bluuebunny/crossref_metadata_2025 huggingface dataset:
Posttraumatic stress disorder: a history and a critique
Authors: Andreasen Nancy C.
Published: October 2010

Although posttraumatic stress disorder (PTSD) is sometimes considered to be a relatively new diagnosis, as the name first appeared in 1980, the concept of the disorder has a very long history. That history has often been linked to the history of war, but the disorder has also been frequently described in civilian settings involving natural disasters, mass catastrophes, and serious accidental injuries. The diagnosis first appeared in the official nomenclature when Diagnostic and Statistical Manual of Mental Disorders (DSM)‐I was published in 1952 under the name gross stress reaction. It was omitted, however, in the next edition in 1968, after a long period of relative peace. When DSM‐III was developed in the mid‐1980s the recent occurrence of the Vietnam War provoked a more thorough examination of the disorder. PTSD was defined as a stress disorder that is a final common pathway occurring as a consequence of many different types of stressors, including both combat and civilian stress. The definition of PTSD has filled an important niche in clinical psychiatry. Its definition continues to raise important questions about the relationship between a stressor, the individual experiencing it, and the characteristic symptoms.
Variant brain‐derived neurotrophic factor Val66Met endophenotypes: implications for posttraumatic stress disorder
Authors: Frielingsdorf Helena , Bath Kevin G. , Soliman Fatima , DiFede JoAnn , Casey B. J. , Lee Francis S.
Published: October 2010

Recently, a common single nucleotide polymorphism (SNP) has been identified in the gene encoding brain‐derived neurotrophic factor (BDNF). The variant BDNFMet has been shown to have decreased activity‐dependent BDNF secretion from neurons and to lead to impairments in specific forms of learning and altered susceptibility to stress. A mouse model containing BDNFMet has also been linked to increased anxiety‐like behavior. In a translational study, mice and human carriers of the BDNFMet allele were compared in their ability to extinguish a learned fear memory. Both showed slower suppression of the learned fear response. In humans, the neural correlates of this behavior were validated using fMRI. As anxiety and fear extinction lie at the core of symptoms and therapeutic approaches to posttraumatic stress disorder (PTSD), we propose that BDNF genotype and neuroimaging may be useful as biomarkers to provide guidance for more customized therapeutic directions. The aim of this paper is to review the available knowledge on the BDNF Val66Met SNP, with emphasis on anxiety‐ and fear‐related endophenotypes and its potential implications for PTSD.
House calls revisited: leveraging technology to overcome obstacles to veteran psychiatric care and improve treatment outcomes
Authors: Olden Megan , Cukor Judith , Rizzo Albert “Skip” , Rothbaum Barbara , Difede JoAnn
Published: October 2010

Despite an increasing number of military service members in need of mental health treatment following deployment to Iraq and Afghanistan, numerous psychological and practical barriers limit access to care. Perceived stigma about admitting psychological difficulties as well as frequent long distances to treatment facilities reduce many veterans’ willingness and ability to receive care. Telemedicine and virtual human technologies offer a unique potential to expand services to those in greatest need. Telemedicine‐based treatment has been used to address multiple psychiatric disorders, including posttraumatic stress disorder, depression, and substance use, as well as to provide suicide risk assessment and intervention. Clinician education and training has also been enhanced and expanded through the use of distance technologies, with trainees practicing clinical skills with virtual patients and supervisors connecting with clinicians via videoconferencing. The use of these innovative and creative vehicles offers a significant and as yet unfulfilled promise to expand delivery of high‐quality psychological therapies, regardless of clinician and patient location.
Psychiatric and neurologic aspects of war: an overview and perspective
Authors: Difede JoAnn , Barchas Jack D.
Published: October 2010

The growing number of soldiers returning home with psychiatric and neurologic disorders, notably posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI), underscores the need for an interdisciplinary framework for understanding the emergent consequences of combat. Among the challenges facing the scientific community is the development of effective treatment strategies for TBI from blast and other injuries, given the confounding effects of comorbid psychological symptoms on accurate diagnoses. At the individual level, emerging technologies—including virtual reality, the use of genetic biomarkers to inform treatment response, and new brain imaging methodology—are playing an important role in the development of differential therapeutics to best address a soldier's particular clinical needs. At the macro level, new approaches toward understanding the political, cultural, and ideological contexts of mass conflict, the decision to join in violence, and ways of preventing genocide are discussed.
Causes and consequences of lymphatic disease
Authors: Rockson Stanley G.
Published: October 2010

The visceral manifestations of lymphatic disorders (lymphangiomatosis and lymphangiectasia) are particularly severe. Any pathology of the lymphatic vasculature, whether superficial or internal, regional, or systemic, is predominated by the appearance of lymphedema, the characteristic form of tissue edema that occurs when lymphatic dysfunction supervenes. Disease manifestations may include dysregulation of body fluid homeostasis, immune traffic impairment, and disturbances of lipid and protein reabsorption from the gut lumen. The appearance of lymphatic edema invokes complex biological alterations. Many of these changes seem to relate uniquely to chronic lymphatic edema, including a profound stimulus to collagen and adipose deposition. Despite the recent advances in our understanding of these disorders, substantial knowledge gaps remain; these gaps inhibit our ability to accurately identify, categorize, treat, and prevent these diseases. Future diagnostic, therapeutic, and reproductive decisions for affected individuals require an accurate knowledge of the clinical and laboratory presentation, mode of inheritance, treatment response, outcomes, and prognosis.
An avian outbreak associated with panzootic equine influenza in 1872: an early example of highly pathogenic avian influenza?
Authors: Morens David M. , Taubenberger Jeffery K.
Published: October 2010

Please cite this paper as: Morens and Taubenberger (2010) An avian outbreak associated with panzootic equine influenza in 1872: an early example of highly pathogenic avian influenza? Influenza and Other Respiratory Viruses 4(6), 373–377.

Background  An explosive fatal epizootic in poultry, prairie chickens, turkeys, ducks and geese, occurred over much of the populated United States between 15 November and 15 December 1872. To our knowledge the scientific literature contains no mention of the nationwide 1872 poultry outbreak.

Objective  To understand avian influenza in a historical context.

Results  The epizootic progressed in temporal‐geographic association with a well‐reported panzootic of equine influenza that had begun in Canada during the last few days of September 1872. The 1872 avian epizootic was universally attributed at the time to equine influenza, a disease then of unknown etiology but widely believed to be caused by the same transmissible respiratory agent that caused human influenza.

Conclusions  Another microbial agent could have caused the avian outbreak; however, its strong temporal and geographic association with the equine panzootic, and its clinical and epidemiologic features, are most consistent with highly pathogenic avian influenza. The avian epizootic could thus have been an early instance of highly pathogenic avian influenza.
A review of methods of analysis in contouring studies for radiation oncology
Authors: Jameson Michael G , Holloway Lois C , Vial Philip J , Vinod Shalini K , Metcalfe Peter E
Published: October 2010

Inter‐observer variability in anatomical contouring is the biggest contributor to uncertainty in radiation treatment planning. Contouring studies are frequently performed to investigate the differences between multiple contours on common datasets. There is, however, no widely accepted method for contour comparisons. The purpose of this study is to review the literature on contouring studies in the context of radiation oncology, with particular consideration of the contouring comparison methods they employ. A literature search, not limited by date, was conducted using Medline and Google Scholar with key words: contour, variation, delineation, inter/intra observer, uncertainty and trial dummy‐run. This review includes a description of the contouring processes and contour comparison metrics used. The use of different processes and metrics according to tumour site and other factors were also investigated with limitations described. A total of 69 relevant studies were identified. The most common tumour sites were prostate (26), lung (10), head and neck cancers (8) and breast (7).The most common metric of comparison was volume used 59 times, followed by dimension and shape used 36 times, and centre of volume used 19 times. Of all 69 publications, 67 used a combination of metrics and two used only one metric for comparison. No clear relationships between tumour site or any other factors that may influence the contouring process and the metrics used to compare contours were observed from the literature. Further studies are needed to assess the advantages and disadvantages of each metric in various situations.
Susceptibility weighted imaging: A pictorial review
Authors: Ong Benjamin C , Stuckey Stephen L
Published: October 2010

Susceptibility weighted imaging (SWI) is a valuable technique in the evaluation of a wide variety of intracranial pathologies. SWI is a gradient echo sequence utilising both phase and magnitude data to achieve exquisite sensitivity to tissue magnetic susceptibility effects. Normal SWI appearances and common artefacts are illustrated. Examples of SWI in common intracranial pathologies such as subarachnoid, intraventricular and intraparenchymal haemorrhage, intra‐axial and extra‐axial tumours, pyogenic and non‐pyogenic infections, trauma, neurodegenerative diseases and vascular disease including aneurysms, vascular malformations are illustrated and discussed. This pictorial essay will enable radiologists to recognise the normal, artefactual and common intracranial pathological appearances of SWI.
The p53/p21Cip1/ Waf1 pathway mediates the effects of SPARC on melanoma cell cycle progression
Authors: Fenouille Nina , Robert Guillaume , Tichet Mélanie , Puissant Alexandre , Dufies Maeva , Rocchi Stéphane , Ortonne Jean‐Paul , Deckert Marcel , Ballotti Robert , Tartare‐Deckert Sophie
Published: October 2010

Secreted protein acidic and rich in cysteine (SPARC), or osteonectin, belongs to the family of matricellular proteins that modulate cell–matrix interactions and cellular functions. SPARC is highly expressed in melanoma, and we reported that SPARC promotes epithelial/mesenchymal‐like changes and cell migration. Here, we used siRNA and conditional shRNA to investigate the contribution of tumor‐derived SPARC to melanoma cell growth in vitro and in vivo. We found that depletion of SPARC induces G2/M cell cycle arrest and tumor growth inhibition with activation of p53 and induction of p21Cip1/Waf1 acting as a checkpoint, preventing efficient mitotic progression. In addition, we demonstrate that reduced mesenchymal features and the invasive potential of SPARC‐silenced cells are independent of p21Cip1/Waf1 induction and cell cycle arrest. Importantly, overexpression of SPARC reduces p53 protein levels and leads to an increase in cell number during exponential growth. Our findings indicate that in addition to its well‐known function as a mediator of melanoma cell migration and tumor–host interactions, SPARC regulates, in a cell‐autonomous manner, cell cycle progression and proliferation through the p53/p21Cip1/Waf1 pathway.
Loss of Klotho during melanoma progression leads to increased filamin cleavage, increased Wnt5A expression, and enhanced melanoma cell motility
Authors: Camilli Tura C. , Xu Mai , O’Connell Michael P. , Chien Bonnie , Frank Brittany P. , Subaran Sarah , Indig Fred E. , Morin Patrice J. , Hewitt Stephen M. , Weeraratna Ashani T.
Published: October 2010

We have previously shown that Wnt5A‐mediated signaling can promote melanoma metastasis. It has been shown that Wnt signaling is antagonized by the protein Klotho, which has been implicated in aging. We show here that in melanoma cells, expressions of Wnt5A and Klotho are inversely correlated. In the presence of recombinant Klotho (rKlotho), we show that Wnt5A internalization and signaling is decreased in high Wnt5A‐expressing cells. Moreover, in the presence of rKlotho, we observe an increase in Wnt5A remaining in the medium, coincident with an increase in sialidase activity, and decrease in syndecan expression. These effects can be inhibited using a sialidase inhibitor. In addition to its effects on Wnt5A internalization, we also demonstrate that Klotho decreases melanoma cell invasive potential by a second mechanism that involves the inhibition of calpain and a resultant decrease in filamin cleavage, which we demonstrate is critical for melanoma cell motility.
Exposed Cross‐section of the Archaean Lower Crust in the Shanxi‐Hebei‐Inner Mongolia Border Region: Problems and Prospects
Authors: Jing ZHAO , Xianglin QIAN
Published: October 2010

Abstract  The Archaean lower crust represented by granulite facies rocks, which is rare in China, is found to be exposed in the Shanxi‐Hebei‐Inner Mongolia border region. Studies of the regional structure and deformation and metamorphism of the region indicate that there occurred at least two phases of deformation and metamorphism in the region. Early‐phase nearly E‐W‐directed deformational structure is well preserved in the Zhangjiakou‐Xuanhua area. Observations of the features of the geological structure from north to south (in the Hengshan metamorphic terrain) have revealed a possible exposed cross‐section through the Archaean lower crust. The structure was superimposed by a NE‐SW‐trending high‐temperature ductile shear zone in the Datong area in the late phase, thus reworking the Archaean sequence.
Pressure—Temperature Contours and PT Paths of the Early Precambrian Rocks through the Yinshan Area and Their Implication to the Crustal Evolution
Authors: Hualin MEI , Changhua WU , Wei JIN
Published: October 2010

Abstract  Four distinct litho‐tectonic belts (zones) in the Yinshan area, North China, were identified by pressure‐temperature contours and litho‐tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt, Wulashan‐Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo‐tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800–1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan‐Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000–1200 MPa to 500–700 MPa. The PT paths of the Jining and Erdaowa Groups show different PTt paths: the former shows counterclockwise while the latter clockwise, which indicates that the Jining and Erdaowa groups formed in different thermo‐tectonic settings.
Biomineralization in the La' erma Gold Deposit of the Western Qinling Mountains
Authors: Li LIN , Lidong ZHU
Published: October 2010

Abstract  Geological and geochemical studies and experiments on mineralization indicate that the source bed of the La' erma gold deposit in the south subbelt of the western Qinling Mountains is hydrothermal cherts in the Cambrian Taiyangding Group. Organic geochemical study of the cherts shows that the organic precursors intimately associated with gold are marine bacteria and algae. The gold content in chert is positively correlated with the amount of bacterial and algal microfossils, and simulation experiments on biomineralization of modern bacteria and algae indicate that bacteria and algae played an important role in the formation of the La' erma gold deposit.
The Relationship between the Distribution of Thick Coal Belts and the Late Carboniferous‐Early Early Permian Marine Transgression—Regression in the North China Platform
Authors: Rong ZHONG , Zeming FU
Published: October 2010

Abstract  Four great second‐order transgressions occurred during the Late Carboniferous to early Early Permian and they came from both the eastern and western sea areas in the North China Platform. As time went on, depocentres, depositional extent, transgression directions, coastline position and distribution of minable coal seams were changing continuously. The third great second‐order transgression occurring at the beginning of the early Early Permian marks the maximum transgression period and before its arrival, i.e. at the close of the late Late Carboniferous, there was the super‐regional coal‐forming environment. During the second, third and fourth transgressions, the northern North China Platform was all along situated on the transgressive margin of the epicontinental sea and became the major distribution area of thick coal belts because it maintained a coal‐forming environment for a long period of time from the close of the late Late Carboniferous to the Early Permian.
207pb/206pb zircon Dating of the Huangtuling Hypersthene‐Garnet‐Biotite Gneiss from the Dabie Mountains, Luotian County, Hubei Province, China: New Evidence for Early Precambrian Evolution
Authors: Ping JIAN , Weiran YANG , Zichao ZHANG
Published: October 2010

Abstract The Huangtuling hypersthene‐garnet‐biotite gneiss at Luotian County, Hubei Province, is a typical granulite‐facies rock of the Dabie Group Complex in the Dabie orogenic belt. Investigations on the morphology and occurrence of zircons and their internal structures shown in the thin sections lead to the recognition of three types of zircons, which are in good agreement with the types identified on the basis of morphology, colour and external features from the related zircon concentrates. The observation of zircons in the rock reveals that part of type 1 zircons show signs of a double‐layered structure. The interval part existed in the protolith prior to the granulite‐facies metamorphism. Type 2, the prismatic zircons which mainly occur in garnet and hypersthene are metamorphic minerals of the granulite‐facies metamorphism. Type 3, the round multifaceted zircons in felsic minerals and biotite, are probably attributed to a later geological event related to migmatization. The 207Pb/206Pb zircon dating by direct evaporation on (thermal evaporation ion mass spectrometer) yields ages ranging from 2814 Ma to 1992 Ma. The age discrepancy among these different zircon types is conspicuous. The yellow‐brown (type 1) zircons give ages of 2814±29 Ma to 2527±6 Ma, the prismatic euhedral zircons (type 2), 2456±7 Ma to 2254±4 Ma, and the round multifaceted zircons (type 3), 1992±10 Ma. The results are geologically interpreted in consideration of the complicated behaviours of zircons during Precambrian geological evolution of the Dabie area. (1) If the protolith of the gneiss is a sedimentary rock, then type 1 zircons are clastic ones and the ages 2814±29 Ma and 2811±27 Ma may reflect the minimum age of the rocks of its source region, also the first geological event in the area. Sedimentation of the protolith occurred between 2814 Ma and 2527 Ma, probably close to 2814 Ma. If the protolith is a volcanic rock, then the formation age of the supracrustal rocks of the Dabie Group Complex is around 2814 Ma. The age 2456±7 Ma reflects the time when the granulite‐facies metamorphism took place. The later migmatization event is dated at about 1992±10 Ma, and is probably the latest early Precambrian event in the area.

The present work provides geochronological evidence for the existence of the Dabie Archaean craton, which had probably experienced 3 or 4 geological events during its early Precambrian evolution.
Episodic Carbonate Deposits on the Triassic Continental Slope in Southern China
Authors: Zhidong Bao
Published: October 2010

Abstract Episodic carbonate deposits on the Triassic continental slope in southern China are mainly composed of gravity‐flow limestones and contourite limestones. Gravity‐flow limestones were well developed in the lower and middle Yangtze area in the Early Triassic and in the Yunnan‐Guizhou‐Guangxi area in the Early and Middle Triassic. Five fundamental types of gravity‐flow limestones are recognized: slide limestone, debris‐flow limestone, grain‐flow limestone, turbidite limestone and rockfall limestone. They form six types of assemblage beds: slide‐debris‐flow limestones, slide‐debris‐flow‐turbidite limestone, slide‐debris‐flow‐grain‐flow‐turbidite limestone, rockfall‐debris‐flow limestone, debris‐flow‐turbidite limestone, and debris‐flow‐grain‐flow‐turbidite limestone. The first two were formed mainly in the Early Triassic slopes. The Middle Triassic slopes were characterized by widespread rockfall limestone. Growth faults, storms, earthquakes and oversteepened slopes are considered to be the probable triggers of the gravity flows.

Contourite limestones appear as isolated lenses or thin and ripple‐laminated beds of grainstones occurring in hemipelagic argillaceous limestones and lime mudstones. They were formed at the base of the slope. Palaeocurrent data indicate that the contour currents are perpendicular to the slope. The contourite limestones are not as common as the gravity‐flow ones, but they are important in the reconstruction of the palaeogeographical and palaeotectonic settings in southern China.
Chronostratigraphic Subdivision and Correlation of the Permian in China
Authors: Yugan JIN , Qinghau SHANG , Xiangdong WANG , Yue WANG , Jinzhang SHENG
Published: October 2010

Abstract Since the principle of multiple stratigraphic classification has been widely accepted by Chinese stratigraphers, various new Permian chronostratigraphic units have been proposed in China, and they need to be redefined. The establishment of a new global chronostratigraphic scheme of the Permian, compilation of Permian lithostratigraphic units and updating of Permian biostratigraphic sequences of China makes it possible to present a revised regional chronostratigraphic succession for the Permian System in China. This succession consists of three series and eight stages. The Chuanshanian Series includes two stages, the Zisongian and the Longlinian; the Yanghsinian (Yangxinian) Series is subdivided into the Chihsian (Qixiaan) and the Maokouan Subseries, of which the former comprises the Luodianian and the Xiangboan Stage, and the latter the Kufengian (Gufengian) and the Lengwuan Stage; the Lopingian (Lepingian) Series includes the Wuchiapingian (Wujiapingian) and the Changhsingian (Changxingian) Stage.
Kinematic History and Changes in the Tectonic Stress Regime during the Cenozoic along the Qinling and Southern Tanlu Fault Zones
Authors: Yueqiao ZHANG , Vergèly Pierre , Mercier Jacques‐Louis , Yongmin WANG , Yong ZHANG , Dezhi HUANG
Published: October 2010

Since the mid‐late Eocene, North China has been subjected to extensional stress, resulting in the formation and development of basins. The dynamic origin of this crustal extension has long been an issue of debate. This paper presents the results of kinematic analyses of faults obtained from two seperated areas in North China. In the Weihe graben situated on the southernmost margin of the Ordos block, analyses of fault kinematics were coupled with an analysis of the basin's subsidence history. Three successive extensional tectonic phases accompaning the basin's formation and development have been distinguished. The Palaeogene extension was oriented in a WNW‐ESE direction; the Neogene extension in a NE‐SW direction and the Pliocene‐Quaternary extension in a NW‐SE direction. Such changes have also been recorded by fault kinematics along the southern Tanlu fault zone. This has been demonstrated by three successive sets of fault striations indicating normal dip slip resulting from NW‐SE extension, then left‐lateral slip with a normal component resulting from NE‐SW extension, and right‐lateral slip with a minor normal component, respectively. The kinematic history of faults and their chronological evolution indicate changes in continental dynamics acting in North China over Cenozoic time.
Grey Prediction of Seismic Activity in the Three Gorges Area of the Yangtze River
Authors: Daogong HU , Shuren WU , Chengxuan TAN
Published: October 2010

On the basis of historical earthquake data and recent observations, two grey models prediction of the next seismic active period and the maximal magnitude of earthquakes which might occur during that period are constructed on the basis of the grey theory. As predicted by the two models, the next seismic active period would last 79 years, and that the maximal magnitude of earthquakes occurring within the period would not exceed 5.2. These results provide an important basis for the assessment of earthquake risks and reduction of disasters in the Three Gorges area.
Geomagnetic Polarity Events in China since 2.48 Ma
Authors: Tongming GE , Jian LIU , Limin FAN
Published: October 2010

This paper presents the results of palaeomagnetic studies of Cenozoic volcanic rocks and Quaternary strata in China, which have confirmed the occurence of some short‐period polarity events. After a correlation with the worldwide palaeomagnetic data, a geomagnetic polarity time scale for the time since 2.48 M*** has been compiled.
Fatigue Testing and S-N Data for Fatigue Analysis of Piles
Authors: Lotsberg Inge , Wästberg Stig , Ulle Hugo , Haagensen Per , Hall Michael E.
Published: October 2010

Design S-N curves in design codes are based on fatigue test data, where the stress cycle is under external tension load. It is observed that during pile driving most of the stress cycle is compressive and the design procedure used for fatigue analysis of piles might therefore be conservative. In order to investigate this further, it was proposed to perform laboratory fatigue testing of specimens that are representative for butt welds in piles under relevant loading conditions. In the present project 30 test specimens made from welded plates were fatigue tested at different loading conditions to assess effect of compressive stress cycles as compared with tensile stress cycles. In 2006, the Edda tripod in block 2/7 was taken ashore. This platform has been in service since 1976 and the piles are considered to be representative for the piles installed in the North Sea jacket structures during the 1970s. Therefore it was suggested to investigate the pile weld at the sea bed in detail to assess the stress due to fabrication and 30 years of in-service life and the residual fatigue life of the pile. Six test specimens made from the Edda pile were fatigue tested. The results from the assessment and the fatigue testing are presented in this paper.
Extreme Value Statistics of Wind Speed Data by the POT and ACER Methods
Authors: Naess A. , Haug E.
Published: October 2010

The paper describes a novel method for predicting the appropriate extreme value distribution derived from an observed time series. The method is based on introducing a cascade of conditioning approximations to the exact extreme value distribution. This allows for a rational way of capturing dependence effects in the time series. The performance of the method is compared with that of the peaks-over-threshold method.
Dynamic Analysis of Deep Water Tension Leg Platforms Under Random Waves
Authors: Jayalekshmi R. , Sundaravadivelu R. , Idichandy V. G.
Published: October 2010

The effect of tether-riser dynamics on the response characteristics of deep water tension leg platforms in water depths 900 m and 1800 m under random waves is investigated using a developed nonlinear finite element analysis program in the time-domain. Updated Lagrangian coordinates and incremental iterative solution based on Newmark’s integration scheme are adopted. Linear wave theory is used. Relative velocity form of Morison’s equation is used for estimating the wave forces. Current forces are also included in the analysis. Results are reported in the form of statistical values of responses. The statistical values of responses are found to increase with water depth and significant increase is observed when risers are included.
Plastic Buckling of Conical Shells
Authors: Błachut J. , Ifayefunmi O.
Published: October 2010

This paper studies the static stability of metal cones subjected to combined, simultaneous action of the external pressure and axial compression. Cones are relatively thick; hence, their buckling performance remains within the elastic-plastic range. The literature review shows that there are very few results within this range and none on combined stability. The current paper aims to fill this gap. Combined stability plot, sometimes called interactive stability plot, is obtained for mild steel models. Most attention is given to buckling caused by a single type of loading, i.e., by hydrostatic external pressure and by axial compression. Asymmetric bifurcation bucklings, collapse load in addition to the first yield pressure and first yield force, are computed using two independent proprietory codes in order to compare predictions given by them. Finally, selected cone configurations are used to verify numerical findings. To this end four cones were computer numerically controlled-machined from a solid steel billet of 252 mm in diameter. All cones had integral top and bottom flanges in order to mimic realistic boundary conditions. Computed predictions of buckling loads, caused by external hydrostatic pressure, were close to the experimental values. But similar comparisons for axially compressed cones are not so good. Possible reasons for this disparity are discussed in the paper.
Mitigation of Vortex-Induced Motion (VIM) on a Monocolumn Platform: Forces and Movements
Authors: Gonçalves Rodolfo T. , Fujarra André L. C. , Rosetti Guilherme F. , Nishimoto Kazuo
Published: October 2010

A great deal of works has been developed on the spar vortex-induced motion (VIM) issue. There are, however, very few published works concerning VIM of monocolumn platforms, partly due to the fact that the concept is fairly recent and the first unit was only installed last year. In this context, a meticulous study on VIM for this type of platform concept is presented here. Model test experiments were performed to check the influence of many factors on VIM, such as different headings, wave/current coexistence, different drafts, suppression elements, and the presence of risers. The results of the experiments presented here are motion amplitudes in both in-line and transverse directions, forces and added-mass coefficients, ratios of actual oscillation and natural periods, and motions in the XY plane. This is, therefore, a very extensive and important data set for comparisons and validations of theoretical and numerical models for VIM prediction.
Microfluidic Fuel Cells as Microscale Power Sources and Analytical Platforms
Authors: Brushett Fikile R. , Hollinger Adam S. , Markoski Larry J. , Kenis Paul J. A.
Published: October 2010

A continuously growing need for high energy density miniaturized power sources for portable electronic applications has spurred the development of a variety of microscale fuel cells. For portable applications, membrane-based fuel cells using small organic fuels (i.e., methanol, formic acid) are among the most promising configurations as they benefit from the high energy density and easy storage of the liquid fuels. Unfortunately, the performance of these fuel cells is often hindered by membrane-related issues such as water management (i.e., electrode dry-out / flooding) and fuel crossover. Furthermore, high costs of, for example, catalysts and membranes as well as durability concerns still hinder commercialization efforts. To address these challenges we have developed membraneless laminar flow-based fuel cells (LFFCs), which exploit microscale transport phenomena (laminar flow) to compartmentalize streams within a single microchannel. The properties of various fuel and media flexible LFFCs will be presented and novel strategies for improving fuel utilization and power density will be discussed. Furthermore, the performance of a scaled-out 14-channel LFFC prototype is presented. We have also developed a microfluidic fuel cell as a powerful analytical platform to investigate and optimize the complex processes that govern the performance of catalysts and electrodes in an operating fuel cell. This platform bridges the gap between a conventional 3-electrode electrochemical cell and a fuel cell, as it allows for standard electrochemical analysis (e.g., CV, CA, EIS) as well as fuel cell analysis (e.g., IV curves).
Monte Carlo Simulations of Phonon Backscattering in Low-Sized Nanowires
Authors: Wang Zan , Chen Yunfei , Li Jiapeng , Zhao Ruijie , Zhao Yanyan
Published: October 2010

Monte Carlo model is used to study the roughness effects on lattice thermal conductivity of silicon nanowires. Based on the Matthiessen’s rule, a roughness influence coefficient is adopted to amend the relaxation time. Individual silicon nanowires growing by vapour-liquid-solid method are different from those making by aqueous electroless etching method in the surface roughness, which are both simulated over a temperature range of 15–315K with various equivalent diameters. The results are close to the laboratory data, proving the validity of the MC model and showing the effects of surface roughness on thermal transport decrease with the increasing of equivalent diameter.
A Stabilized Boiling/Evaporation Two-Phase Flow in Microchannels
Authors: Li Ji , Peterson G. P. , Li Chen , Su Guoguang
Published: October 2010

The high degree of instability in boiling two-phase flow in parallel microchannels is a widely recognized phenomenon. However, if the maldistribution of flow is eliminated and the generated vapor is discharged smoothly through the careful design of the inlet and outlet plenums, in addition, by using part of each channel as a virtual throttle to depress the flow excursions, some of these instabilities can be reduced or eliminated. Furthermore, with the aid of the capillarity resulting from the phase change in the microchannels, the current investigation indicates that boiling/evaporation two-phase flow in parallel microchannels with the proposed unique structure will result in a highly stable flow in terms of the overall flow characteristics, with only small oscillations inside the individual channels. This highly stable flow will facilitate the implementation of boiling/evaporation two-phase flow in the thermal management of microelectronics devices and in the miniaturization of two-phase power devices.
Nanofluids by Quantum Mechanics
Authors: Prevenslik Thomas
Published: October 2010

The enhanced heat transfer of nanofluids is shown not to be caused by the increase in thermal conductivity based on the concentration of nanoparticles (NPs) given by the longstanding Hamilton and Crosser (HC) mixing rules. Instead, heat transfer is enhanced because quantum mechanics (QM) restricts the specific heat of NPs to vanish, the consequence of which is that thermal kT energy absorbed from collisions of solvent molecules cannot be conserved by an increase in temperature. Conservation may only proceed by the QED induced up-conversion of the low frequency absorbed kT energy to the EM frequency of the NP, typically in the VUV. Here EM stands for electrodynamics, QED for quantum electrodynamics, and VUV for vacuum ultraviolet. The EM confinement is quasi-bound so that the VUV radiation promptly leaks from the NPs. Classically, collisions increase the NP temperature with EM emission occurring in the far infrared (FIR) that is absorbed with little penetration at the NP surface. But the VUV is absorbed at large penetrations, thereby enhancing heat transfer in proportion to the number of NPs without increasing the nanofluid conductivity — the process called QED induced heat transfer. Nanofluid conductivity given by the HC mixing rules for NPs in solvents is still valid and need not be modified.
Fouling Risk Using Micro-Tube Heat Exchangers in a Power Generation System
Authors: Dai Chuanshan , Wang Qiu Xiang , Sun Ping Le
Published: October 2010

A micro-tube heat exchanger has a large area-volume ratio and is more compact than traditional heat exchangers with larger diameter tubes. This makes it increasingly attractive to be applied in a power generation system. However, the clogging risk and the decreasing of heat transfer coefficient due to fouling are the two major disadvantages in obstructing its real applications. This paper proposed a theoretical model for evaluating the fouling risk while micro-tube heat exchangers are to be utilized in a power generation system. The drawdown of overall heat transfer coefficient and increment of flowing drag are numerically simulated. The size effect of micro-tube heat exchangers on power generation and optimum selection of tube diameter are also discussed.
Effect of Diamond Nanolubricant on R134a Pool Boiling Heat Transfer
Authors: Kedzierski Mark A.
Published: October 2010

This paper quantifies the influence of diamond nanoparticles on the pool boiling performance of R134a/polyolester mixtures on a roughened, horizontal, flat surface. Nanofluids are liquids that contain dispersed nano-size particles. A lubricant based nanofluid (nanolubricant) was made by suspending 10 nm diameter diamond particles in a synthetic ester to roughly a 2.6% volume fraction. For the 0.5% nanolubricant mass fraction, the nanoparticles caused a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) as large as 129% for the best performing tests. A similar enhancement was observed for the R134a/nanolubricant (99/1) mixture, which had a heat flux that was on average 91% larger than that of the R134a/polyolester (99/1) mixture. Further increase in the nanolubricant mass fraction to 2% resulted in boiling heat transfer degradation of approximately 19% for the best performing tests. It was speculated that the poor quality of the nanolubricant suspension caused the performance of the (99.5/0.5), and the (98/2) nanolubricant mixtures to decay over time to, on average, 36% and 76% of the of pure R134a/polyolester performance, respectively. Thermal conductivity and viscosity measurements and a refrigerant\lubricant mixture pool-boiling model were used to suggest that increases in thermal conductivity and lubricant viscosity are mainly responsible for the heat transfer enhancement due to nanoparticles. Particle size measurements were used to suggest that particle agglomeration induced a lack of performance repeatability for the (99.5/0.5) and the (98/2) mixtures. From the results of the present study, it is speculated that if a good dispersion of nanoparticles in the lubricant is not obtained, then the agglomerated nanoparticles will not provide interaction with bubbles, which is favorable for heat transfer. Further research with nanolubricants and refrigerants are required to establish a fundamental understanding of the mechanisms that control nanofluid heat transfer.
Numerical Simulation of Multiple Seeds Interaction During Three-Dimensional Dendritic Solidification With Fluid Flow
Authors: Yoon Ikroh , Shin Seungwon
Published: October 2010

Most material of engineering interest undergoes solidification process from liquid to solid state which governs the microstructure of materials. Identifying the growth characteristic of the microstructure during the solidification process is essential to determine the physical properties of final product. Numerical simulation can provide valuable information during solidification process since heat and mass transfer associated with micro-structural growth of dendrite is in greatly small scale which is almost impossible to obtain by experiments. In real situations, dendrite tends to grow from multiple seeds as well as with external fluid flow. Growth characteristics of the dendrites will be greatly influenced by both external fluid convection and interaction between dendrites. In this paper, three-dimensional numerical simulation of multiple dendritic growth during solidification process with melt fluid convection is presented. The high-order Level Contour Reconstruction Method (LCRM), a hybrid form of Front-Tracking and Level-Set, is used to track the moving liquid-solid interface explicitly and sharp interface technique has been used to implement correct phase changing boundary conditions on the moving interface. To get the indicator function and the interface curvature more efficiently and accurately for three-dimensional simulation, we have generated the distance function directly from the interface. The method is validated by comparing with other numerical technique and showed good agreements. Three-dimensional results showed clear difference compared to two-dimensional simulation on growth behavior, especially with multiple seeds.
Phase-Change Nanofluids With Enhanced Thermophysical Properties
Authors: Han Zenghu , Yang Bao , Liu Yung Y.
Published: October 2010

The colloidal dispersion of solid nanoparticles (1–100nm) has been shown experimentally to be an effective way to enhance the thermal conductivity of heat transfer fluids. Moreover, large particles (micrometers to tens of micrometers) of phase-change materials have long been used to make slurries with improved thermal storage capacity. Here, a hybrid concept that uses nanoparticles made of phase-change materials is proposed to simultaneously enhance the effective thermal conductivity and the effective heat capacity of fluids. Water-in-perfluorohexane nanoemulsion fluids and indium-in-polyalphaolefin nanofluids are examples of fluids that have been successfully synthesized for experimental studies of their thermophysical properties (i.e., thermal conductivity, viscosity, and heat capacity) as functions of particle loading and temperature. The thermal conductivity of perfluorohexane was found to increase by up to 52% for nanoemulsion fluids containing 12 vol. % water nanodroplets with a hydrodynamic radius of ∼10 nm. Also observed in water-in-perfluorohexane nanoemulsion fluids was a remarkable improvement in effective heat capacity, about 126% for 12 vol. % water loading, due to the melting-freezing transitions of water nanodroplets to ice nanoparticles and vice versa. The increases in the thermal conductivity and dynamic viscosity of these nanoemulsion fluids were found to be highly nonlinear against water loading, indicating the important roles of the hydrodynamic interaction and the aggregation of nanodroplets. For indium-in-polyalphaolefin nanofluids, the thermal conductivity enhancement increases slightly with increasing temperature (i.e., about 10.7% at 30°C to 12.9% at 90°C) with a nanoparticle loading of 8 vol. %. The effective volumetric heat capacity can be increased by about 20% for the nanofluids containing 8 vol. % indium nanoparticles with an average diameter of 20 nm. Such types of phase-change nanoemulsions and nanofluids possess long-term stability and can be mass produced without using as-prepared nanoparticles. The observed melting-freezing phase transitions of nanoparticles of phase-change materials (i.e., water nanodroplets and indium nanoparticles) considerably augmented the effective heat capacity of the base fluids. The use of phase-change nanoparticles would thus provide a way to substantially enhance the thermal transport properties of conventional heat transfer fluids. Future development of these phase-change nanofluids is expected to open new opportunities for studies of thermal fluids.
A Modified Thermal Boundary Resistance Model for FCC Structures
Authors: Zhao Ruijie , Chen Yunfei , Bi Kedong , Lin Meihui , Wang Zan
Published: October 2010

A modified lattice-dynamical model is proposed to calculate the thermal boundary resistance at the interface between two fcc lattices. The nonequilibrium molecular dynamics (MD) simulation is employed to verify the theoretical calculations. In our physical model, solid crystal argon is set at the left side and the right side structure properties are tunable by setting the atomic mass and the interactive energy strength among atoms with different values. In the case of mass mismatch, the predictions of the lattice-dynamical (LD) model agree well at low temperature while the calculations of the diffuse mismatch model (DMM) based on the detailed phonon dispersion agree well at high temperature with the MD simulations. The modified LD model, considering a partially specular and partially diffuse phonon scattering, can explain the simulations reasonably in the whole temperature rage. The good agreement between the theoretical calculations and the simulations may be attributed to that phonon scattering mechanisms are dominated by elastic scattering at the perfect interfaces. In the case of interactive energy strength mismatch, the simulations are under the predictions of both the theoretical models, which may be attributed to the fact that this mismatch can bring about an outstanding contribution to opening up an inelastic channel for heat transfer at the interfaces.
Investigations of Femtosecond-Nanosecond Dual-Beam Laser Ablation of Dielectrics
Authors: Rao Z. H. , Lin C. H. , Jiang L. , Tsai W. J. , Wu P. H. , Chien C. W. , Tsai H. L.
Published: October 2010

A multi-scale (in temporal domain) model was developed to study the ablation of dielectrics using a femtosecond (fs)-nanosecond (ns) dual-beam laser system. The model is an integration of the plasma model and improved two-temperature model for the fs laser ablation, and Fourier’s law for the ns laser ablation. The model is used to investigate the ablation for dielectrics when a fs pulse is shot at the peak of a ns pulse. It is found that the fs laser pulse can result in the increase of absorption of the ns laser energy, leading to a much higher material removal rate as compared to fs laser ablation alone or ns laser ablation alone. The enhancement of ns laser energy absorption is caused by the increased electron density and the formation of a tiny crater in the material created by the fs laser pulse. The corresponding experiment using a Ti:Sapphire fs laser (Legend-F, Coherent) and a Nd:YAG ns UV laser (Avia-X, Coherent) was also conducted and the results are consistent with the modeling predictions.
Proper Cell Dimension and Number of Particles Per Cell for DSMC
Authors: Sun Z. X. , He Y. L. , Tao W. Q.
Published: October 2010

Different opinions still exist on some basic principles of DSMC method, such as the proper grid dimension and the proper number of particles in a cell. In this paper DSMC simulation of Poiseuille flow is made to evaluate the dependence of simulation results on cell dimension and number of particles per cell. In the simulation process a self adapting block structured grid system is employed to make sure that the number of particles per cell is constant. The simulation covers both slip flow regime and transition flow regime and each regime covers both high pressure and low pressure. Our simulation results indicate that the number of particles per cell and scaling factor exert little influence on simulation result for both slip flow and transition flow when the number of particles per cell surpasses 5, but the dimension of cell influences the accuracy of result obviously. The error caused by cell dimension decreases as the diminish of cell dimension. It is concluded that in the DSMC method it is necessary to make sure that the cell is less than 1/2 of molecular mean free path.