in positions 4 and 8 altered the rat VP/oxytocin receptor selectivity. We synthesized a series of 13 [deamino1,Arg8]VP analogs modified in positions 4 and 8. Among them, one seemed very promising, d[Leu4, Lys8]VP. In this paper, we describe its pharmacological and physiological properties. This analog exhibited a nanomolar affinity for the rat, human, and mouse V1b VP receptors and a strong V1b selectivity for the rat species. On AtT20 cells stably transfected with the rat V1b receptor, d[Leu4, Lys8]VP behaved as a full agonist on both phospholipase C and MAPK assays. Additional experiments revealed its ability to induce the internalization of enhanced green fluorescent protein-tagged human and mouse V1b receptors as expected for a full agonist. Additional physiological experiments were performed to further confirm the selectivity of this peptide. Its antidiuretic, vasopressor, and in vitro oxytocic activities were weak compared with those of VP. In contrast, used at low doses, its efficiency to stimulate adrenocorticotropin or insulin release from mouse pituitary or perfused rat pancreas, respectively, was similar to that obtained with VP. In conclusion, d[Leu4, Lys8]VP is the first selective agonist available for the rat V1b VP receptor. It will allow a better understanding of V1b receptor-mediated effects in rodents.
Sensory Stimuli Directly Acting at the Central Nervous System Regulate Gastric Ghrelin Secretion. An ex Vivo Organ Culture Study
Authors: Seoane Luisa M. , Al-Massadi Omar , Caminos J. Eduardo , Tovar Sulay A. , Dieguez Carlos , Casanueva Felipe F.
Published: May 2007

Ghrelin, a novel gastrointestinal hormone involved in GH regulation, has been postulated as a relevant orexigenic peptide released by splanchnic tissues. Descriptive studies have shown that plasma ghrelin levels increase in states of negative energy balance or fasting, while decreasing in obesity and after feeding. In the present study, a novel organ-culture model of gastric tissue explants obtained from rat donors has been validated for ex vivo experiments. Fasting induced gastric ghrelin release as well as ghrelin mRNA expression that were reflected in plasma. Interestingly, those changes were fully reverted by 15 min of refeeding before stomach extraction. Unexpectedly, when animals were allowed 15 min before explant extraction to see or smell, but not eat, the food (tease feeding), ghrelin secretion was suppressed just like in gastric explants from refed animals. This effect was blocked when the animals were subjected to surgical vagotomy or treated with atropine sulphate. In conclusion, gastric explants were a suitable model for testing ghrelin mechanism of secretion in vitro, and they were found to maintain memory of the previously received signals. Similar to feeding, tease feeding resulted in suppression of ghrelin discharge by explants.
Disruption of Peripheral Leptin Signaling in Mice Results in Hyperleptinemia without Associated Metabolic Abnormalities
Authors: Guo Kaiying , McMinn Julie E. , Ludwig Thomas , Yu Yi-Hao , Yang Guoqing , Chen Lulu , Loh Daniella , Li Cai , Chua Streamson , Zhang Yiying
Published: May 2007

Although central leptin signaling appears to play a major role in the regulation of food intake and energy metabolism, the physiological role of peripheral leptin signaling and its relative contribution to whole-body energy metabolism remain unclear. To address this question, we created a mouse model (Cre-Tam mice) with an intact leptin receptor in the brain but a near-complete deletion of the signaling domain of leptin receptor in liver, adipose tissue, and small intestine using a tamoxifen (Tam)-inducible Cre-LoxP system. Cre-Tam mice developed marked hyperleptinemia (∼4-fold; P < 0.01) associated with 2.3-fold increase (P < 0.05) in posttranscriptional production of leptin. Whereas this is consistent with the disruption of a negative feedback regulation of leptin production in adipose tissue, there were no discernable changes in energy balance, thermoregulation, and insulin sensitivity. Hypothalamic levels of phosphorylated signal transducer and activator of transcription 3, neuropeptide expression, and food intake were not changed despite hyperleptinemia. The percentage of plasma-bound leptin was markedly increased (90.1–96 vs. 41.8–74.7%; P < 0.05), but plasma-free leptin concentrations remained unaltered in Cre-Tam mice. We conclude from these results that 1) the relative contribution to whole-body energy metabolism from peripheral leptin signaling is insignificant in vivo, 2) leptin signaling in adipocyte constitutes a distinct short-loop negative feedback regulation of leptin production that is independent of tissue metabolic status, and 3) perturbation of peripheral leptin signaling alone, although increasing leptin production, may not be sufficient to alter the effective plasma levels of leptin because of the counter-regulatory increase in the level of leptin binding protein(s).
Real-time loading actuator control for an advanced aerospace test rig
Authors: Jacazio G , Balossini G
Published: May 2007

The growing complexity of aircraft systems requires that extensive testing be performed on dedicated test rigs to grant the necessary flight clearance and to provide troubleshooting of the problems that may arise during prototype flight trials. A new test rig is described herein, that was recently built to provide comprehensive testing of the flight controls, landing gear, and hydraulic systems of the M-346 advanced trainer aircraft. All these subsystems are connected together on the rig as in the real aircraft to ensure that the entire system operates on the rig exactly as on the aircraft. To that purpose, a high-performance force control system was developed to provide accurate dynamic loading of the primary and secondary flight control actuators, and the structure onto which the flight control actuators are mounted provides a mechanical load path with the same stiffness as in the real aircraft.

The present paper describes the main characteristics of the test rig and puts particular emphasis on the force control system that makes use of an adaptive control law to provide a very accurate control of the force acting upon the actuators during fast transients.
Hardware-in-the-loop simulation of magnetorheological dampers for vehicle suspension systems
Authors: Batterbee D. C. , Sims N. D.
Published: May 2007

Magnetorheological (MR) fluids provide an elegant means to enhance vibration control in primary vehicle suspensions. Such fluids can rapidly modify their flow characteristics in response to a magnetic field, so they can be used to create semi-active dampers. However, the behaviour of MR dampers is inherently non-linear and as a consequence, the choice of an effective control strategy remains an unresolved problem.

Previous research has developed a method to linearize the damper's force/velocity response, to allow implementation of classical control techniques. In the present study, this strategy is used to implement skyhook damping laws within primary automotive suspensions. To simulate the vehicle suspension, a two-degree-of-freedom quarter car model is used, which is excited by realistic road profiles. The controller performance is investigated experimentally using the hardware-in-the-loop-simulation (HILS) method. This experimental method is described in detail and its performance is validated against numerical simulations for a simplified problem.

The present authors demonstrate that feedback linearization can provide significant performance enhancements in terms of passenger comfort, road holding, and suspension working space compared with other control strategies. Furthermore, feedback linearization is shown to desensitize the controller to uncertainties in the input excitation such as changes in severity of the road surface roughness.
Human Amniotic Epithelial Cells as Novel Feeder Layers for Promoting Ex Vivo Expansion of Limbal Epithelial Progenitor Cells
Authors: Chen Ying-Ting , Li Wei , Hayashida Yasutaka , He Hua , Chen Szu-Yu , Tseng David Y. , Kheirkhah Ahmad , Tseng Scheffer C. G.
Published: May 2007

Human amniotic epithelial cells (HAECs) are a unique embryonic cell source that potentially can be used as feeder layers for expanding different types of stem cells. In vivo, HAECs uniformly expressed pan-cytokeratins (pan-CK) and heterogeneously expressed vimentin (Vim). The two phenotypes expressing either pan-CK(+)/Vim(+) or pan-CK(+)/Vim(-) were maintained in serum-free media with high calcium. In contrast, all HAECs became pan-CK(+)/Vim(+) in serum-containing media, which also promoted HAEC proliferation for at least eight passages, especially supplemented with epidermal growth factor and insulin. Mitomycin C-arrested HAEC feeder layers were more effective in promoting clonal growth of human limbal epithelial progenitors than conventional 3T3 murine feeder layers. Cells in HAEC-supported clones were uniformly smaller, sustained more proliferation, and expressed less CK12 and connexin 43 but higher levels of stem cell-associated markers such as p63, Musashi-1, and ATP-binding cassette subfamily G2 than those of 3T3-supported clones. Subculturing of clonally expanded limbal progenitors from HAEC feeder layers, but not from 3T3 feeder layers, gave rise to uniformly p63-positive epithelial progenitor cells as well as nestin-positive neuronal-like progenitors. Collectively, these results indicated that HAECs can be used as a human feeder layer equivalent for more effective ex vivo expansion of adult epithelial stem cells from the human limbus.

Disclosure of potential conflicts of interest is found at the end of this article.
Haematological Profile of Broiler Chickens under Acute Stress Due to Shackling
Authors: Bedáňová I. , Voslářová E. , Večerek V. , Pištěková V. , Chloupek P.
Published: May 2007

The aim of our experiment was to assess the stress response of broilers to different periods of shackling when conditions similar to practice at slaughterhouses were simulated. In this study, heterophil to lymphocyte (H/L) ratios were used as an index of stress status. Also total erythrocyte and leukocyte counts, haematocrit, haemoglobin, mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC) values were monitored and differential leukocyte count was assessed. At 42 days of age, 10 broilers were subjected to a 2-min shackling period (S2 group) and other 10 broilers were subjected to a 5-min shackling period (S5 group). Broilers were suspended from shackles placed in an experimental processing line and other stress factors (e.g. preslaughter transport, crating and ambient disturbances) were eliminated in order to assess the stress response to shackling particularly. When compared with an unshackled control, both S2 and S5 groups exhibited a highly significant increase in heterophil counts and H/L ratio 20 h following shackling. When compared, the mean value of the H/L ratio of S2 and S5 chickens was higher due to the longer shackling period. The difference, however, was not statistically significant. In addition, S5 broilers exhibited a statistically significant elevation in the number of basophils in comparison with the control. When compared with the control, S2 broilers exhibited a significant decrease in haemoglobin level, a highly significant decrease in erythrocyte cell count and MCHC values due to shackling. Both S2 and S5 groups of broilers manifested a highly significant increase in MCV values and markedly depressed erythrocyte count and MCHC values in comparison with unshackled broilers. When S2 and S5 broilers were compared, none of the monitored haematological indices of the erythrocyte count manifested any significant changes due to the different periods of shackling. Results of our experiment proved that the preslaughter shackling induced considerable changes in haematological indices of both leukocyte and erythrocyte count in broilers and indicated a markedly increased level of stress effects. In conclusion, using a method that eliminates the stress associated with the shackling of live birds before electrical stunning should be considered as a better option as far as bird welfare is concerned.
Queering Seduction: Eros and the Erotic in the Construction of Gay Teacher Identity
Authors: McNinch James
Published: May 2007

This article situates itself in cross-disciplinary work to combine reflection on my own teaching and my own “queer locatedness” (Grace, 2000) with more traditional elements of media studies and critical pedagogy. The circle around this reflection is defined by ruminations on the relationship between eros and the erotic, media representations of teachers, and morality and mortality in male identity and pedagogy. I offer several tentative conclusions: the role of a queer teacher is more conflicted than that of a heterosexual; good teaching may not be possible unless there is an element in it of seduction, but it is teachers who are seduced by their students. Good teaching—ethical teaching—celebrates differences by exploring them. Interrogating Eros in teaching leads to an appreciation of the sweetness of morality and the stench of mortality along the parabola connecting body and mind, and the construction of a queer teaching identity.
Occupational asbestos exposure among respiratory cancer patients in Lithuania
Authors: Everatt Rūta Petrauskaitė , Smolianskienė Gražina , Tossavainen Antti , Cicėnas Saulius , Jankauskas Remigijus
Published: May 2007

Background

Despite intensive use of asbestos, no cancer case has ever been diagnosed as asbestos related in Lithuania. This paper attempts to estimate the proportion of those occupationally exposed to asbestos among respiratory cancer patients.

Material and methods

Occupational exposure to asbestos was assessed retrospectively for 298 lung cancer and four mesothelioma patients, admitted to the Institute of Oncology, Vilnius. The evaluation was based on personal interview data using an internationally established questionnaire covering most likely activities of asbestos exposure at the workplace. Cumulative exposure to asbestos at work was estimated in fiber years. Lung tissue asbestos fiber burden analysis was conducted by scanning transmission electron microscopy on 23 samples.

Results

A cumulative asbestos exposure of ≥25 fiber years was found for 10 lung cancer patients (3.4%). They worked in foundries, construction, installation, shipyard, power plant, railway, asbestos cement, glass and chemical industry. In a further 56 lung cancer patients (18.8%) and for one (25%) mesothelioma patient, a cumulative exposure from 5 to 24.9 fiber years was assessed. Asbestos fibers were detected in 18 cases, the burden ranged from 0.1 to 4.1 million fibers/g dry lung tissue; concentrations exceeding 1 million f/g dry lung tissue were found in four cases. All fibers were chrysotile.

Conclusions

Findings indicate that a fraction (3.4%) of the lung cancer cases could be attributed to heavy occupational exposure to asbestos using the Helsinki criterion of ≥25 fiber years. Therefore, approximately 50 lung cancer cases per year in Lithuania could be asbestos‐related compensable occupational diseases. Am. J. Ind. Med. 50:455–463, 2007. © 2007 Wiley‐Liss, Inc.
Fortuitous detection of a submicroscopic deletion at 1q25 in a girl with Cornelia‐de Lange syndrome carrying t(5;13)(p13.1;q12.1) by array‐based comparative genomic hybridization
Authors: Hayashi Shin , Ono Masae , Makita Yoshio , Imoto Issei , Mizutani Shuki , Inazawa Johji
Published: May 2007

We report on a 2‐year‐old Japanese girl with Cornelia‐de Lange syndrome (CdLS) who had mental and growth retardation, together with characteristic facial anomalies and mild extremity malformations. She had a balanced chromosomal translocation, 46,XX,t(5;13)(p13.1;q12.1) de novo. Surprisingly, this was the same translocation that had provided a clue to the identification of a major causative gene for CdLS, NIPBL [Krantz et al., 2004; Tonkin et al., 2004]. Using fluorescence in situ hybridization (FISH), the breakpoint was confirmed to lie within NIPBL at 5p13.1. Furthermore, array‐based comparative genomic hybridization (array‐CGH) demonstrated a cryptic 1‐Mb deletion harboring six known genes at 1q25–q31.1. A FISH analysis of her parents confirmed that the deletion was de novo. Although patients with interstitial deletions at 1q are rare, some of their features were similar to those observed in our patient, indicating that her clinical manifestations are likely to be affected by not only the disruption of NIPBL but also the concomitant microdeletion at 1q25–q31.1. The present case suggests that array‐CGH can uncover cryptic genomic aberrations affecting atypical phenotypes even in well‐known congenital disorders. © 2007 Wiley‐Liss, Inc.
Castor oil‐based polyurethane–polyester nonwoven fabric composites: Mechanical properties, chemical resistance, and water sorption behavior at different temperatures
Authors: Satheesh Kumar M. N. , Manjula K. S. , Siddaramaiah
Published: May 2007

Castor oil‐based polyurethane (PU)–polyester nonwoven fabric composites were fabricated by impregnating the polyester nonwoven fabric in a composition containing castor oil and diisocyanate. The effects of different diisocyanates such as toluene‐2,4‐diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties have been studied for neat PU sheets and their composites with polyester nonwoven fabric. Chemical resistance of the PU composites has been assessed by exposing the specimens to different chemical environments. Percentage water absorption of composites and neat PU sheets has been determined both at room temperature and in boiling water. Both TDI‐ and HMDI‐based PU composites showed a marginal improvement in tensile strength retention at 100°C heat ageing. Water sorption studies were carried out at different temperatures, viz, 30, 50, and 70°C, based on immersion weight gain method. From the sorption results, the diffusion (D) and permeation (P) coefficients of water penetrant have been calculated. Attempts were made to estimate the empirical parameters such as n, which suggests the mode of transport (non‐Fickian), and K, a constant which depends on the structural characteristics of the polymer in addition to its interaction in boiling water. The temperature dependence of the transport coefficients has been used to estimate the activation energy parameters for diffusion (ED) and permeation (Ep) processes from Arrhenius plots. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
ϵ‐caprolactone grafting on a poly(vinyl alcohol‐co‐vinyl acetate) in the melt without added initiator
Authors: Becquart Frédéric , Taha Mohamed , Zerroukhi Amar , Chalamet Yvan , Kaczun Jürgen , Llauro Marie‐France
Published: May 2007

Polycaprolactone (PCL) grafting on vinyl alcohol‐co‐vinyl acetate) (PVA‐Ac), was investigated in the melt at high temperature (170°C), below the PVA‐Ac melting point, by ring opening polymerization of ϵ‐caprolactone initiated by metal alkoxyde sites present in PVA‐Ac: no additional initiator was used. The obtained average structures were determined by 1H NMR. As expected, small grafts, with low average polymerization degree (DP), were obtained, between 4 and 12 h of reaction. These DP are due to exchange reactions between hydroxyl groups and PCL growing chains. The PVA‐Ac was shown to be partially substituted by short PCL grafts. The DP linearly increased with the initial Lactone/PVA‐Ac ratio, and the substituted alcohol sites rate were limited to 63%.It was shown that the used reactive system is characterized by a quazi‐living polymerization mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
A novel approach to interpenetrating networks of epoxy resin and polydimethylsiloxane
Authors: Jia Li‐Ya , Zhang Chen , Du Zhong‐Jie , Li Cong‐Ju , Li Hang‐Quan
Published: May 2007

A novel methodology for preparing interpenetrating polymer networks (IPNs) between an epoxy resin, diglycidylether of bisphenol A (DGEBA) and polydimethylsiloxane (PDMS) was proposed. The vinyl‐terminated PDMS (vinyl‐PDMS) was partially crosslinked with hydrogen‐containing PDMS (H‐PDMS) and was mixed with DGEBA, modified silica (m‐silica), and a methyl tetrahydrophtalic anhydride (MTHPA) curing agent. Subsequently, the curing reactions of the DGEBA/m‐silica and PDMS were allowed to occur separately and simultaneously leading to an IPN. The m‐silica played a double‐fold role: Cocuring with DGEBA and H‐bonding with the oxygen atoms on the PDMS segments, and thus acted as a compatibilizer between DGEBA and PDMS and promoted the generation of the IPN structure. The resulted partially miscible structure was characterized through the dispersion of silica particles and the glass transition behavior of the samples. The mechanical properties of the IPNs were also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Catalytic Asymmetric Phase‐Transfer Michael Reaction and Mannich‐Type Reaction of Glycine Schiff Bases with Tartrate‐Derived Diammonium Salts
Authors: Shibuguchi Tomoyuki , Mihara Hisashi , Kuramochi Akiyoshi , Ohshima Takashi , Shibasaki Masakatsu
Published: May 2007

Catalytic asymmetric Michael and Mannich‐type reactions of glycine Schiff bases with chiral two‐center organocatalysts, tartrate‐derived diammonium salts (TaDiASs), are described. On the basis of conformational studies, optimized TaDiASs with a 2,6‐disubstituted cyclohexane spiroacetal were newly designed. These TaDiASs catalyzed the asymmetric Michael and Mannich‐type reactions of glycine Schiff bases with higher enantioselectivity than previous catalysts. In the Mannich‐type reaction, aromatic N‐Boc‐protected imines (Boc=tert‐butoxycarbonyl) as well as enolizable alkyl imines were applicable. As a synthetic application of the catalytic asymmetric Mannich‐type reaction with the optimized TaDiASs, we developed a catalytic asymmetric total synthesis of (+)‐nemonapride, which is an antipsychotic agent.
Der Seeigel von Sanssouci
Authors: Neumann Christian , Schultka Stephan
Published: May 2007

The sea urchin of Sanssouci. – Here we describe the history of the holotype of the Cretaceous sea urchin Salenia sigillata which is derived from diluvial deposits of the Park of Sanssouci (Potsdam). In our study we present a picture of the growing network of educated citizens in the Prussian society interested in natural sciences during the first half of the 19th century on the basis of the history of the way on which the find wandered from a young gardener to the famous geologist Leopold von Buch. In addition, we also show how the scientific significance of this remarkable fossil changed, reflecting the rapid progress of the young discipline of palaeontology in the 19th and early 20th century.
Mild steatosis impairs functional recovery after liver resection in an experimental model
Authors: Veteläinen R , Bennink R J , van Vliet A K , van Gulik T M
Published: May 2007

Background

Mild steatosis has been thought not to affect outcome after liver resection. However, recent studies have reported impaired postoperative recovery of patients with mild steatosis. This study evaluated the recovery of hepatic functional reserve during regeneration in a rat model of mild steatosis and liver resection.

Methods

Male Wistar rats had a standard methione- and choline-deficient diet to induce mild steatosis before 70 per cent liver resection. Evaluation of hepatobiliary function was by 99mTc-labelled mebrofenin scintigraphy. Mebrofenin uptake rate, the time for maximum uptake (T peak) and the time required for peak activity to decrease by 50 per cent (T1/2 peak) were assessed 1, 2, 3 and 7 days after liver resection, along with regeneration of the remnant liver, hepatocellular and sinusoidal damage, and hepatic adenosine 5′-triphosphate (ATP) levels.

Results

Liver regeneration and proliferative response in mild steatotic rats were no different from those in controls. However, the mebrofenin uptake rate was lower (P < 0·050) and the recovery of hepatic ATP impaired (P < 0·050) in animals with mild steatosis. Hepatocellular damage was increased (P < 0·050) but sinusoidal endothelial cell function was not affected after liver resection in mildly steatotic rats.

Conclusion

Mild steatosis impaired functional recovery and increased hepatocellular damage after liver resection.
Correctors of Protein Trafficking Defects Identified by a Novel High‐Throughput Screening Assay
Authors: Carlile Graeme W. , Robert Renaud , Zhang Donglei , Teske Katrina A. , Luo Yishan , Hanrahan John W. , Thomas David Y.
Published: May 2007

High‐throughput small‐molecule screens hold great promise for identifying compounds with potential therapeutic value in the treatment of protein‐trafficking diseases such as cystic fibrosis (CF) and nephrogenic diabetes insipidus (NDI). The approach usually involves expressing the mutant form of the gene in cells and assaying function in a multiwell format when cells are exposed to libraries of compounds. Although such functional assays are useful, they do not directly test the ability of a compound to correct defective trafficking of the protein. To address this we have developed a novel corrector‐screening assay for CF, in which the appearance of the mutant protein at the cell surface is measured. We used this assay to screen a library of 2000 compounds and have isolated several classes of trafficking correctors that had not previously been identified. This novel screening approach to protein‐trafficking diseases is robust and general, and could enable the selection of molecules that could be translated rapidly to a clinical setting.
Highly Efficient Synthesis of Stereodefined Multisubstituted 1,4‐Dicyano‐ and 1‐Cyano‐1,3‐butadienes and Their Reactions with Organolithium Reagents
Authors: Wang Congyang , Wang Chao , Wang Qifeng , Wang Zhihui , Sun Hui , Guo Xiangyu , Xi Zhenfeng
Published: May 2007

Stereodefined multisubstituted 1‐cyano‐ and 1,4‐dicyano‐1,3‐butadiene derivatives were obtained in excellent yields of the isolated product from their corresponding monohalo‐ and dihalobutadienes and CuCN. This reaction proceeded with high stereoselectivity and retention of the stereochemistry of the starting halobutadienes. A study of the utility of the thus‐obtained 1‐cyano‐ and 1,4‐dicyano‐1,3‐butadiene derivatives was demonstrated by their reactions with organolithium reagents. 2H‐Pyrrole or iminocyclopentadiene derivatives were formed in high yields from 1‐cyano‐4‐halo‐1,3‐butadienes and organolithium reagents. When 1,4‐dicyano‐1,3‐butadienes were treated with organolithium reagents followed by trapping with electrophiles, a tandem process took place to afford 2H‐pyrrolyl nitriles in excellent yields. Reduction of 1,4‐dicyano‐1,3‐butadiene derivatives with LiAlH4 showed novel reaction patterns relative to normal nitriles.
Cobalt(I)‐Mediated Preparation of Polyborylated Cyclohexadienes: Scope, Limitations, and Mechanistic Insight
Authors: Geny Anaïs , Lebœuf David , Rouquié Gabriel , Vollhardt K. Peter C. , Malacria Max , Gandon Vincent , Aubert Corinne
Published: May 2007

A series of 1,3‐ and 1,4‐diboryl‐1,3‐cyclohexadienes have been prepared by intermolecular CoCp‐mediated [2+2+2] cocyclizations of alkynylboronic pinacolate esters with alkenes, followed by oxidative demetallation with iron(III) chloride. The effect of substitution at the borylated alkyne on chemo‐ and regioselectivities has been studied, suggesting steric control. The proper choice of substituents allowed the preparation of 1,3‐diborylated cyclohexadienes in a highly selective manner. Alternatively, 1,4‐diborylated cyclohexadienes could be prepared from diborylated diynes. The scope of this reaction has been examined and found to include electron‐poor, electron‐rich, linear, and cyclic alkenes. The diborylated cyclohexadienes were submitted to single or double Suzuki–Miyaura cross‐coupling reactions with haloarenes to afford polyarylated systems. The mechanism of the title reaction, including the regioselectivity of the cycloaddition steps, has been analyzed by means of DFT computations.
Practical Tactics in Resolution of Racemates via Diastereomeric Salt Formation
Authors: He Xu‐Chang , Qi Chuang‐Yu
Published: May 2007

A practical tactics in the classical resolutions was illustrated for affording the desired isomers in maximum yields. According to the practical tactics resolution of racemic ethyl nipecotate, Corey lactone and huperzine A intermediate was successfully practiced. The basis of this practicability is the well‐known Marckwald principle.
Low‐Temperature Heat Capacities and Thermodynamic Properties of Octahydrated Barium Dihydroxide, Ba(OH)2·8H2O(s)
Authors: Di You‐Ying , Tan Zhi‐Cheng , Sun Li‐Xian
Published: May 2007

Low‐temperature heat capacities of octahydrated barium dihydroxide, Ba(OH)2·8H2O(s), were measured by a precision automated adiabatic calorimeter in the temperature range from T=78 to 370 K. An obvious endothermic process took place in the temperature range of 345–356 K. The peak in the heat capacity curve was correspondent to the sum of both the fusion and the first thermal decomposition or dehydration. The experimental molar heat capacities in the temperature ranges of 78–345 K and 356–369 K were fitted to two polynomials. The peak temperature, molar enthalpy and entropy of the phase change have been determined to be (355.007±0.076) K, (73.506±0.011) kJ·mol−1 and (207.140±0.074) J·K−1·mol−1, respectively, by three series of repeated heat capacity measurements in the temperature region of 298–370 K. The thermodynamic functions, (HT−H298.15 K) and (ST−S298.15 K), of the compound have been calculated by the numerical integral of the two heat‐capacity polynomials. In addition, DSC and TG‐DTG techniques were used for the further study of thermal behavior of the compound. The latent heat of the phase change became into a value larger than that of the normal compound because the melting process of the compound must be accompanied by the thermal decomposition or dehydration of 7H2O.
Chemical Composition of Hydrilla Verticillata (L. f.) Royle in Taihu Lake
Authors: Xiao Yu , Wang Yan‐Li , Gao Shi‐Xiang , Sun Cheng , Zhou Zhong‐Yuan
Published: May 2007

Hydrilla verticillata (Linn. f.) Royle is a submerged plant for phytoremediation on Taihu Lake, China. The planted submerged plant should be harvested in every autumn to reduce the nutrition burden of the lake. Five compounds were firstly isolated by column chromatography and purified from the extractions of Hydrilla verticillata (Linn. f.) Royle. 1‐(5′‐Hydroxy‐4′‐hydroxymethyl‐1′‐methyl‐1H‐pyrrol‐2′‐yl)‐henicosa‐2,12,15‐trien‐1‐one (2) and thymidine (3) were identified by EIMS, 1H NMR, 13C NMR and IR spectra. Crystal loliolide (1) and sulfur‐gamma (4) were identified by X‐ray diffraction. Octadecanedioic acid (5) was also elucidated. Among them, compound 2 is a new natural compound, loliolide (1) and thymidine (3) are known bioactive substances. The results provided basic research data for exploring their application as medical materials.
Methyl Iodide Accelerated Asymmetric Epoxidation of Alkenes Catalyzed by Chiral Salen‐Mn(III) Complexes with Tertiary Amine Units
Authors: Sun Yang , Tang Ning
Published: May 2007

A series of chiral salen‐Mn(III) complexes featuring two tertiary amine units were synthesized and employed in the enantioselective epoxidation of unfunctionalized alkenes in the presence of pyridine N‐oxide and 2,6‐dimeth‐ ylpyridine N‐oxide as proximal ligands, respectively. Moderate to high enantioselectivity and acceptable yields were achieved when NaClO was used as terminal oxidant under CH2Cl2/H2O biphasic media. Methyl iodide was found to be an effective additive to accelerate the epoxidation, possibly owing to the formation of quaternary ammonium units on catalysts, which may facilitate the reaction in an oil/water biphasic medium. The subsequent stimulation experiment was carried out, and the resulting ESI‐HRMS analysis revealed the formation of a novel (salen)manganese(III) intermediate featuring two quaternary ammonium units, and bearing a pyridine N‐oxide and a molecule of water simultaneously axially‐coordinated backbone.
Study on Synthesis and Binding Ability of a New Anion Receptor Containing NH Binding Sites
Authors: Qiao Yan‐Hong , Lin Hai , Lin Hua‐Kuan
Published: May 2007

A new colorimetric recognition receptor 1 based on the dual capability containing NH binding sites of selectively sensing anionic guest species has been synthesized. Compared with other halide anions, its UV/Vis absorption spectrum in dimethyl sulfoxide showed the response toward the presence of fluoride anion with high selectivity, and also displayed dramatic color changes from colorless to yellow in the presence of TBAF (5×10−5 mol/L). The similar UV/Vis absorption spectrum change also occurred when 1 was treated with AcO− while a little change with H2PO−4 and OH−. Receptor 1 has almost not affinity abilities to Cl−, Br− and I−. The binding ability of receptor 1 to fluoride with high selectivity over other halides contributes to the anion size and the ability of forming hydrogen bonding. While the different ability of binding with geometrically triangular (AcO−), tetrahedral (H2PO−4) and linear (OH−) anions maybe result from their geometry configuration.
Thiourea Based Tweezer Anion Receptors for Selective Sensing of Fluoride Ions
Authors: Zhang You‐Ming , Cao Cheng , Wei Wei , Xie Tai‐Bao
Published: May 2007

Three 3,3′‐di(4‐substituted‐phenyl)‐1,1′‐isophthaloylbis(thiourea) compounds were designed as novel neutral anion receptors, and synthesized by simple steps in good yields. The single crystal structure of receptor 1 shows that a solvent molecule was captured by the host molecule through intermolecular hydrogen bonding. Moreover, it was self‐assembled as a supramolecular system for the presence of abundant inter‐ and intramolecular hydrogen bonding and π‐π interactions between phenyl groups. Their application as anion receptors has been examined by UV‐Vis and 1H NMR spectroscopy, showing that they had a higher selectivity for fluoride than other halides. The host and guest formed a 1:1 stoichiometry complex through hydrogen bonding interactions in the first step, then following a process of deprotonation in presence of an excess of F− in the solvent of DMF.
Synthesis and Structural Characterization of 1,4‐Di(2‐methoxyphenyl)‐2,5‐piperazinedione
Authors: Zhang Shu‐Sheng , Wen Yong‐Hong , Tang Xiao‐Fang , Li Xue‐Mei
Published: May 2007

A new derivative of 2,5‐piperazinedione, 1,4‐di(2‐methoxyphenyl)‐2,5‐piperazinedione (I), was synthesized by the cyclocondensation reaction of N‐2‐methoxyphenyl chloroacetamide, and its structure was characterized by elemental analysis, IR, 1H NMR and single crystal X‐ray diffraction method. The crystal belongs to monoclinic system, space group P21/c with unit cell dimensions a=0.56934(10) nm, b=1.3880(2) nm, c=1.00329(17) nm, β=90.376(3)°, V=0.7928(2) nm3, Z=2, Dc=1.367 g·cm−3, μ=0.98 cm−1, R and wR being 0.0606 and 0.1564 respectively for 1549 unique reflections with 1247 observed reflections [I>2σ(I)]. The molecule has a crystallographically imposed symmetry center. The three rings in the molecule are each coplanar with their attached groups, excluding methyl H atoms and the H atoms attached to the piperazinedione ring, while the whole molecule is not planar, with dihedral angles of 74.7(1)° between the piperazinedione and each of the two aromatic rings. The crystal structure is stabilized by van der Waals and dipole‐dipole forces.