bluuebunny/crossref_metadata_2025 huggingface dataset:
Adult granulosa cell tumour‐like areas occurring in ovarian epithelial neoplasms: report of a case series with investigation of FOXL2 mutation status
Authors: Singh Naveena , Gilks C Blake , Huntsman David G , Smith John H , Coutts Michael , Ganesan Raji , McCluggage W Glenn
Published: October 2013

Aims

To look for FOXL2 mutation in rare ovarian epithelial lesions showing stromal components with morphological features of adult granulosa cell tumour (AGCT).

Methods and results

We report the 402C→G FOXL2 mutation status in five epithelial ovarian lesions in women aged 45–77 years showing stromal proliferations that were morphologically indistinguishable from AGCT. The lesions were mucinous cystadenoma, mixed epithelial cystadenoma, endometriotic cyst, mucinous borderline tumour (intestinal type), and mucinous carcinoma. In one case, the AGCT component formed a discrete nodule, and in the others it was distributed within the septa and cyst walls. FOXL2 mutation was present in two cases and absent in three cases. One mutation‐positive case showed an AGCT nodule abutting a mucinous borderline tumour, interpreted as a collision tumour. The other positive case had an AGCT component within the septa of a mucinous carcinoma, and both components are likely to be neoplastic. In the three cases without FOXL2 mutation, the stromal component most likely represents a non‐neoplastic AGCT‐like proliferation.

Conclusions

Areas typical of AGCT are rarely associated with epithelial ovarian lesions. These are heterogeneous and likely to be truly neoplastic in only a subset of cases. FOXL2 mutation testing may be useful in confirming a true neoplastic AGCT component.
Microencapsulation of peppermint oil in an alginate–pectin matrix using a coaxial electrospray system
Authors: Koo Song Yi , Cha Kwang Hyun , Song Dae‐Geun , Chung Donghwa , Pan Cheol‐Ho
Published: October 2013

This study investigated the microencapsulation of peppermint oil in alginate (A)–pectin (P) matrix using an electrospray system where the microcapsules were characterised by determining their compositions and properties. The minimum size (1.58 μm) was obtained with A80P20, while the maximum (3.24 μm) was obtained with A0P100. The zeta potential ranged from −53.1 to −21.7 mV with all combinations. The polydispersity index (PDI) tended to increase with the pectin content. There was a gradual increase in microparticles in terms of the loss modulus (G′) and the storage modulus (G″) with increasing frequency. The δ value (loss tangent) increased with the pectin content, indicating more unstable. The encapsulation efficiency increased relative to the alginate content. The maximum encapsulation efficiency (85.15%) was obtained with A80P20. This study showed that an electrospray system can be used to make an alginate–pectin microcapsule containing peppermint oil, which has an adequate composition in terms of rheological properties and encapsulation efficiency.
Heterogeneous base catalytic transesterification synthesis of sucrose ester and parallel reaction control
Authors: Zhao Rongrong , Chang Zhidong , Jin Qiong , Li Wenjun , Dong Bin , Miao Xiaowen
Published: October 2013

The equilibrium solubility of sucrose in methyl stearate, methyl oleate and methyl laurate with or without the addition of surfactants was investigated. The side reactions, pyrolysis of the sucrose, glucose and fructose, are also discussed through studying their data of differential thermal analysis and thermal gravimetric analysis. Results show that the solubilities of sucrose in methyl esters of fatty acids range from 0.01 g/100 g to 0.21 g/100 g in a surfactant‐free system with the temperature range of 40–140 °C. The addition of surfactants increased the sucrose solubility in the fatty acid esters. Under the strict anhydrous conditions, the soap concentration can be controlled at a very low level. With the increase in the temperature, sucrose began to decrease in weight at 225 ± 5 °C, glucose began to decrease in weight at 85 ± 5 °C, and fructose began to decrease in weight at 170 ± 5 °C.
Involvement of a membrane potassium channel in heparan sulphate‐induced activation of macrophages
Authors: Ren Jian‐Dong , Fan Li , Tian Fu‐Zhou , Fan Kai‐Hua , Yu Bo‐Tao , Jin Wei‐Hua , Tan Yong‐Hong , Cheng Long
Published: October 2013

Increasing evidence has demonstrated that Toll‐like receptor 4 (TLR4) ‐mediated systemic inflammatory response syndrome accompanied by multiple organ failure, is one of the most common causes of death in patients with severe acute pancreatitis. Recent reports have revealed that heparan sulphate (HS) proteoglycan, a component of extracellular matrices, potentiates the activation of intracellular pro‐inflammatory responses via TLR4, contributing to the aggravation of acute pancreatitis. However, little is known about the participants in the HS/TLR4‐mediated inflammatory cascades. Our previous work provided a clue that a membrane potassium channel (MaxiK) is responsible for HS‐induced production of inflammatory cytokines. Therefore, in this report we attempted to reveal the roles of MaxiK in the activation of macrophages stimulated by HS. Our results showed that incubation of RAW264.7 cells with HS up‐regulated MaxiK and TLR4 expression levels. HS could also activate MaxiK channels to promote the efflux of potassium ions from cells, as measured by the elevated activity of caspase‐1, whereas this was significantly abolished by treatment with paxilline, a specific blocker of the MaxiK channel. Moreover, it was found that paxilline substantially inhibited HS‐induced activation of several different transcription factors in macrophages, including nuclear factor‐κB, p38 and interferon regulatory factor‐3, followed by decreased production of tumour necrosis factor‐α and interferon‐β. Taken together, our investigation provides evidence that the HS/TLR4‐mediated intracellular inflammatory cascade depends on the activation of MaxiK, which may offer an important opportunity for a new approach in therapeutic strategies of severe acute pancreatitis.
Letting Go is Never Easy: Abscission and Receptor‐Like Protein Kinases
Authors: Niederhuth Chad E. , Cho Sung Ki , Seitz Kati , Walker John C.
Published: October 2013

Abscission is the process by which plants discard organs in response to environmental cues/stressors, or as part of their normal development. Abscission has been studied throughout the history of the plant sciences and in numerous species. Although long studied at the anatomical and physiological levels, abscission has only been elucidated at the molecular and genetic levels within the last two decades, primarily with the use of the model plant Arabidopsis thaliana. This has led to the discovery of numerous genes involved at all steps of abscission, including key pathways involving receptor‐like protein kinases (RLKs). This review covers the current knowledge of abscission research, highlighting the role of RLKs.

image

John C. Walker

(Corresponding author)
Conventional digital cameras as a tool for assessing leaf area index and biomass for cereal breeding
Authors: Casadesús Jaume , Villegas Dolors
Published: October 2013

Affordable and easy‐to‐use methods for assessing biomass and leaf area index (LAI) would be of interest in most breeding programs. Here, we describe the evaluation of a protocol for photographic sampling and image analysis aimed at providing low‐labor yet robust indicators of biomass and LAI. In this trial, two genotypes of triticale, two of bread wheat, and four of tritordeum were studied. At six dates during the growing cycle, biomass and LAI were measured destructively, and digital photography was taken on the same dates. Several vegetation indices were calculated from each image. The results showed that repeatable and consistent values of the indices were obtained in consecutive photographic samplings on the same plots. The photographic indices were highly correlated with the destructive measurements, though the magnitude of the correlation was lower after anthesis. This work shows that photographic assessment of biomass and LAI can be fast, affordable, have good repeatability, and can be used under bright and overcast skies. A practical vegetation index derived from pictures is the fraction of green pixels over the total pixels of the image, and as it shows good correlations with all biomass variables, is the most robust to lighting conditions and has easy interpretation.
Removable Dental Prosthesis Splint. An Occlusal Device for Nocturnal Bruxing Partial Denture Users
Authors: Zoidis Panagiotis , Polyzois Gregory
Published: October 2013

Nocturnal bruxing is a parafunctional activity of the masticatory system that may create problems for removable dental prosthesis (RDP) users. Such problems may include root fractures, increased mobility of abutment teeth, excessive wear of resin denture teeth, minor connector bending, or denture base cracking. This clinical report presents an occlusal device fabricated for an RDP patient. The device used existing ERA attachments for added retention designed with the intended purpose of protecting the definitive fixed and RDP from damage due to nocturnal bruxing activity and providing for even distribution of parafunctional forces.
Incorporation of Antimicrobial Macromolecules in Acrylic Denture Base Resins: A Research Composition and Update
Authors: Sivakumar Indumathi , Arunachalam Kuthalingam Subbiah , Sajjan Suresh , Ramaraju Alluri Venkata , Rao Bheemalingeshwara , Kamaraj Bindu
Published: October 2013

Contemporary research in acrylic denture base materials focuses on the development of a novel poly(methyl methacrylate) (PMMA) resin with antimicrobial properties. Although PMMA resin has fulfilled all the requirements of an ideal denture base material, its susceptibility to microbial colonization in the oral environment is a formidable concern to clinicians. Many mechanisms including the absence of ionic charge in the methyl methacrylate resins, hydrophobic interactions, electrostatic interactions, and mechanical attachment have been found to contribute to the formation of biofilm. The present article outlines the basic categories of potential antimicrobial polymer (polymeric biocides) formulations (modified PMMA resins) and considers their applicability, biological status, and usage potential over the coming years.
A Novel Catalytic Function of Synthetic IgG‐Binding Domain (Z Domain) from Staphylococcal Protein A: Light Emission with Coelenterazine
Authors: Inouye Satoshi , Sahara‐Miura Yuiko
Published: October 2013

The synthetic IgG‐binding domain (Z domain) of staphylococcal protein A catalyzes the oxidation of coelenterazine to emit light like a coelenterazine‐utilizing luciferase. The Z domain derivatives (ZZ‐gCys, Z‐gCys and Z‐domain) were purified and the luminescence properties were characterized by comparing with coelenterazine‐utilizing luciferases, including Renilla luciferase, Gaussia luciferase and the catalytic 19 kDa protein of Oplophorus luciferase. Three Z domain derivatives showed luminescence activity with coelenterazine and the order of the initial maximum intensity of luminescence was ZZ‐gCys (100%) > Z‐gCys (36.8%) > Z‐domain (1.1%) > bovine serum albumin (BSA; 0.9%) > staphylococcal protein A (0.1%) and the background value of coelenterazine (0.1%) in our conditions. The luminescence properties of ZZ‐gCys showed the similarity to that of Gaussia luciferase, including the luminescence pattern, the emission spectrum, the stimulation by halogen ions and nonionic detergents and the substrate specificity for coelenterazine analogues. In contrast, the luminescence properties of Z‐gCys were close to the catalytic 19 kDa protein of Oplophorus luciferase. The catalytic region of the Z domain for the luminescence reaction might be different from the IgG‐binding region of the Z domain.
Risk‐Related and Protective Correlates of Nonsuicidal Self‐Injury and Co‐Occurring Suicide Attempts among Incarcerated Women
Authors: Chapman Alexander L. , Gratz Kim L. , Turner Brianna J.
Published: October 2013

Individual and environmental correlates of nonsuicidal self‐injury (NSSI) and co‐occurring suicide attempts (SA) among incarcerated women (N = 104) were examined. Participants completed measures of putative risk and protective factors, including coping styles, childhood maltreatment, and hopelessness. Results indicated that active coping was uniquely, negatively associated with the presence and frequency of NSSI, whereas avoidant coping and childhood physical/emotional abuse were positively associated with NSSI frequency. Conversely, among women with a history of NSSI, hopelessness was uniquely, positively associated with the presence and frequency of SA. Further, childhood sexual abuse was associated with the presence of SA, while physical/emotional abuse was associated with SA frequency. Hopelessness was more strongly related to SA frequency than NSSI frequency. These findings help disentangle the unique risk and protective factors for NSSI and co‐occurring SA in incarcerated samples.
Suicide Attempts in Major Depressed Patients with Personality Disorder
Authors: Amore Mario , Innamorati Marco , Vittorio Cristina Di , Weinberg Igor , Turecki Gustavo , Sher Leo , Paris Joel , Girardi Paolo , Pompili Maurizio
Published: October 2013

Suicide attempters who met criteria for borderline personality disorder (BPD) comorbid with major depressive disorder (MDD) were compared to both suicide attempters suffering from MDD alone and to attempters with comorbid MDD and other personality disorders (PD). Participants were 239 (158 patients with comorbid PD and 81 patients with MDD without comorbidity) inpatients consecutively admitted after a suicide attempt made in the last 24 hours. Suicide attempters with comorbid MDD and BPD had more frequent previous suicide attempts and were more likely to have a history of aggressive behaviors and alcohol and drug use disorders compared with patients suffering from MDD without Axis II comorbidity.
Adenosine receptor inhibition attenuates the decrease in cutaneous vascular conductance during whole‐body cooling from hyperthermia
Authors: Swift Brendan , McGinn Ryan , Gagnon Daniel , Crandall Craig G. , Kenny Glen P.
Published: October 2013

New Findings

What is the central question of this study?

Adenosine has been implicated in mediating both vasoconstriction and vasodilatation in a variety of tissues throughout the body. No study has yet examined its influence in cutaneous vasoconstriction elicited by whole‐body cooling from normothermia or from hyperthermia.

What is the main finding and its importance?

Through the use of the non‐selective adenosine receptor antagonist, theophylline, a role for adenosine in the control of the cutaneous circulation when cooling from a state of hyperthermia is suggested.

Adenosine has both vasodilatory and vasoconstrictive properties, yet its influence on cutaneous vascular conductance (CVC) during whole‐body cooling remains unknown. The present study evaluated the influence of adenosine on reflex cutaneous vasoconstriction. Four microdialysis probes were inserted into the dorsal forearm skin of eight subjects and infused with the following solutions: (i) lactated Ringer solution (CON); (ii) 4 mm theophylline (Theo), a non‐selective adenosine receptor antagonist; (iii) 10 mm l‐NAME, an inhibitor of nitric oxide synthase; and (iv) combined 4 mm theophylline and 10 mm l‐NAME (Theo +l‐NAME). Subjects subsequently donned a water‐perfusion garment. Following a thermoneutral baseline period, the suit was perfused with water at 10°C for 20 min (Cooling 1). The suit was then perfused with water at 49°C for 45 min (Heating), followed by a second cooling period of 20 min using 10°C water (Cooling 2). Cutaneous blood flow (laser‐Doppler) was measured over each microdialysis probe and used to calculate CVC as a percentage of the maximum determined by sodium nitroprusside infusion and local heating. Cutaneous vascular conductance was significantly elevated at the Theo site relative to CON following Cooling 1 (18 ± 6 versus 8 ± 2%; P= 0.01) and Cooling 2 (27 ± 11 versus 14 ± 5%; P= 0.022). Likewise, CVC at the Theo + l‐NAME site remained greater compared with l‐NAME after Cooling 1 (13 ± 4 versus 7 ± 3%; P= 0.030) and Cooling 2 (15 ± 3 versus 9 ± 2%; P= 0.009). The present findings demonstrate that non‐selective antagonism of adenosine receptors attenuates the decrease in cutaneous vascular conductance during whole‐body cooling from hyperthermia.
Centrally administered angiotensin‐(1–7) increases the survival of stroke‐prone spontaneously hypertensive rats
Authors: Regenhardt Robert W. , Mecca Adam P. , Desland Fiona , Ritucci‐Chinni Phillip F. , Ludin Jacob A. , Greenstein David , Banuelos Cristina , Bizon Jennifer L. , Reinhard Mary K. , Sumners Colin
Published: October 2013

New Findings

What is the central question of this study?

Activation of angiotensin‐converting enzyme 2, resulting in production of angiotensin‐(1–7) and stimulation of its receptor, Mas, exerts beneficial actions in a number cardiovascular diseases, including ischaemic stroke. A potential beneficial role for angiotensin‐(1–7) in haemorrhagic stroke has not previously been reported.

What is the main finding and its importance?

Central administration of angiotensin‐(1–7) into stroke‐prone spontaneously hypertensive rats, a model of haemorrhagic stroke, increases lifespan and improves the neurological status of these rats, as well as decreasing microglial numbers in the striatum (implying attenuation of cerebral inflammation). These actions of angiotensin‐(1–7) have not previously been reported and identify this peptide as a potential new therapeutic target in haemorrhagic stroke.

Angiotensin‐(1–7) [Ang‐(1–7)] exerts cerebroprotective effects in ischaemic stroke, and this action is associated with a blunting of intracerebral inflammatory processes and microglial activation. Given that intracerebral inflammation and microglial activation play key roles in the mechanism of injury and brain damage in both ischaemic and haemorrhagic stroke, we have investigated the potential beneficial actions of Ang‐(1–7) in stroke‐prone spontaneously hypertensive rats (spSHRs), an established animal model of hypertension‐induced haemorrhagic stroke. Angiotensin‐(1–7) was administered by continuous infusion via the intracerebroventricular route for 6 weeks into spSHRs fed a high‐sodium (4%) diet, starting at 49 days of age. This treatment resulted in a significant increase in survival of the spSHRs. Median survival was 108 days in control, artificial cerebrospinal fluid‐infused spSHRs and 154 days in Ang‐(1–7)‐treated spSHRs. This effect was partly reversed by intracerebroventricular infusion of the Mas receptor blocker, A779. This Ang‐(1–7) treatment also decreased the number of haemorrhages in the striatum, improved neurological status (reduced lethargy), decreased the number of microglia in the striatum and tended to increase neuron survival at the same site. Importantly, infusions of Ang‐(1–7) had no effect on kidney pathology, heart pathology, body weight, serum corticosterone levels or blood pressure. This study is the first to demonstrate the cerebroprotective actions of Ang‐(1–7), including increased survival time, in spSHRs. As such, these data reveal a potential therapeutic target for haemorrhagic stroke.
Exercise training effects on hypoxic and hypercapnic ventilatory responses in mice selected for increased voluntary wheel running
Authors: Kelly Scott A. , Rezende Enrico L. , Chappell Mark A. , Gomes Fernando R. , Kolb Erik M. , Malisch Jessica L. , Rhodes Justin S. , Mitchell Gordon S. , Garland Theodore
Published: October 2013

New Findings

What is the central question of this study?

We used experimental evolution to determine how selective breeding for high voluntary wheel running and exercise training (7–11 weeks) affect ventilatory chemoreflexes of laboratory mice at rest.

What is the main finding and its importance?

Selective breeding, although significantly affecting some traits, did not systematically alter ventilation across gas concentrations. As with most human studies, our findings support the idea that endurance training attenuates resting ventilation. However, little evidence was found for a correlation between ventilatory chemoreflexes and the amount of individual voluntary wheel running. We conclude that exercise ‘training’ alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running.

Ventilatory control is affected by genetics, the environment and gene–environment and gene–gene interactions. Here, we used an experimental evolution approach to test whether 37 generations of selective breeding for high voluntary wheel running (genetic effects) and/or long‐term (7–11 weeks) wheel access (training effects) alter acute respiratory behaviour of mice resting in normoxic, hypoxic and hypercapnic conditions. As the four replicate high‐runner (HR) lines run much more than the four non‐selected control (C) lines, we also examined whether the amount of exercise among individual mice was a quantitative predictor of ventilatory chemoreflexes at rest. Selective breeding and/or wheel access significantly affected several traits. In normoxia, HR mice tended to have lower mass‐adjusted rates of oxygen consumption and carbon dioxide production. Chronic wheel access increased oxygen consumption and carbon dioxide production in both HR and C mice during hypercapnia. Breathing frequency and minute ventilation were significantly reduced by chronic wheel access in both HR and C mice during hypoxia. Selection history, while significantly affecting some traits, did not systematically alter ventilation across all gas concentrations. As with most human studies, our findings support the idea that endurance training (access to wheel running) attenuates resting ventilation. However, little evidence was found for a correlation at the level of the individual variation between ventilatory chemoreflexes and performance (amount of individual voluntary wheel running). We tentatively conclude that exercise ‘training’ alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running.
Influence of Thermomechanical Parameters on the Hot Deformation Behavior of AA1070
Authors: Rezaei Ashtiani H. R. , Bisadi H. , Parsa M. H.
Published: October 2013

The experimental stress–strain data from isothermal hot compression tests, in a wide range of temperatures (350–500 °C) and strain rates (0.005–0.5 s−1), were employed to develop constitutive equations in a commercially pure aluminum (AA1070). The effects of temperature and strain rate on the hot deformation behavior were represented by Zener–Hollomon parameter including Arrhenius term. The results show that the hardening rate and flow stress are evidently affected by both deformation temperature and strain rate. The power law, exponential, and hyperbolic sinusoidal types of Zener–Hollomon equations were used to determine the hot deformation behavior of AA1070. The results suggested that the highest correlation coefficient was achieved for the hyperbolic sine law for the studied material. So the proposed deformation constitutive equations can give an accurate and precise estimate of the flow stress for AA1070, which means it can be used for numerical simulation of hot forming processes and for choosing proper forming parameters in engineering practice accurately.
Numerical Evaluation of High-Order Modes for Stepped Beam
Authors: Xu Wei , Cao Maosen , Ren Qingwen , Su Zhongqing
Published: October 2013

The numerical evaluation of high-order modes of a uniform Euler–Bernoulli beam has been studied by reformatting the classical expression of mode shapes. That method, however, is inapplicable to a stepped beam due to the nonuniform expressions of the mode shape for each beam segment. Given that concern, this study develops an alternative method for the numerical evaluation of high-order modes for stepped beams. This method effectively expands the space of high-order modal solutions by introducing local coordinate systems to replace the conventional global coordinate system. This set of local coordinate systems can significantly simplify the frequency determinant of vibration equations of a stepped beam, in turn, largely eliminating numerical round-off errors and conducive to high-order mode evaluation. The efficacy of the proposed scheme is validated using various models of Euler–Bernoulli stepped beams. The principle of the method has the potential for extension to other types of Euler–Bernoulli beams with discontinuities in material and geometry. (The Matlab code for the numerical evaluation of high-order modes for stepped beams can be provided by the corresponding author upon request.)
Constructal Underground Designs for Ground-Coupled Heat Pumps
Authors: Bejan A. , Lorente S. , Anderson R.
Published: October 2013

In this paper, we review the main advances made by our research group on the heat transfer performance of complex flow architectures embedded in a conducting solid. The immediate applications of this work include the design of ground-coupled heat pumps, seasonal thermal energy storage systems, and district heating and cooling systems. Various configurations are considered: U-shaped ducts with varying spacing between the parallel portions of the U, serpentines with three elbows, and trees with T-shaped and Y-shaped bifurcations. In each case, the volume ratio of fluid to soil is fixed. We found the critical geometric features that allow the heat transfer density of the stream-solid configuration to be the highest. In the case of U-tubes and serpentines, the best spacing between parallel portions is discovered, whereas the vascular designs morph into bifurcations and angles of connection that provide progressively greater heat transfer rate per unit volume. We show that the flow of heat into or out of a solid volume must have an S-shaped history curve that is entirely deterministic. This constructal-design principle unites a wide variety of previously disconnected S-curve phenomena (ground heat storage and retrieval, population growth, cancer, chemical reactions, contaminants, languages, news, information, innovations, technologies, economic activity).
Prioritizing Design for Environment Strategies Using a Stochastic Analytic Hierarchy Process
Authors: Ramanujan Devarajan , Bernstein William Z. , Choi Jun-Ki , Koho Mikko , Zhao Fu , Ramani Karthik
Published: October 2013

This paper describes a framework for applying design for environment (DfE) within an industry setting. Our aim is to couple implicit design knowledge such as redesign/process constraints with quantitative measures of environmental performance to enable informed decision making. We do so by integrating life cycle assessment (LCA) and multicriteria decision analysis (MCDA). Specifically, the analytic hierarchy process (AHP) is used for prioritizing various levels of DfE strategies. The AHP network is formulated so as to improve the environmental performance of a product while considering business-related performance. Moreover, in a realistic industry setting, the onus of decision making often rests with a group, rather than an individual decision maker (DM). While conducting independent evaluations, experts often do not perfectly agree and no individual expert can be considered representative of the ground truth. Hence, we integrate a stochastic simulation module within the MCDA for assessing the variability in preferences among DMs. This variability in judgments is used as a metric for quantifying judgment reliability. A sensitivity analysis is also incorporated to explore the dependence of decisions on specific input preferences. Finally, the paper discusses the results of applying the proposed framework in a real-world case.
Nonlinear Strain Energy Formulation of a Generalized Bisymmetric Spatial Beam for Flexure Mechanism Analysis
Authors: Sen Shiladitya , Awtar Shorya
Published: October 2013

Analytical load–displacement relations for flexure mechanisms, formulated by integrating the individual analytical models of their building-blocks (i.e., flexure elements), help in understanding the constraint characteristics of the whole mechanism. In deriving such analytical relations for flexure mechanisms, energy based approaches generally offer lower mathematical complexity, compared to Newtonian methods, by reducing the number of unknowns—specifically, the internal loads. To facilitate such energy based approaches, a closed-form nonlinear strain energy expression for a generalized bisymmetric spatial beam flexure is presented in this paper. The strain energy, expressed in terms of the end-displacement of the beam, considers geometric nonlinearities for intermediate deformations, enabling the analysis of flexure mechanisms over a finite range of motion. The generalizations include changes in the initial orientation and shape of the beam flexure due to potential misalignment or manufacturing. The effectiveness of this approach is illustrated via the analysis of a multilegged table flexure mechanism. The resulting analytical model is shown to be accurate using nonlinear finite elements analysis, within a load and displacement range of interest.
A Kriging-Interpolated Level-Set Approach for Structural Topology Optimization
Authors: Hamza Karim , Aly Mohamed , Hegazi Hesham
Published: October 2013

Level-set approaches are a family of domain classification techniques that rely on defining a scalar level-set function (LSF), then carrying out the classification based on the value of the function relative to one or more thresholds. Most continuum topology optimization formulations are at heart, a classification problem of the design domain into structural materials and void. As such, level-set approaches are gaining acceptance and popularity in structural topology optimization. In conventional level set approaches, finding an optimum LSF involves solution of a Hamilton-Jacobi system of partial differential equations with a large number of degrees of freedom, which in turn, cannot be accomplished without gradients information of the objective being optimized. A new approach is proposed in this paper where design variables are defined as the values of the LSF at knot points, then a Kriging model is used sto interpolate the LSF values within the rest of the domain so that classification into material or void can be performed. Perceived advantages of the Kriging-interpolated level-set (KLS) approach include alleviating the need for gradients of objectives and constraints, while maintaining a reasonable number of design variables that is independent from the mesh size. A hybrid genetic algorithm (GA) is then used for solving the optimization problem(s). An example problem of a short cantilever is studied under various settings of the KLS parameters in order to infer the best practice recommendations for tuning the approach. Capabilities of the approach are then further demonstrated by exploring its performance on several test problems.
Design Point for Predicting Year-Round Performance of Solar Parabolic Trough Concentrator Systems
Authors: Wirz Men , Roesle Matthew , Steinfeld Aldo
Published: October 2013

Thermal efficiencies of the solar field of two different parabolic trough concentrator (PTC) systems are evaluated for a variety of operating conditions and geographical locations, using a detailed 3D heat transfer model. Results calculated at specific design points are compared to yearly average efficiencies determined using measured direct normal solar irradiance (DNI) data as well as an empirical correlation for DNI. It is shown that the most common choices of operating conditions at which solar field performance is evaluated, such as the equinox or the summer solstice, are inadequate for predicting the yearly average efficiency of the solar field. For a specific system and location, the different design point efficiencies vary significantly and differ by as much as 11.5% from the actual yearly average values. An alternative simple method is presented of determining a representative operating condition for solar fields through weighted averages of the incident solar radiation. For all tested PTC systems and locations, the efficiency of the solar field at the representative operating condition lies within 0.3% of the yearly average efficiency. Thus, with this procedure, it is possible to accurately predict year-round performance of PTC systems using a single design point, while saving computational effort. The importance of the design point is illustrated by an optimization study of the absorber tube diameter, where different choices of operating conditions result in different predicted optimum absorber diameters.
Performance of Rigid Porous Stratification Manifolds With Interpretation for Off-Design Operation
Authors: Wang Shuping , Davidson Jane H.
Published: October 2013

Thermal stratification of solar water storage tanks improves collector efficiency and provides higher quality energy to the user. A crucial aspect of maintaining stratification is preventing mixing in the tank, particularly during solar charging and hot water draws. An effective and simple approach to flow control is an internal stratification manifold. In this paper, the performance of the rigid porous manifold, which consists of a series of vertical hydraulic resistance elements placed within a perforated tube, is considered for charging operation. A 1D model of the governing mass, momentum, and energy conservation equations is used to illustrate the procedure for designing a manifold and to explore its performance over a broad range of operating conditions expected in solar water storage tanks. A manifold performance indicator (MPI) is used to evaluate the effectiveness of the manifold relative to an inlet pipe positioned at the top of the tank. The rigid porous manifold improves the stratification in the tank over a wide range of operating conditions unless the inlet flow rate is significantly reduced from the design point.
Discretization of Nonautonomous Nonlinear Systems Based on Continualization of an Exact Discrete-Time Model
Authors: Nguyen-Van Triet , Hori Noriyuki
Published: October 2013

An innovative approach is proposed for generating discrete-time models of a class of continuous-time, nonautonomous, and nonlinear systems. By continualizing a given discrete-time system, sufficient conditions are presented for it to be an exact model of a continuous-time system for any sampling periods. This condition can be solved exactly for linear and certain nonlinear systems, in which case exact discrete-time models can be found. A new model is proposed by approximately solving this condition, which can always be found as long as a Jacobian matrix of the nonlinear system exists. As an example of the proposed method, a van der Pol oscillator driven by a forcing sinusoidal function is discretized and simulated under various conditions, which show that the proposed model tends to retain such key features as limit cycles and space-filling oscillations even for large sampling periods, and out-performs the forward difference model, which is a well-known, widely-used, and on-line computable model.
An Analytical Solution of Fracture-Induced Stress and Its Application in Shale Gas Exploitation
Authors: Li Jia , Guo Boyun , Feng Yin
Published: October 2013

Natural gas and oil exploration and production from shale formations have gained a great momentum in many regions in the past five years. Producing hydrocarbons from shale is challenging because of low productivity of wells. Optimal design of transverse fractures is a key to achieving successful well completion and field economics. This paper presents a simple analytical method to determine the minimum fracture spacing required for preventing fracture-merging. Result of the analytical method has been verified by a Finite Element Method for a typical fracturing condition in a shale gas formation. Field performances of shale gas wells are found consistent with what suggested by this work. The analytical method presented in this paper can replace the sophisticated solutions and time-consuming numerical simulators in calculating stresses around hydraulic fractures and identifying the minimum required fracture spacing. The method can be applied to designing of multifrac completions in shale plays to optimize placement of transverse fractures for maximizing well productivity and hydrocarbon recovery. This work provides engineers a simple tool for optimizing their well completion design in shale gas reservoirs.
Experimental Study With Analytical Validation of Thermally Driven Flow in Risers of Solar Water Heaters Under Varying Scale Thickness and Heat Flux
Authors: Arunachala U. C. , Siddhartha Bhatt M. , Sreepathi L. K.
Published: October 2013

This paper investigates the deterioration in the performance of thermosiphon flat plate solar water heaters (SWH) with water side scaling. The study presents the analytical and experimental variation of mass flow rate of water with scale thickness in risers of conventional solar flat plate water heater for different electrical power inputs (covering the full range of solar incident radiation up to 1 kW/m2). This information is extended further to determine the drop in efficiency characteristics represented by the Hottel–Whillier–Bliss (H–W–B) constants for full–fledged SWH. To simulate scaling in risers in the absorber plate of a SWH, an artificial method of coating has been used to create single pipe riser of different uniform scale thicknesses. Four such risers are created with scale thickness of 0 mm, 0.7 mm, 1.7 mm, 2.7 mm, and 3.7 mm. The observed drop in mass flow rate through the range of risers between 0 mm and 3.7 mm scale thickness is 58.5% for the thermal input power (supplied through electric heating) of 129.5 W (corresponding to a solar incident radiation of 980 W/m2). In comparison, the analytical results show a corresponding drop of 70.12%. A comparison of the coated riser with a cut tube of an actually scaled riser indicates excellent matching of thermal conductivity. The divergence between experimental and analytical mass flow rate in the case of a riser of the highest scale thickness, viz., 3.7 mm, is the lowest because of increased pressure gain in the flow region together with higher temperature than predicted by the general equation. The experimental data of various energy parameters from the single tube scaled riser studies are matching with analytical values for the different input electrical power levels (corresponding to the different solar radiation levels). As identical conditions are used in the experimental analysis, the results for risers of various scale thicknesses and electrical power inputs are applicable to corresponding full–fledged SWH.
Computational Study of the Blood Flow in Three Types of 3D Hollow Fiber Membrane Bundles
Authors: Zhang Jiafeng , Chen Xiaobing , Ding Jun , Fraser Katharine H. , Ertan Taskin M. , Griffith Bartley P. , Wu Zhongjun J.
Published: October 2013

The goal of this study is to develop a computational fluid dynamics (CFD) modeling approach to better estimate the blood flow dynamics in the bundles of the hollow fiber membrane based medical devices (i.e., blood oxygenators, artificial lungs, and hemodialyzers). Three representative types of arrays, square, diagonal, and random with the porosity value of 0.55, were studied. In addition, a 3D array with the same porosity was studied. The flow fields between the individual fibers in these arrays at selected Reynolds numbers (Re) were simulated with CFD modeling. Hemolysis is not significant in the fiber bundles but the platelet activation may be essential. For each type of array, the average wall shear stress is linearly proportional to the Re. For the same Re but different arrays, the average wall shear stress also exhibits a linear dependency on the pressure difference across arrays, while Darcy's law prescribes a power-law relationship, therefore, underestimating the shear stress level. For the same Re, the average wall shear stress of the diagonal array is approximately 3.1, 1.8, and 2.0 times larger than that of the square, random, and 3D arrays, respectively. A coefficient C is suggested to correlate the CFD predicted data with the analytical solution, and C is 1.16, 1.51, and 2.05 for the square, random, and diagonal arrays in this paper, respectively. It is worth noting that C is strongly dependent on the array geometrical properties, whereas it is weakly dependent on the flow field. Additionally, the 3D fiber bundle simulation results show that the three-dimensional effect is not negligible. Specifically, velocity and shear stress distribution can vary significantly along the fiber axial direction.
Using Morphing Techniques in Early Variation Analysis
Authors: Wagersten Ola , Lindau Björn , Lindkvist Lars , Söderberg Rikard
Published: October 2013

Today, in order to be competitive in a fierce global car market, higher demands are placed on the perceived quality (PQ) of the products. The end customer's visual impression of fit and finish are one of several factors influencing the overall PQ. When assessing the PQ of split-lines, the assumed geometric variation of the ingoing parts is an important prerequisite for trustworthy visualization and for correct judgments. To facilitate early decision making in conceptual phases, new demands are set on virtual tools and methods to support the engineers. In this study, a method for early evaluation of the impact of geometrical variation on PQ of split-lines is proposed. Starting from an exterior styling model, mesh morphing techniques have been used to distort the exterior model according to measurement data acquired in running production. Morphing techniques have also been used to adopt previous structural design solutions onto the new styling, in order to make an early assumption of the assembly stiffness. The used method is described and adopted in an industrial case. The study shows that the presented technique can be used to create continuous and correlated datasets. Non-rigid part behavior can be included in early PQ evaluations, even if the final detailed engineering design models do not yet exist.
Effect of Injection Timing on PPCI and MPCI Mode Fueled With Straight-Run Naphtha
Authors: Yang Hongqiang , Shuai Shijin , Wang Zhi , Wang Jianxin
Published: October 2013

Partially premixed compression ignition (PPCI) and multiple premixed compression ignition (MPCI) mode of straight-run naphtha have been investigated under different injection strategies. The MPCI mode is realized by the multiple premixed combustion processes in a sequence of “spray-combustion-spray-combustion” around the compression top dead center. The spray and combustion events are preferred to be completely separated, without any overlap in the temporal sequence in order to ensure the multiple-stage premixed compression ignition. The PPCI mode is well known as the “spray-spray-combustion” sequence, with the start of combustion separated from the end of injection. Straight-run naphtha with a research octane number (RON) of 58.8 is tested in a single cylinder compression ignition engine whose compression ratio is 16.7 and displacement is 0.5 l. Double and triple injection strategies are investigated as the last injection timing sweeping at 1.0 MPa IMEP and 1800 rpm conditions. The MPCI mode is achieved using the double injection strategy, but its soot emission is higher than the PPCI mode under triple injection strategy. This is mainly because of the lower RON of the straight-run naphtha and the ignition delay is too short to form an ideally premixed combustion process after the second injection of straight-run naphtha. Diesel fuel is also tested under the same operating conditions, except for employing a single injection strategy. The naphtha PPCI and MPCI mode both have lower fuel consumption and soot emission than diesel fuel single injection mode, but the THC emissions are both higher than that of diesel fuel.
Creep Life Prediction for Aero Gas Turbine Hot Section Component Using Artificial Neural Networks
Authors: Abdul Ghafir M. F. , Li Y. G. , Wang L.
Published: October 2013

Accurate and reliable component life prediction is crucial to ensure safety and economics of gas turbine operations. In pursuit of such improved accuracy and reliability, model-based creep life prediction methods have become more complicated and demand higher computational time. Therefore, there is a need to find an alternative approach that is able to provide a quick solution to creep life prediction for production engines while at the same time maintain the same accuracy and reliability as that of the model-based methods. In this paper, a novel creep life prediction approach using artificial neural networks is introduced as an alternative to the model-based creep life prediction approach to provide a quick and accurate estimation of gas turbine creep life. Multilayer feed forward backpropagation neural networks have been utilized to form three neural network–based creep life prediction architectures known as the range-based, functional-based, and sensor-based architectures. The new neural network creep life prediction approach has been tested with a model single-spool turboshaft gas turbine engine. The results show that good generalization can be achieved in all three neural network architectures. It was also found that the sensor-based architecture is better than the other two in terms of accuracy, with 98% of the post-test samples possessing prediction errors within ±0.4%.
First and Second Law Analysis of Future Aircraft Engines
Authors: Grönstedt Tomas , Irannezhad Mohammad , Lei Xu , Thulin Oskar , Lundbladh Anders
Published: October 2013

An optimal baseline turbofan cycle designed for a performance level expected to be available around year 2050 is established. Detailed performance data are given in take-off, top of climb, and cruise to support the analysis. The losses are analyzed, based on a combined use of the first and second law of thermodynamics, in order to establish a basis for a discussion on future radical engine concepts and to quantify loss levels of very high performance engines. In light of the performance of the future baseline engine, three radical cycles designed to reduce the observed major loss sources are introduced. The combined use of a first and second law analysis of an open rotor engine, an intercooled recuperated engine, and an engine working with a pulse detonation combustion core is presented. In the past, virtually no attention has been paid to the systematic quantification of the irreversibility rates of such radical concepts. Previous research on this topic has concentrated on the analysis of the turbojet and the turbofan engine. In the developed framework, the irreversibility rates are quantified through the calculation of the exergy destruction per unit time. A striking strength of the analysis is that it establishes a common currency for comparing losses originating from very different physical sources of irreversibility. This substantially reduces the complexity of analyzing and comparing losses in aero engines. In particular, the analysis sheds new light on how the intercooled recuperated engine establishes its performance benefits.
Unsteady Convection Flow of Some Nanofluids Past a Moving Vertical Flat Plate With Heat Transfer
Authors: Turkyilmazoglu M.
Published: October 2013

This paper is devoted to the study of heat and mass transfer characteristics of some nanofluid flows past an infinite flat plate moving vertically. Some water-based nanofluids containing copper (Cu), silver (Ag), copper oxide (CuO), alumina (Al2O3), and titanium oxide (TiO2) are analytically analyzed taking into consideration the thermal radiation effect for two types of temperature boundary conditions. The physically significant properties like skin friction coefficient and Nusselt number are easy to conceive from the derived exact analytical expressions for the velocity and temperature profiles. Results are believed to constitute a tool to verify the validity of numerical solutions for more complicated transient free/forced convection nanofluid flow problems.