bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcriptional Repression of Estrogen Receptor α Signaling by SENP2 in Breast Cancer Cells
Authors: Nait Achour Thiziri , Sentis Stéphanie , Teyssier Catherine , Philippat Amandine , Lucas Annick , Corbo Laura , Cavaillès Vincent , Jalaguier Stéphan
Published: December 2013

Estrogen receptors (ERs) are ligand-activated transcription factors involved in many physiological and pathological processes, including breast cancer. Their activity is fine-tuned by posttranslational modifications, notably sumoylation. In the present study, we investigated the role of the small ubiquitin-related modifier (SUMO) protease, SUMO1/sentrin/suppressor of Mif 2-specific peptidase 2 (SENP2), in the regulation of ERα activity. We first found SENP2 to significantly repress estradiol-induced transcriptional activity in breast cancer cells (MCF7 and T47D). This effect was observed with a reporter plasmid and on endogenous genes such as TFF1 and CTSD, which were shown to recruit SENP2 in chromatin immunoprecipitation experiments. Using glutathione S-transferase pull-down, coimmunoprecipitation and proximity ligation assays, SENP2 was found to interact with ERα and this interaction to be mediated by the amino-terminal region of the protease and the hinge region of the receptor. Interestingly, we demonstrated that ERα repression by SENP2 is independent of its SUMO protease activity and requires a transcriptional repressive domain located in the amino-terminal end of the protease. Using small interfering RNA assays, we evidenced that this domain recruits the histone deacetylase 3 (HDAC3), to be fully active. Furthermore, using both overexpression and knockdown strategies, we showed that SENP2 robustly represses estrogen-dependent and independent proliferation of MCF7 cells. We provided evidence that this effect requires both the proteolytic and transcriptional activities of SENP2. Altogether, our study unravels a new property for a SUMO protease and identifies SENP2 as a classical transcription coregulator.
PTK7 modulates Wnt signaling activity via LRP6
Authors: Bin-Nun Naama , Lichtig Hava , Malyarova Anastasia , Levy Michal , Elias Sara , Frank Dale
Published: December 2013

Protein tyrosine kinase 7 (PTK7) is a transmembrane protein expressed in the developing Xenopus neural plate. PTK7 regulates vertebrate planar cell polarity (PCP), controlling mesodermal and neural convergent-extension (CE) cell movements, neural crest migration and neural tube closure in vertebrate embryos. Besides CE phenotypes, we now show that PTK7 protein knockdown also inhibits Wnt/β-catenin activity. Canonical Wnt signaling caudalizes the neural plate via direct transcriptional activation of the meis3 TALE-class homeobox gene, which subsequently induces neural CE. PTK7 controls meis3 gene expression to specify posterior tissue and downstream PCP activity. Furthermore, PTK7 morphants phenocopy embryos depleted for Wnt3a, LRP6 and Meis3 proteins. PTK7 protein depletion inhibits embryonic Wnt/β-catenin signaling by strongly reducing LRP6 protein levels. LRP6 protein positively modulates Wnt/β-catenin, but negatively modulates Wnt/PCP activities. The maintenance of high LRP6 protein levels by PTK7 triggers PCP inhibition. PTK7 and LRP6 proteins physically interact, suggesting that PTK7 stabilization of LRP6 protein reciprocally regulates both canonical and noncanonical Wnt activities in the embryo. We suggest a novel role for PTK7 protein as a modulator of LRP6 that negatively regulates Wnt/PCP activity.
Notch signaling is required for the formation of mesangial cells from a stromal mesenchyme precursor during kidney development
Authors: Boyle Scott C. , Liu Zhenyi , Kopan Raphael
Published: December 2013

Mesangial cells are specialized pericyte/smooth muscle cells that surround and constrain the vascular network within the glomerulus of the kidney. They are derived from the stromal mesenchyme, a progenitor population distinct from nephron stem cells. Whether mesangial cells have a distinct origin from vascular smooth muscle cells (VSMCs) and the pathways that govern their specification are unknown. Here we show that Notch signaling in stromal progenitors is essential for mesangial cell formation but is dispensable for the smooth muscle and interstitial cell lineages. Deletion of RBPjk, the common DNA-binding partner of all active Notch receptors, with Foxd1tgCre results in glomerular aneurysm and perinatal death from kidney failure. This defect occurs early in glomerular development as stromal-derived, desmin-positive cells fail to coalesce near forming nephrons and thus do not invade the vascular cleft of the S-shaped body. This is in contrast to other mutants in which the loss of the mesangium was due to migration defects, and suggests that loss of Notch signaling results in a failure to specify this population from the stroma. Interestingly, Pdgfrb-positive VSMCs do not enter the vascular cleft and cannot rescue the mesangial deficiency. Notch1 and Notch2 act redundantly through γ-secretase and RBPjk in this process, as individual mutants have mesangial cells at birth. Together, these data demonstrate a unique origin of mesangial cells and demonstrate a novel, redundant function for Notch receptors in mesangial cell specification, proliferation or survival during kidney development.
Differential activation of natriuretic peptide receptors modulates cardiomyocyte proliferation during development
Authors: Becker Jason R. , Chatterjee Sneha , Robinson Tamara Y. , Bennett Jeffrey S. , Panáková Daniela , Galindo Cristi L. , Zhong Lin , Shin Jordan T. , Coy Shannon M. , Kelly Amy E. , Roden Dan M. , Lim Chee Chew , MacRae Calum A.
Published: December 2013

Organ development is a highly regulated process involving the coordinated proliferation and differentiation of diverse cellular populations. The pathways regulating cell proliferation and their effects on organ growth are complex and for many organs incompletely understood. In all vertebrate species, the cardiac natriuretic peptides (ANP and BNP) are produced by cardiomyocytes in the developing heart. However, their role during cardiogenesis is not defined. Using the embryonic zebrafish and neonatal mammalian cardiomyocytes we explored the natriuretic peptide signaling network during myocardial development. We observed that the cardiac natriuretic peptides ANP and BNP and the guanylate cyclase-linked natriuretic peptide receptors Npr1 and Npr2 are functionally redundant during early cardiovascular development. In addition, we demonstrate that low levels of the natriuretic peptides preferentially activate Npr3, a receptor with Gi activator sequences, and increase cardiomyocyte proliferation through inhibition of adenylate cyclase. Conversely, high concentrations of natriuretic peptides reduce cardiomyocyte proliferation through activation of the particulate guanylate cyclase-linked natriuretic peptide receptors Npr1 and Npr2, and activation of protein kinase G. These data link the cardiac natriuretic peptides in a complex hierarchy modulating cardiomyocyte numbers during development through opposing effects on cardiomyocyte proliferation mediated through distinct cyclic nucleotide signaling pathways.
Design and Synthesis of 24-Fluorinated Bafilomycin Analogue as an NMR Probe with Potent Inhibitory Activity to Vacuolar-type ATPase
Authors: Shibata Hajime , Tsuchikawa Hiroshi , Matsumori Nobuaki , Murata Michio , Usui Takeo
Published: December 2013

A fluorine-labeled bafilomycin analogue was designed and convergently synthesized from three segments via the Stille coupling, macrolactonization, and diastereoselective aldol reaction. The V-ATPase inhibitory activity of the analogue was comparable to that of the natural product, indicating its utility as a potential molecular probe for investigating the inhibition mechanism of bafilomycin by NMR.
Turn-and-Earn Incentives with a Product Line
Authors: Cohen-Vernik Dinah A. , Purohit Devavrat
Published: December 2013

When manufacturers do not have sufficient capacity to meet demand and cannot increase prices, they have to determine other methods to allocate goods among retailers. A common allocation mechanism is based on a retailer's sales history: a retailer that has ordered larger quantities in the past should get a greater allocation than a retailer that has historically ordered smaller quantities. This mechanism, known as a turn-and-earn allocation rule, is commonly used in many industries such as automobiles, microprocessors, video game consoles, etc. The existing literature has considered the effect of turn-and-earn allocation rules when a manufacturer sells a single product. However, when we consider a product line, it is not clear whether the manufacturer is better off basing its allocation on the sales history of the entire product line or solely on the sales history of the product in short supply. In particular, a shortage of one product can lead retailers and consumers to move toward other products in the line. This, in turn, can have an effect on the manufacturer's optimal allocation mechanism. We examine this issue by developing a model of a supplier selling two substitutable goods through two retailers. Within this setup, we introduce a general turn-and-earn allocation rule that allows the entire sales history to influence allocation levels. Counter to previous work, we show that certain turn-and-earn rules not only help the manufacturer but can also help the retailer and increase total supply chain profits.

This paper was accepted by Martin Lariviere, operations management.
Entrepreneurial Exits and Innovation
Authors: Aggarwal Vikas A. , Hsu David H.
Published: December 2013

We examine how initial public offerings (IPOs) and acquisitions affect entrepreneurial innovation as measured by patent counts and forward patent citations. We construct a firm-year panel data set of all venture capital-backed biotechnology firms founded between 1980 and 2000, tracked yearly through 2006. We address the possibility of unobserved self-selection into exit mode by using coarsened exact matching, and in two additional ways: (1) comparing firms that filed for an IPO (or announced a merger) with those not completing the transaction for reasons unrelated to innovation, and (2) using an instrumental variables approach. We find that innovation quality is highest under private ownership and lowest under public ownership, with acquisition intermediate between the two. Together with a set of within-exit mode analyses, these results are consistent with the proposition that information confidentiality mechanisms shape innovation outcomes. The results are not explained by inventor-level turnover following exit events or by firms' preexit window dressing behavior.

This paper was accepted by Lee Fleming, entrepreneurship and innovation.
Antipsychotic property of solvent-partitioned fractions of Lonchocarpus cyanescens leaf extract in mice
Authors: Arowona Ismot T. , Sonibare Mubo A. , Umukoro Solomon
Published: December 2013

Background: This study was carried out to evaluate the antipsychotic property of solvent-partitioned fractions of the leaf extract of Lonchocarpus cyanescens (LC), a reputable medicinal plant used in folk medicine for the treatment of mental illnesses in Nigeria.

Methods: The n-hexane fraction, ethyl acetate fraction (EAF), and aqueous ethanol fraction (AEF) of LC were tested for antipsychotic property based on the antagonism of stereotypy induced by apomorphine (APO). Antagonism of hyperactivity and lethality in aggregated mice induced by amphetamine (AMPH) were further employed for screening the antipsychotic effect of the fractions. EAF was tested for catalepsy utilising the horizontal plane paradigm. Thin-layer chromatography (TLC) was used to screen EAF for the presence of secondary metabolites.

Results: AEF (100–400 mg/kg) significantly (p<0.05) suppressed stereotypy induced by APO (2 mg/kg, intraperitoneal [IP]) in comparison with control, suggesting antipsychotic activity. However, EAF (200 mg/kg, IP) was most potent in inhibiting the stereotypic effect of APO. EAF was also the most active in antagonising AMPH-induced hyperactivity and in protecting against death caused by AMPH in grouped mice. However, in contrast to haloperidol, EAF did not produce cataleptic behaviour in the horizontal plane paradigm. The TLC analysis revealed that EAF contains several compounds, with some of them having R
f values similar to that of haloperidol, which suggests the presence of active substances with the same chemical structural identity.

Conclusions: These findings suggest that EAF contains the major active constituent(s) mediating the antipsychotic property of LC and further support its use for the management of psychosis in traditional medicine.
Homocysteine metabolism in different human cells
Authors: Kurz Katharina , Frick Barbara , Fürhapter Christina , Weiss Günter , Wirleitner Barbara , Sepp Norbert , Fuchs Dietmar
Published: December 2013

The effects of cytokine and mitogen stimulation on homocysteine (HCY) metabolism in different cells were investigated: in human dermal microvascular endothelial cells (HDMEC), T lymphocytes, mature and immature dendritic cells, and myelomonocytic (THP-1) and monocytic cell lines (U-937). Furthermore, the influence of supplementation of cells with folate acid, methionine and the combination of both on HCY metabolism was investigated. Unstimulated HDMEC and dendritic cells only produced very little amounts of HCY, and stimulation did not change HCY formation significantly either. However, higher HCY concentrations were detected in HDMEC and dendritic cells under supplementation with methionine and slightly less under supplementation with folate. Proliferating T lymphocytes showed an increase in HCY production on stimulation with increasing doses of mitogens; proliferative activity was associated with HCY formation. THP-1 and U-937 cells produced significantly more HCY than endothelial cells; U-937 cells produced most HCY, which was mainly due to their high proliferation rate. Stimulation of both cell lines with lipopolysaccharide and interferon-γ, respectively, showed a significant effect on HCY production of cells; in THP-1 cells, stimulation with IFN-γ and lipopolysaccharide induced neopterin formation. Methionine supplementation strongly increased and folate supplementation slightly decreased HCY formation in both cell lines. Thus, inflammation may play a role in moderate hyperhomocysteinemia.
Experimental and finite element studies on buckling of skew plates under uniaxial compression
Authors: Venkateshappa Srinivasa Chikkol , Jayadevappa Suresh Yalaburgi , Puttiah Prema Kumar Wooday
Published: December 2013

Experimental studies were made on isotropic skew plates made of aluminum 7075-T6 and laminated composite skew plates under uniaxial compression with unloaded edges completely free and one loaded edge restrained completely and the other loaded edge restrained except translationally in the direction of loading. Experimental values of the buckling load have been determined using five different methods. The buckling load has also been determined using CQUAD8 finite element of MSC/NASTRAN. Comparison is made between the various experimental values of buckling load and the finite element solution. The effects of the skew angle and the aspect ratio on the critical buckling load of isotropic skew plates made of aluminum 7075-T6 have been studied. The effects of the skew angle, aspect ratio, and the laminate stacking sequence on the critical buckling load of laminated composite skew plates have also been studied. The critical buckling load is found to increase with the increase in the skew angle and decrease with the increase in aspect ratio. Method IV yields the highest value for critical buckling load and Method III the lowest value for critical buckling load. Among the various experimental values, the one given by Method IV is closest to the finite element solution, and the discrepancy between them is less than about 5% in the case of isotropic skew plates and about 10–15% in the case of laminated composite skew plates.
Effect of Fly Ash on Cement Admixture for a Low Plasticity Marine Soil
Authors: Bushra I. , Robinson Retnamony G.
Published: December 2013

The deep cement mixing (DCM) method is one of the popular methods of ground-improvement techniques for enhancing the bearing capacity and reducing settlements of thick deposits of soft clay with high water content. High cement content, of the order of 10 % to 25 %, are often used in practice. To reduce the requirement of cement, an attempt is made in the present study to replace the cement partially with fly ash, as a fly ash–cement composite. Different percentages of Class F fly ash (10 %, 20 %, and 30 %) to Ennore marine clay with different proportions of cement (10 %, 15 %, and 20 %) were added and tested. The optimum clay water content at which maximum strength is achieved was determined for various mixes based on unconfined compressive strength tests. A detailed study showed that addition of 20 % Class F fly ash is effective in all combinations. The behavior of the composite under one-dimensional consolidation was also tested.
Evaluating digestive neuroendocrine tumor progression and therapeutic responses in the era of targeted therapies: state of the art
Authors: de Mestier Louis , Dromain Clarisse , d'Assignies Gaspard , Scoazec Jean-Yves , Lassau Nathalie , Lebtahi Rachida , Brixi Hedia , Mitry Emmanuel , Guimbaud Rosine , Courbon Frédéric , d'Herbomez Michèle , Cadiot Guillaume
Published: December 2013

Well-differentiated neuroendocrine tumors (NETs) are a group of heterogeneous rare tumors. They are often slow-growing and patients can have very long survival, even at the metastatic stage. The evaluation of tumor progression and therapeutic responses is currently based on Response Evaluation Criteria In Solid Tumors v1.1 (RECIST) criteria. As for other malignancies, RECIST criteria are being reexamined for NETs in the era of targeted therapies because tumor response to targeted therapies is rarely associated with shrinkage, as opposed to prolonged progression-free survival. Therefore, size-based criteria no longer seem to be suitable to the assessment of NET progression and therapeutic responses, especially considering targeted therapies. New imaging criteria, combining morphological and functional techniques, have proven relevant for other malignancies treated with targeted therapies. To date, such studies have rarely been conducted on NETs. Moreover, optimizing the management of NET patients also requires considering clinical, biological, and pathological aspects of tumor evolution. Our objectives herein were to comprehensively review current knowledge on the assessment of tumor progression and early prediction of therapeutic responses and to broaden the outlook on well-differentiated NETs, in the era of targeted therapies.
Testosterone and glucose metabolism in men: current concepts and controversies
Authors: Grossmann Mathis
Published: December 2013

A wealth of observational studies show that low testosterone is associated with insulin resistance and with an increased risk of diabetes and the metabolic syndrome. Experimental studies have identified potential mechanisms by which low testosterone may lead to insulin resistance. Visceral adipose tissue is an important intermediate in this relationship. Actions of testosterone or its metabolite oestradiol on other tissues such as muscle, liver, bone or the brain, and body composition-independent effects may also play a role. However, definitive evidence from randomised controlled trials (RCTs) to clarify whether the association of low testosterone with disordered glucose metabolism is causative is currently lacking. It therefore remains possible that this association is due to reverse causation, or simply originates by association with common health and lifestyle factors. RCTs of testosterone therapy in men with or without diabetes consistently show modest metabolically favourable changes in body composition. Despite this, testosterone effects on glucose metabolism have been inconsistent. Recent evidence suggests that the hypothalamic–pituitary–testicular axis suppression in the majority of obese men with metabolic disorders is functional, and may be, at least in part, reversible with weight loss. Until further evidence is available, lifestyle measures with emphasis on weight reduction, treatment of comorbidities and optimisation of diabetic control should remain the first-line treatment in these men. Such measures, if successful, may be sufficient to normalise testosterone levels in men with metabolic disorders, who typically have only modest reductions in circulating testosterone levels.
Sex-specific Esr2 mRNA expression in the rat hypothalamus and amygdala is altered by neonatal bisphenol A exposure
Authors: Cao Jinyan , Joyner Linwood , Mickens Jillian A , Leyrer Stephanie M , Patisaul Heather B
Published: December 2013

Perinatal life is a critical window for sexually dimorphic brain organization, and profoundly influenced by steroid hormones. Exposure to endocrine-disrupting compounds may disrupt this process, resulting in compromised reproductive physiology and behavior. To test the hypothesis that neonatal bisphenol A (BPA) exposure can alter sex-specific postnatalEsr2(Erβ) expression in brain regions fundamental to sociosexual behavior, we mappedEsr2mRNA levels in the principal nucleus of the bed nucleus of the stria terminalis (BNSTp), paraventricular nucleus (PVN), anterior portion of the medial amygdaloid nucleus (MeA), super optic nucleus, suprachiasmatic nucleus, and lateral habenula across postnatal days (PNDs) 0–19. Next, rat pups of both sexes were subcutaneously injected with 10 μg estradiol benzoate (EB), 50 μg/kg BPA (LBPA), or 50 mg/kg BPA (HBPA) over the first 3 days of life andEsr2levels were quantified in each region of interest (ROI) on PNDs 4 and 10. EB exposure decreasedEsr2signal in most female ROIs and in the male PVN. In the BNSTp,Esr2expression decreased in LBPA males and HBPA females on PND 10, thereby reversing the sex difference in expression. In the PVN,Esr2mRNA levels were elevated in LBPA females, also resulting in a reversal of sexually dimorphic expression. In the MeA, BPA decreasedEsr2expression on PND 4. Collectively, these data demonstrate that region- and sex-specificEsr2expression is vulnerable to neonatal BPA exposure in regions of the developing brain critical to sociosexual behavior in rat.
The Atomic Metron – a Basis for Synthesis of Metal Sub-Nanometer Particles with a Discrete Number of Atoms
Authors: Love Oksana , Kidwell David A. , Epshteyn Albert
Published: December 2013

Few techniques are available to systematically synthesize and characterize metal particles below 1nm in size. We build nanoparticles in an atomically defined manner through the use of a high-fidelity molecular container we call an atomic metron, which is used to select and count the metallic ions that will make up the resultant nanoparticle. After a defined number of ions are selected, the metron may be spatially isolated and the metallic ions reduced to an isolated nanoparticle. Each step in the process is characterized via analytical methods. AFM is used to demonstrate the formation of sub-nanometer particles. The counting of atoms, isolation, and formation of nanoparticles, shows high potential for easy synthesis of sub-nanometer particles with fine control over the number of atoms in each particle.
Mechanisms overview of Thermocompression Process for Copper Metal Bonding
Authors: Gondcharton Paul , Baudin Floriane , Benaissa Lamine , Imbert Bruno
Published: December 2013

Wafer level metal bonding involving copper material is widely used to achieve 3D functional integration of ICs and ensure effective packaging sealing for various applications. In this paper we focus on thermocompression bonding technology where temperature and pressure are used in parallel to assist the bonding process. More specifically a broad range of conditions was explored and interesting results were observed and are reported. Indeed, despite a relatively high roughness, the presence of a native oxide and the lack of surface preparation, there still exists a process window where wafer level bonding is allowed. In these conditions, limiting the bonding mechanisms to basic copper diffusion is no longer satisfactory. In this study, a specific scenario inspired by both wafer bonding and metal welding state of the art is put forward. Accordingly, pure copper diffusion through the bonding interface is lined with plastic deformation and metallic oxide fracture. In addition, polycrystalline film deformation due to thermomechanical stress is highlighted and grain growth and voiding formation are observed and confirmed.
Self-biased Dual-phase Energy Harvesting System
Authors: Zhou Yuan , Bhalla Amar , Priya Shashank
Published: December 2013

In this study, we report the design and fabrication of a dual-phase energy harvester which can synchronously harvest both mechanical and magnetic energy in the absence of DC magnetic field. The harvester consists of a magnetostrictive cantilever beam and a magnetostrictive/ piezoelectric (M/P) self-biased laminate composite structure. This structure allows us to utilize piezoelectric and self-biased magnetoelectric effect simultaneously. By combining these mechanisms together, a sum effect for harvesting both magnetic and vibration energy was realized under DC magnetic field free condition. The bilayer structure provides a simplified geometry that can be easily incorporated into MEMS devices. We demonstrate a hybrid synthesis method for fabrication of complex three-dimensional thin films using a cost-effective and mask-less aerosol jet deposition process. The combination of the hybrid aerosol jet process with dual phase harvester design provides the opportunity to fabricate small scale power sources required for structural health monitoring applications.
Wide Bandwidth Piezoelectric MEMS Energy Harvesting
Authors: Xu Ruize , Kim Sang-Gook
Published: December 2013

Piezoelectric Microelectromechanical Systems (MEMS) has been proven to be an attractive technology for harvesting small energy from the ambient vibration. Recent advancements in piezoelectric materials and harvester structural design, individually or in combination, have improved MEMS energy harvesters to achieve high enough power density, compactness and ultra wide bandwidth, bringing us closer towards battery-less autonomous sensors systems and networks in near future. Among the breakthroughs, non-linear resonating beam for wide bandwidth resonance is the key development to enable robust operation of MEMS energy harvesters over the unpredictable and uncontrollable frequency spectra of ambient vibration. We expect that a coin size harvester will be able to harvest about 100μW continuous power at below 100 Hz and less than 0.5 g input vibration and at reasonable cost.
Analysis of Leakage Currents through PLD Grown Ultrathin a-LaGdO3 Based High-k Metal Gate Devices
Authors: Pavunny Shojan P. , Misra Pankaj , Thomas Reji , Kumar Ashok , Scott James F. , Katiyar Ram S.
Published: December 2013

A detailed analysis of leakage current density-gate voltage measurements of gate stacks composed of PLD grown ultra thin films of LaGdO3 (LGO) on p-type silicon substrates with 8.4 Å EOT is presented. Temperature dependent leakage measurements revealed that forward bias current was dominated by Schottky emission over trap assisted tunneling below 1.2 MV/cm and quantum mechanical tunneling above this field. The physical origin of the reverse bias current was found to be a combination of Schottky emission and trap assisted tunneling. Low leakage current densities in the range from 2.3×10-3 to 29×10-3 A/cm2 were recorded for films with EOT from 1.8 to 0.8 nm, that are at least four or more orders below the ITRS specifications and its SiO2 competitors.
Ellipsometry Study on Nanoparticles Grown by Atomic Layer Deposition
Authors: Zhou Xueqi , Zhang Ying , Dong Zhengqiong , Liu Shiyuan , Zhang Chuanwei , Huang Bin , Cao Kun , Shan Bin , Chen Rong
Published: December 2013

Spectroscopic Ellipsometry (SE) was chosen to study thin film growth in atomic layer deposition (ALD). It was shown that Cauchy model had limitations in predicting the ultrathin film thickness at initial few deposition cycles, and the fitting results depend on wavelengths range greatly. Effective Medium Approximation (EMA) model is capable of predicting ultrathin film’s physical properties. Our experiments on Al2O3growth give supporting evidence on the applicability of EMA model, where it is used to successfully explain the initial nucleation and island like growth. EMA model can be extended to be used for Palladium thin film, which can give reasonable thickness and void content.
Electrical Contact Resistance of Electroless Nickel to Nanocrystalline Silicon and the Fabrication of a Thermoelectric Generator
Authors: Kessler V. , Dehnen M. , Chavez R. , Engenhorst M. , Stoetzel J. , Petermann N. , Hesse K. , Huelser T. , Spree M. , Schierning G. , Schmechel R.
Published: December 2013

We present the fabrication of a high-temperature stable thermoelectric generator based on nanocrystalline silicon. Highly doped silicon nanoparticles were sintered by a current activated sintering technique to get nanocrystalline bulk silicon. The metalization of silicon was realized by (electro-)chemical plating and the specific electrical contact resistance ρc of the semiconductor-metal interface was measured by a transfer length method. Values as low as $\rho _C < 1 \cdot 10^{ - 6} \,\Omega cm^2 $ were measured. The metalized nanocrystalline silicon legs were sintered to metalized ceramic substrates using a silver-based sinter paste. The device figure of merit of the thermoelectric generator was determined by a Harman measurement with a maximum ZT of approximately 0.13 at 600 °C.
Kinetics of Frenkel Defect Formation in TiO2 from First Principles
Authors: Barabash Sergey V. , Chen Charlene , Pramanik Dipu , Magyari-Köpe Blanka , Nishi Yoshio
Published: December 2013

Motivated by the unusual behavior of TiO2 films seen in electrical stress and defect annealing experiments, we studied the energy profile for forming a Frenkel defect in rutile TiO2, using first-principles calculations with a nudged-elastic-band method. We found strongly asymmetric diffusion barriers. The Frenkel pairs with small separation are exceedingly short-lived: the Ti interstitial position nearest to the the Ti vacancy is separated by only a 0.15eV barrier, and the next-nearest interstitial position is dynamically unstable. The formation enthalpies of Frenkel pairs with larger separation gradually vary between 4.2 and 5.0 eV, separated by 0.3-0.4eV barriers along the (001) direction. Contrary to some previous studies, we do not find Frenkel configurations with tetrahedrally bonded Ti interstitials. The very low barriers for Frenkel defect evolution are consistent with the observations from the electrical stress damage annealing experiments.
Eletroforese em papel das proteínas do líqüido cefalorraquidiano: II. Principais resultados registrados na literatura
Authors: Spina-França A.
Published: December 2013

Partindo dos dados referentes à aplicação da eletroforese em papel de filtro na separação das frações proteicas do LCR, apresentados em publicação anterior, são revistos os dados da literatura sob o ponto de vista do laboratório clínico. Tanto os valores relativos normais referentes a cada uma das reações proteicas, como alterações patológicas mais freqüentemente encontradas em diversos tipos de afecções do sistema nervoso são apresentados, ressaltando-se a importância dos achados frente à fisiopatologia do liqüido cefalorraquidiano e frente à Clínica Neurológica.
Propriedades físicas do solo e crescimento de raízes de milho em um argissolo vermelho sob tráfego controlado de máquinas
Authors: Mazurana Michael , Fink Jessé Rodrigo , Silveira Victor Hugo da , Levien Renato , Zulpo Lucas , Brezolin Darlan
Published: December 2013

O desempenho das funções do solo pode ser influenciado pela compactação imposta pelo manejo inadequado. Algumas propriedades físicas do solo são tomados como indicadores da presença de camadas compactadas, as quais podem interferir no desenvolvimento radicular de culturas. Práticas agrícolas, como o uso de plantas de cobertura, que melhoram as propriedades do solo, podem mitigar problemas relacionados à compactação. O objetivo deste trabalho foi avaliar propriedades físicas de solo e de plantas, estas cultivadas em condições controladas. Em um Argissolo Vermelho sob sistema plantio direto consolidado com dois manejos de cobertura de inverno (pousio e aveia + ervilhaca) e tráfego controlado de máquinas [sem tráfego (ST), antes do tráfego (AT) e depois do tráfego (DT)], avaliaram-se a pressão de pré-consolidação, a resistência do solo à penetração, a densidade do solo, a porosidade e o diâmetro médio ponderado de agregados. Amostras indeformadas de solo das condições antes e depois do tráfego foram coletadas em vasos de PVC e acondicionadas em casa de vegetação, nos quais foram semeadas três sementes de milho, e cultivadas durante 25 dias sob diferentes condições de disponibilidade hídrica. Após esse período, determinaram-se a área foliar, massa verde e seca da parte aérea e massa úmida e seca das raízes de plantas de milho. A densidade do solo independentemente da camada avaliada não foi influenciada pela condição de cobertura do solo, mas sim pela condição de tráfego. Já a macroporosidade foi influenciada pelo tráfego no sistema pousio até 0,10 m, indicando ter esse sistema menor capacidade de suportar perturbações, comprovado pelos menores valores de pressão de pré-consolidação. A resistência do solo à penetração aumentou em profundidade, estando relacionada à maior densidade, menor macroporosidade e maior pressão de pré-consolidação. Sem restrição hídrica, o crescimento radicular do milho foi influenciado positivamente pelo tráfego de máquinas. Nas condições da experimentação, o plantio direto com sistema de rotação de culturas apresentou maior resiliência frente às perturbações do meio.
Silicate fertilization of tropical soils: silicon availability and recovery index of sugarcane
Authors: Camargo Mônica Sartori de , Rocha Gabriela , Korndörfer Gaspar Henrique
Published: December 2013

Sugarcane is considered a Si-accumulating plant, but in Brazil, where several soil types are used for cultivation, there is little information about silicon (Si) fertilization. The objectives of this study were to evaluate the silicon availability, uptake and recovery index of Si from the applied silicate on tropical soils with and without silicate fertilization, in three crops. The experiments in pots (100 L) were performed with specific Si rates (0, 185, 370 and 555 kg ha-1 Si), three soils (Quartzipsamment-Q, 6 % clay; Rhodic Hapludox-RH, 22 % clay; and Rhodic Acrudox-RA, 68 % clay), with four replications. The silicon source was Ca-Mg silicate. The same Ca and Mg quantities were applied to all pots, with lime and/or MgCl2, when necessary. Sugarcane was harvested in the plant cane and first- and second-ratoon crops. The silicon rates increased soil Si availability and Si uptake by sugarcane and had a strong residual effect. The contents of soluble Si were reduced by harvesting and increased with silicate application in the following decreasing order: Q>RH>RA. The silicate rates promoted an increase in soluble Si-acetic acid at harvest for all crops and in all soils, except RA. The amounts of Si-CaCl2 were not influenced by silicate in the ratoon crops. The plant Si uptake increased according to the Si rates and was highest in RA at all harvests. The recovery index of applied Si (RI) of sugarcane increased over time, and was highest in RA.
Coberturas vegetais, manejo do solo, doses de nitrogênio e seus efeitos na nutrição mineral e nos atributos agronômicos do milho
Authors: Kappes Claudinei , Arf Orivaldo , Andrade João Antonio da Costa
Published: December 2013

Pesquisas são desenvolvidas buscando identificar a melhor dose de N para o milho nos mais diferenciados sistemas de manejo do solo. O objetivo deste trabalho foi avaliar a influência de coberturas vegetais, os sistemas de manejo do solo e as doses de N em cobertura sobre a produção de matéria seca, nutrição mineral, quebramento e altura de planta e inserção de espiga do milho. Os experimentos foram conduzidos no município de Selvíria, MS, durante os anos agrícolas 2009/2010 e 2010/2011, em Latossolo Vermelho distrófico típico argiloso (20º 20' S e 51º 24' W, com altitude de 340 m). Foram estabelecidos 36 tratamentos com quatro repetições, em blocos casualizados, resultantes da combinação entre coberturas vegetais (milheto, Crotalaria juncea e milheto + Crotalaria juncea), manejo do solo (preparo com escarificador + grade "leve", grade "pesada" + grade "leve" e sistema plantio direto) e doses de N em cobertura (0, 60, 90 e 120 kg ha-1 - utilizando-se ureia como fonte). O híbrido de milho utilizado foi o DKB 350 YG® e o N, aplicado no estádio V5 (quinta folha expandida). O cultivo de crotalária e de milheto + crotalária, como antecessoras, resultou em maior massa de matéria seca da parte aérea, teor de P foliar e quantidade de N, P e K acumulada. O sistema plantio direto proporcionou maior população inicial e final de plantas e matéria seca de parte aérea e menor altura de planta e de espiga. A aplicação de 120 kg ha-1 de N em cobertura proporcionou maior teor de P foliar, teores de N e de P na planta inteira, matéria seca de parte aérea, quantidade de N, P e K acumulada, altura de planta e de inserção de espiga do milho.
Soil physical properties and grape yield influenced by cover crops and management systems
Authors: Rosa Jaqueline Dalla , Mafra Alvaro Luiz , Medeiros João Carlos , Albuquerque Jackson Adriano , Miquelluti Davi José , Nohatto Marcos André , Ferreira Evandro Zacca , Oliveira Odoni Loris Pereira de
Published: December 2013

The use of cover crops in vineyards is a conservation practice with the purpose of reducing soil erosion and improving the soil physical quality. The objective of this study was to evaluate cover crop species and management systems on soil physical properties and grape yield. The experiment was carried out in Bento Gonçalves, RS, Southern Brazil, on a Haplic Cambisol, in a vineyard established in 1989, using White and Rose Niagara grape (Vitis labrusca L.) in a horizontal, overhead trellis system. The treatments were established in 2002, consisting of three cover crops: spontaneous species (SS), black oat (Avena strigosa Schreb) (BO), and a mixture of white clover (Trifolium repens L.), red clover (Trifolium pratense L.) and annual rye-grass (Lolium multiflorum L.) (MC). Two management systems were applied: desiccation with herbicide (D) and mechanical mowing (M). Soil under a native forest (NF) area was collected as a reference. The experimental design consisted of completely randomized blocks, with three replications. The soil physical properties in the vine rows were not influenced by cover crops and were similar to the native forest, with good quality of the soil structure. In the inter-rows, however, there was a reduction in biopores, macroporosity, total porosity and an increase in soil density, related to the compaction of the surface soil layer. The M system increased soil aggregate stability compared to the D system. The treatments affected grapevine yield only in years with excess or irregular rainfall.
Erosão hídrica em semeadura direta de milho e soja nas direções da pendente e em contorno ao declive, comparada ao solo sem cultivo e descoberto
Authors: Marioti Juliana , Bertol Ildegardis , Ramos Júlio César , Werner Romeu de Souza , Padilha Juscelia , Bandeira Douglas Henrique
Published: December 2013

Dados de perdas de água e solo obtidos em estudos de erosão hídrica são necessários nos planos de conservação do solo. Mesmo com o advento do sistema de semeadura direta, difundido no Brasil a partir dos anos de 1970, ainda se fazem necessárias práticas conservacionistas para o efetivo controle da erosão hídrica, como o uso do cultivo em contorno e o terraceamento, especialmente em regiões com altos volumes de chuva. Outra opção para o controle da erosão é o uso de culturas protecionistas do solo. O objetivo deste trabalho consistiu em quantificar as perdas de água e solo por erosão hídrica, em um solo cultivado com soja e milho sob semeadura direta, nas direções da pendente e em contorno ao declive. O experimento foi realizado em um Cambissolo Húmico alumínico léptico, no período de 2010-2011, sob a aplicação de quatro testes de chuva simulada. Estudaram-se cinco tratamentos, com duas repetições, sendo eles: semeadura de soja no sentido do declive (SD); semeadura de soja no sentido da curva de nível (SC); semeadura de milho no sentido do declive (MD); semeadura de milho no sentido da curva de nível (MC); e testemunha - solo sem cultivo e descoberto (T). Os cultivos foram implantados sobre resíduo cultural de trigo, no sistema de semeadura direta. A semeadura da soja em contorno foi mais eficaz no controle das perdas de solo do que a semeadura dessa no sentido do declive. A cultura do milho foi mais eficaz no controle das perdas de solo do que a soja, independentemente da forma de semeadura, e ambas foram mais eficazes do que a testemunha. As perdas de água foram influenciadas apenas pela forma de semeadura e relacionaram-se negativamente com a umidade do solo antes do início das chuvas e com o tempo de início da enxurrada.
Propriedades físicas do solo em área sob milho em monocultivo ou consorciado com leguminosas de verão
Authors: Chieza Emerson Dalla , Lovato Thomé , Araújo Ednaldo Da Silva , Tonin Jonatan
Published: December 2013

O uso de plantas de cobertura é uma prática que pode prover melhorias na qualidade física dos solos. Objetivou-se com este trabalho avaliar o potencial de consórcios entre leguminosas de verão e milho, na melhoria de propriedades físicas do solo. O estudo foi conduzido em campo no período entre setembro de 2008 e setembro de 2009, em um Argissolo no município de Santa Maria, RS. O delineamento experimental foi em blocos ao acaso, com cinco tratamentos e quatro repetições. Os tratamentos consistiram nos seguintes cultivos: milho + feijão-caupi, milho + guandu anão, milho + mucuna-preta, milho em monocultivo, além de uma área em pousio como testemunha. Em cada parcela, foram coletadas amostras indeformadas do solo nas profundidades de 0-5 e 5-10 cm em três épocas: na instalação do experimento, aos 30 dias após a deposição da palhada de cada cultivo sobre o solo e um ano após a instalação do experimento. Foram mensurados os seguintes atributos: densidade do solo, porosidade total, macro e microporosidade e estabilidade dos agregados. Todos os cultivos estudados diminuíram a densidade do solo e aumentaram a macroporosidade e a porosidade total na profundidade de 0-5 cm do solo, em comparação à área em pousio. O consórcio de milho e guandu anão aumentou o diâmetro médio ponderado de agregados na profundidade de 0-5 cm do solo, em relação ao tratamento em pousio, mas esse efeito foi temporário, pois não persistiu até a coleta final. O consórcio entre milho e guandu anão foi o mais promissor em promover melhorias na estrutura do solo.
Qualidade de vida de estudantes de Medicina: uma revisão
Authors: Feodrippe André Luiz Oliveira , Brandão Maria Carolina da Fonseca , Valente Tânia Cristina de Oliveira
Published: December 2013

Apresenta-se uma revisão de literatura sobre a qualidade de vida dos estudantes de Medicina, por meio da análise de bibliografia, usando como descritores "qualidade de vida" e "estudantes de Medicina", tendo como fonte de busca a Biblioteca Virtual em Saúde nas Bases Eletrônicas Medline, Lilacs, SciELO e PubMed, e a plataforma Mendeley. Foram claramente identificados dois grupos de publicações: um de cunho quantitativo, que focaliza a medida da qualidade de vida de cada grupo de estudantes; e outro de abordagem qualitativa, voltado não só para a avaliação da percepção do aluno sobre o tema, mas também para o entendimento dos motivos que transformam o curso em um fator estressor para esse indivíduo. O predomínio de artigos quantitativos e a escassez de qualitativos, além de poucas conclusões que poderiam motivar intervenções práticas, mostram que o tema necessita ser mais estudado e debatido.
Levantamento fitossociológico e caráter sucessional de um trecho de floresta secundária ciliar em Juquitiba, SP, Brasil
Authors: Polisel Rodrigo Trassi
Published: December 2013

O objetivo deste trabalho foi levantar as estruturas horizontal e vertical da comunidade arbórea em regeneração de trecho de floresta secundária ciliar de aproximadamente trinta anos de idade e conhecer quais as espécies mais abundantes em cada estrato da floresta, para se conhecer o grau sucessional deste trecho florestal. Foram levantados 800 m² de área, sub-divididos em dezesseis parcelas de 10 x 5 m, no interior das quais todos os indivíduos com DAP ≥ 1 cm foram amostrados e identificados para as análises horizontal (DR, FR, DoR, IVC e IVI), vertical (PSR e RNT) e mista, a partir do índice de valor de importância ampliado (IVIa). Foram amostrados 689 indivíduos, pertencentes a 38 famílias, 74 gêneros e 109 espécies. A densidade total foi de 8.614 indivíduos/ha. O índice de diversidade de Shannon foi de 3,99 e o de eqüabilidade de Pielou, 0,85. Tibouchina pulchra, Psychotria suterella e Endlicheria paniculata se destacaram com elevados valores de IVIa. Guarea macrophylla, Gomidesia anacardiaefolia, Xylopia langsdorffiana e Endlicheria paniculata obtiveram elevados valores de RNT, indicando adequada regeneração natural no trecho. As espécies secundárias iniciais e umbrófilas apresentaram a maior importância ecológica nesse trecho de floresta com trinta anos de pousio, com os maiores valores de posição sociológica e índice de valor de importância. Além destas, as espécies secundárias tardias presentes em todos os estratos sugerem o grau sucessional intermediário para o trecho estudado.
Tolerância de fungos ectomicorrízicos e plantas associadas a níveis tóxicos de metais
Authors: Targhetta Bianca Lucchesi , Oliveira Vetúria Lopes de , Rossi Márcio José
Published: December 2013

As ectomicorrizas são associações entre raízes de plantas e fungos, de grande importância para a sobrevivência e crescimento vegetal, por aumentar o aporte nutricional e a proteção contra fatores adversos. Os fungos ectomicorrízicos podem quelar íons de metais tóxicos, retirando-os do solo e diminuindo os danos ao hospedeiro. Quatro isolados de fungos ectomicorrízicos foram utilizados neste estudo: UFSC-Sc68 (Scleroderma sp.); UFSC-Ch163 (Chondrogaster angustisporus); UFSC-Pt116 e UFSC-Pt188 (Pisolithus microcarpus). Mudas de Eucalyptus dunnii foram testadas quanto à sua tolerância aos metais alumínio (Al), cádmio (Cd), cromo (Cr) e manganês (Mn) misturados ao substrato de plantio, em dois experimentos em casa de vegetação. No primeiro, em ausência dos fungos e, no segundo, após inoculação com esses organismos. No experimento sem inoculação, o metal mais tóxico foi o Cr. Nenhuma planta sobreviveu nas doses 1000 e 10000 mg.kg-1 desse metal. Para os outros metais, a matéria seca diminuiu com o aumento da dose. Já no estudo com plantas inoculadas, o Cd foi o metal mais tóxico, que reduziu significativamente a sobrevivência e o crescimento das plantas. Os isolados fúngicos UFSC-Pt188 e UFSC-Ch163 foram os mais eficientes na proteção contra os metais, melhorando a sobrevivência e a produção de matéria seca das plantas. O isolado UFSC-Ch163, em particular, foi o mais eficiente na tolerância das plantas, o que indica seu potencial de utilização em solos contaminados para favorecer o estabelecimento e o crescimento das plantas.