bluuebunny/crossref_metadata_2025 huggingface dataset:
Main Pulmonary Artery Aneurysm Described by Transthoracic Echocardiography in an Adult Without Pulmonary Stenosis or Pulmonary Hypertension
Authors: Zemanek Mark D.
Published: March 2012

Aneurysm of the main pulmonary artery is a rare finding in adults. This case presents the finding of an asymptomatic 4.6-cm pulmonary artery aneurysm in a woman in her early 60s detected on routine transthoracic echocardiography. All pertinent data are presented, and the clinical significance of the pulmonary artery aneurysm is discussed. The case emphasizes the importance of following a complete and thorough echocardiographic examination protocol. A limited study is likely to miss significant incidental findings such as is reported here, particularly if it involves the right heart.
Diagnostic Imaging of Late-Stage Breast Cancer
Authors: Ball Taylor
Published: March 2012

Diagnostic imaging has proven to be a beneficial tool in the screening, diagnosis, and prognosis of breast cancer. Most cancers are found early with breast screening methods, such as mammography. In some instances, breast cancer will go unidentified or untreated up to the point that the cancer becomes more advanced. This case study investigates a form of breast cancer that was diagnosed within a month after the patient’s first meeting with her physician. The breast cancer was examined with x-ray, computed tomography, and sonography. The role of sonography is discussed in detail with the aim of illustrating the usefulness of this technology in identifying cancerous breast tissue.
A generalization and improvement of Chidume theorems for total asymptotically nonexpansive mappings in Banach spaces
Authors: Chang Shih-sen , Kim Jong Kyu , Lee H W Joseph , Chan Chi Kin
Published: March 2012

The purpose of this article is to establish some new approximation theorems of common fixed points for a countable family of total asymptotically quasi-nonexpansive mappings in Banach spaces which generalize and improve the corresponding theorems of Chidume et al. and others.

2000 AMS Subject Classification: 47J05; 47H09; 49J25.
In vitro antiproliferative/cytotoxic activity on cancer cell lines of a cardanol and a cardol enriched from Thai Apis mellifera propolis
Authors: Teerasripreecha Dungporn , Phuwapraisirisan Preecha , Puthong Songchan , Kimura Kiyoshi , Okuyama Masayuki , Mori Haruhide , Kimura Atsuo , Chanchao Chanpen
Published: March 2012

Background

Propolis is a complex resinous honeybee product. It is reported to display diverse bioactivities, such as antimicrobial, anti-inflammatory and anti-tumor properties, which are mainly due to phenolic compounds, and especially flavonoids. The diversity of bioactive compounds depends on the geography and climate, since these factors affect the floral diversity. Here, Apis mellifera propolis from Nan province, Thailand, was evaluated for potential anti-cancer activity.

Methods

Propolis was sequentially extracted with methanol, dichloromethane and hexane and the cytotoxic activity of each crude extract was assayed for antiproliferative/cytotoxic activity in vitro against five human cell lines derived from duet carcinoma (BT474), undifferentiated lung (Chaco), liver hepatoblastoma (Hep-G2), gastric carcinoma (KATO-III) and colon adenocarcinoma (SW620) cancers. The human foreskin fibroblast cell line (Hs27) was used as a non-transformed control. Those crude extracts that displayed antiproliferative/cytotoxic activity were then further fractionated by column chromatography using TLC-pattern and MTT-cytotoxicity bioassay guided selection of the fractions. The chemical structure of each enriched bioactive compound was analyzed by nuclear magnetic resonance and mass spectroscopy.

Results

The crude hexane and dichloromethane extracts of propolis displayed antiproliferative/cytotoxic activities with IC50 values across the five cancer cell lines ranging from 41.3 to 52.4 μg/ml and from 43.8 to 53.5 μg/ml, respectively. Two main bioactive components were isolated, one cardanol and one cardol, with broadly similar in vitro antiproliferation/cytotoxicity IC50 values across the five cancer cell lines and the control Hs27 cell line, ranging from 10.8 to 29.3 μg/ml for the cardanol and < 3.13 to 5.97 μg/ml (6.82 - 13.0 μM) for the cardol. Moreover, both compounds induced cytotoxicity and cell death without DNA fragmentation in the cancer cells, but only an antiproliferation response in the control Hs27 cells However, these two compounds did not account for the net antiproliferation/cytotoxic activity of the crude extracts suggesting the existence of other potent compounds or synergistic interactions in the propolis extracts.

Conclusion

This is the first report that Thai A. mellifera propolis contains at least two potentially new compounds (a cardanol and a cardol) with potential anti-cancer bioactivity. Both could be alternative antiproliferative agents for future development as anti-cancer drugs.
Inflammation and neurological adverse drugs reactions: a case of long lasting impaired consciousness after oxatomide administration in a patient with gastroenteritis
Authors: Antoniazzi Stefania , Cattaneo Dario , Perrone Valentina , Carnovale Carla , Cherubini Simonetta , Mugolino Maria Carmela , Clementi Francesco , Zuccotti Gianvincenzo , Clementi Emilio , Radice Sonia
Published: March 2012

Oxatomide at therapeutic doses generates occasionally drowsiness in children. When administered at toxic doses, however oxatomide may induce long lasting impaired consciousness. We now report a case of severe long lasting impaired consciousness induced by therapeutic doses of oxatomide occurring in a child affected by acute gastroenteritis. The clinical symptoms, the pharmacogenetic tests of polymorphisms in cytochrome P450 metabolizing enzymes (CYPs) and the clinical and laboratory analyses indicate that the enhanced drug sedative effect is likely due to an acute, yet mild, inflammatory state of the patient. These findings highlight the importance of assessing common, not serious inflammatory states when oxatomide is prescribed in paediatric patients.
In vitro production of two chitinolytic proteins with an inhibiting effect on the insect coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae) and the fungus Hemileia vastatrix the most limiting pests of coffee crops
Authors: Martínez Claudia P , Echeverri Claudia , Florez Juan C , Gaitan Alvaro L , Góngora Carmenza E
Published: March 2012

Two genes fromStreptomyces albidoflavus, one exochitinase (905-bp) and an endochitinase (1100-bp) were functionally expressed inEscherichia coliin form of a fusion protein with a maltose binding protein (MBP). The goal was to produce and test proteins that inhibit both the coffee berry borer insectHypothenemus hampeiand the coffee rust fungusHemileia vastatrix. Both recombinant proteins MBP/exochitinase and MBP/endochitinase showed chitinolytic activity. When recombinant purified proteins were added to an artificial coffee-based diet for the coffee berry borer, MBP/exochitinase at a concentration of 0.5% W/W caused delayed growth of larvae and 100% mortality between days 8 and 15, while MBP/endochitinase caused 100% mortality at day 35.H. vastatrixurediniospores presented total cell wall degradation in their germinative tubes within 18 h of exposure to the proteins at enzyme concentrations of 5 and 6 mg ml-1, with exochitinase having the greatest effect. The dual deleterious effect ofS. albidoflavuschitinases on two of the most limiting coffee pests worldwide, the coffee borer and the coffee rust, make them potential elements to be incorporated in integrated control strategies.
BTLA expression contributes to septic morbidity and mortality by inducing innate inflammatory cell dysfunction
Authors: Shubin Nicholas J , Chung Chun S , Heffernan Daithi S , Irwin Lydea R , Monaghan Sean F , Ayala Alfred
Published: March 2012

BTLA expression contributes to increased septic morbidity, mortality, and decreased innate cell activity in mice, while BTLA+ blood monocyte levels increase in septic ICU patients.

A proper innate inflammatory response is essential for prevention of the systemic inflammation associated with sepsis. BTLA is an immune-regulatory receptor demonstrated to be expressed not only on adaptive immune populations and have potent inhibitory effects on CD4+ T cells but is also expressed on innate cell populations (CD11c+ and CD11b+ cells) and has been shown to diminish pathogen clearance following bacterial and parasite infection. The role of BTLA in sepsis and the mechanisms by which BTLA alters pathogen clearance, however, have not been addressed clearly. Here, we show that following acute experimental sepsis induction in mice (CLP), the number of infiltrating BTLA- and HVEM (the ligand for BTLA)-expressing macrophages, inflammatory monocytes, mature and immature DCs, and neutrophils increased in the peritoneum compared with sham surgery, suggesting that a high level of HVEM:BTLA interactions occurs between these cells at the site of septic insult. Given this, we evaluated BTLA−/− mice, 24 h post-CLP, and observed a marked increase in the degree of activation on these cell populations, as well as a reduction in peritoneal bacterial burden and IL-10 induction, and most importantly, BTLA−/− mice exhibited a higher rate of survival and protection from organ injury when compared with WT mice. Such changes were not restricted to experimental mice, as circulating BTLA+ and HVEM+ monocytes and HVEM+ granulocytes were increased in septic ICU patients, supporting a role for BTLA and/or HVEM as potential, novel diagnostic markers of innate immune response/status and as therapeutic targets of sepsis.
Four Problems About Self-Locating Belief
Authors: Bradley Darren
Published: March 2012

This article defends the Doomsday Argument, the Halfer Position in Sleeping Beauty, the Fine-Tuning Argument, and the applicability of Bayesian confirmation theory to the Everett interpretation of quantum mechanics. It will argue that all four problems have the same structure, and it gives a unified treatment that uses simple models of the cases and no controversial assumptions about confirmation or self-locating evidence. The article will argue that the troublesome feature of all these cases is not self-location but selection effects.
Freedom and the Fixity of the Past
Authors: Holliday Wesley H.
Published: March 2012

According to the Principle of the Fixity of the Past (FP), no one can now do anything that would require the past to have unfolded differently than it actually did, for the past is fixed, over and done with. Why might doing something in the future require the past to be different? Because if determinism is true—if the laws of nature and the initial conditions of the Big Bang determined a unique future for our universe—then doing anything other than what you are determined to do would require one of two things: either a miracle, a violation of the actual laws of nature, or a different past, all the way back to the Big Bang or beyond. Which would it be? Those who reject miracles accept a Backtracking Principle (BT), according to which the past would (have to) be different. If this is correct, then it follows by (FP) that you cannot now do anything other than what you are determined to do. The conclusion of this much-discussed argument is that the freedom to do otherwise is incompatible with determinism. In order to break a stalemate between incompatibilists and compatibilists in the debate over (FP), this article presents a new Action-Type Argument for (FP). The aim is to refute Backtracking Compatibilism, the view that (BT) is true and yet the freedom to do otherwise is compatible with determinism. The form of the Action-Type Argument for (FP) also leads to a Simple Argument for incompatibilism, which does not assume (BT). What the Simple Argument does assume is a “governing” view of laws of nature, a view of laws as more than mere regularities that turn out to be exceptionless over all time. Incompatibilism follows.
Accuracy, Chance, and the Principal Principle
Authors: Pettigrew Richard
Published: March 2012

In “A Nonpragmatic Vindication of Probabilism,” James M. Joyce attempts to “depragmatize” de Finetti’s prevision argument for the claim that our credences ought to satisfy the axioms of the probability calculus. This article adapts Joyce’s argument to give nonpragmatic vindications of David Lewis’s original Principal Principle as well as recent reformulations due to Ned Hall and Jenann Ismael. Joyce enumerates properties that a function must have if it is to measure the distance from a set of credences to a set of truth values; he shows that, on any such measure, and for any set of credences that violates the probability axioms, there is a set that satisfies those axioms that is closer to every possible set of truth values. This article replaces truth values with objective chances in this argument; it shows that for any set of credences that violates the probability axioms or the Principal Principle, there is a set that satisfies both that is closer to every possible set of objective chances and similarly for Ned Hall’s New Principle and Jenann Ismael’s Generalized Principal Principle. Along the way, the article provides new arguments for some of Joyce’s central conditions on distance measures, and it answers two pressing objections to Joyce’s strategy.
WNT signaling increases proliferation and impairs differentiation of stem cells in the developing cerebellum
Authors: Pei Yanxin , Brun Sonja N. , Markant Shirley L. , Lento William , Gibson Paul , Taketo Makoto M. , Giovannini Marco , Gilbertson Richard J. , Wechsler-Reya Robert J.
Published: March 2012

The WNT pathway plays multiple roles in neural development and is crucial for establishment of the embryonic cerebellum. In addition, WNT pathway mutations are associated with medulloblastoma, the most common malignant brain tumor in children. However, the cell types within the cerebellum that are responsive to WNT signaling remain unknown. Here we investigate the effects of canonical WNT signaling on two important classes of progenitors in the developing cerebellum: multipotent neural stem cells (NSCs) and granule neuron precursors (GNPs). We show that WNT pathway activation in vitro promotes proliferation of NSCs but not GNPs. Moreover, mice that express activated β-catenin in the cerebellar ventricular zone exhibit increased proliferation of NSCs in that region, whereas expression of the same protein in GNPs impairs proliferation. Although β-catenin-expressing NSCs proliferate they do not undergo prolonged expansion or neoplastic growth; rather, WNT signaling markedly interferes with their capacity for self-renewal and differentiation. At a molecular level, mutant NSCs exhibit increased expression of c-Myc, which might account for their transient proliferation, but also express high levels of bone morphogenetic proteins and the cyclin-dependent kinase inhibitor p21, which might contribute to their altered self-renewal and differentiation. These studies suggest that the WNT pathway is a potent regulator of cerebellar stem cell growth and differentiation.
Wnt9b-dependent FGF signaling is crucial for outgrowth of the nasal and maxillary processes during upper jaw and lip development
Authors: Jin Yong-Ri , Han Xiang Hua , Taketo Makoto M. , Yoon Jeong Kyo
Published: March 2012

Outgrowth and fusion of the lateral and medial nasal processes and of the maxillary process of the first branchial arch are integral to lip and primary palate development. Wnt9b mutations are associated with cleft lip and cleft palate in mice; however, the cause of these defects remains unknown. Here, we report that Wnt9b–/– mice show significantly retarded outgrowth of the nasal and maxillary processes due to reduced proliferation of mesenchymal cells, which subsequently results in a failure of physical contact between the facial processes that leads to cleft lip and cleft palate. These cellular defects in Wnt9b–/– mice are mainly caused by reduced FGF family gene expression and FGF signaling activity resulting from compromised canonical WNT/β-catenin signaling. Our study has identified a previously unknown regulatory link between WNT9B and FGF signaling during lip and upper jaw development.
Orthopaedics in the developing world
Authors: Lavy C.
Published: March 2012

Chris Lavy is an orthopaedic surgeon in Oxford (UK) who lived and worked in Malawi for ten years. There he helped build an orthopaedic hospital and research unit. He was also one of the founders of COSECSA, the regional college of surgeons for East and Central Africa in 1999.
Orthopaedics and industry
Authors: Field R. E. , Shimmin A. , Cattani L.
Published: March 2012

The need to demonstrate probity and fair market competition has increased scrutiny of the relationships between orthopaedic surgeons and the industry that supplies them with their tools and devices. Investigations and judgements from the US Department of Justice and the introduction of the AdvaMed and Eucomed codes have defined new boundaries for interactions between these groups. This article summarises the current interplay between orthopaedic surgeons and industry, and provides recommendations for the future.
An Lp
-theory for non-divergence form SPDEs driven by Lévy processes
Authors: Chen Zhen-Qing , Kim Kyeong-Hun
Published: March 2012

In this paper we present an Lp
-theory for
a class of stochastic partial differential equations (SPDEs in abbreviation)
driven by Lévy processes. The SPDEs under consideration can have random
coefficients that depend both on the time and space
variable. Existence and uniqueness of solutions
in various Sobolev spaces are obtained. These Sobolev spaces describe the regularity of the solutions
of the SPDEs.
From Electrochemical Capacitors to Supercapatteries
Authors: Chae Jung Hoon , Zhou Xiaohang , Chen George Zheng
Published: March 2012

The enormous technical developments and rapid changes in life patterns made in the recent decades have largely been attributed to the exploitation of contemporary forms of energy sources, i.e. fossil fuels. However, their finite availability and significantly high environmental impacts have aroused concerns and spurred research to find alternatives and more efficient ways to store energy. In particular, recent developments of batteries and fuel cells as energy storage devices have been proven to be very promising, but their poor power characteristics and cyclic stability hinder their wider applications. Conversely, conventional capacitors display a great outputting pulsed power, but disappointing energy characteristics. Electrochemical capacitors (ECs), which are also known as supercapacitors, bridge the crucial performance disparity between fuel cells or batteries with high energy capacities and the traditional capacitors capable of outputting pulsed high power. The main focus of this review is to outline the latest developments of the ECs and determine their current status in terms of energy and power characteristics. In particular, recent developments in materials including new synthesis methods, structural studies and advanced configurations of ECs are discussed. Moreover, several technical challenges to further development are identified. Based on the latest results, the potential of developing supercapatteries, whose performance is in between batteries and contemporary supercapacitors, are also discussed in this review.
High-efficiency Silicon Heterojunction Solar Cells: A Review
Authors: De Wolf Stefaan , Descoeudres Antoine , Holman Zachary C. , Ballif Christophe
Published: March 2012

Silicon heterojunction solar cells consist
of thin amorphous silicon layers deposited on
crystalline silicon wafers. This design
enables energy conversion efficiencies above
20% at the industrial production level. The
key feature of this technology is that the
metal contacts, which are highly recombination
active in traditional, diffused-junction
cells, are electronically separated from the
absorber by insertion of a wider bandgap
layer. This enables the record open-circuit
voltages typically associated with
heterojunction devices without the need for
expensive patterning techniques. This article
reviews the salient points of this
technology. First, we briefly elucidate device
characteristics. This is followed by a
discussion of each processing step, device
operation, and device stability and industrial
upscaling, including the fabrication of solar
cells with energy-conversion efficiencies over
21%. Finally, future trends are pointed
out.
Nitrogen-doped Hydrothermal Carbons
Authors: Titirici Maria-Magdalena , White Robin J. , Zhao Li
Published: March 2012

Nitrogen doped carbon materials are now playing an important role in cutting edge innovations for energy conversion and storage technologies such as supercapacitors and proton exchange membrane fuel cells as well as in catalytic applications, adsorption and CO
2
capture. The production of such materials using benign aqueous based processes, mild temperatures and renewable precursors is of great promise in addressing growing environmental concerns for cleaner power sources at a time of increasing global demand for energy. In this perspective, we show that nitrogen doped carbons prepared using sustainable processes such as “Hydrothermal Carbonisation” has advantages in many applications over the conventional carbons. We also summarize an array of synthetic strategies used to create such nitrogen doped carbons, and discuss the application of these novel materials.
Van der Waerden's Theorem on Homothetic Copies of {1,1+s,1+s+t}
Authors: Kim Byeong Moon , Rho Yoomi
Published: March 2012

For all positive integers
Comparison of risk calculation approaches in a screening programme for Down syndrome
Authors: Koster Maria P.H. , Heetkamp Kirsten M. , de Miranda Esteriek , Schielen Peter C.J.I.
Published: March 2012

In the Netherlands, both the LifeCycle Elipse (LC) and the Astraia software package are used to calculate the risk of having a child with Down syndrome. Therefore, pregnant women can be presented with dissimilar risks. In this study the conformity between these risks before and after harmonization of the screening program and its influence on the performance indicators of the first trimester screening were evaluated. The agreement between combined risks (based on the biochemical parameters PAPP-A and fβ-hCG and a nuchal translucency measurement) was expressed as intraclass correlation coefficient (ICC)=0.99. Conformity between combined risks was better after harmonization (Cohen’s κ=0.75) than before harmonization (Cohen’s κ=0.63). For both risk calculation software packages the area under the ROC-curve was 0.84. The database contained 42 Down syndrome cases; based on the odds of being affected given a positive result (OAPR), LC performed slightly better than Astraia before harmonization (17.9 vs. 21.5, respectively). It has been acknowledged that using different software packages could lead to dissimilar risk calculations. In this study the screening performance indicators of two software packages were quite similar. The agreement of the screening performance after harmonization remains to be seen, but is expected to be even higher.
Individual decisions in placenta increta and percreta: a case series
Authors: Chantraine Frédéric , Nisolle Michelle , Petit Philippe , Schaaps Jean-Pierre , Foidart Jean-Michel
Published: March 2012

Objective: Placenta increta or percreta is an uncommon pathology, sometimes associated with high maternal morbidity. Its prevalence increases proportionally to the number of cesarean sections. This study analyzed the changes of our management strategy to devise treatment guidelines for this uncommon disorder.

Materials and methodology: Between 2005 and 2011, 10 cases of placenta increta or percreta were managed at our university hospital maternity department.

Results: Among the 10 cases, seven were diagnosed prenatally. Two patients were diagnosed early, at 14 and 17 weeks of gestational age, and their pregnancies were terminated. Five had hysterectomies during the intrapartum period, and despite attempted conservative treatment for the two others, hysterectomy proved necessary 2 months postpartum because of intrauterine infections. Seven of the 10 women had hysterectomies.

Conclusion: Prenatal diagnosis of placenta increta or percreta is essential to plan the delivery in a competent tertiary care center. The decision to perform a cesarean hysterectomy or leave the placenta in situ for spontaneous delivery is based on the extent of infiltration, the patient’s hemodynamic status, and her desire to remain fertile. The high-risk of infection and severe hemorrhage must not be overlooked should conservative treatment be chosen. This situation requires prolonged close monitoring.
Perinatal impact of the use of metformin and glyburide for the treatment of gestational diabetes mellitus
Authors: Silva Jean Carl , Fachin Débora Raquel Rigon Narciso , Coral Morgana Leonora , Bertini Anna Maria
Published: March 2012

Objective: To evaluate the perinatal impact of metformin and glyburide in the treatment of gestational diabetes mellitus (GDM).

Methods: A randomized clinical trial conducted from July 2008 until September 2010 studied 200 pregnant women with GDM who required adjunctive therapy to diet and physical activity. Patients were randomized to use metformin (n=104) or glyburide (n=96). The drugs were replaced by insulin when they reached the maximum dose without glycemic control. Assessed outcomes: weight and neonatal blood glucose.

Results:: No difference was found (P>0.05) between the groups regarding maternal age, gestational age at inclusion, body mass index, glucose levels in oral glucose tolerance test (OGTT) 75 g and glycemic control. Difference was found in the number of previous pregnancies (2.84 vs. 2.47, P=0.04) and weight gain during pregnancy (7.78 vs. 9.84, P=0.04) in the metformin group and glyburide respectively. The perinatal results showed no difference (P>0.05) in the percentage of cesarean deliveries, gestational age at delivery, number of newborns large for gestational age (LGA), neonatal hypoglycemia, admission to intensive care unit and perinatal death. We found differences in weight (3193 g vs. 3387 g, P=0.01) and ponderal index (2.87 vs. 2.96, P=0.05) of newborns, and in neonatal blood glucose levels at the 1st (59.78 vs. 54.08, P=0.01) and 3rd h (61.53 vs. 55.89, P=0.01) after birth between the metformin and glyburide groups respectively.

Conclusions: Weight and ponderal index were lower in the newborns of the metformin group; glucose levels (1st and 3rd h after birth) were lower in the glyburide group.
No “masculinization” effect of a male on birth weight of its female co-twin
Authors: Tul Nataša , Lučovnik Miha , Novak Živa , Verdenik Ivan , Blickstein Isaac
Published: March 2012

Objective: To test the hypothesis that the presence of a male affects birth weight of its female co-twin.

Patients and methods: We evaluated a large population dataset of bichorionic twins after exclusion of potential confounders and after controlling for parity and gestational age. We tested the hypotheses that males (M) are heavier than females (F) irrespective of gender mix, parity and gestational age, and the hypothesis that birth weight of twins might be influenced by the gender of the co-twin.

Results : There were 819 MM pairs, 777 FF pairs and 1097 MF sets, for a total of 2735 males and 2651 female twins. Male twins were heavier than female twins, irrespective of parity or gestational age; twins born to multiparas were heavier than twins born to nulliparas, except for very preterm births (≤32 weeks); males from MF pairs were heavier than males from MM pairs, but the mean birth weight of females from MF was not different from that of females from FF sets suggesting no “masculinization” effect of the male on birth weight of its female co-twin, irrespective of parity and gestational age.

Conclusions: After exclusion of potential confounders and controlling for chorionicity, parity, and gestational age, our data do not support the presence of a “masculinization” effect on birth weight.
The Role of Sn, Zr and Hf in the Radiation Damage in II, III, IV and V Pyrochlores
Authors: Whittle Karl R. , de los Reyes Massey , Blackford Mark G. , Zaluzec Nestor J. , Lumpkin Gregory R.
Published: March 2012

Ceramics based on the general compositions CaLnXNbO7 (where Ln = La, Nd and Sm, and X=Zr and Sn) have been prepared, and irradiated with 1 MeV Kr ions at the IVEM-TANDEM user facility. The radiation tolerance of these materials has been found to be less than Zr and Hf equivalents. The results also suggest that the amorphisation cross section for these materials is related to the Ln component, and is similar to those observed for Zr and Hf equivalents.
PVDF-based Polymer Blend Films for Fuel Cell Membranes
Authors: Huang Wenwen , Zhao Meng , Yang Fan , Farovitch Lorne , Haghighi Parisa , Macisco Leonard James , Swob Tyler , Smith Thomas , Cebe Peggy
Published: March 2012

We report the preparation and characterization of binary blend films of poly(vinylidene fluoride) (PVDF) and poly(1- ethyl-3-vinylimidazolium trifluoromethylsulfonylimide) (PVIm+TFSI-) derived from ionic liquid imidazolium monomers and doped with TFSI- salt. The potential utility of such materials in capacitive electronic devices and in proton exchange membrane fuel cells is of particular interest. Thin PVDF/ PVIm+TFSI- films were fabricated from solutions of dimethly formamide (DMF) by doctor blading. The nature of the PVDF crystalline polymorph and degree of crystallinity were evaluated as a function of the volume fraction of imidazolium polymer and thermal treatment. The morphology, thermal and mechanical characteristics and crystallinity of PVDF, in semicrystalline blend films was studied by wide angle X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis. In these materials, conditions such as choice of solvent, drying conditions, and thermal treatment affect the crystal phase, crystallite size, and degree of crystallinity of PVDF as well as the distribution of the minor component, the vinylimidazolium polymer. The polar beta phase of PVDF crystals dominates in as-cast films, while the non-polar alpha phase is observed after cooling from the melt. PVDF imparts mechanical strength and chemical stability to the composite films, and because of its high crystal melting point (Tm > 160 °C), serves to improve the high temperature stability of resulting films.
Semiconducting Arylacetylene:Insulating Polymer Blends for Organic-Based Electronic Devices
Authors: Wolfer Pascal , Santarelli Maria Laura , Vaccaro Luigi , Broggi Alessandra , Lanari Daniela , Yu Liyang , Anthopoulos Thomas D. , Smith Paul , Stingelin Natalie , Marrocchi Assunta
Published: March 2012

In this contribution we have reported about bi-component blends of readily accessible semiconducting molecular arylacetylenes with insulating high-density polyethylene (HDPE) and poly(vinylidene fluoride) (PVDF) that may exhibit electronic characteristics comparable to those of the neat semiconductors, as measured in field-effect transistors (FETs).
Selective Formation of Graphene on a Si Wafer
Authors: Yue Naili , Zhang Yong , Tsu Raphael
Published: March 2012

We report a technique that can, in principle, selectively convert SiC into graphene at any location and in any size or shape, limited only by the ability of the available lithographic techniques. This technique relies on our discovery that, at ambient condition, a laser beam can convert SiC into graphene layers at the illuminated site, and the conversion can be realized in two ways. One can pattern the SiC film, which is already grown on a Si wafer, with desirable features and then illuminate the SiC film with the laser, or simply “write” the graphene features directly onto the unpatterned SiC film with the laser. Alternatively, one can pre-pattern the Si substrate to achieve selective growth of SiC, then perform the laser conversion. We have demonstrated the feasibility of both approaches. Fullerene (C60) was used to grow a thin SiC film on a Si (111) substrate using molecular beam epitaxy (MBE) at 700-800 oC. The results are verified by various structural, chemical and optical characterization techniques. This work yields the possibility of fabricating graphene based (electronic) nanostructures or superlattices, photonic crystals, and integrated electronic and optoelectronic devices on a large Si wafer.
Design a Biologically Inspired Nanostructured Coating for Better Osseointegration
Authors: Wang Mian , Li Jian , Keidar Michael , Zhang Lijie Grace
Published: March 2012

To date, there are a strikingly growing number of patients who need various orthopedic implants. However, traditional orthopedic implants face many complications such as infection and implant loosening which may lead to implant failures. Conventional metal implants such as titanium were chosen for orthopedic applications mainly based on their excellent mechanical properties and biological inertness. Since natural bone matrix is nanometer in dimension, it is desirable to design a biologically inspired nanostructured coating that can turn conventional inert titanium surfaces into biomimetic active interfaces, thus enhance bone cell adhesion and osseointegration. For this purpose, we designed a biomimetic nanostructured coating based on nanocrystalline hydroxyapatites (nHA) and single wall carbon nanotubes (SWCNTs). Specifically, nHA with good crystallinity and biomimetic dimensions were prepared via a wet chemistry method and hydrothermal treatment; and the SWCNTs were synthesized via an arc plasma method with or without magnetic fields. TEM images showed that the hydrothermally treated nHA possessed regular rod-like nanocrystals and biomimetic nanostructure. In addition, the length of SWCNTs can be significantly increased under external magnetic fields when compared to nanotubes produced without magnetic fields. More importantly, our results showed that the above nHA and SWCNTs nanomaterials can greatly promote osteoblast (bone-forming cell) adhesion on titaniumin vitro, thus holding great promise to improve osseointegration and lengthen the lifetime of current orthopedic implants.
Failure of bone at the sub-lamellar level usingin situAFM-SEM investigations
Authors: Jimenez-Palomar Ines , Barber Asa H.
Published: March 2012

In this paper we examine the mechanical properties of individual lamellae from bone material using novel atomic force microscopy (AFM)-scanning electron microscopy (SEM) techniques. Individual lamellar beams were selected from bone using focussed ion beam (FIB) microscopy and mechanically deformed with the AFM while observing failure modes using SEM. Both the elastic and fracture behavior of the bone lamellae were determined using these techniques.
Activation Energy and Blistering Rate in Hydrogen-implanted Semiconductors
Authors: Pyke Daniel J. , Elliman Robert G. , McCallum Jeffrey C.
Published: March 2012

Hydrogen blister rates in Si (100), Si (111) and Ge (100) substrates are compared as a function of annealing temperature and time, for a range of implant energies and fluences. For each material, the rate of blister formation was found to exhibit Arrhenius behavior and to be characterised by a single activation energy over the temperature range examined. The extracted activation energies were 2.28±0.03 eV, 2.17±0.06 eV and 1.4±0.03 eV for (100) Si; (111) Si and (100) Ge, respectively. These results are compared with reported measurements and discussed in relation to proposed models of hydrogen blistering.
Dielectric Gradient Force Actuation with on-chip electrode and Free-Space Optical Measurement of SiNx Nanomechanical Resonator
Authors: Cho Sungwan , Cho Myung Rae , Shim Seung-Bo , Park Yun Daniel
Published: March 2012

Nanomechanical resonators made from silicon nitride with residual stress is actuated using dielectric field gradient force. Doubly clamped nanomechanical resonators are made from SiNx-SiO2-Si tri-layer substrate and DC electric field induces a temporary dipole moment while a small AC electric field drives beam resonator by dielectric force. Realized nanomechanical resonators show resonant motion of high resonant frequency (up to ~31 Mhz) and mechanical quality factor up to over 48,000 at room temperature and moderate vacuum condition. From the FEA (Finite Element Analysis) of resonant motion, doubly clamped resonator shows torsional motion and in-plane motion which can be assigned to additional multiple modes in resonant response measurement
Water Concentration Influence on Catalytic Growth of Carbon Nanotubes in a Suspended Bed Reactor
Authors: Mordkovich V.Z. , Karaeva A.R. , Khaskov M.A. , Solomonik I.G. , Mitberg E.B. , Kulnitskiy B.A. , Perezhogin I.A.
Published: March 2012

One of the most important problems in the synthesis of carbon nanotubes is the problem of controlling their morphology, namely: length, aspect ratio, alignment, etc. Catalytic synthesis of carbon nanotubes in a suspended bed reactor allowed to study the possibilities of controlling the growth of nanotubes by introducing a certain amount of water vapor and carbon-containing materials in the reaction zone. The synthesized long carbon nanotubes were studied by Raman spectroscopy, transmission and scanning electron microscopy. We found that water concentration influences both yield and the structure of nanotubes. It is shown that the yield of centimeter-long nanotubes can be maximized at an optimum H2O/C ratio, while deviations dramatically change morphology and thickness of the nanotubes.
A "reforma agrária assistida pelo mercado" do Banco Mundial no Brasil: dimensões políticas, implantação e resultados
Authors: Pereira João Márcio Mendes , Sauer Sérgio
Published: March 2012

O artigo analisa a implementação e os resultados do projeto piloto Cédula da Terra (1997-2002) e a sua continuidade, a partir de 2003, por meio do Programa Nacional de Crédito Fundiário. Tais iniciativas foram inspiradas na proposta de "reforma agrária assistida pelo mercado", impulsionada pelo Banco Mundial em diversos países, em particular na América Latina, a partir de 1994, como alternativa à reforma agrária, a qual está em curso, nos dias atuais, apenas no Brasil. Com base em pesquisas empíricas, argumenta-se que o Cédula da Terra, ao contrário do que afirma o Banco Mundial, não foi bem sucedido em prover um modelo de acesso à terra a ser reproduzido em maior escala. Este artigo faz ainda um balanço dos desdobramentos desse modelo na política fundiária do governo Luis Inácio Lula da Silva (2003-2010).
Paleohistological estimation of bone growth rate in extinct archosaurs
Authors: Cubo Jorge , Le Roy Nathalie , Martinez-Maza Cayetana , Montes Laetitia
Published: March 2012

The clade Archosauria contains two very different sister groups in terms of diversity (number of species) and disparity (phenotypic variation): Crurotarsi (taxa more closely related to crocodiles than to birds) and Ornithodira (pterosaurs and dinosaurs including birds). The extant species of Crurotarsi may constitute a biased sample of past biodiversity regarding growth patterns and metabolic rates. Bone histological characters can be conserved over hundreds of millions of years in the fossil record and potentially contain information about individual age at death, age at sexual maturity, bone growth rates, and basal metabolic rates of extinct vertebrates. Using a sample of extant amniotes, we have constructed a paleobiological model to estimate bone growth rate from bone histological traits. Cross-validation tests show that this model is reliable. We then used it to estimate bone growth rates in a sample of extinct archosaurs including Crurotarsi and Ornithodira. After testing for phylogenetic signal, optimization of femoral growth rates through squared change parsimony onto a time-calibrated tree of amniotes shows two divergent evolutionary trends: whereas bone growth rates increase from the last common ancestor of Ornithodira to extant birds, they decrease from the last common ancestor of Crurotarsi to extant crocodiles. However, we conclude, on the basis of recent evidence for unidirectional airflow in the lungs of alligators, that crocodiles may have retained the capacity of growing at high rates.
Vegetation history, diversity patterns, and climate change across the Triassic/Jurassic boundary
Authors: Bonis Nina R. , Kürschner Wolfram M.
Published: March 2012

High-resolution palynological data sets from shallow marine Triassic-Jurassic (Tr/J) boundary beds of two principal sections in Europe (Hochalplgraben in Austria and St. Audrie's Bay in the United Kingdom) were analyzed to reconstruct changes in vegetation, biodiversity, and climate. In Hochalplgraben, a hardwood gymnosperm forest with conifers and seed ferns is replaced by vegetation with dominant ferns, club mosses and liverworts, which concurs with an increased diversification of spore types during the latest Rhaetian. Multivariate statistical analysis reveals a trend to warmer and wetter conditions across the Tr/J boundary in Hochalplgraben. The vegetation changes in St. Audrie's Bay are markedly different. Here, a mixed gymnosperm forest is replaced by monotonous vegetation consisting mainly of Cheirolepidiaceae (80–100%). This change is caused by a transition to a warmer and more arid climate. The observed diversity decrease in St. Audrie's Bay affirms this interpretation. Although both sections show major vegetation changes, neither of them demonstrates a distinctive floral mass extinction. A compilation of Tr/J boundary sections across the world demonstrates the presence of Cheirolepidiaceae-dominated forests in the Pangaean interior and increases in abundance of spore-producing plants adjacent to the Tethys Ocean. We propose that the non-uniform vegetation changes reflected in the Tr/J palynological records are the result of environmental changes caused by Central Atlantic Magmatic Province volcanism. The increase in greenhouse gases caused a warmer climate and an enhanced thermal contrast between the continent and the seas. Consequently, the monsoon system got stronger and induced a drier continental interior and more intensive rainfall near the margins of the Tethys Ocean.
Environmental and biological controls on the diversity and ecology of Late Cretaceous through early Paleogene marine ecosystems in the U.S. Gulf Coastal Plain
Authors: Sessa Jocelyn A. , Bralower Timothy J. , Patzkowsky Mark E. , Handley John C. , Ivany Linda C.
Published: March 2012

The late Mesozoic through early Cenozoic is an interval of significant biologic turnover and ecologic reorganization within marine assemblages, but the timing and causes of these changes remain poorly understood. Here, we quantify the pattern and timing of shifts in the diversity (richness and evenness) and ecology of local (i.e., sample level) mollusk-dominated assemblages during this critical interval using field-collected and published data sets from the U.S. Gulf Coastal Plain. We test whether the biologic and ecologic patterns observed primarily at the global level during this time are also expressed at the local level, and whether the end-Cretaceous (K/Pg) mass extinction and recovery moderated these trends. To explore whether environment had any effect on these patterns, we examine data from shallow subtidal and offshore settings.

Assemblages from both settings recovered to pre-extinction diversity levels rapidly, in less than 7 million years. Following initial recovery, diversity remained unchanged in both settings. The trajectory of ecological restructuring was distinct for each setting in the wake of the K/Pg extinction. In offshore assemblages, the abundance and number of predatory carnivorous taxa dramatically increased, and surficial sessile suspension feeders were replaced by more active suspension feeders. In contrast, shallow subtidal assemblages did not experience ecological reorganization following the K/Pg extinction. The distinct ecological patterns displayed in each environment follow onshore-offshore patterns of innovation, whereby evolutionary novelties first appear in onshore settings relative to offshore habitats. Increased predation pressure may explain the significant ecological restructuring of offshore assemblages, whereby the explosive radiation of predators drove changes in their prey. Habitat-specific ecological restructuring, and its occurrence solely during the recovery interval, implies that disturbance and incumbency were also key in mediating these ecological changes.
Functional constraints on coiling geometry and aperture inclination in gastropods
Authors: Noshita Koji , Asami Takahiro , Ubukata Takao
Published: March 2012

We studied the morphological diversity of gastropod shell forms from the viewpoint of theoretical morphology, emphasizing the relationships of shell form to postural stability and the available space for soft body, which we assessed in terms of the moment of force and soft-tissue ratio calculations, respectively. The results of computer simulations suggest a functional trade-off between postural stability and available space for soft body: a compact shell possessing a low spire and small umbilicus exhibits high postural stability, whereas a less overlapped shell form with a high spire and large umbilicus makes available space for soft body. A functional morphospace analysis using theoretical models reveals that outward and downward inclination of the aperture moderates the functional trade-off between these parameter values and permits compatibility between stable posture and efficient shell construction. The hypothetical optimum that realizes this compatibility is consistent with the observed range of forms estimated from 359 extant gastropod species. The biometric results also suggest that land snails are more highly constrained than marine species in achieving a balance between postural stability and available space for soft body.
Testing a developmental model in the fossil record: molar proportions in South American ungulates
Authors: Wilson Laura A. B. , Madden Richard H. , Kay Richard F. , Sánchez-Villagra Marcelo R.
Published: March 2012

A developmental model, based upon murine rodents, has been proposed by Kavanagh et al. (2007) to explain lower molar proportions in mammals. We produce a clade-wide macroevolutionary test of the model using the dental evolutionary trends in a unique radiation of extinct mammals endemic to South America (“Meridiungulata”) that comprise a diverse array of molar morphologies. All of the South American ungulate groups examined follow the inhibitory cascade model with the exception of two groups: Interatheriidae (Notoungulata) and Astrapotheria. For most taxa studied, ratios between lower molar areas are greater than 1.0, indicating a weak inhibition by m1 on the subsequent molars in the tooth row, and a trend to greater absolute size of the posterior molars. Comparisons of mean ratios between clades indicate that a significant phylogenetic signal can be detected, particularly between the two groups within Notoungulata— Typotheria and Toxodontia. Body mass estimates were found to be significantly correlated with both m3/m1 and m2/m1 ratios, suggesting that the larger body size achieved the weaker inhibition between the lower molars. Molar ratio patterns are examined and discussed in relation to the independent and numerous acquisitions of hypsodonty that are characteristic of dental evolution in “Meridiungulata.”