bluuebunny/crossref_metadata_2025 huggingface dataset:
Rhythmic activity of feline dorsal and ventral spinocerebellar tract neurons during fictive motor actions
Authors: Fedirchuk Brent , Stecina Katinka , Kristensen Kasper Kyhl , Zhang Mengliang , Meehan Claire F. , Bennett David J. , Hultborn Hans
Published: October 2012

Neurons of the dorsal spinocerebellar tracts (DSCT) have been described to be rhythmically active during walking on a treadmill in decerebrate cats, but this activity ceased following deafferentation of the hindlimb. This observation supported the hypothesis that DSCT neurons primarily relay the activity of hindlimb afferents during locomotion, but lack input from the spinal central pattern generator. The ventral spinocerebellar tract (VSCT) neurons, on the other hand, were found to be active during actual locomotion (on a treadmill) even after deafferentation, as well as during fictive locomotion (without phasic afferent feedback). In this study, we compared the activity of DSCT and VSCT neurons during fictive rhythmic motor behaviors. We used decerebrate cat preparations in which fictive motor tasks can be evoked while the animal is paralyzed and there is no rhythmic sensory input from hindlimb nerves. Spinocerebellar tract cells with cell bodies located in the lumbar segments were identified by electrophysiological techniques and examined by extra- and intracellular microelectrode recordings. During fictive locomotion, 57/81 DSCT and 30/30 VSCT neurons showed phasic, cycle-related activity. During fictive scratch, 19/29 DSCT neurons showed activity related to the scratch cycle. We provide evidence for the first time that locomotor and scratch drive potentials are present not only in VSCT, but also in the majority of DSCT neurons. These results demonstrate that both spinocerebellar tracts receive input from the central pattern generator circuitry, often sufficient to elicit firing in the absence of sensory input.
Exponential Convergence of an Observer Based on Partial Field Measurements for the Wave Equation
Authors: Chapelle Dominique , Cîndea Nicolae , De Buhan Maya , Moireau Philippe
Published: October 2012

We analyze an observer strategy based on partial—that is, in a subdomain—measurements of the solution of a wave equation, in order to compensate for uncertain initial conditions. We prove the exponential convergence of this observer under a nonstandard observability condition, whereas using measurements of the time derivative of the solution would lead to a standard observability condition arising in stabilization and exact controlabillity. Nevertheless, we directly relate our specific observability condition to the classical geometric control condition. Finally, we provide some numerical illustrations of the effectiveness of the approach.
Molecular Imaging Reveals a Role for AKT in Resistance to Cisplatin for Ovarian Endometrioid Adenocarcinoma
Authors: Wang Hanxiao , Galbán Stefanie , Wu Rong , Bowman Brittany M. , Witte Amanda , Vetter Katrin , Galbán Craig J. , Ross Brian D. , Cho Kathleen R. , Rehemtulla Alnawaz
Published: October 2012

Purpose: Ovarian cancer is the fifth leading cause of cancer-related deaths among American women. Platinum-based chemotherapy, such as cisplatin, represents the standard-of-care for ovarian cancer. However, toxicity and acquired resistance to cisplatin have proven challenging in the treatment of patients with ovarian cancer.

Experimental Design: Using a genetically engineered mouse model of ovarian endometrioid adenocarcinoma (OEA) in combination with molecular-imaging technologies, we studied the activation of the AKT serine/threonine kinase in response to long-term cisplatin therapy.

Results: Treatment of cells in culture and tumor-bearing animals with cisplatin resulted in activation of AKT, a key mediator of cell survival. On the basis of these results, we investigated the therapeutic use of AKT inhibition in combination with cisplatin, which resulted in enhanced and prolonged induction of apoptosis and in significantly improved tumor control as compared with either agent alone.

Conclusion: These results provide an impetus for clinical trials using combination therapy. To facilitate these trials, we also show the use of diffusion-weighted MRI as an imaging biomarker for evaluation of therapeutic efficacy in OEA. Clin Cancer Res; 19(1); 158–69. ©2012 AACR.
Neuregulin in Cardiovascular Development and Disease
Authors: Odiete Oghenerukevwe , Hill Michael F. , Sawyer Douglas B.
Published: October 2012

Studies in genetically modified mice have demonstrated that neuregulin-1 (NRG-1), along with the erythroblastic leukemia viral oncogene homolog (ErbB) 2, 3, and 4 receptor tyrosine kinases, is necessary for multiple aspects of cardiovascular development. These observations stimulated in vitro and in vivo animal studies, implicating NRG-1/ErbB signaling in the regulation of cardiac cell biology throughout life. Cardiovascular effects of ErbB2-targeted cancer therapies provide evidence in humans that ErbB signaling plays a role in the maintenance of cardiac function. These and other studies suggest a conceptual model in which a key function of NRG-1/ErbB signaling is to mediate adaptations of the heart to physiological and pathological stimuli through activation of intracellular kinase cascades that regulate tissue plasticity. Recent work implicates NRG-1/ErbB signaling in the regulation of multiple aspects of cardiovascular biology, including angiogenesis, blood pressure, and skeletal muscle responses to exercise. The therapeutic potential of recombinant NRG-1 as a potential treatment for heart failure has been demonstrated in animal models and is now being explored in clinical studies. NRG-1 is found in human serum and plasma, and it correlates with some clinical parameters, suggesting that it may have value as an indicator of prognosis. In this review, we bring together this growing literature on NRG-1 and its significance in cardiovascular development and disease.
Long Noncoding RNAs in Cardiac Development and Pathophysiology
Authors: Schonrock Nicole , Harvey Richard P. , Mattick John S.
Published: October 2012

Heart function requires sophisticated regulatory networks to orchestrate organ development, physiological responses, and environmental adaptation. Until recently, it was thought that these regulatory networks are composed solely of protein-mediated transcriptional control and signaling systems; consequently, it was thought that cardiac disease involves perturbation of these systems. However, it is becoming evident that RNA, long considered to function primarily as the platform for protein production, may in fact play a major role in most, if not all, aspects of gene regulation, especially the epigenetic processes that underpin organogenesis. These include not only well-validated classes of regulatory RNAs, such as microRNAs, but also tens of thousands of long noncoding RNAs that are differentially expressed across the entire genome of humans and other animals. Here, we review this emerging landscape, summarizing what is known about their functions and their role in cardiac biology, and provide a toolkit to assist in exploring this previously hidden layer of gene regulation that may underpin heart adaptation and complex heart diseases.
Myosin Light Chain Phosphorylation Is Critical for Adaptation to Cardiac Stress
Authors: Warren Sonisha A. , Briggs Laura E. , Zeng Huadong , Chuang Joyce , Chang Eileen I. , Terada Ryota , Li Moyi , Swanson Maurice S. , Lecker Stewart H. , Willis Monte S. , Spinale Francis G. , Maupin-Furlowe Julie , McMullen Julie R. , Moss Richard L. , Kasahara Hideko
Published: October 2012

Background—

Cardiac hypertrophy is a common response to circulatory or neurohumoral stressors as a mechanism to augment contractility. When the heart is under sustained stress, the hypertrophic response can evolve into decompensated heart failure, although the mechanism(s) underlying this transition remain largely unknown. Because phosphorylation of cardiac myosin light chain 2 (MLC2v), bound to myosin at the head-rod junction, facilitates actin-myosin interactions and enhances contractility, we hypothesized that phosphorylation of MLC2v plays a role in the adaptation of the heart to stress. We previously identified an enzyme that predominantly phosphorylates MLC2v in cardiomyocytes, cardiac myosin light-chain kinase (cMLCK), yet the role(s) played by cMLCK in regulating cardiac function in health and disease remain to be determined.

Methods and Results—

We found that pressure overload induced by transaortic constriction in wild-type mice reduced phosphorylated MLC2v levels by ≈40% and cMLCK levels by ≈85%. To examine how a reduction in cMLCK and the corresponding reduction in phosphorylated MLC2v affect function, we generated
Mylk3
gene-targeted mice and transgenic mice overexpressing cMLCK specifically in cardiomyocytes. Pressure overload led to severe heart failure in cMLCK knockout mice but not in mice with cMLCK overexpression in which cMLCK protein synthesis exceeded degradation. The reduction in cMLCK protein during pressure overload was attenuated by inhibition of ubiquitin-proteasome protein degradation systems.

Conclusions—

Our results suggest the novel idea that accelerated cMLCK protein turnover by the ubiquitin-proteasome system underlies the transition from compensated hypertrophy to decompensated heart failure as a result of reduced phosphorylation of MLC2v.
Anti-Tumor Necrosis Factor-α Therapy Reduces Aortic Inflammation and Stiffness in Patients With Rheumatoid Arthritis
Authors: Mäki-Petäjä Kaisa M. , Elkhawad Maysoon , Cheriyan Joseph , Joshi Francis R. , Östör Andrew J.K. , Hall Frances C. , Rudd James H.F. , Wilkinson Ian B.
Published: October 2012

Background—

Rheumatoid arthritis (RA) is a systemic inflammatory condition associated with increased cardiovascular risk. This is not fully explained by traditional risk factors, but direct vascular inflammation and aortic stiffening may play a role. We hypothesized that patients with RA exhibit aortic inflammation, which can be reversed with anti-tumor necrosis factor-α therapy and correlates with aortic stiffness reduction.

Methods and Results—

Aortic inflammation was quantified in 17 patients with RA, before and after 8 weeks of anti-tumor necrosis factor-α therapy by using
18
F-fluorodeoxyglucose positron emission tomography with computed tomography coregistration. Concomitantly, 34 patients with stable cardiovascular disease were imaged as positive controls at baseline. Aortic fluorodeoxyglucose target-to-background ratios (TBRs) and aortic pulse wave velocity were assessed. RA patients had higher baseline aortic TBRs in comparison with patients who have cardiovascular disease (2.02±0.22 versus 1.74±0.22,
P
=0.0001). Following therapy, aortic TBR fell to 1.90±0.29,
P
=0.03, and the proportion of inflamed aortic slices (defined as TBR >2.0) decreased from 50±33% to 33±27%,
P
=0.03. Also, TBR in the most diseased segment of the aorta fell from 2.51±0.33 to 2.05±0.29,
P
<0.0001. Treatment also reduced aortic pulse wave velocity significantly (from 9.09±1.77 to 8.63±1.42 m/s,
P
=0.04), which correlated with the reduction of aortic TBR (
R
=0.60,
P
=0.01).

Conclusions—

This study demonstrates that RA patients have increased aortic
18
F-fluorodeoxyglucose uptake in comparison with patients who have stable cardiovascular disease. Anti-tumor necrosis factor-α therapy reduces aortic inflammation in patients with RA, and this effect correlates with the decrease in aortic stiffness. These results suggest that RA patients exhibit a subclinical vasculitis, which provides a mechanism for the increased cardiovascular disease risk seen in RA.
Hybrid Reassemblage: An Exploration of Craft, Digital Fabrication and Artifact Uniqueness
Authors: Zoran Amit , Buechley Leah
Published: October 2012

Digital fabrication, and especially 3D printing, is an emerging field that is opening up new possibilities for craft, art and design. The process, however, has important limitations; in particular, digitally designed artifacts are intrinsically reproducible. In stark contrast, traditional craft artifacts are individually produced by hand. The authors combine digital fabrication and craft in their work involving object destruction and restoration: an intentionally broken crafted artifact and a 3D printed restoration. The motivation is not to restore the original work but to transform it into a new object in which both the destructive event and the restoration are visible and the re-assembled object functions as a memorial.
Experimental 4D-Var Assimilation of SYNOP Rain Gauge Data at ECMWF
Authors: Lopez Philippe
Published: October 2012

Four-dimensional variational data assimilation (4D-Var) experiments with 6-hourly rain gauge accumulations observed at synoptic stations (SYNOP) around the globe have been run over several months, both at high resolution in an ECMWF operations-like framework and at lower resolution with the reference observational coverage reduced to surface pressure data only, as would be expected in early twentieth-century periods. The key aspects of the technical implementation of rain gauge data assimilation in 4D-Var are described, which include the specification of observation errors, bias correction procedures, screening, and quality control. Results from experiments indicate that the positive impact of rain gauges on forecast scores remains limited in the operations-like context because of their competition with all other observations already available. In contrast, when only synoptic station surface pressure observations are assimilated in the data-poor control experiment, the additional assimilation of rain gauge measurements substantially improves not only surface precipitation scores, but also analysis and forecast scores of temperature, geopotential, wind, and humidity at most atmospheric levels and for forecast ranges up to 10 days. The verification against Meteosat infrared imagery also shows a slight improvement in the spatial distribution of clouds. This suggests that assimilating rain gauge data available during data-sparse periods of the past might help to improve the quality of future reanalyses and subsequent forecasts.
Impact of Graupel Parameterization Schemes on Idealized Bow Echo Simulations
Authors: Adams-Selin Rebecca D. , van den Heever Susan C. , Johnson Richard H.
Published: October 2012

The effect of changes in microphysical cooling rates on bow echo development and longevity are examined through changes to graupel parameterization in the Advanced Research Weather Research and Forecasting Model (ARW-WRF). Multiple simulations are performed that test the sensitivity to different graupel size distributions as well as the complete removal of graupel. It is found that size distributions with larger and denser, but fewer, graupel hydrometeors result in a weaker cold pool due to reduced microphysical cooling rates. This yields weaker midlevel (3–6 km) buoyancy and pressure perturbations, a later onset of more elevated rear inflow, and a weaker convective updraft. The convective updraft is also slower to tilt rearward, and thus bowing occurs later. Graupel size distributions with more numerous, smaller, and lighter hydrometeors result in larger microphysical cooling rates, stronger cold pools, more intense midlevel buoyancy and pressure gradients, and earlier onset of surface-based rear inflow; these systems develop bowing segments earlier. A sensitivity test with fast-falling but small graupel hydrometeors revealed that small mean size and slow fall speed both contribute to the strong cooling rates. Simulations entirely without graupel are initially weaker, because of limited contributions from cooling by melting of the slowly falling snow. However, over the next hour increased rates of melting snow result in an increasingly more intense system with new bowing. Results of the study indicate that the development of a bow echo is highly sensitive to microphysical processes, which presents a challenge to the prediction of these severe weather phenomena.
Model Bias in a Continuously Cycled Assimilation System and Its Influence on Convection-Permitting Forecasts
Authors: Romine Glen S. , Schwartz Craig S. , Snyder Chris , Anderson Jeff L. , Weisman Morris L.
Published: October 2012

During the spring 2011 season, a real-time continuously cycled ensemble data assimilation system using the Advanced Research version of the Weather Research and Forecasting Model (WRF) coupled with the Data Assimilation Research Testbed toolkit provided initial and boundary conditions for deterministic convection-permitting forecasts, also using WRF, over the eastern two-thirds of the conterminous United States (CONUS). In this study the authors evaluate the mesoscale assimilation system and the convection-permitting forecasts, at 15- and 3-km grid spacing, respectively. Experiments employing different physics options within the continuously cycled ensemble data assimilation system are shown to lead to differences in the mean mesoscale analysis characteristics. Convection-permitting forecasts with a fixed model configuration are initialized from these physics-varied analyses, as well as control runs from 0.5° Global Forecast System (GFS) analysis. Systematic bias in the analysis background influences the analysis fit to observations, and when this analysis initializes convection-permitting forecasts, the forecast skill is degraded as bias in the analysis background increases. Moreover, differences in mean error characteristics associated with each physical parameterization suite lead to unique errors of spatial, temporal, and intensity aspects of convection-permitting rainfall forecasts. Observation bias by platform type is also shown to impact the analysis quality.
Memory and Decision Making: Determining Action when the Sirens Sound
Authors: Drost Robert
Published: October 2012

Memories, both semantic, or learned knowledge, and episodic, or personal experiences, play an important role in an individual’s decision making under risk. In addition, varying levels of knowledge and experience exist in each individual. These memories enable individuals to make informed decisions based on previous knowledge or experience, and ultimately influence one’s behavior under risk. In this study, 49 undergraduate students participated in a 1-h, classroom-based experiment focusing on decision making. The sample contained n = 23 “episodic” participants, referred to as “high episodic,” who reported having personally experienced a tornado and n = 24 participants, referred to as “low episodic,” who had no reported tornado experience. Incomplete data reported by the remaining participants were not included in this study. All participants completed a decision-making task both before and after viewing a 5-min slideshow stimulus related to tornadoes and associated damage. This decision-making task prompted participants to describe the actions they would anticipate taking during an actual tornado warning. Prior to the stimulus, high episodic participants exhibited a marginally higher tendency to ignore a tornado warning than those participants without episodic (low episodic) memories. After the tornado stimulus, all participants reported a greater likelihood to engage in precautionary action than reported prior to the stimulus. It is also found that 1) those participants with low episodic memory showed greater precaution than the high episodic memory group, and 2) participants with greater knowledge of tornadoes showed the greatest gains in anticipated precautionary behavior. This study suggests that increasing a population’s general knowledge of tornadoes could result in greater individual precaution and overall safety during a tornadic event.
The lessons of failure: learning and blame avoidance in public policy-making
Authors: Howlett Michael
Published: October 2012

Recent studies by Hood have underscored the significance of the desire of decision-makers to avoid blame for poor policy initiatives, highlighting the importance to policy-making of learning about how best to avoid policy failure. This article examines several different concepts of policy failure in the literature on the subject, such as policy accidents, errors, mistakes, and anomalies, along with recent work by McConnell and his colleagues on the general types and sources of such failures. The article distinguishes between ‘thin’ (technical-strategic) and ‘thick’ (political-experiential) policy learning and links them to McConnell’s three categories of political, programme, and process failures. The analysis points to the significant and underappreciated roles played by process and political problems in the analysis of policy failure and the need to draw lessons in these areas as well as in more technically oriented programme-related ones if the prospects of policy success are to be enhanced.
Explaining African ethnic diversity
Authors: Green Elliott
Published: October 2012

The consequences of ethnic diversity in Africa have been widely noted. However, the sources of this diversity remain unexplained, which is surprising in light of Africa’s high level of ethnic diversity as well as its large internal variation. Here I show that ethnic diversity in Africa is a result of its tropical location, the pre-colonial slave trade, the colonial creation of large states, and low levels of urbanization, and that my results are robust to various controls. I also show that controlling for the slave trade eliminates the statistical significance of an Africa dummy variable in regressions using data on global ethnic diversity.
Insensible water loss from the Hilite 2400LT oxygenator: an in vitro study
Authors: Gill MC , O’Shaughnessy K
Published: October 2012

Background:

Neonatal extracorporeal membrane oxygenation (ECMO) patients are particularly vulnerable to the effects of uncompensated insensible water loss resulting in hypernatraemia. There exists a long-standing relationship between hypernatraemia and varying degrees of cerebral dysfunction. The aim of this study is to explore the degree to which free water loss occurs across a commonly used ECMO oxygenator, the polymethylpentene (PMP) membrane Hilite® 2400LT (Medos, Medizintechnik AG, Stolberg, Germany). The secondary aim is to assess to what extent the addition of heat and/or humidity ameliorates this water loss.

Methods:

An ECMO circuit consisting of a centrifugal pump and a Hilite® 2400LT oxygenator was primed with crystalloid and albumin. Each experimental trial was carried out in triplicate, with gas flow rates of 1, 3 and 4.8 L/min being investigated. Fluid loss was assessed at six time points over a 24-hour period.

Results:

Water loss increased significantly from 1 to 3 L/min gas flow (p=0.05) and from 3 to 4.8 L/min gas flow (p=0.025). The mean water loss differences between the differing gas flow trials per L/min gas flow were non-significant (72.4 ±3.9 ml/24hrs). The effect of heating the gas to 37°C did not significantly alter water loss, whereas heat and humidity reduced water loss significantly (p=0.009).

Conclusions:

Insensible water loss from a Hilite® 2400LT oxygenator is approximately 72 ml/day per L/min gas flow over 24 hrs. Heating and humidifying the gas reduces the fluid loss significantly to approximately 8 ml/L/min gas flow over 24 hrs (p=0.009).
Subacute effects of ecstasy on mood: an exploration of associated risk factors
Authors: Scott Rebecca M , Hides Leanne , Allen J Sabura , Lubman Dan I
Published: October 2012

Ecstasy use may result in lowered mood, anxiety or aggression in the days following use. Yet, few studies have investigated what factors increase the risk of experiencing such symptoms. Ecstasy users (at least once in the last 12 months) who subsequently took ecstasy ( n=35) over the period of one week, were compared on measures of mood, sleep, stress and drug use, with those who abstained from ecstasy ( n=21) that week. Measures were administered the week prior to ecstasy use and one and three days following use, or the equivalent day for abstainers. Mood symptoms were assessed using the Kessler-10 self-report psychological distress scale, a subjective mood rating (1–10), and using the depression, anxiety and hostility items from the clinician-rated Brief Psychiatric Rating Scale. Timeline Followback methods were used to collect information on drug use and life stress in the past month. Self-reported sleep quality was also assessed. Ecstasy use was not associated with subacute depressive, anxiety or aggressive symptoms. Rather, lowered mood and increased psychological distress were associated with self-reported hours and quality of sleep obtained during the three-day follow-up. These findings highlight the importance of considering sleep disruption in understanding the short-term mood effects of ecstasy use.
Preparation and characterization of tetrapod-shaped ZnO whisker filled polyurethane cross-linked epoxy/polyurethane damping composites
Authors: Ma Chi , Chen Erfan , Sun Ting , Shi Shan , Fang Qinghong
Published: October 2012

A novel kind of damping composite was prepared, which consisted of the tetrapod-shaped ZnO whisker and polyurethane cross-linked epoxy/polyurethane. The dynamic mechanical properties of these materials were investigated by dynamic thermal analysis. Results indicated that the effective damping temperature range (tan δ > 0.3) was obviously broadened from 33.7°C to 178.8°C due to the formation of graft interpenetrating polymer network. With addition of tetrapod-shaped ZnO whisker, the maximal value of damping peak was improved to 1.44 for the increase of the internal friction. The morphological studies proved the existence of partial phase separation, and it was also observed that uniformly dispersed tetrapod-shaped ZnO whiskers were tightly implanted into the polymer matrix. The thermal stability and the tensile strength of composite were improved by the incorporation of tetrapod-shaped ZnO whisker. The results revealed that morphology of graft interpenetrating polymer network and addition of tetrapod-shaped ZnO whisker could provide excellent damping properties for the polymer matrix composite.
Creep failure strain estimation of glass fibre/polypropylene composites based on short-term tests and Weibull characterisation
Authors: Vas László Mihály , Bakonyi Péter
Published: October 2012

In order to study the short- and long-term creep behaviours of injection moulded, unreinforced and glass fibre reinforced polypropylene composites, tensile and creep measurements were carried out and analysed. Based on the linear viscoelastic behaviour and variable transformations as well as Weibull-based distribution characterisation, estimations for the tensile strength parameters and creep failure strain were determined and fitted to the measurements. These mathematical estimations and the relationships between the material model czonstants and the fibre content, determined by fitting, give a possibility for designers’ calculations at arbitrary creep load levels and fibre contents.
Acoustic emission wavelet transform on adhesively bonded single-lap joints of composite laminate during tensile test
Authors: Bak K Mohamed , KalaiChelvan K , Vijayaraghavan GK , Sridhar BTN
Published: October 2012

Acoustic emission detection in composites is complicated in comparison with metallic structures due to the complex nature of acoustic emission wavelet transform in anisotropic materials. In this study, the adhesively bonded single-lap joints with zero-degree orientation are used to trigger different failure mechanisms when subjected to tensile test with acoustic emission monitoring. Acoustic emission signals which are studied for damage characterization are obtained during tensile tests. The range of peak frequency with time, pertaining to the failure mode in adhesively bonded single-lap joints has been identified using wavelet transform. Signals and their characteristics representing different failure modes are identified and validated using wavelet transform analysis. Continuous wavelet transform is then applied to identify the frequency range and time history for failure modes in each signal. The fractured surface area of the bonded single-lap joint specimen was examined directly using a scanning electron microscope and also identified the failure mechanism of bonded single-lap joints. The results obtained from acoustic emission technique are compared with scanning electron microscope results, to find the evidence of predicted damage. This study of the frequency content of each test using continuous wavelet transform is then performed and the classification of several failure modes is identified.
Mechanical properties of polyvinylchloride-coated fabrics processed with Precontraint® technology
Authors: Zhang Yingying , Zhang Qilin , Lv Henglin
Published: October 2012

This article presents the mechanical properties of polyvinylchloride-coated fabrics with Precontraint® technology. First, groups of off-axial tests are carried out, and the corresponding strength criteria are discussed. Then, the biaxial tests are carried out on the material without initial loading and the material after cyclic loading, and the corresponding stress–strain surfaces are studied. Finally, the effects of temperature on the mechanical properties are studied. Results show that this material is typically orthotropic and its strength can be predicted by the Tsai–Hill strength criterion. The differences between the mechanical properties of the warp and the weft are not significant, because the Precontraint® technology used in the processing reduces significantly the discrepancies, compared with common plain woven fabrics. The material without initial loading is nonlinear and viscoelastic, and after cyclic loading it becomes linear and its stiffness increases. The biaxial tensile behaviors are affected by biaxial loading significantly, and then different constitutive relations should be conducted regarding to different service conditions. With temperature increasing, the tensile strength and the elastic modulus gradually decreases, and the breaking strain increases.
Continuous glass fiber reinforced wood plastic composite in extrusion process: Feasibility and processing
Authors: Zolfaghari Abbas , Behravesh Amir Hossein , Adli Alireza , Sarabi Majid TabkhPaz
Published: October 2012

This article presents an experimental investigation on developing wood plastic composites reinforced with continuous glass fibers in an extrusion process. The main role of wood component in wood plastic composite is mainly as a filler to reduce cost, and not reinforcing. Adding wood component causes a noticeable reduction in strength and toughness. This will hinder their usage in load-bearing applications. In this study, a novel method for production of hybrid wood plastic composites is introduced. This manufacturing process takes the advantages of a cost-effective and flexible production line. First, E-glass rovings were impregnated with a polymer in an especially designed (impregnating) die. Then, six melt impregnated glass rovings were integrated with wood plastic composites in a single step via an extrusion process. Another unique die was designed and manufactured to feed and position the impregnated glass rovings into a round shaped wood plastic composite profile. Wood content was changed in three levels to investigate its effect on the processability and the final properties of the hybrid composites. The experimentation on the extruded hybrid wood plastic composites proved the feasibility of the process and the relative uniformity of the roving positions in the extrudate. Three-point bending tests were conducted to evaluate the flexural properties. Improvements in strength, modulus, and toughness were dramatic.
Shape memory characteristics of woven glass fibre fabric reinforced epoxy composite in flexure
Authors: Fejős M , Romhány G , Karger-Kocsis J
Published: October 2012

Shape memory characteristics of a woven glass fibre fabric reinforced epoxy composite (reinforcement content: 38 vol.%) were assessed in three-point bending mode in a dynamic mechanical analysis device and compared to those of the parent epoxy resin. From unconstrained tests, the shape fixity and recovery ratios and the recovery rate, whereas from constrained tests the recovery stress were determined. The shape fixity and recovery rate decreased due to the glass fibre reinforcement which had, however, no effect on the shape recovery. Major benefit of the woven glass fibre fabric was that the recovery stress could be enhanced by two orders of magnitude in comparison to the neat epoxy. Glass fibre reinforcement was accompanied with a substantial decrease in the failure-free flexural deformability of the composite specimen.
Mechanical characterization of sisal fiber reinforced polymer mortars: Compressive and flexural properties
Authors: Reis JML , Carneiro EP
Published: October 2012

In this study, polymer mortars manufactured with epoxy and unsaturated polyester resins reinforced with 1%, in weight, of sisal fibers were prepared. The fibers were chemically modified in order to improve their compatibility with inorganic aggregate, foundry sand, organic binder, and polymer resin. Sisal fibers were treated with 5% and 10% of NaOH and 20% of acetic acid diluted in an aqueous solution. Flexural and compressive tests were performed to evaluate the mechanical properties of such materials. Results showed that untreated sisal fibers improve the mechanical properties but treated fibers contribute to lower polymer mortars’ mechanical properties. An increase in stiffness is observed in all reinforced mortars due to fiber bridging.
A review on the characteristics of gomuti fibre and its composites with thermoset resins
Authors: Ticoalu Adriana , Aravinthan Thiru , Cardona Francisco
Published: October 2012

Gomuti fibre is obtained from Arenga pinnata tree and is known with other names such as sugar-palm fibre, gomutu, ijuk, serat aren and black fibre. This article presents a review on the physical, mechanical, chemical and thermal properties of gomuti fibre in comparison with other common natural fibres. Furthermore, this article reviews the mechanical properties of gomuti fibre composites with thermoset polymer resins based on the existing published literature. It is observable that gomuti fibre has a close similarity to coir fibre in its physical and mechanical properties than the other natural fibres. It has the characteristics of lower density, strength and modulus, but higher elongation. The composites with gomuti fibre also exhibit properties similar to coir fibre composites.
Algebraic rectilinear model for multilayer resin transfer molding injection
Authors: Oliveira Cristiano P , Souza Jeferson A , Isoldi Liércio A , Amico Sandro C
Published: October 2012

An analytical model for the multilayer rectilinear injection applied to the RTM process has been developed. The model takes into account the permeability in both in-plane ( Kxx and Kyy) and transverse ( Kzz) directions of each layer of the reinforcement media and calculates the transverse permeability ( Kt) through adjacent layers. Porosity and thickness are set independent for each layer of the assembly. Mass balance of resin within the layers is used to develop an expression that estimates resin position ( xi) as a function of time ( t) independently of each layer. The resulting equation was solved using: (i) Numerical integration and (ii) algebraic integration of the simplified expression resulting in a closed expression for xi =  xi( t). Results of both proposed methods were compared with the calculations performed using the PAM-RTM software for cases with three, five and seven layers and the maximum calculated error in all cases was less than 12%.
Microstructure, mechanical behaviour, damage mechanisms of polypropylene/short hemp fibre composites: Experimental investigations
Authors: Gehring Florian , Bouchart Vanessa , Dinzart Florence , Chevrier Pierre
Published: October 2012

This article is devoted to the study of mechanical behaviour of a polypropylene reinforced with short hemp fibres available industrially. The main objective of this study is to understand the major physical phenomena to be taken into account to propose, in an upcoming work, a relevant modelling of these composites. Important experimental investigations were performed and revealed quasi-isotropic microstructure at fibres scale in terms of spatial distribution and orientation using X-ray tomography. Influence of hemp fibres on behaviour of polypropylene/hemp composites was examined at controlled temperature upon monotonic and complex path uniaxial tensile loading at different strain rates (10−4, 10−3 and 10−2 s−1) and fibres weight fraction (0, 5, 10 and 20%w/w). Resulting stress–strain curves pointed out a reinforcing effect of hemp fibres at initial stage. Furthermore, the noted high strain rate sensitivity is accounted for quasi-brittle failure. Use of infrared thermography technique highlighted the presence of ‘two breaking modes’ depending on strain rate, i.e. at low strain rate one single damaged zone appeared, on the contrary at higher strain rate many damaged areas occurred in all calibrated zone. In accordance of all conducted experiments, non-linear behaviour of polypropylene/hemp composites is mainly attributed to matrix behaviour.
Helium gas barrier and water absorption behavior of bamboo fiber reinforced recycled polypropylene
Authors: Boukehili H , Nguyen-Tri P
Published: October 2012

Helium gas permeability and water absorption behavior of the recycled polypropylene/short bamboo fiber composite membrane were investigated. The effects of short bamboo fiber content and fiber chemical treatment on gas permeability and water absorption properties of composites have been examined. Our research showed that the solubility coefficient of helium increased as the fiber content of the bamboo increases but the diffusivity coefficient seemed to decrease with increasing amount of bamboo fiber in the composite formulation due to the poor adhesion between bamboo fiber and polymer matrix. The structure of recycled polypropylene/bamboo fibers have also investigates by X-ray diffraction technique. The chemical treatment of the bamboo fiber by alkali solution increased fiber surface roughness within the composite; in consequence, a more homogeneous dispersion of these fibers appears in the polymer matrix. The process of absorption of water was found to follow the kinetics and mechanisms described by Fick’s theory. A considerable loss in mechanical properties of the water-saturated samples after 3 months of aging in water was observed and this reduction could be delayed by fiber chemical treatment. This study provided the useful information about the behavior of recycled polypropylene/bamboo fiber composite materials during their service life time.
Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms
Authors: Ahmad Nisar , Mahmood Fazal , Khalil Shahid Akbar , Zamir Roshan , Fazal Hina , Abbasi Bilal Haider
Published: October 2012

Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs ( Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains ( Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains ( Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain ( Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi.
Run-to-run process control of magnetic abrasive finishing using bonded abrasive particles
Authors: Ahn Byung Woon , Lee Seoung Hwan
Published: October 2012

In this study, magnetic abrasive finishing, a polishing method using novel bonded magnetic abrasive particles, is implemented in the nanometer-scale surface polishing of STAVAX (S136) die steel workpieces, which are widely used for precision lens molds. With the aid of run-to-run control, a process control method, nanometer-scale mold surface quality is achieved and maintained over multiple runs. A specially designed magnetic quill equipped with an electromagnet was connected to a computer numerical control machining center to construct the polishing setup. Based on Preston’s equation and a set of preliminary experiments, design of experiment and analysis of variance were used to select and evaluate the relevant control parameters for the process. The finishing results show that the magnetic abrasive finishing has a nanometer-scale finishing capability (down to 8 nm surface roughness). Under run-to-run control with the selected parameters, the surface roughness values were successfully maintained below the target values (10 and 50 nm for Ra and Rmax, respectively), which shows that the proposed magnetic abrasive finishing scheme is readily adaptable to ultraprecision polishing applications, which are subject to disturbances for a relatively long period of time.
Distal humerus cortical strains following total elbow arthroplasty
Authors: Craik Johnathan D , Laffer Caroline HL , Richards Simon W , Walsh Sean P , Evans Sam L
Published: October 2012

The aseptic loosening of total elbow replacements is a serious complication resulting in significant patient morbidity. It is thought to occur secondary to stress shielding of the distal humeral cortex by the stiff stem of the implant. Some total elbow prostheses incorporate an anterior flange intended to improve implant stability and peri-articular load transfer in an attempt to reduce this effect. However, few studies have directly assessed the changes in cortical strains following total elbow arthroplasty or the biomechanical advantage of the anterior flange design. A regular and a long flange Coonrad–Morrey total elbow prosthesis were implanted into six Sawbone synthetic humeri. The constructs were subjected to physiological loads in axial compression (500 N), antero-posterior bending (50 N) and antero-posterior compression with condylar supports (300 N). Digital image correlation was used to measure the distal antero-lateral cortical strains and the results compared with those of whole Sawbones that had been tested in the same way. Significant stress shielding was demonstrated over the distal humeral cortex following prosthesis implantation during axial compression. In contrast, cortical strains increased following prosthesis implantation during antero-posterior compression with condylar supports. The increase in cortical strains following total elbow arthroplasty may help to maintain the integrity of the anterior cortex offering additional stability for implants with an anterior flange. These results are important for the development of future total elbow prosthesis designs and indicate that simulating the action of the forearm muscles is essential when evaluating changes in strain about the distal humerus in vitro.
Mid-Holocene drought and lake-level change at Elk Lake, Clearwater County, Minnesota: Evidence from CHIRP seismic-reflection data
Authors: Colman SM , Brown ET , Rush RA
Published: October 2012

Despite many studies of Holocene paleoclimate records from small lakes in the mid-continent of North America, direct estimates of lake-level changes associated with mid-Holocene aridity are rare. Varved sediments from Elk Lake, Clearwater County, Minnesota, are among the best studied in terms of paleoenvironmental proxies, yet the sedimentary architecture of those sediments has not been previously studied and the hydrological responses of the lake – changes in level and volume – are poorly known. High-resolution seismic-reflection (CHIRP) profiles of Elk Lake reveal complex sedimentary basins in the lake, a pattern of nearshore onlap of sediments onto older substrates, and the focusing of sediments into several deep basins. Biogenic gas obscures sediments in the deepest parts of the basins, but beneath the rest of the lake, a three-part Holocene sequence is clear. The transitions between these parts are correlated with lithological changes defined in earlier core studies. Sediments of the modern stage are less focused than those of the prairie lake stage. A prominent erosional unconformity occurs within the Holocene sequence, separating sediments from the prairie and modern stages of the lake. Erosion associated with this unconformity extends to a depth of 18.2 m below the modern water surface, at which point the unconformity grades into a conformable horizon within the sequence in the deep basins of the lake. This transition is an analog of the onlap of modern sediments onto older substrates, which occurs at a depth of about 8.2 m. The configuration of the erosional unconformity and its modern analog indicates a lake-level fall in the mid Holocene of 10.0 m. At its mid-Holocene minimum, the lake was 39% of its present size and 30% of its present volume, providing quantitative evidence to aid in constraining and evaluating reconstructions of mid-Holocene aridity in the mid-continent of North America.
Fingerprinting of poultry isolates of Enterococcus cecorum using three molecular typing methods
Authors: Wijetunge Dona Saumya , Dunn Patricia , Wallner-Pendleton Eva , Lintner Valerie , Lu Huaguang , Kariyawasam Subhashinie
Published: October 2012

Enterococcus cecorum is an emerging challenge to the broiler industry. The organism has been implicated in septicemia, spondylitis, arthritis, and osteomyelitis in commercial broilers and broiler breeders, which lead to economic losses attributed to increased mortality and culling rates, decreased average processing weights, and increased feed conversion ratios. The current study evaluated the genetic variability of 30 clinical isolates of E. cecorum from outbreaks in Pennsylvania, using 3 molecular typing methods, namely, pulsed-field gel electrophoresis (PFGE), randomly amplified polymorphic DNA analysis, and enterobacterial repetitive intergenic consensus–PCR (polymerase chain reaction), in order to understand their genetic relatedness and to identify possible pathogenic clones. The study revealed the existence of genotypic polymorphism among E. cecorum associated with clinical disease. Of the 3 typing methods used, PFGE analysis demonstrated higher genetic variability of E. cecorum isolates compared to PCR-based methods. Also, each molecular typing method was evaluated in terms of typeability, discriminatory power, and reproducibility for application of these typing methods in fingerprinting of E. cecorum in future reference. Pulsed-field gel electrophoresis provided the most reliable results with greater discriminatory power and higher reproducibility compared to the 2 PCR-based methods.