bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Metal Arc Welding (GMAW) Process Optimization of 2.0 mm Uncoated Boron Steel to 1.0 mm Usibor® 1500 P Steel Joint for Automotive Body Structural Applications
Authors: Koganti Ramakrishna , Elliott Adrian
Published: May 2012

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to heat affected zones (HAZ) at the weld joint. In this study, Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 2.0 mm uncoated boron steel and 1.0 mm Usibor® 1500 steel was investigated. The objective of the study was to understand the wire feed rate (WFR) and torch (or robot) travel speed (TTS) influence on lap joint tensile strength. Design of Experiments (DOE) methodology was used to understand the process parameter influence on the joint strength. Based on the statistical analysis, wire feed rate and torch travel speed were significant factors on static tensile strength. The interaction effect between wire feed rate and torch travel speed was not significant. Metallurgical properties of the lap joints were evaluated using optical microscopy. Significant drops in hardness at the HAZ were observed on both Usibor® 1500 P and boron steels.
A Structure Based Constitutive Model for Bat Wing Skins, A Soft Biological Tissue
Authors: Son Seyul , Wang Yanli , Goulbourne N. C.
Published: May 2012

Bat wing skin is a soft biological tissue that is used to enable flight (amongst other physiological roles) in bats such as the Glossophaga Soricina. To describe and predict wing behavior during flight, a high fidelity constitutive model validated by rigorous experimentation is required. Understanding the role that the tissue microstructure plays in achievable flight patterns and maneuverability will bring closer understanding of adaptations between species that yield specific flight behaviors and will also provide a template for developing synthetic skins for biomimicry in unmanned micro air vehicles. A structural continuum model that incorporates principal structural features of the wing skin can potentially provide a link between structure and functionality. Mesoscopic elastin fiber bundles on the order of hundreds of microns are the key constituents in the structure of bat wing. They are embedded in a base matrix composed by elastic ground substance and randomly oriented collagen fibers. The wing sweeps through very large deformations during flight and the fiber bundles undergo finite strains and large rotations presumed affine in the current treatment. To date, all the biological materials studied and modeled are comprised of stiff collagen fibers. The wing skin, on the other hand, is modeled as hyperelastic with distributed elastin fiber bundles with orientations belonging to two disparate families. Two families of fiber bundles have shown prominent difference in mechanical properties. More importantly, the bundle diameters vary dramatically with respect to bundle orientation even within each family. A mathematical treatment is formulated in this paper to capture the overall effect of distribution of diameters and distribution of orientations of fiber bundles based on the framework of Gasser et al [1]. This formulation is suitable in a general case when two fiber properties both vary spatially and they can be described using distribution functions such as Von Mises distribution.
Fabrication and Applications of Ordered Au Nanodisk and Nanohole Arrays
Authors: Gao Tieyu , Zheng Yue Bing , Juluri Bala Krishna , Huang Tony Jun
Published: May 2012

We have fabricate ordered Au nanodisk and nanohole arrays on glass substrates using nanosphere lithography (NSL) combined with reactive ion etching (RIE) techniques. The morphology and size distribution of the Au nanodisks and nanoholes were examined with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensitivity of the localized surface plasmon resonance (LSPR) of the Au nanodisk arrays to change in the surroundings’ refractive index was evaluated by integrating the Au nanodisk arrays into microfluidic channels. In addition, we show that the NSL-fabricated Au nanohole arrays can be applied as templates for patterning micro-/nano-particles under capillary force. The unique structural and optical characteristics of the Au nanodisk and nanohole arrays, as well as the low-cost and high-throughput of NSL-based nanofabrication technique, render these arrays excellent platforms for numerous engineering applications.
Nanoporous Polymeric Grating-Based Biosensors
Authors: Gao Tieyu , Hsiao Vincent , Zheng Yue Bing , Huang Tony Jun
Published: May 2012

We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays.
Simulation-Based Design of Orthopedic Trauma Implants
Authors: Arnone Joshua C. , Ward Carol V. , Della Rocca Gregory J. , Crist Brett D. , El-Gizawy A. Sherif
Published: May 2012

A computer-aided simulation model is developed to aid in the design and optimization of orthopaedic trauma implants. The developed model uses digital imaging, computer-aided solid modeling, and finite element methods in order to study the effects of various geometric parameters of fixation devices in orthopedic surgery practice. The results of the present simulation model would lead to the determination of the optimum implant design that provides the best match with the geometry of the human femur — reducing the risk of over-stressing bone tissue during implant insertion. The effectiveness of the presented simulation model is demonstrated through the design of intramedullary (IM) nails used in treating femoral shaft fractures. CT scans were taken of forty intact human femora. A technique was developed in order to digitally reconstruct the scans into 3D solid models using image segmentation, surface simplification, and smoothing methods while maintaining accurate representation of the original scans. Each resulting surface model is characterized by a network of nearly equilateral triangles of approximately the same size allowing for quality finite element meshing. Femoral lengths, curvature, shaft diameters, and location of maximum curvature were then quantified. An average geometric model was then generated for the investigated sample by averaging corresponding nodal coordinates in each femur model. Using the average model, a length-standardized function representing the curvature of the medullary canal was derived to create a geometrically optimized IM nail for the entire sample. “Virtual surgery” simulating the insertion process was then performed using finite element methods in order to validate the proposed optimal IM nail design. The results of both the optimum nail and a current nail were compared using the femur having the highest curvature in the sample. The present study shows that the developed simulation model leads to a nail design that reduces the insertion-induced stress within the femur to an acceptable level compared to current nails.
Comparative CFD Analysis of Maldistribution in a Shell and Tube Heat Exchanger With Conical and Cylindrical Headers
Authors: Paruchuri Rohitha , Ravigururajan T. S. , Muley Arun
Published: May 2012

The analysis of flow maldistribution in a shell and tube heat exchanger is presented. The flow field within the headers was obtained through numerical solution of conservation equations of mass and momentum in addition to the equations of the turbulence model. The flow maldistribution inside the header was a 3-D numerical simulation with the help of commercial software To increase the performance of the heat exchanger, flow maldistribution among the tubes should be minimized.. Flow maldistribution in the header affects the heat transfer performance. The effects of the pressure drop and velocity distribution in the headers were analyzed, as it effects the heat transfer performance. The study showed that by changing the header geometry, the maldistribution can be reduced leading to improved performance. Two types of headers were considered with varying header length and inlet flow velocities from 0.8373mm/sec to 2.344mm/sec are considered. The uniformity of flow distribution improved with increasing header length, whereas it decreased with increasing flow rate. As the header length increased to 1500mm the flow maldistribution decreased and the static pressure was almost equal for all the tubes in case of a conical header. The results show that conical header minimizes flow maldistribution compared to a cylindrical header.
An Adaptive Neuro-Fuzzy Controller for a Wind Turbine Operating in Region 3
Authors: Ayoubi Mohammad A. , Tai Li-Chou
Published: May 2012

An adaptive neuro-fuzzy controller for large and flexible wind turbines operating in high-speed winds is presented. The control objective is to regulate the rotor speed at the given rated power in region 3 (full load) via collective blade pitch angle. The modeled turbine is a three-bladed, upwind machine with flexible blade and tower. We use the particle swarm optimization (PSO) method in off-line training of our adaptive neuro-fuzzy controller. Numerical simulations are performed using wind inflow step change with the nonlinear wind turbine model. We compare the performance of the proposed controller with the baseline PI controller. Simulation results confirm successful performance of the proposed controller.
Project-Oriented Learning of Mechanical Engineering Design
Authors: Koutny´ Daniel , Palousˇek David , Brandejs Jan
Published: May 2012

The article explains a newly utilized project-oriented curriculum at the Institute of Machine and Industrial Design. In addition to digital technologies, the curriculum focuses on practical tasks with the utilization of advanced technologies in the area of mechanical design processes, such as Rapid Prototyping, Vacuum Casting etc. The paper describes a new approach to teamwork, where groups of students manage project tasks from the design phase up to the manufacturing of the real product.
Simulation and Measurement of the Self Heating and Thermal Stability of Polymers Under Fatigue Sollicitations
Authors: Pichon Pascal G. , Boutaous M’hamed , Me´chin Franc¸oise , Sautereau Henry
Published: May 2012

Polymer materials are widely used in structural applications. It is known that the mechanical work of plastic deformation transforms partly into heat, which can cause a noticeable temperature rise in the material. Hence it is very important to control their self heating and the rate of conversion during their sollicitations. This paper concerns the analysis of the deformation-induced self heating in a cylindrical specimen, made of a polymeric material under a fatigue test. A 3 D numerical model, based on Finite Elements Method, is built in order to compute the heat transfers in segmented polyurethane formulations, PP. We also develop experimental measurements, and assess the extent to which agreement with theoretical analyses has been attained. The viscoelastic behaviour of polyurethane formulations leads to a dissipation of the supplied mechanical work during a dynamic mechanical test. Part of this dissipated work is converted into heat and leads to a self-heating of the sample during the test, and to a decrease in the material modulus. Temperature distributions are then calculated in the specimen, and the existence and stability of steady-state distributions of temperature are analyzed. The results show a good agreement between the calculated and the measured temperatures, by adjusting only one parameter, leading to identify the ratio of the thermal to mechanical power conversion. The effects of the loading frequency on the steady-state solutions are discussed, and a quantification of the rate of energy conversion in both the two different material is analysed and discussed: For the PP formulation, part of the dissipated energy is assigned to structural modifications at the beginning of the test. At the end of the sollicitation, all the mechanical work is converted into heat. For the flexible material, the totality of energy is converted to heat source throughout the test. The conversion rate during tests at 10 Hz gives a good discrimination between the mechanical work dissipated in heat form and mechanical reorganizations. For the tests at 27 Hz, the conversion rates are approximately 50%, for various volumes and formulations of samples.
Modern Theories of Carbon-Based Electrochemical Capacitors: A Short Review
Authors: Meunier Vincent , Huang Jingsong , Feng Guang , Qiao Rui , Sumpter Bobby G.
Published: May 2012

Theoretical models for electrochemical capacitors range from the original Helmholtz model and mean-field continuum models, to the surface curvature-based post-Helmholtz models, and to modern atomistic simulations. Here, we review current theoretical models that have been useful at shedding light on experimental findings but also provide predictive capabilities that are needed to achieve the optimization of supercapacitors. Due to the non-planar surface of materials at the nanoscale, the original Helmholtz model is gradually found to be outdated, in particular for carbon materials. We show that the surface curvature-based models provide a better description of the interfacial behavior of carbon materials.
Deflection and Vibration Analysis of a Spherical Structure Using a Newly Designed Spherical Super Element
Authors: Ahmadian M. T. , Sarvi Masoud Nasiri , Nasiripour Amir Ashkan
Published: May 2012

The Finite Element Methods (FEM) are important numerical techniques for analysis of physical problems. Quick prediction of dynamic and static response of structures is one of the interests of both industry and scientists. One of the key elements to achieve this goal is 3D super element compatible with regular geometrical configuration by which a series of structures can be analyzed with less time and higher accuracy. In this paper, a newly designed spherical super element is presented. In this super element, the user can enjoy as many numbers of nodes as he wishes and consequently reaches the desired accuracy and consuming computational time. It can also be used to analyze structures from hollow sphere in solid structures to cell behavior in biological science. This super element is implemented for finding the deflection and natural frequencies of a hollow sphere and the results are nicely compatible with findings of the applied conventional elements.
Computational/Theoretical Modeling of Flow Physics and Transport in Disk Rotor Drag Turbine Expanders for Green Energy Conversion Technologies
Authors: Carey Van P.
Published: May 2012

This paper explores the theoretical and computational challenges associated with modeling of flow, momentum transport, and energy conversion processes in disk rotor drag turbine expanders. This category of expander devices, also known as Tesla turbines, has distinct advantages for Rankine power generation using low temperature heat from renewable source such as solar, waste heat, or geothermal steam or hot water. Specifically, the nozzle and rotor designs and the overall expander can be simple to manufacture, low cost, and durable, making this type of expander an attractive option in green energy technology applications where low maintenance costs and rapid capital investment payback are important qualities. Efficient energy conversion performance in rotor disk drag expanders requires that the nozzle efficiently convert flow exergy to fluid kinetic energy, and the rotor be designed to efficiently convert fluid angular momentum to shaft torque and power. To achieve these goals, modeling and analysis tools must provide the designer with a means to predict the performance of these components that accurately represents the physics, and can be effectively used to illuminate the parametric trends in performance. Two categories of modeling are examined in this paper: (1) computational fluid dynamics (CFD) modeling, and (2) more idealized one- and two-dimensional analysis frameworks. The advantages and disadvantages of these two approaches are examined here for the specific flows of interest in this type of expander design. The implications of model predictions for optimal design of disk rotor expanders for green energy applications are also discussed.
Temporal Dynamics of the Human Vaginal Microbiota
Authors: Gajer Pawel , Brotman Rebecca M. , Bai Guoyun , Sakamoto Joyce , Schütte Ursel M. E. , Zhong Xue , Koenig Sara S. K. , Fu Li , Ma Zhanshan (Sam) , Zhou Xia , Abdo Zaid , Forney Larry J. , Ravel Jacques
Published: May 2012

The vaginal microbiome is dynamic, varying over time in composition and function with implications for women’s health.
Learning from Hackers: Open-Source Clinical Trials
Authors: Dunn Adam G. , Day Richard O. , Mandl Kenneth D. , Coiera Enrico
Published: May 2012

The open-source software movement can serve as a model for a similar initiative in the clinical trial community.
Texting Can Be Healthy
Authors: Barnabas Ruanne V.
Published: May 2012

Text-message reminders can modestly increase influenza vaccine uptake among a low-income urban population.
Brain Tumor Diagnostics Go Micro
Authors: Bettegowda Chetan
Published: May 2012

MicroRNA levels in cerebrospinal fluid can be used as biomarkers to identify and track brain tumors.
Changing the Receptor Specificity of Anthrax Toxin
Authors: Mechaly Adva , McCluskey Andrew J. , Collier R. John
Published: May 2012

The actions of many bacterial toxins depend on their ability to bind to one or more cell-surface receptors. Anthrax toxin acts by a sequence of events that begins when the protective-antigen (PA) moiety of the toxin binds to either one of two cell-surface proteins, ANTXR1 and ANTXR2, and is proteolytically activated. The activated PA self-associates to form oligomeric pore precursors, which, in turn, bind the enzymatic moieties of the toxin and transport them to the cytosol. We introduced a double mutation into domain 4 of PA to ablate its native receptor-binding function and fused epidermal growth factor (EGF) to the C terminus of the mutated protein. The resulting fusion protein transported enzymatic effector proteins into a cell line that expressed the EGF receptor (A431 cells), but not into a line lacking this receptor (CHO-K1 cells). Addition of excess free EGF blocked transport of effector proteins into A431 cells via the fusion protein, but not via native PA. We also showed that fusing the diphtheria toxin receptor-binding domain to the C terminus of the mutated PA channeled effector-protein transport through the diphtheria toxin receptor. PA fusion proteins with altered receptor specificity may be useful in biological research and could have practical applications, including ablation or perturbation of selected populations of cells
in vivo
.

IMPORTANCE
Bacterial toxins that act within mammalian cells have receptor-dependent mechanisms to transport their enzymatic components to the cytoplasmic compartment. By inactivating or otherwise modifying their respective intracellular targets, these intracellular effectors disrupt metabolic pathways and in some cases cause death of the cell. Our results show that the receptor specificity of the transport protein of anthrax toxin may be readily changed, raising the possibility that receptor-redirected forms of protective antigen (PA) and PA homologs may be useful for research and medical applications requiring modification or ablation of designated populations of cells.
The impact of early identification of permanent childhood hearing impairment on speech and language outcomes
Authors: Pimperton Hannah , Kennedy Colin R
Published: May 2012

It is well established that permanent childhood hearing impairment (PCHI) has a detrimental impact on speech and language development. The past two decades have seen the gradual introduction of universal newborn hearing screening (UNHS) programmes coupled with early intervention programmes. We review studies that have capitalised on the advent of newborn hearing screening to assess the impact of early identification of PCHI on language outcomes in deaf children. The research supports the conclusion that, in children with PCHI, newborn hearing screening and early identification lead to beneficial effects on language development, with the most consistent evidence provided for links between early identification of PCHI and positive language outcomes. Future research needs to encompass a wider range of outcomes and to assess the impact of UNHS in adolescents and young adults.
Genistein ameliorates hyperglycemia in a mouse model of nongenetic type 2 diabetes
Authors: Fu Zhuo , Gilbert Elizabeth R. , Pfeiffer Liliane , Zhang Yanling , Fu Yu , Liu Dongmin
Published: May 2012

While peripheral insulin resistance is common during obesity and aging in mice and people, the progression to type 2 diabetes (T2D) is largely due to loss of β-cell mass and function through apoptosis. We recently reported that genistein, a soy derived isoflavone, can improve glycemic control and β-cell function in insulin-deficient diabetic mice. However, whether it can prevent β-cell loss and diabetes in T2D mice is unknown. Our current study aimed to investigate the effect of dietary supplemented genistein in a nongenetic T2D mouse model. Nongenetic, middle-aged obese diabetic mice were generated by high fat diet and a low dose of streptozotocin injection. The effect of dietary supplementation of genistein on glycemic control and β-cell mass and function was determined. Dietary intake of genistein (250 mg·kg–1 diet) improved hyperglycemia, glucose tolerance, and blood insulin level in obese diabetic mice, whereas it did not affect body weight gain, food intake, fat deposit, plasma lipid profile, and peripheral insulin sensitivity. Genistein increased the number of insulin-positive β-cell in islets, promoted islet β-cell survival, and preserved islet mass. In conclusion, dietary intake of genistein could prevent T2D via a direct protective action on β-cells without alteration of periphery insulin sensitivity.
Effects of resistance or aerobic exercise training on total and regional body composition in sedentary overweight middle-aged adults
Authors: Donges Cheyne E. , Duffield Rob
Published: May 2012

The purpose of this study was to examine the effects of 10 weeks of aerobic endurance training (AET), resistance exercise training (RET), or a control (CON) condition on absolute and relative fat mass (FM) or fat-free mass (FFM) in the total body (TB) and regions of interest (ROIs) of sedentary overweight middle-aged males and females. Following prescreening, 102 subjects underwent anthropometric measurements, dual-energy X-ray absorptiometry, and strength and aerobic exercise testing. Randomized subjects (male RET, n = 16; female RET, n = 19; male AET, n = 16; and female AET, n = 25) completed supervised and periodized exercise programs (AET, 30–50 min cycling at 70%–75% maximal heart rate; RET, 2–4 sets × 8–10 repetitions of 5–7 exercises at 70%–75% 1 repetition maximum) or a nonexercising control condition (male CON, n = 13 and female CON, n = 13). Changes in absolute and relative TB-FM and TB-FFM and ROI-FM and ROI-FFM were determined. At baseline, and although matched for age and body mass index, males had greater strength, aerobic fitness, body mass, absolute and relative TB-FFM and ROI-FFM, but reduced absolute and relative TB-FM and ROI-FM, compared with females (p < 0.05). After training, both female exercise groups showed equivalent or greater relative improvements in strength and aerobic fitness than did the male exercise groups (p < 0.05); however, the male exercise groups increased TB-FFM and reduced TB-FM more than did the female exercise groups (p < 0.05). Male AET altered absolute FM more than male RET altered absolute FFM, thus resulting in a greater enhancement of relative FFM. Despite equivalent or greater responses to RET or AET by female subjects, the corresponding respective increases in FFM or reductions in FM were lower than those in males, indicating that a biased dose–response relationship exists between sexes following 10 weeks of exercise training.
The effects of high-intensity resistance exercise on the blood lipid profile and liver function in hypercholesterolemic hamsters
Authors: Frajacomo Fernando Tadeu Trevisan , Demarzo Marcelo Marcos Piva , Fernandes Cleverson Rodrigues , Martinello Flávia , Bachur José Alexandre , Uyemura Sérgio Akira , Perez Sérgio Eduardo de Andrade , Garcia Sérgio Britto
Published: May 2012

It is well established that atherogenic dyslipidemia, characterized by high levels of triglycerides (TG), total cholesterol (TC), and low-density lipoprotein (LDL) cholesterol and low levels of high-density lipoprotein (HDL) cholesterol, constitutes important risk factors for cardiovascular disease. Regular exercise has been associated with a reduced risk for metabolic diseases. However, studies supporting the concept that resistance exercise is a modifier of blood lipid parameters are often contradictory. The aim of this study was to investigate the effects of high-intensity resistance exercise on the serum levels of TG, TC, HDL and non-HDL cholesterol, glucose, and the liver function enzymes alanine aminotransferase (ALT, EC 2.6.1.2) and aspartate aminotransferase (AST, EC 2.6.1.1) in golden Syrian hamsters (Mesocricetus auratus (Waterhouse, 1839)) fed a hypercholesterolemic diet. Sedentary groups (S) and exercise groups (E) were fed a standard diet (SS and ES) or a cholesterol-enriched diet (standard plus 1% cholesterol, SC and EC). Resistance exercise was performed by jumps in the water, carrying a load strapped to the chest, representing 10 maximum repetitions (10 RM, 30 s rest, five days per week for five weeks). Mean blood sample comparisons were made by ANOVA + Tukey or ANOVA + Kruskal–Wallis tests (p < 0.05) to compare parametric and nonparametric samples, respectively. There were no differences in blood lipids between the standard diet groups (SS and ES) (p > 0.05). However, the EC group increased the glucose, non-HDL, and TC levels in comparison with the ES group. Moreover, the EC group increased the TG levels versus the SC group (p < 0.05). In addition, the ALT levels were increased only by diet treatment. These findings indicated that high-intensity resistance exercise contributed to dyslipidemia in hamsters fed a hypercholesterolemic diet, whereas liver function enzymes did not differ in regards to the exercise protocol.
mTORC1 and the regulation of skeletal muscle anabolism and mass
Authors: Adegoke Olasunkanmi A.J. , Abdullahi Abdikarim , Tavajohi-Fini Pegah
Published: May 2012

The mass and integrity of skeletal muscle is vital to whole-body substrate metabolism and health. Indeed, defects in muscle metabolism and functions underlie or exacerbate diseases like diabetes, rheumatoid arthritis, and cancer. Physical activity and nutrition are the 2 most important environmental factors that can affect muscle health. At the molecular level, the mammalian target of rapamycin complex 1 (mTORC1) is a critical signalling complex that regulates muscle mass. In response to nutrition and resistance exercise, increased muscle mass and activation of mTORC1 occur in parallel. In this review, we summarize recent findings on mTORC1 and its regulation in skeletal muscle in response to resistance exercise, alone or in combination with intake of protein or amino acids. Because increased activity of the complex is implicated in the development of muscle insulin resistance, obesity, and some cancers (e.g., ovarian, breast), drugs that target mTORC1 are being developed or are in clinical trials. However, various cancers are associated with extensive muscle wasting, due in part to tumour burden and malnutrition. This muscle wasting may also be a side effect of anticancer drugs. Because loss of muscle mass is associated not only with metabolic abnormalities but also dose limiting toxicity, we review the possible implications for skeletal muscle of long-term inhibition of mTORC1, especially in muscle wasting conditions.
Cardiovascular drift and cerebral and muscle tissue oxygenation during prolonged cycling at different pedalling cadences
Authors: Kounalakis Stylianos N. , Geladas Nickos D.
Published: May 2012

We hypothesized that a faster cycling cadence could exaggerate cardiovascular drift and affect muscle and cerebral blood volume and oxygenation. Twelve healthy males (mean age, 23.4 ± 3.8 years) performed cycle ergometry for 90 min on 2 separate occasions, with pedalling frequencies of 40 and 80 r·min–1, at individual workloads corresponding to 60% of their peak oxygen consumption. The main measured variables were heart rate, ventilation, cardiac output, electromyographic activity of the vastus lateralis, and regional muscle and cerebral blood volume and oxygenation. Cardiovascular drift developed at both cadences, but it was more pronounced at the faster than at the slower cadence, as indicated by the drop in cardiac output by 1.0 ± 0.2 L·min–1, the decline in stroke volume by 9 ± 3 mL·beat–1, and the increase in heart rate by 9 ± 1 beats·min–1 at 80 r·min–1. At the faster cadence, minute ventilation was higher by 5.0 ± 0.5 L·min–1, and end-tidal CO2 pressure was lower by 2.0 ± 0.1 torr. Although higher electromyographic activity in the vastus lateralis was recorded at 80 r·min–1, muscle blood volume did not increase at this cadence, as it did at 40 r·min–1. In addition, muscle oxygenation was no different between cadences. In contrast, cerebral regional blood volume and oxygenation at 80 r·min–1 were not as high as at 40 r·min–1 (p < 0.05). Faster cycling cadence exaggerates cardiovascular drift and seems to influence muscle and cerebral blood volume and cerebral oxygenation, without muscle oxygenation being radically affected.
Composite versus single transportable carbohydrate solution enhances race and laboratory cycling performance
Authors: Rowlands David S. , Swift Marilla , Ros Marjolein , Green Jackson G.
Published: May 2012

When ingested at high rates (1.8–2.4 g·min–1) in concentrated solutions, carbohydrates absorbed by multiple (e.g., fructose and glucose) vs. single intestinal transporters can increase exogenous carbohydrate oxidation and endurance performance, but their effect when ingested at lower, more realistic, rates during intermittent high-intensity endurance competition and trials is unknown. Trained cyclists participated in two independent randomized crossover investigations comprising mountain-bike races (average 141 min; n = 10) and laboratory trials (94-min high-intensity intervals followed by 10 maximal sprints; n = 16). Solutions ingested during exercise contained electrolytes and fructose + maltodextrin or glucose + maltodextrin in 1:2 ratio ingested, on average, at 1.2 g carbohydrate·kg–1·h–1. Exertion, muscle fatigue, and gastrointestinal discomfort were recorded. Data were analysed using mixed models with gastrointestinal discomfort as a mechanism covariate; inferences were made against substantiveness thresholds (1.2% for performance) and standardized difference. The fructose–maltodextrin solution substantially reduced race time (–1.8%; 90% confidence interval = ±1.8%) and abdominal cramps (–8.1 on a 0–100 scale; ±6.6). After accounting for gastrointestinal discomfort, the effect of the fructose–maltodextrin solution on lap time was reduced (–1.1%; ±2.4%), suggesting that gastrointestinal discomfort explained part of the effect of fructose–maltodextrin on performance. In the laboratory, mean sprint power was enhanced (1.4%; ±0.8%) with fructose–maltodextrin, but the effect on peak power was unclear (0.7%; ±1.5%). Adjusting out gastrointestinal discomfort augmented the fructose–maltodextrin effect on mean (2.6%; ±1.9%) and peak (2.5%; ±3.0%) power. Ingestion of multiple transportable vs. single transportable carbohydrates enhanced mountain-bike race and high-intensity laboratory cycling performance, with inconsistent but not irreconcilable effects of gut discomfort as a possible mediating mechanism.
Should postactivation potentiation be the goal of your warm-up?
Authors: MacIntosh Brian R. , Robillard Marie-Eve , Tomaras Elias K.
Published: May 2012

Athletes expect improved high-intensity performance following warm-up, and postactivation potentiation (PAP) is assumed to contribute to this improvement. However, the scientific evidence supporting this assumption is incomplete. PAP is known to result from prior muscle activation, and should enhance maximal effort contractions of very short duration. However, PAP dissipates over 4–6 min after the PAP-inducing contraction, so PAP should not contribute to enhanced performance more than 5 min after the warm-up.
Beneficial effects of cod protein on skeletal muscle repair following injury
Authors: Dort Junio , Sirois Amélie , Leblanc Nadine , Côté Claude H. , Jacques Hélène
Published: May 2012

This study examined the effect of peanut and cod proteins on post-damage skeletal muscle repair, compared with casein. We hypothesized that because of their high arginine content, these proteins would improve the resolution of inflammation and muscle mass recovery following injury. One hundred and twenty-eight male Wistar rats were assigned to isoenergetic diets composed of casein and peanut (experiment 1) or cod protein (experiment 2). After 21 days of feeding, one tibialis anterior muscle (TA) was injured with bupivacaine, while the contralateral TA was injected with saline (sham muscle). Measurements were taken at days 0, 3, 14, and 24 post-injury. Compared with casein, peanut protein reduced muscle mass at days 0 (–12%, p = 0.005) and 14 post-injury in the injured muscle (–13%, p = 0.04), and lowered myofiber cross-sectional area in both the sham (–21%, p = 0.008) and injured muscles (–26%, p = 0.05) at day 24 post-injury, showing that peanut protein has a weak potential to support muscle growth. At day 14 post-injury, muscle mass in the sham (13%, p = 0.02) and injured muscles (12%, p = 0.01) was higher in cod-protein-fed rats, indicating better muscle mass recovery, than in casein-fed rats. Cod protein tended (p = 0.06) to decrease the density of neutrophils (–24%) at day 14 post-injury in the injured muscle, and to decrease the density of ED1+macrophages at day 24 post-injury in both sham (–29%, p = 0.03) and injured (–40%, p = 0.01) muscles. No effects were observed for peanut protein. These data indicate that cod protein is better for promoting growth and regeneration of skeletal muscle after trauma, partly because of the improved resolution of inflammation.
Bigger weights may not beget bigger muscles: evidence from acute muscle protein synthetic responses after resistance exercise
Authors: Burd Nicholas A. , Mitchell Cameron J. , Churchward-Venne Tyler A. , Phillips Stuart M.
Published: May 2012

It is often recommended that heavier training intensities (∼70%–80% of maximal strength) be lifted to maximize muscle growth. However, we have reported that intensities as low as 30% of maximum strength, when lifted to volitional fatigue, are equally effective at stimulating muscle protein synthesis rates during resistance exercise recovery. This paper discusses the idea that high-intensity contractions are not the exclusive driver of resistance exercise-induced changes in muscle protein synthesis rates.
Moderate-intensity, premeal cycling blunts postprandial increases in monocyte cell surface CD18 and CD11a and endothelial microparticles following a high-fat meal in young adults
Authors: Strohacker Kelley , Breslin Whitney L. , Carpenter Katie C. , Davidson Tiffany R. , Agha Nadia H. , McFarlin Brian K.
Published: May 2012

High-fat meals promote transient increases in proatherogenic factors, implicating the postprandial state in cardiovascular disease (CVD) progression. Although low-grade inflammation is associated with CVD, little research has assessed postprandial inflammation. Because of its anti-inflammatory properties, premeal exercise may counteract postprandial inflammation. The purpose of this study was to determine postprandial alterations in monocytes and circulating markers of endothelial stress and inflammation following a high-fat meal in young adults with or without premeal cycle exercise. Each subject completed two trials and was randomized to rest or cycle at a moderate intensity prior to eating a high-fat meal. Flow cytometry was used to assess monocyte cell surface receptor expression and concentration of endothelial microparticles (EMP). Plasma cytokines were assessed using Luminex MagPix. Statistical analysis was completed using separate linear mixed models analyses with first-order autoregressive (AR(1)) heterogeneous covariance structure. Significance was set at P ≤ 0.05. Percentage increases in classic monocyte CD11a and CD18 were greater overall in the postprandial period in the meal-only condition compared with the meal + exercise condition (P < 0.05). EMP concentration was 47% greater 3 h after the meal compared with premeal values in the meal-only condition (P < 0.05); no significant increase was observed in the meal + exercise condition. Premeal cycling blunted postprandial increases in EMP and CD11a and CD18. Acute, moderate-intensity exercise may help counteract possibly deleterious postprandial monocyte and endothelial cell activation.
Overweight and obese boys reduce food intake in response to a glucose drink but fail to increase intake in response to exercise of short duration
Authors: Tamam Shlomi , Bellissimo Nick , Patel Barkha P. , Thomas Scott G. , Anderson G. Harvey
Published: May 2012

The effect of short duration exercise (EXR) on food intake (FI) and energy balance (EB) is not well understood in either normal weight (NW) or overweight (OW) and obese (OB) 9–14 years old children. Our purpose was to describe the effects of activity and a glucose drink on short term FI, appetite, and EB in NW, OW, and OB boys. Each boy received in random order either a noncaloric Sucralose sweetened control or glucose (1.0 g·kg–1 body weight) drink 5 min after either exercise (EXR) or sedentary (SED) activity. Boys exercised for 15 min at their ventilation threshold (VT) in experiment 1 or at 25% above their VT in experiment 2. FI was measured at an ad libitum pizza meal 30 min after drink consumption. FI was lower after the glucose drink (p < 0.001) but not affected by activity, even though EXR increased appetite (p < 0.001). OW/OB boys ate more total food than NW boys (p = 0.020). EB over the duration of the experiments was reduced by EXR in OW/OB boys (p = 0.013) but not in NW boys in either experiment (p > 0.05). We conclude that intake regulation in OW/OB boys in response to a glucose drink is similar to NW boys, but it may be less responsive to activity.
Ring-opening polymerization of rac-lactide and ε-caprolactone using zinc and calcium salicylaldiminato complexes
Authors: Gallaway Joshua B. L. , McRae Justin R. K. , Decken Andreas , Shaver Michael P.
Published: May 2012

Tridentate Schiff base complexes of zinc and calcium were prepared and tested in the ring-opening polymerization of ε-caprolactone and rac-lactide to generate biodegradable polymeric materials from biocompatible metals. Alteration of the pendant donor arm attached to the imine backbone provides some control over catalyst composition and polymerization activity. Complexes of the formula [ONN]ZnN(SiMe3)2, where [ONN] = 2-(N-donor arm-imine)[4,6-di(tert-butyl)phenoxide], were isolated with ethyldimethylamine, ethylpiperidine, and ethylmorpholine substituents, while disproportionation led to the isolation of [ONN]2Zn complexes with methylpyridine, quinoline, and ethyldiisopropylamine derivatives, two of which were crystallographically characterized. Calcium complexes were more stable and novel [ONN]CaN(SiMe3)2 complexes with ethylpiperidine and ethyldiisopropylamine substituents were reported. Zinc and calcium catalysts coordinated to a single tridentate ligand were effective at initiating the polymerization of ε-caprolactone, but did not control the polymerizations, whereas the bis(ligand) complexes produced no polymer. These catalysts were effective at controlling the polymerization of rac-lactide. Coordinatively saturated complexes inhibit the polymerization, while initiation from either the amido or ligand alkoxide functionalities produces poly(lactic acid) with low polydispersities.
Synthesis and demethylation of 4,22-dimethoxy[2.10]metacyclophan-1-yne with BBr3 to afford a novel [10](2,9)-5a,11a-benzofuro-5a-bora-11-bromochromenophane
Authors: Uchikawa Yuki , Tazoe Kazuya , Tanaka Syogo , Feng Xing , Matsumoto Taisuke , Tanaka Junji , Yamato Takehiko
Published: May 2012

4,22-Dimethoxy[2.10]metacyclophan-1-yne was prepared by bromination of [2.10]metacyclophan-1-ene followed by the dehydrobromination of the bromine adduct with KOBu-t. Treatment of 4,22-dimethoxy[2.10]metacyclophan-1-yne with BBr3 in CH2Cl2 at room temperature led to the demethylation and a successive intramolecular cyclization reaction to afford a novel [10](2,9)-5a,11a-benzofuro-5a-bora-11-bromochromenophane in good yield. Similar treatment of a mixture of the corresponding meso- and dl-1,2-dibromo-4,22-dimethoxy[2.10]metacyclophane with BBr3 in CH2Cl2 under the same conditions described above afforded cis-4b,9b-dihydro[10]benzofuro[3,2-b]benzofuranophane in 83% yield.
Synthesis of β- and β,β-substituted Morita–Baylis–Hillman adducts using a two-step protocol
Authors: Magee David I. , Ratshonka Same , McConaghy Jessica , Hood Maggie
Published: May 2012

The synthesis of a large number of β- and β,β-substituted keto esters was successful by the use of the Knoevenagel condensation reaction. The stereoselectivity of these reactions was improved by alteration of various substituent groups. Although there were few examples of complete Z selectivity, the use of tert-butyl acetoacetate with either aromatic or aliphatic aldehydes afforded Z selectivity. The selective reductions of these substituted keto esters was successfully achieved by using a combination of NaBH4 and CeCl3·7H2O or Yb(OTf)3, which allowed a facile synthesis of a large number of stereochemically pure substituted Morita–Baylis–Hillman adducts, including β,β-substituted adducts.
Denaturing gradient gel electrophoresis for nonlethal detection of Aeromonas salmonicida in salmonid mucus and its potential for other bacterial fish pathogens
Authors: Quinn Robert A. , Stevenson Roselynn M.W.
Published: May 2012

Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA was used to nonlethally detect Aeromonas salmonicida and other bacteria in salmonid skin mucus. Mucus samples from wild spawning coho salmon ( Oncorhynchus kisutch ) with endemic A. salmonicida and from cultured lake trout ( Salvelinus namaycush ) were tested by PCR–DGGE and were compared with mucus culture on Coomassie brilliant blue agar and internal organ culture. PCR–DGGE gave a highly reproducible 4-band pattern for 9 strains of typical A. salmonicida, which was different from other Aeromonas spp. Aeromonas salmonicida presence in mucus was evident as a band that comigrated with the bottom band of the A. salmonicida 4-band pattern and was verified by sequencing. PCR–DGGE found 36 of 52 coho salmon positive for A. salmonicida, compared with 31 positive by mucus culture and 16 by organ culture. Numerous other bacteria were detected in salmonid mucus, including Pseudomonas spp., Shewanella putrefaciens , Aeromonas hydrophila and other aeromonads. However, Yersinia ruckeri was not detected in mucus from 27 lake trout, but 1 fish had a sorbitol-positive Y. ruckeri isolated from organ culture. Yersinia ruckeri seeded into a mucus sample suggested that PCR–DGGE detection of this bacterium from mucus was possible. PCR–DGGE allows nonlethal detection of A. salmonicida in mucus and differentiation of some Aeromonas spp. and has the potential to allow simultaneous detection of other pathogens present in fish mucus.
Chromosomal bacterial type II toxin–antitoxin systems
Authors: Syed Mohammad Adnan , Lévesque Céline M.
Published: May 2012

Most prokaryotic chromosomes contain a number of toxin–antitoxin (TA) modules consisting of a pair of genes that encode 2 components, a stable toxin and its cognate labile antitoxin. TA systems are also known as addiction modules, since the cells become “addicted” to the short-lived antitoxin product (the unstable antitoxin is degraded faster than the more stable toxin) because its de novo synthesis is essential for their survival. While toxins are always proteins, antitoxins are either RNAs (type I, type III) or proteins (type II). Type II TA systems are widely distributed throughout the chromosomes of almost all free-living bacteria and archaea. The vast majority of type II toxins are mRNA-specific endonucleases arresting cell growth through the mechanism of RNA cleavage, thus preventing the translation process. The physiological role of chromosomal type II TA systems still remains the subject of debate. This review describes the currently known type II toxins and their characteristics. The different hypotheses that have been proposed to explain their role in bacterial physiology are also discussed.
Nitrogen source and growth stage of Candida albicans influence expression level of vacuolar aspartic protease Apr1p and carboxypeptidase Cpy1p
Authors: Bauerová Václava , Pichová Iva , Hrušková-Heidingsfeldová Olga
Published: May 2012

Vacuoles play an important role in the physiology of pathogenic Candida spp. However, information on Candida albicans vacuolar enzymes, their properties, and regulation is scarce. Expression of the genes APR1 and CPY1 encoding vacuolar aspartic protease and serine carboxypeptidase, respectively, was analyzed using a clinical isolate of C. albicans. The transcription of both APR1 and CPY1 was upregulated in midexponential phase, together with increasing size of the vacuoles, when C. albicans was cultivated in yeast extract–peptone–dextrose agar at 30 °C. However, simultaneous upregulation of protein synthesis occurred only for Cpy1p. Analysis of APR1 and CPY1 expression under nitrogen-limited conditions revealed that the genes were regulated on both the transcriptional and translational levels and detectable amounts of Apr1p were synthesized only when C. albicans was grown in nitrogen-limited media.
Abundance and composition dynamics of soil ammonia-oxidizing archaea in an alpine fir forest on the eastern Tibetan Plateau of China
Authors: Wang Ao , Wu Fu-Zhong , Yang Wan-Qin , Wu Zhi-Chao , Wang Xu-Xi , Tan Bo
Published: May 2012

Real-time qPCR and clone library sequencing targeting amoA genes were used to investigate the seasonal dynamics of an ammonia-oxidizing archaea (AOA) community in an alpine fir forest in western China. AOA were detected at all sampling dates, and there were significant variations in archaeal amoA gene copy numbers (7.63 × 105to 8.35 × 108per gram of dry soil) throughout the nongrowing season. Compared with ammonia-oxidizing bacteria (AOB), the AOA displayed a higher abundance on the majority of sampling dates during the freeze–thaw period. All of the AOA sequences fell within soil and sediment lineages and were affiliated with 7 clusters. Compared with the other clusters, cluster 1 was more sensitive to low temperature and was the dominant group in August. In contrast, cluster 3 dominated the AOA community in winter and probably represents a group of cold-adapted archaea. Redundancy analysis (RDA) revealed that the seasonality of the AOA community was mainly attributed to changes in soil temperature and nutrient availability (e.g., dissolved organic nitrogen and carbon). Our results indicate that AOA exist in frozen soils in the alpine coniferous forest ecosystem of the eastern Tibetan Plateau. Moreover, soil temperature may directly and (or) indirectly affect AOA abundance and composition and may further influence the soil N cycle during the winter.