bluuebunny/crossref_metadata_2025 huggingface dataset:
R‐roscovitine (Seliciclib) affects CLL cells more strongly than combinations of fludarabine or cladribine with cyclophosphamide: Inhibition of CDK7 sensitizes leukemic cells to caspase‐dependent apoptosis
Authors: Rogalińska Małgorzata , Błoński Jerzy Z. , Komina Oxana , Góralski Paweł , Żołnierczyk Jolanta D. , Piekarski Henryk , Robak Tadeusz , Kiliańska Zofia M. , Węsierska‐Gądek Józefa
Published: November 2009

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of malignant, apoptosis‐resistant B CD19+/CD5+ cells. Populations of CLL cells are heterogeneous and consist primarily of quiescent cells with a minor subset of dividing cells. In this study the efficacy of a first‐line in vivo therapy was compared with treatment by R‐roscovitine (ROSC) alone or by purine analogues (cladribine and fludarabine) combined with maphosphamide for 14 CLL patients under ex vivo conditions. ROSC induced the highest reduction in numbers of living B‐cells, coinciding with an increased rate of apoptosis. After 24 h the percentage of apoptotic cells in ROSC‐treated cultures was markedly higher than in untreated controls. ROSC also induced strong activation of the apoptosome and effector caspases in CLL cells. During progression of apoptosis the plasma membrane became permeable, resulting in the release of activated caspases into the culture medium. Leukemic cells were more sensitive to ROSC than normal mononuclear cells. Treatment with ROSC did not affect the activating phosphorylation of CDK2 or CDK1. However, ROSC decreased phosphorylation of survivin, CDK7, and RNA‐Pol II, resulting in inhibition of transcription elongation and subsequent down‐regulation of levels of anti‐apoptotic factors, thereby facilitating apoptosis. Unlike ROSC, two other purine analogues barely affected the cellular levels of anti‐apoptotic proteins and more weakly activated effector caspases. In addition, the efficacies of in vivo and ex vivo therapies were found to be correlated. Marked between‐patient differences in expression patterns of apoptosis‐regulating factors in CLL cells were observed, explaining the variations in patients' sensitivity to therapy. J. Cell. Biochem. 109: 217–235, 2010. © 2009 Wiley‐Liss, Inc.
Synthesis of C‐pivot lariat ethers
Authors: Abbas Ashraf A. , Elwahy Ahmed H. M.
Published: November 2009

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This review covers the main strategies for the synthesis of C‐pivot lariat ethers as well as their specific syntheses. J. Heterocyclic Chem., (2009).
Syntheses of chromenes and chromanes via o‐quinone methide intermediates
Authors: Ferreira Sabrina B. , da Silva Fernando de C. , Pinto Angelo C. , Gonzaga Daniel T. G. , Ferreira Vitor F.
Published: November 2009

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This review intends to explore synthetic methodologies for the preparation of 2H‐chromenes and their analog chromanes through ortho‐quinone methide (o‐QM) intermediates associated with inter and intramolecular hetero‐Diels‐Alder and electrocyclization reactions. J. Heterocyclic Chem., (2009).
Synthetic approaches to 3H‐naphtho[2,1‐b]pyrans and 2,3‐dihydro‐1H‐naphtho[2,1‐b]pyrans
Authors: Jha Amitabh , Jimmy Huang Po‐Jung
Published: November 2009

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Naphtho[2,1‐b]pyran nuclei are prevalent in natural products with significant biological and medicinal properties. 3,3‐Disubstituted 3H‐naphtho[2,1‐b]pyrans are photochromic and find use in electronic display systems, ophthalmic lenses, optical switches, and temporary or permanent memories. Of the various possible structural isomers of naphthopyran framework, this review is an account of reported synthetic procedures to produce 3H‐naphtho[2,1‐b]pyrans and their dihydro analogs, 2,3‐dihydro‐1H‐naphtho[2,1‐b]pyrans. The advantages and disadvantages of each procedure in terms of yields, complexity, formation of side‐products, use of uncommon/expensive reagents, etc., are also described. J. Heterocyclic Chem., (2009).
In situ Gelation of Supramolecular Hydrogel for Anti‐Tumor Drug Delivery
Authors: He Bin , Zeng Jing , Nie Yu , Ji Li , Wang Rui , Li Yuan , Wu Yao , Li Li , Wang Gang , Luo Xianglin , Zhang Zhirong , Gu Zhongwei
Published: November 2009

A supramolecular injectable hydrogel was fabricated. The hydrogel was in situ gelated by the host‐guest interaction between α‐cyclodextrins (α‐CDs) and methylated poly(ethylene glycol) grafted poly(α,β‐malic acid) (mPEG‐g‐PMA). The hydrogel was characterized by 1NMR, XRD, DSC, TGA and SEM. The results showed that the polyrotaxanes of α‐CDs/mPEG‐g‐PMA acted as physical crosslink sites in the hydrogel. Anti‐tumor drug doxorubicin hydrochloride (DOX) was loaded in the hydrogel. The release and anti‐tumor effect were studied in vitro. The burst release of DOX was restrained obviously. The sustaining release time lasted more than 3 d and the cell viability decreased greatly. This hydrogel is a promising injectable hydrogel for minimally invasive therapeutic drug delivery.

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Strahlverschleiß von Stahl mit niedrigem Kohlenstoffgehalt: Untersuchungen zur Verschleißpartikelgeometrie
Authors: Momber A.
Published: November 2009

Die geometrische Form von Verschleißpartikeln nach Strahlverschleiß von Oberflächen aus Stahl mit niedrigem Kohlenstoffgehalt wurde mittels einer Bildbearbeitungssoftware bestimmt. In Abhängigkeit vom Streckungsgrad (Verhältnis von Länge zu Breite der Partikel) wurden drei Verschleißpartikelformen unterschieden. 60 % aller Partikel konnten dem Plättchenmodel von Bellmann‐Levy (1981) zugeordnet werden; sie dominierten den Verschleißprozess. Ein reines Mikroschneiden nach Finnie (1959) spielte eine untergeordnete Rolle, während Mikrofurchen nach Winter‐Hutchings (1974) wesentlich stärker hervortrat. Die statistische mittlere Größe der Verschleißpartikel betrug 14 μm. 92 % aller Verschleißpartikel waren kleiner als die Korngröße des verschlissenen Werkstoffes. Die Ergebnisse stützen die Ansicht, dass im Wesentlichen mehrstufig ablaufende Vorgänge, insbesondere Bildung und nachträgliches Abschlagen von Lippen und Plättchen, den Werkstoffabtrag herbeiführen.
Werkstoffe und Oberflächenmodifikationen – Schlüssel für eine ökonomische Spritzgießfertigung
Authors: Heine B.
Published: November 2009

Eine ökonomische Spritzgießfertigung umfasst eine kostengünstige Fertigung des Werkzeugs, eine kräftereduzierte Werkzeugbetätigung, eine Ressourcen schonende Produktion mit kurzen Zykluszeiten sowie einen geringen Instandsetzungsbedarf auf Seiten des Werkzeugs. Es zeigt sich, dass kein Werkstoff allen Forderungen gerecht wird. Daher empfiehlt es sich, die Eigenschaften, die von der Beschaffenheit der Werkzeugoberfläche bestimmt werden, von einer Beschichtung erbringen zu lassen. Die Volumeneigenschaften dagegen werden vom Grundwerkstoff geleistet. Mit diesem Konzept ist es möglich, ein Leichtbauwerkzeug auszulegen, das über lange Zeit wartungsfrei betrieben werden kann und geringe Zykluszeiten erlaubt. Es zeigt sich, dass ein Grundkörper aus einer Aluminiumlegierung und die Applikation einer Chemisch‐Nickel‐Schicht eine zum Ziel führende Lösung ist.
Quick‐mount grips: Towards an improved standard for uniaxial tensile testing of metallic superplastic sheets
Authors: Abu‐Farha F. , Curtis R.
Published: November 2009

It is the steady interest in the extraordinary ductility of superplastic materials that led to the launch of several standards on characterising their tensile behaviour, all within the past decade. However, those standards do not agree on many of the issues they cover, and fail to tackle some of the important and controversial issues in superplastic materials’ testing; leaving the reader without adequate guidelines on those particular issues. In this work, a detailed review of the three main standards that describe the proper method for testing superplastic materials (JIS H7501, ASTM E2448 and BS ISO 20032) is carried out. The review focuses on the critical issues that significantly impact testing results, pointing out the points of agreement and disagreement among the three standards. And in an attempt to resolve some of those critical issues, an integrated testing methodology centred about a unique set of quick‐mounting grips that facilitates mounting and retrieving the test specimen in a very short time, is presented. The methodology promises resolving the majority of the aforementioned testing issues, and is hoped to provoke the development of a new more universally‐accepted standard method for testing superplastic materials at elevated temperatures.
Characterization and modification of commercial acrylic fibers grafted with acrylic acid
Authors: Bagheri A.R. , Abdouss M. , Shoushtari A.M.
Published: November 2009

The graft copolymerization of acrylic acid (AA) onto commercial acrylic fibers (PAN) has been studied using Azobis(isobutyro)nitrile (AIBN) as an initiator. AA grafting initiated by radicals formed from thermal decomposition of AIBN. In this study, the effects of monomer and initiator concentration, time and temperature reaction on the grafting yield have been investigated.

The optimum conditions for this grafting reaction were obtained with an AA concentration of 1.67 M, an AIBN concentration of 0.0097 M, a reaction temperature of T=85 °C and with reaction time of 60 minutes.

The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water absorption and also in this study has been investigated the mechanical property. The thermal analysis data showed that increasing in grafting yield, decreases the thermal stability of fiber. Grafting also affected slightly the fiber morphology. The experimental data of mechanical properties show clearly that by increasing of grafting yield, max extension will decrease. Grafting of poly AA improved water absorption.
Hochfrequenzschweißen von Feinblech aus mikrolegiertem Stahl mit integrierter thermomechanischer Nahtbehandlung
Authors: Wesling V. , Schram A. , Wiche H.
Published: November 2009

Dargestellt werden die Verbindungseigenschaften von konduktiv hochfrequenzgeschweißten Feinblechen aus dem mikrolegierten Stahl H340LA. Im Fokus stehen hierbei insbesondere die statische Festigkeit sowie die Dauerfestigkeit. Des Weiteren wird die Möglichkeit einer prozessintegrierten thermomechanischen Behandlung der Schweißnaht vorgestellt und ihr Einfluss auf die Umformeigenschaften der Schweißnaht analysiert.
Design of Optimal Sequential Experiments to Improve Model Predictions from a Polyethylene Molecular Weight Distribution Model
Authors: Thompson Duncan E. , McAuley Kim B. , McLellan P. James
Published: November 2009

Reliable model predictions require an appropriate model structure and also good parameter estimates. For good parameter estimates to be obtained, it is important that the data used in parameter estimation are informative. Alphabet‐optimal experimental designs can be used to ensure that new experiments are as informative as possible. This work presents the development of D‐ and A‐optimal sequential experimental designs for improving parameter precision in a molecular‐weight‐distribution model for Ziegler‐Natta‐catalyzed polyethylene. Novel V‐optimal designs techniques are developed to improve the precision of model predictions, and anticipated benefits are quantified. Problems with local minima are discussed and comparisons between the optimality criteria are made.

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Neighborhood search heuristics for selecting hierarchically well‐formulated subsets in polynomial regression
Authors: Brusco Michael J. , Steinley Douglas
Published: November 2009

The importance of subset selection in multiple regression has been recognized for more than 40 years and, not surprisingly, a variety of exact and heuristic procedures have been proposed for choosing subsets of variables. In the case of polynomial regression, the subset selection problem is complicated by two issues: (1) the substantial growth in the number of candidate predictors, and (2) the desire to obtain hierarchically well‐formulated subsets that facilitate proper interpretation of the regression parameter estimates. The first of these issues creates the need for heuristic methods that can provide solutions in reasonable computation time; whereas the second requires innovative neighborhood search approaches that accommodate the hierarchical constraints. We developed tabu search and variable neighborhood search heuristics for subset selection in polynomial regression. These heuristics are applied to a classic data set from the literature and, subsequently, evaluated in a simulation study using synthetic data sets. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Solid state photopolymerization of acrylic acid at low temperature
Authors: Dai Mingzhi , Xiao Ming , Xiao Pu , Nie Jun
Published: November 2009

Near‐infrared spectroscopy was used to investigate the kinetic characteristics of acrylic acid photopolymerized at −70°C and room temperature, respectively. The obtained results showed that at −70°C the double bond conversion increased with increase in the initiator's concentration. Addition of soft chain component polyethylene glycol 400 (PEG400) could lead to high conversion in the solid state, and then high final double bond conversion after post‐curing. The introduction of water at low temperature also contributed largely to the enhancement in the initial and final double bond conversion in solid state. SEM photographs showed that more pores came up in the cured films with the increase in the water content in the reaction system. The change in the photoinitiator concentration, amount of PEG400, and content of water had significant effect on samples cured at lower temperature than at room temperature under the same conditions. Different kinds of photoinitiators showed different contributions to the initial and final double bond conversion on photopolymerization of acrylic acid at low temperature. Significant post‐curing phenomena for photopolymerization of acrylic acid at low temperature could be observed as well. Copyright © 2009 John Wiley & Sons, Ltd.
Preparation of fluorine containing hybrid coatings: investigation of coating performance onto ABS and PMMA substrates
Authors: Kahraman Memet Vezir , Akdemir Zümrüt Seden , Kartal İlyas , Kayaman‐Apohan Nilhan , Güngör Atilla
Published: November 2009

UV‐curable fluorinated organic–inorganic hybrid coatings were prepared by the sol–gel technique. Perfluorinated urethane modified alkoxysilane was synthesized by the reaction between perfluoro alcohol and 3‐isocyanatopropyltrimethoxysilane. The prepared formulations were applied onto poly(methyl methacrylate) (PMMA) and acrylonitrile butadiene styrene (ABS) panels and polymerized by UV‐curing. The properties of the hybrid coatings such as hardness, chemical resistance, thermal stability, surface morphology, double bond conversion, and also contact angle measurements were investigated. Contact angle measurements have shown that the addition of fluorinated silane precursor to the hybrid system improved the water repellency and increased the contact angle from 65° to 106°. Copyright © 2009 John Wiley & Sons, Ltd.
Fly ash particles and precipitated silica as fillers in NR/CR vulcanizates under thermal and thermal‐oil ageing
Authors: Kongvasana Napalai , Kositchaiyong Apisit , Wimolmala Ekachai , Sirisinha Chakrit , Sombatsompop Narongrit
Published: November 2009

The loading effect of precipitated silica (PSi) and fly ash‐based silica (FASi) on mechanical properties of natural rubber/chloroprene (NR/CR) under thermal and thermal‐oil ageing was investigated with variation in NR content in the NR/CR blends. The selected results were compared with vulcanized NR/nitrile rubber (NR/NBR) blends. The cure time of CR vulcanizate was found to decrease with increasing NR content, but increased with silica fillers. The Mooney viscosity for CR vulcanizates reduced with increasing NR content. The addition of NR had no effect on tensile modulus and tensile strength for the FASi filled NR/CR, but the opposite trend was observed for the PSi filled NR/CR. The post‐curing effect was more significant in PSi filled NR/CR than in FASi filled NR/CR. The tensile strength of the NR/CR vulcanizates was slightly reduced after thermal ageing especially at high NR content, more extreme reduction being found by thermal‐oil ageing. The elongation at break of NR/CR with both silica fillers ranged from 400 to 900%. The hardness results were similar to the tensile modulus. The addition of PSi in NR/CR considerably increased the tear strength, but less pronounced effect was found for FASi. The resilience properties of NR/CR tended to decrease with increasing silica content. The compression set became poorer when NR content was increased. The PSi showed higher improvement in compression set than the FASi. The effects of silica and ageing on the mechanical properties for NR/CR vulcanizates were similar to those for NR/NBR vulcanizates. Copyright © 2009 John Wiley & Sons, Ltd.
Hyperechoic congenital lung lesions in a non‐selected population: from prenatal detection till perinatal management
Authors: Lecomte Bénédicte , Hadden Hélène , Coste Karen , Gallot Denis , Laurichesse Hélène , Lemery Didier , Scheye Thierry , Dechelotte Pierre , Labbé André
Published: November 2009

Objective

To present longitudinal observations of hyperechoic lung lesions (HLL) in a non‐selected population from the time of prenatal diagnosis by ultrasound (US) until postnatal surgery.

Methods

We conducted a retrospective study of all fetuses diagnosed with an HLL between 1990 and 2005 in our Fetal Medicine Unit.

Results

We observed 21 cases of HLL. Among the 17 fetuses with unilateral lesion, two cyst punctures were attempted on fetuses with signs of fetal compromise. Termination of pregnancy (TOP) was performed on seven fetuses. Fourteen fetuses were followed till birth. First Chest X‐ray was abnormal in ten cases, while delayed CT scans revealed a lung lesion in 12 cases. Two neonates required emergency surgery and died post operatively. Surgery was successfully performed in all other cases (n = 10). Pathological examination revealed congenital high airway obstruction syndrome, CHAOS (n = 4), lower airway stenosis (n = 2), bronchogenic cyst (n = 1), congenital lobar emphysema (n = 1), and congenital cystic adenomatoid malformation, CCAM (n = 11) including two cases associated with a sequestration.

Conclusion

HLL cover a wide spectrum of lung abnormalities of various severities. Post natal management should always include an early chest X‐ray and CT scan to allow appropriate selection for surgery. Copyright © 2009 John Wiley & Sons, Ltd.
Electrical Discharges in Polar Organic Liquids
Authors: Thagard Selma Mededovic , Takashima Kazunori , Mizuno Akira
Published: November 2009

Electrical discharges in water for pollutant degradation have been studied intensively, but there are almost no studies on electrical discharges in organic solvents. In this study, three separate experiments are conducted in relatively polar organic solvents: diamond‐like carbon (DLC) film synthesis, ammonia production, and hydrogen generation from methanol. The synthesis of DLC is attempted by conducting electrical discharge in four different organic liquids: acetone, methanol, acetonitrile, and dimethyl sulfoxide. Ammonia production is reported from both acetonitrile/water mixtures and hydrogen and methanol in the presence of nitrogen, although higher yields are measured from acetonitrile. Hydrogen production by electrical discharge from varying methanol/water mixtures is studied and the major liquid‐ and gas‐phase byproducts of methanol decomposition are identified.

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Lung clearance index: Normal values, repeatability, and reproducibility in healthy children and adolescents
Authors: Fuchs Susanne I. , Eder Johannes , Ellemunter Helmut , Gappa Monika
Published: November 2009

There is increasing interest in using the Multiple Breath Washout technique and the lung clearance index (LCI) for detecting early pulmonary changes, for example, in cystic fibrosis lung disease. However, there are still limited data regarding equipment specific reference ranges, repeatability and reproducibility. The aim of this prospective study was to assess within‐test repeatability, short term reproducibility and long term reproducibility, and to establish normal values for the LCI in healthy children and adolescents using the sidestream ultrasonic flow sensor (EasyOne Pro, MBW Module, ndd Medical Technologies, Switzerland). Fourty‐four volunteers (5.3–20.3 years) were recruited for the 1st test. Twenty‐two out of 44 were measured on a 2nd test occasion after an interval of 1 hr (2nd test). Thirty‐four out of 44 agreed to come back for a follow up test 6–15 months later (3rd test). Mean LCI (SD) was 6.2 (0.4), 6.3 (0.4), and 6.0 (0.4) at the 1st, 2nd, and 3rd test. The upper limit of normal was 7.0 for all subjects. Within‐test repeatability was 5.1%. Short‐term reproducibility (1st test vs. 2nd test) was 4.2% with a mean difference of −0.13 (95% CI −0.350; 0.087). Long‐term reproducibility (1st test vs. 3rd test) was 5.1%, with a mean difference of 0.017 (95% CI −0.016; 0.348). With this low variability of the LCI for both, within and between tests, our study demonstrates reliability and robustness of equipment, protocol and analysis and the reliability of the MBW technique in general. The present data will help to interpret the effect of therapeutic interventions and interpretation of longitudinal data in patients with pulmonary diseases. Pediatr Pulmonol. 2009; 44:1180–1185. © 2009 Wiley‐Liss, Inc.
Pediatric parapneumonic pleural effusion: Epidemiology, clinical characteristics, and microbiological diagnosis
Authors: Hernández‐Bou Susanna , García‐García Juan José , Esteva Cristina , Gené Amadeu , Luaces Carles , Almagro Carmen Muñoz
Published: November 2009

Background

In recent years an increase in the incidence and severity of parapneumonic pleural effusion (PPE) in pediatric populations has been observed. Streptococcus pneumoniae remains the main causal agent. New molecular and antigen techniques have increased the microbiological diagnosis of this pathology.

Objectives

To describe the epidemiology and clinical characteristics of PPE in our population.

Patients and Methods

Prospective study of patients under the age of 18 years admitted for PPE in a tertiary‐care pediatric hospital in Barcelona (Spain) between September 2003 and December 2006.

Results

One hundred ninety cases of PPE were diagnosed. The annual incidence of PPE in the population under 18 years of age increased from 19.9 cases per 100,000 in 2004 to 35.2 per 100,000 in 2006. S. pneumoniae was the main causal agent identified: 82.9% of the 21.6% patients with positive culture. Non‐vaccine serotypes (NVS) predominated (81.5%), and serotype 1 was responsible for 38.5% of cases. The use of polymerase chain reaction (PCR) test to detect S. pneumoniae increased etiological diagnosis from 21.6% to 42.1%. Antigen assays used to detect pneumococcus in pleural fluid demonstrated 87.9% sensitivity and 100% specificity when PCR was used as the gold standard.

Conclusions

There has been an increase in the incidence of PPE that parallels the increase in CAP. S. pneumoniae remains the principal causal agent, and NVS clearly predominate. The use of PCR to detect S. pneumoniae substantially increases etiologic diagnosis. The use of antigen assays to detect pneumococcus in pleural fluid is a quick and sensitive diagnostic method, and thus a valid alternative to PCR. Pediatr Pulmonol. 2009; 44:1192–1200. © 2009 Wiley‐Liss, Inc.
Nutritional rickets and vitamin D deficiency—association with the outcomes of childhood very severe pneumonia: A prospective cohort study
Authors: Banajeh Salem M.
Published: November 2009

Background

The association of rickets and vitamin D deficiency (VDD) with pneumonia is well documented, but not with its outcomes.

Objectives

To investigate whether rickets and VDD predict the outcomes in very severe pneumonia (VSP).

Design

A prospective cohort study conducted at Al‐Sabeen hospital in Sana'a, Yemen. A total of 152 children aged 2–59 months with WHO‐defined VSP were enrolled, managed, and followed for up to 30 days. Treatment outcome was either successful or failure (antibiotic modification for clinical worsening, death, relapse after 10‐day antibiotics, or development of complications). Serum vitamin D (25OHD) was measured in 79 cases. A concentration of ≤30 nmol/L defines VDD.

Main Outcome Measures

Association of rickets with treatment outcome; and VDD with the circulating neutrophils (PMNs), and oxygen saturation% (SpO2%), respectively.

Results

Treatment failure occurred in 24 (15.8%), all aged 2–12 months, and 21 (87.5%) were rachitic. Of the 79 subset, 29 had VDD of which 23 (79.3%) had rickets. Treatment failure was significantly higher in the rachitic compared to non‐rachitic [20.6% (21/102) vs. 6% (3/50); OR 1.38 (95% CI 1.13–1.69), P = 0.031]. In multivariate regression, rickets significantly predict a reduced successful treatment compared with non‐rachitic [79.4% (81/102) vs. 94% (47/50); Adjusted OR 0.41 (95% CI 0.20–0.85); P = 0.02]. VDD was strongly associated with reduced PMNs% [Mean (SD) 37 (17) vs. 47 (17); Adjusted OR 0.71 (95% CI 0.53–0.95), P = 0.02], and reduced SpO2% [Mean (SD) 85.9 (7.9) vs. 89.8 (7.1); OR 0.96 (95% CI 0.93–0.99), P = 0.021].

Conclusions

In VSP, rickets was significantly associated with treatment outcome and VDD significantly predict both reduced circulating PMNs, and Day‐5 hypoxemia (SpO2%, <88%). Pediatr Pulmonol. 2009; 44:1207–1215. © 2009 Wiley‐Liss, Inc.
Mapping of ligand‐binding cavities in proteins
Authors: Andersson C. David , Chen Brian Y. , Linusson Anna
Published: November 2009

The complex interactions between proteins and small organic molecules (ligands) are intensively studied because they play key roles in biological processes and drug activities. Here, we present a novel approach to characterize and map the ligand‐binding cavities of proteins without direct geometric comparison of structures, based on Principal Component Analysis of cavity properties (related mainly to size, polarity, and charge). This approach can provide valuable information on the similarities and dissimilarities, of binding cavities due to mutations, between‐species differences and flexibility upon ligand‐binding. The presented results show that information on ligand‐binding cavity variations can complement information on protein similarity obtained from sequence comparisons. The predictive aspect of the method is exemplified by successful predictions of serine proteases that were not included in the model construction. The presented strategy to compare ligand‐binding cavities of related and unrelated proteins has many potential applications within protein and medicinal chemistry, for example in the characterization and mapping of “orphan structures”, selection of protein structures for docking studies in structure‐based design, and identification of proteins for selectivity screens in drug design programs. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Photoluminescence from disorder induced states in individual single‐walled carbon nanotubes
Authors: Harutyunyan Hayk , Gokus Tobias , Green Alexander A. , Hersam Mark C. , Allegrini Maria , Hartschuh Achim
Published: November 2009

We report on the generation of new low‐energy photoluminescence (PL) bands in the spectra of semiconducting single‐walled carbon nanotubes (SWNTs). The new bands, that are brightened because of local modifications of the nanotube structure or the metal adsorption on the SWNT surface, are attributed to PL from different nominally dark excitons that are “brightened” due to defect‐induced mixing of states with different parity and/or spin. The effect of the created structural disorder on the dynamical properties of the emission is studied by time‐resolved PL measurements revealing a significant reduction of the bright exciton lifetime. The lowest energy dark state has a longer lifetime and is not in thermal equilibrium with the bright state.
Raman spectroscopy study on concentrated acid treated carbon nanotubes
Authors: Costa Sara , Scheibe Blazej , Rummeli Mark , Borowiak‐Palen Ewa
Published: November 2009

A comparative study will be presented on the effect of strong acid treatments in both single‐walled (SWCNT) and multi‐walled carbon nanotubes (MWCNT). The effects were studied by Raman spectroscopy. The results show that in SWCNT the raw sample shows a broader G band, well fitted by a Breit–Wigner–Fano line in comparison with the acid treated sample, which can be fitted using a Lorentzian lineshape. The original shape of this feature is recovered after the annealing step. In MWCNT samples, a two‐peak G′ band profile was observed after the acid treatment, originated by an exfoliation effect.

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Schematic illustration of the effects of acid treatment. On SWCNT, phase I corresponds to the intercalation in the interstitial channels of the bundles, while phase II is assigned to the intercalation between the walls of neighbouring nanotubes. On MWCNT, intercalation into the walls and consequent exfoliation is represented.
The anomaly of the $\nu$1‐resonance Raman band of bβ‐carotene in solution and in photosystem I and II
Authors: Tschirner Norman , Brose Katharina , Schenderlein Matthias , Zouni Athina , Schlodder Eberhard , Mroginski Maria Andrea , Hildebrandt Peter , Thomsen Christian
Published: November 2009

We have studied the resonance Raman spectra of β‐carotene in solution and in protein‐complexes using laser excitation at various wavelengths in the visible region. Main focus was laid on the ν1‐band, which shows an anomalous behaviour upon variation of the excitation wavelength resulting in a frequency shift of the peak maximum. This shift is due to different excitation profiles of two closely spaced modes as shown previously for β‐carotene in solution. In this work, we have extended the studies to the antenna pigment in photosystems I and II (PS I and PS II).
Interband transmission in armchair graphene ribbons with a step‐like profile of potential energy: Relevance to Klein's tunneling
Authors: Malysheva Lyuba , Petrenko Evgenij , Onipko Alexander
Published: November 2009

Three principal results concerning graphene‐based wires and their ambipolar behavior are presented. First, it is the exact expression of the transmission coefficient for armchair graphene wires described by the tight‐binding Hamiltonian with the step‐like change U of site energies. Second, the exact relation between the energy of incident electrons or holes and potential U at which there is no backscattering for the given mode of the transverse motion. Third, the range of relevance of Klein's formula describing the motion of relativistic particles in the same potential profile is established. Analysis of newly derived results shows that physics of interband transitions at constant energy in graphene wires is richer than it was believed.
Electronic transport measurements and Raman spectroscopy on carbon nanotube devices
Authors: Herranen Olli , Rintala Jyri , Johansson Andreas , Queipo Paula , Nasibulin Albert G. , Kauppinen Esko I. , Pettersson Mika , Ahlskog Markus
Published: November 2009

An individual single wall carbon nanotube (SWCNT) device has been fabricated and measured using both low temperature transport and Raman measurements. With these mutually independent methods we can study the correlation between the techniques on semiconducting or metallic behavior of the tube. Furthermore, we study the structure of the nanotube by probing Raman measurements at different spots along the tube axis.
Quantitative composition of a single‐walled carbon nanotube sample: Raman scattering versus photoluminescence
Authors: Heeg Sebastian , Malić Ermin , Casiraghi Cinzia , Reich Stephanie
Published: November 2009

We investigated the spectral data of three carbon nanotube (CNT) species obtained by Raman spectroscopy and photoluminescence (PL) measurements. The corresponding relative signal intensities without further corrections yielded significantly different relative distributions of the CNT species. Theoretical calculations of optical transition probabilities and electron–phonon coupling were included, providing simple models in order to estimate the relative distribution of the three species within the sample. We proposed the product of PL and PL excitation intensities to be a candidate for quantitative analysis of CNT species. Applying the models, we confirmed that both spectroscopic methods agree on one nanotube species dominating the distribution.
Pulsed electrically detected magnetic resonance in organic semiconductors
Authors: Boehme C. , McCamey D. R. , van Schooten K. J. , Baker W. J. , Lee S.‐Y. , Paik S.‐Y. , Lupton J. M.
Published: November 2009

Carbon‐based materials have an intrinsically weak spin–orbit coupling which imposes spin selection rules on many electronic transitions. The spin degree of freedom of electrons and nuclei can therefore play a crucial role in the electronic and optical properties of these materials. Spin‐selection rules can be studied via magnetic resonance techniques such as electron–spin resonance and optically detected magnetic resonance as well as electrically detected magnetic resonance (EDMR). The latter has progressed in recent years to a degree where the observation of coherent spin motion via current detection has become possible, providing experimental access to many new insights into the role that paramagnetic centers play for conductivity and photoconductivity. While mostly applied to inorganic semiconductor materials such as silicon, this new, often called pulsed‐(p) EDMR spectroscopy, has much potential for organic (carbon‐based) semiconductors. In this study, progress on the development of pEDMR spectroscopy on carbon‐based materials is reviewed. Insights into materials properties that can be gained from pEDMR experiments are explained and limitations are discussed. Experimental data on radiative polaron‐pair recombination in poly[2‐methoxy‐5‐(20‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene] (MEH‐PPV) organic light emitting diodes (OLEDs) are shown, revealing that under operating conditions the driving current of the device can be modulated by spin‐Rabi nutation of the polaron spin within the charge carrier pairs. From this experimental data it becomes clear that for polaron pairs, the precursor states during exciton formation, exchange interaction is not the predominant influence on the observed pEDMR spectra.
Hydrogen‐induced defect engineering in dilute nitride semiconductors
Authors: Trotta Rinaldo , Polimeni Antonio , Capizzi Mario
Published: November 2009

In dilute nitrides, such as GaAsN, hydrogen‐induced passivation of the electronic activity of N atoms offers an unprecedented opportunity to tune the electronic and structural properties of those materials. By deposition of hydrogen‐opaque metallic masks on GaAsN and subsequent hydrogen irradiation, it is possible to alternate in the growth plane regions having the physical properties of GaAsN with those of N‐passivated GaAsN. After reporting the main characteristics of deuterium diffusion in GaAsN as derived by secondary ion mass spectrometry, we present two examples of hydrogen–induced defect engineering. In the first case, we show that anisotropic strain fields can be created by selective H incorporation. The resulting in‐plane symmetry breaking determines an in‐plane polarization dependence of the light emitted along the crystal growth, otherwise unattainable in bulk GaAsN. Secondly, we report evidence of quantum confinement effects in dot‐like structures obtained by in‐plane patterning of the crystal band gap energy. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical nonlinearities and carrier dynamics in semi‐insulating crystals
Authors: Jarašiūnas K. , Kadys A. , Aleksiejūnas R. , Malinauskas T.
Published: November 2009

We analyze conditions when the deep‐impurity governed carrier generation and transport in semi‐insulating crystals create the coexisting free carrier, photorefractive, and absorptive nonlinearities. By monitoring the nonequilibrium carrier and space charge field dynamics via the probe beam diffraction on transient gratings, number of electrical parameters in bulk semi‐insulating crystal have been determined, as carrier lifetime, diffusion coefficient, diffusion length, and sign of carriers, photogenerated from deep traps. We show a novel possibility to record a transient reflection grating via spatial modulation of the deep trap occupation and applicability of this technique to evaluate the compensation ratio of these traps as well as their recombination properties. Experimentally measured diffraction kinetics on free carrier, photorefractive and absorptive gratings in few nanosecond time interval provided the values of diffusion coefficient and carrier lifetime in bulk CdTe and ZnTe crystals, doped by V, Ge, Al, Sc as well in InP:Fe. Carrier transport peculiarities in these crystals revealed the type (n or p) of dominant carriers, generated from the deep impurity levels. In n‐type HVPE GaN crystals, we observed impact of light‐induced space‐charge field to carrier diffusion. The transient reflection gratings in semi‐insulating CdTe:V allowed discrimination of deep trap governed carrier recombination rate from the other recombination channels. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Docking Study and Three‐Dimensional Quantitative Structure‐Activity Relationship (3D‐QSAR) Analyses of Transforming Growth Factor‐β Type I Receptor Kinase Inhibitors
Authors: Yang Min , Zhou Lu , Zuo Zhili , Mancera Ricardo , Song Hang , Tang Xiangyang , Ma Xiang
Published: November 2009

Transforming growth factor‐β Type I Receptor Kinase (TGF‐β RI) is an important and novel drug target for the treatment of fibrosis and cancer. In this study, docking and comparative molecular field analysis (CoMFA) were performed and the structural characteristics of TGF‐β RI ligands were rationalized. The genetic algorithm search method in the docking program GOLD 3.0.1 was employed to determine the likely binding mode conformations of 70 inhibitors in the active site of TGF‐β RI. Based on the binding mode conformations, a highly predictive 3D‐QSAR model was developed with a q2 value of 0.589 for CoMFA. The predictive ability of this model was validated with a number of compounds that were not included in the original training set. Furthermore, the 3D‐QSAR model was mapped back to the binding site of the TGF‐β RI to obtain a better understanding of the essential interactions between the inhibitors and TGF‐β RI. The robustness, predictive ability and automated alignment generation of this model make it a potential tool for the design and development of new drug leads to inhibit TGF‐β RI.
Synthesis, Antimycobacterial Activity and 3‐D QSAR Studies of Some New Derivatives of p‐Hydroxybenzohydrazide
Authors: Bhole Ritesh. P. , Bhusari Kishore P.
Published: November 2009

Various N′‐[3‐(4‐substituted alkyl/aryl thiaiazolidin‐2‐ylidene]‐4‐hydroxy benzohydrazide (4.a–i) and N′‐[‐(3,4‐disubstituted)‐1,3‐thiazolidin‐2ylidene)]‐4‐hydroxybenzohydrazide from (5.a–i) to (10.a–i) were synthesized using appropriate synthetic route. The entire test compounds (4.a–i) and compounds from (5.a–i) to (10.a–i) were assayed in vitro against H37Rv strain of M. tuberculosis. The minimum inhibitory concentration (MIC) was determined for test compounds and for reference standards. The test compounds showed significant antimycobacterial activity against the microbial strains used, when tested in vitro. In general, p‐hydroxybenzohydrazide ring and substituted thiazoline ring are essential for antimicrobial activity. Among the compounds tested, compounds 5.i, 6.f, 7.d, 8.g and 9.f were found to be most potent. The test compounds were found to be nontoxic up to a dose level of 1000 μg/mL. All compounds were then subjected for 3D‐QSAR studies. 3D‐QSAR study based on the principal of alignment of pharmacophoric features by Schrodinger PHASE module. The 3D‐QSAR study allowed us to confirm the preferential binding mode of p‐hydroxybenzohydrazide inside the active site.
Ultrasmall Near‐Infrared Non‐cadmium Quantum Dots for in vivo Tumor Imaging
Authors: Gao Jinhao , Chen Kai , Xie Renguo , Xie Jin , Lee Seulki , Cheng Zhen , Peng Xiaogang , Chen Xiaoyuan
Published: November 2009

The high tumor uptake of ultrasmall near‐infrared quantum dots (QDs) attributed to the enhanced permeability and retention effect is reported. InAs/InP/ZnSe QDs coated by mercaptopropionic acid (MPA) exhibit an emission wavelength of about 800 nm (QD800‐MPA) with very small hydrodynamic diameter (<10 nm). Using 22B and LS174T tumor xenograft models, in vivo and ex vivo imaging studies show that QD800‐MPA is highly accumulated in the tumor area, which is very promising for tumor detection in living mice. The ex vivo elemental analysis (Indium) using inductively coupled plasma (ICP) spectrometry confirm the tumor uptake of QDs. The ICP data are consistent with the in vivo and ex vivo fluorescence imaging. Human serum albumin (HSA)‐coated QD800‐MPA nanoparticles (QD800‐MPA‐HSA) show reduced localization in mononuclear phagocytic system‐related organs over QD800‐MPA plausibly due to the low uptake of QD800‐MPA‐HSA in macrophage cells. QD800‐MPA‐HSA may have great potential for in vivo fluorescence imaging.
A Genetic Strategy for Single and Combinatorial Analysis of miRNA Function in Mammalian Hematopoietic Stem Cells
Authors: Papapetrou Eirini P. , Korkola James E. , Sadelain Michel
Published: November 2009

The regulatory role of micro-RNAs (miRNAs) in hematopoietic development is increasingly appreciated. Reverse genetics strategies based on the targeted disruption of miRNAs offer a powerful tool to study miRNA functions in mammalian hematopoiesis. The miR-144/451 cluster comprises two miRNAs coexpressed from a common precursor transcript in an erythroid-specific manner. To decipher the contribution of each miRNA of the cluster in mammalian erythropoiesis, we developed a strategy for stable in vivo individual and combinatorial miRNA inhibition. We developed decoy target sequences for each miRNA expressed by lentiviral vectors marked with distinct fluorescent proteins and used them to probe the functions of miR-144 and miR-451 in the murine hematopoietic system in a competitive repopulation setting. Murine hematopoietic chimeras expressing lentiviral-encoded inhibitory sequences specific for miR-144 or miR-451 exhibited markedly reduced Ter119+ erythroblast counts, with the combined knockdown showing additive effect. These chimeras showed abnormal patterns of erythroid differentiation primarily affecting the proerythroblast to basophilic erythroblast transition, coinciding with the stage where expression of the miRNA cluster is dramatically induced and posttranscriptional gene regulation becomes prominent. These results reveal a role for the miR-144/451 locus in mammalian erythropoiesis and provide the first evidence of functional cooperativity between clustered miRNAs in the hematopoietic system. The strategy described herein will prove useful in functional miRNA studies in mammalian hematopoietic stem cells.
Modeling Concordance Correlation Coefficient for Longitudinal Study Data
Authors: Ma Yan , Tang Wan , Yu Qin , Tu X. M.
Published: November 2009

Measures of agreement are used in a wide range of behavioral, biomedical, psychosocial, and health-care related research to assess reliability of diagnostic test, psychometric properties of instrument, fidelity of psychosocial intervention, and accuracy of proxy outcome. The concordance correlation coefficient (CCC) is a popular measure of agreement for continuous outcomes. In modern-day applications, data are often clustered, making inference difficult to perform using existing methods. In addition, as longitudinal study designs become increasingly popular, missing data have become a serious issue, and the lack of methods to systematically address this problem has hampered the progress of research in the aforementioned fields. In this paper, we develop a novel approach to tackle the complexities involved in addressing missing data and other related issues for performing CCC analysis within a longitudinal data setting. The approach is illustrated with both real and simulated data.
Electrical Conductivity Studies on Individual Conjugated Polymer Nanowires: Two-Probe and Four-Probe Results
Authors: Long YunZe , Duvail JeanLuc , Li MengMeng , Gu Changzhi , Liu Zongwen , Ringer Simon P
Published: November 2009

Two- and four-probe electrical measurements on individual conjugated polymer nanowires with different diameters ranging from 20 to 190 nm have been performed to study their conductivity and nanocontact resistance. The two-probe results reveal that all the measured polymer nanowires with different diameters are semiconducting. However, the four-probe results show that the measured polymer nanowires with diameters of 190, 95–100, 35–40 and 20–25 nm are lying in the insulating, critical, metallic and insulting regimes of metal–insulator transition, respectively. The 35–40 nm nanowire displays a metal–insulator transition at around 35 K. In addition, it was found that the nanocontact resistance is in the magnitude of 104Ω at room temperature, which is comparable to the intrinsic resistance of the nanowires. These results demonstrate that four-probe electrical measurement is necessary to explore the intrinsic electronic transport properties of isolated nanowires, especially in the case of metallic nanowires, because the metallic nature of the measured nanowires may be coved by the nanocontact resistance that cannot be excluded by a two-probe technique.
One-Pot Green Synthesis and Bioapplication ofl-Arginine-Capped Superparamagnetic Fe3O4 Nanoparticles
Authors: Lai Yongchao , Yin Weiwei , Liu Jinting , Xi Rimo , Zhan Jinhua
Published: November 2009

Water-solublel-arginine-capped Fe3O4 nanoparticles were synthesized using a one-pot and green method. Nontoxic, renewable and inexpensive reagents including FeCl3,l-arginine, glycerol and water were chosen as raw materials. Fe3O4 nanoparticles show different dispersive states in acidic and alkaline solutions for the two distinct forms of surface bindingl-arginine. Powder X-ray diffraction and X-ray photoelectron spectroscopy were used to identify the structure of Fe3O4 nanocrystals. The products behave like superparamagnetism at room temperature with saturation magnetization of 49.9 emu g−1 and negligible remanence or coercivity. In the presence of 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride, the anti-chloramphenicol monoclonal antibodies were connected to thel-arginine-capped magnetite nanoparticles. The as-prepared conjugates could be used in immunomagnetic assay.

(See supplementary material 1)
Synthesis and Properties of Polyurethane Elastomers with Castor Oil as Crosslinker
Authors: Oprea Stefan
Published: November 2009

Castor oil–polyurethane elastomers were prepared by reacting poly (1,4‐butane diol) (Terathane 1400) with aliphatic 1,6‐hexamethylene diisocyanate. The prepolymers were chain‐extended with bifunctional precursor chains and/or with castor oil as a trifunctional crosslinker at stoichiometric ratios. These resulted in a series of crosslinked polyurethane elastomers with different structures of the hard segment. The properties of the material were measured by differential scanning calorimetry, thermogravimetric analysis, atomic force microscopy, as well as tensile properties measurements. The effect of stoichiometric balance (i.e., OH/NCO molar ratio) on the final properties was evaluated. The formation of hydrogen bonds was observed by Fourier transform infrared.spectroscopy The measured properties were found to be strongly influenced by the molar ratio of chain extenders to the diisocyanate component. The glass transition temperatures (Tg) for the polyurethanes with OHpolyol/NCO/OHchain extender having molar ratios of 1:2:1 and 1:4:3 were found to be −70 and −57 °C, respectively. The polyurethanes networks with a OH/NCO molar ratio of 1:2:1 had excellent mechanical properties, indicating that this is the optimum ratio to be used in castor oil polyurethane elastomer formulations. The objective of this work was to study the effect of the castor oil crosslinker on the morphology of the resulting crosslinked polyurethanes and to correlate the morphology with the properties of these bio‐based crosslinked polyurethanes.