bluuebunny/crossref_metadata_2025 huggingface dataset:
Intellectual development after treatment in children with acute leukemia and brain tumor
Authors: Watanabe Shizuka , Azami Yuriko , Ozawa Miwa , Kamiya Takahiro , Hasegawa Daisuke , Ogawa Chitose , Ishida Yasushi , Hosoya Ryota , Kizu Junko , Manabe Atsushi
Published: March 2011

Background:  The influence of central nervous system (CNS)‐directed chemotherapy on intelligence remains controversial. In this study, we investigated the influence of treatment on intellectual development in acute lymphoblastic leukemia (ALL) and brain tumor patients undergoing CNS‐directed treatments.

Methods:  Among patients treated in the Department of Pediatrics, St Luke's International Hospital between April 2000 and March 2009, the subjects were 38 patients with ALL or brain tumors who underwent regular Wechsler intelligence tests.

Results:  The subjects consisted of 26 patients with ALL and 12 with brain tumors. Prophylactic cranial irradiation was not performed in patients with ALL, whereas it was done for all those with brain tumor. In patients with ALL, the IQ 1 year later was not changed from the start of treatment. In those with brain tumors, the verbal IQ 1 year later was significantly lower than that at the start of treatment. In patients with ALL, intelligence tests were performed 3 years after the start of treatment and there were no marked changes between the two time‐points (n= 11). In those with a brain tumor, intellectual functions further decreased after the completion of treatment to as late as 5 years after the initiation of treatment (n= 7).

Conclusions:  There is no intellectual impairment in any patient with ALL at post‐treatment follow‐up 3 years after the start of treatment, while intelligence is serially reduced in brain tumor patients. An innovative intervention may be needed for this group of patients.
Referential communication tasks: performance by normal and pragmatically impaired children
Authors: LEINONEN EEVA , LETTS CAROLYN
Published: March 2011

Two groups of children, a pragmatically impaired (PI) group and a group of language‐normal (LN) age‐matched peers, were compared by use of a referential communication task. Experimenter and child both played the roles of listener and instructor during the task and, in addition, the experimenter sometimes failed to give adequate information when in the role of instructor. Lexical content and structural complexity were controlled, and it was hypothesised that difficulties for the PI group would arise when in the role of instructor, as a result of failing to specify necessary information in order for the experimenter to respond appropriately. In fact, the main difference between the two groups arose when the experimenter failed to give adequate information to the child; the LN children were quick to realise this and to request clarification, whereas the PI children requested clarification to a lesser extent and appeared less aware of the need to do so. Possible explanations for this pattern of results are explored.
Are your minimal pairs too neat? The dangers of phonemicisation in phonology therapy
Authors: GARDNER HILARY
Published: March 2011

Using Conversation Analysis (CA) to look at the interactional dynamics of therapy repair sequences, this paper shows exactly what happens for children when idealised misrepresentations of their phonology are used in therapy. The primary video extract involves a 4‐year‐old phonologically disordered boy and his therapist. It is not new to warn of the dangers of overlooking any subtle phonetic distinctions that the phonologically disordered child may have but this paper adds something new to the debate. The child's interpretation of the adult's prior turn in the sequence is made explicit and the likelihood of the child producing phonetic revision following an error is seen to be affected by the way the therapist chooses to initiate repair. This is especially true where a ‘redoing’ of the error is incorporated into such an initiation, when the child's phonetic output is ‘tidied up’ so that it fits in with the neat minimal pair which forms part of the therapy programme. This is one factor that can be seen to militate against appropriate phonetic repair by the child, especially when used in certain turn structures that are routinely associated with lexical rather than phonetic matters. When the adult ‘redoing’ more accurately reflects the child's output phonetic revision is more likely to occur. Implications for assessment and therapy are drawn from this evidence, with accurate phonological assessment and continuing interactional error analysis being recommended.
A Note on ‘The Limitations of School League Tables to Inform School Choice’
Authors: Leckie George , Goldstein Harvey
Published: March 2011

In earlier work, we showed that, for any given year, England’s secondary school league tables poorly predict schools’ future performances. We generalize our prediction formula to calculate predictions based on multiple years of school league table data and show that this does very little to improve precision. This reinforces the conclusion of our earlier work: school league tables are unreliable and misleading guides for school choice and that this is still the case even if several years of school league table data are considered.
Gifts, talismans and tokens in analysis: symbolic enactments or sinister acts?
Authors: Schaverien Joy
Published: March 2011

Abstract:  Analysis is nuanced with many non‐verbal cues and interactions. This is vividly illustrated when gifts are presented to the analyst. Their physical presence transcends the symbolic frame of analysis because, although their meaning may be metaphorical, their presence is real. Unlike other material objects and pictures, the gift may seem to invite the analyst to receive it personally. It may apparently demand some form of action. A gift may be consciously given as a token, or it may be magically invested as a talisman. On the surface, it might appear to be an expression of love; it may be a communication of a wish for acceptance; but it may have more ‘sinister’, unconscious intent. It may embody the wish to expel unwanted affect, ward off evil or control the analyst. Therefore disposal, that is the resolution and settling of the object, is significant. The case with which this paper is illustrated traces the meaning of a series of gifts in a single analysis. It is hoped that this will enhance a wider understanding of this common analytic phenomenon.
A visit paid to Jung by Alwine von Keller
Authors: Bernardini Riccardo , Quaglino Gian Piero , Romano Augusto
Published: March 2011

Abstract:  In the winter of 1943–1944, Jung had suffered a coronary thrombosis which almost cost him his life. During his illness, Jung experienced a series of visions, described in his Memories, Dreams, Reflections, which were also to influence significantly the development of his theoretical thinking. On 27th September 1944, Alwine von Keller (1878–1965) paid a visit to Jung, while he was still convalescing, in Zurich and documented her meeting with him in a series of notes, recently discovered, which testify to the fact that, at the time of their meeting, Jung was engaged in writing the ‘Salt’ chapter of Mysterium coniunctionis and investigating the alchemistic symbolism of the ‘sea’. This theme seems to testify to a continuity of interests on Jung's part with the seminar he held at Eranos the previous year on the cartographic art of Opicinus de Canistris (1296‐c.1352). With its addition of many unpublished details, Alwine von Keller's notes supplement the report which Jung made of his visions experienced during his sickness in MDR. In particular, these attest to the fact that Jung had attributed the terrible experience which he had endured to the problem of the conjunctio, which was confronting him from the theoretical point of view in his writing of Mysterium coniunctionis.
The calcium‐sensing receptor and calcimimetics in blood pressure modulation
Authors: Smajilovic Sanela , Yano Shozo , Jabbari Reza , Tfelt‐Hansen Jacob
Published: March 2011

Calcium is a crucial second messenger in the cardiovascular system. However, calcium may also be an extracellular first messenger through a G‐protein‐coupled receptor that senses extracellular concentration (Ca2+o), the calcium‐sensing receptor (CaR). The most prominent physiological function of the CaR is to maintain the extracellular Ca2+ level in a very tight range by regulating the circulating levels of parathyroid hormone (PTH). This control over PTH and Ca2+ levels is partially lost in patients suffering from primary and secondary hyperparathyroidism. Allosteric modulators of the CaR (calcimimetics) are the first drugs in their class to become available for clinical use and have been shown to successfully treat certain forms of primary and secondary hyperparathyroidism. In addition, several studies suggest beneficial effects of calcimimetics on cardiovascular risk factors associated with hyperparathyroidism. Although a plethora of studies demonstrated the CaR in heart and blood vessels, exact roles of the receptor in the cardiovascular system still remain to be elucidated. However, several studies point toward a possibility that the CaR might be involved in the regulation of vascular tone. This review will summarize the current knowledge on the possible functions of the CaR and calcimimetics on blood pressure regulation.

LINKED ARTICLES This article is part of a themed issue on Vascular Endothelium in Health and Disease. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.164.issue‐3
Acetaminophen hepatotoxicity and repair: the role of sterile inflammation and innate immunity
Authors: Jaeschke Hartmut , Williams C. David , Ramachandran Anup , Bajt Mary L.
Published: March 2011

Acetaminophen (APAP) hepatotoxicity because of overdose is the most frequent cause of acute liver failure in the western world. Metabolic activation of APAP and protein adduct formation, mitochondrial dysfunction, oxidant stress, peroxynitrite formation and nuclear DNA fragmentation are critical intracellular events in hepatocytes. However, the early cell necrosis causes the release of a number of mediators such as high‐mobility group box 1 protein, DNA fragments, heat shock proteins (HSPs) and others (collectively named damage‐associated molecular patterns), which can be recognized by toll‐like receptors on macrophages, and leads to their activation with cytokine and chemokine formation. Although pro‐inflammatory mediators recruit inflammatory cells (neutrophils, monocytes) into the liver, neither the infiltrating cells nor the activated resident macrophages cause any direct cytotoxicity. In contrast, pro‐ and anti‐inflammatory cytokines and chemokines can directly promote intracellular injury mechanisms by inducing nitric oxide synthase or inhibit cell death mechanisms by the expression of acute‐phase proteins (HSPs, heme oxygenase‐1) and promote hepatocyte proliferation. In addition, the newly recruited macrophages (M2) and potentially neutrophils are involved in the removal of necrotic cell debris in preparation for tissue repair and resolution of the inflammatory response. Thus, as discussed in detail in this review, the preponderance of experimental evidence suggests that the extensive sterile inflammatory response during APAP hepatotoxicity is predominantly beneficial by limiting the formation and the impact of pro‐inflammatory mediators and by promoting tissue repair.
The Limits of Hermeticity Test Methods for Micropackages
Authors: Vanhoestenberghe Anne , Donaldson Nick
Published: March 2011

Hermeticity is crucial for the long‐term implantation of electronic packages. Pushed by advances in micromachining, package volumes are decreasing and current leak detection methods are no longer sensitive enough. This article reviews the limits of the most common methods and exposes their inadequateness for medical electronic applications where the device's life is 50 years or longer.
Current‐Distance Relations for Microelectrode Stimulation of Pyramidal Cells
Authors: Wenger Cornelia , Paredes Liliana , Rattay Frank
Published: March 2011

Microelectrodes placed within the densely packed cortical neuronal region are surrounded by many thin processes. Although dendrites are considered to be functionally different to axons, they also possess voltage sensitive membrane channels. Therefore, dendritic regions are suitable candidates for spike initiation sites when stimulated externally, although they demand two to three times higher thresholds in comparison with thin axons. Simulations based upon recently reported distributions of two types of sodium channels and traced pyramidal cell data accompanied by a simplified model structure enlightened the spike initiation sites for extracellular cortical microstimulation and revealed insights into dendritic excitation patterns. Surprisingly low dendritic threshold values for cathodic stimulation were detected, that is, 3.3 µA for a 0.4‐µm diameter fiber excited with a 100‐µs pulse in 4‐µm distance. However, according to the activating function concept the excited region is calculated by 1414*electrode‐distance, therefore a minimum electrode‐fiber distance is required as sufficient sodium channels are needed to produce enough intracellular current for spike conduction. The minimum distance for dendritic spike initiation increases with diameter and hinders low current stimulation of thick dendrites. This effect is in contrast to the inverse recruitment order known from functional electrical stimulation. Simulations were performed using NEURON and MATLAB.
Sleep Optimizes Motor Skill in Older Adults
Authors: Tucker Matthew , McKinley Sophia , Stickgold Robert
Published: March 2011

OBJECTIVES: To determine whether sleep benefits motor memory in healthy elderly adults and, if so, whether the observed sleep‐related benefits are comparable with those observed in healthy young adults.

DESIGN: Repeated‐measures cross‐over design.

SETTING: Boston, Massachusetts (general community) and Harvard University.

PARTICIPANTS: Sixteen healthy older and 15 healthy young participants.

MEASUREMENTS: Motor sequence task (MST) performance was assessed at training and at the beginning and end of the retest session; polysomnographic sleep studies were recorded for the elderly participants.

RESULTS: After 12 hours of daytime wakefulness, elderly participants showed a dramatic decline in MST performance on the first three retest trials, and only a nonsignificant improvement by the end of retest (the last 3 retest trials). In contrast, when the same participants trained in the morning but were retested 24 hours after training, after a day of wake plus a night of sleep, they maintained their performance at the beginning of retest and demonstrated a highly significant 17.4% improvement by the end of the retest session, essentially identical to the 17.3% improvement seen in young participants. These strikingly similar improvements occurred despite the presence of other age‐related differences, including overall slower motor speed, a lag in the appearance of sleep‐dependent improvement, and an absence of correlations between overnight improvement and sleep architecture or sleep spindle density in the elderly participants.

CONCLUSION: These findings provide compelling evidence that sleep optimizes motor skill performance across the adult life span.
Selective predation of threespine stickleback by rainbow trout
Authors: Lescak Emily A. , von Hippel Frank A.
Published: March 2011

Abstract – Threespine stickleback (Gasterosteus aculeatus) with divergent pelvic phenotypes from Wallace Lake, Alaska, were exposed to rainbow trout (Oncorhynchus mykiss) to test for selective predation. Trout more often successfully preyed upon individuals with pelvic reduction, which supports the hypothesis that robust pelvic girdles are maintained in stickleback populations because of selection by fish predators. Stickleback with complete pelvic girdles experienced a higher incidence of wounds from unsuccessful predation attempts, although this finding was not statistically significant, possibly because of low frequencies of wounded individuals. Spines likely facilitate postcapture defence, although stickleback with spines may also be less targeted by trout. This study supports the hypothesis that stocked rainbow trout pose a conservation threat to pelvic‐reduced stickleback populations.
Morphological evaluation of cranial and maxillary shape differences of the brachymorphic mouse with spontaneous malocclusion using three‐dimensional micro‐computed tomography
Authors: Saito F , Kajii TS , Sugawara‐Kato Y , Tsukamoto Y , Arai Y , Hirabayashi Y , Fujimori O , Iida J
Published: March 2011

To cite this article:
 Saito F, Kajii TS, Sugawara‐Kato Y, Tsukamoto Y, Arai Y, Hirabayashi Y, Fujimori O, Iida J:  Morphological evaluation of cranial and maxillary shape differences of the brachymorphic mouse with spontaneous malocclusion using three‐dimensional micro‐computed tomography  Orthod Craniofac Res 2011;14:100–106

Structured Abstract

Authors –  Saito F, Kajii TS, Sugawara‐Kato Y, Tsukamoto Y, Arai Y, Hirabayashi Y, Fujimori O, Iida J

Objectives –  The aim of this study was to determine whether significant cranial and maxillary deformity exists in BALB/c‐bm/bm (brachymorphism) mouse with spontaneous malocclusion using three‐dimensional (3D) images.

Materials and Methods –  Thirty female mice were divided into the following three groups: control group (BALB/c mice, n = 10), Norm group (BALB/c‐bm/bm mice with normal occlusion, n = 10), and Mal group (BALB/c‐bm/bm mice with malocclusion, n = 10). Nine points in the skull were selected, and transverse and antero‐posterior distances were measured using three‐dimensional images of micro‐computed tomography (CT). Moreover, 3D images were superimposed at the median plane to visualize the skull shape asymmetry.

Results –  The transverse distances at the posterior cranial and maxillary region and the antero‐posterior distances in the Norm and Mal groups were significantly shorter than those in the control group. The nasal septum of the Mal group was significantly shorter than that of the Norm group. Morphological measurements and superimposed 3D images showed that lateral deviation occurred at the anterior cranial and maxillary region in the Mal group.

Conclusion –  The 3D micro‐CT images revealed that the antero‐posterior length and posterior transverse width at the cranium and maxilla in BALB/c‐bm/bm mice were significantly smaller than those in BALB/c mice. It was quantitatively and morphologically clear that BALB/c‐bm/bm mice show a spontaneous transverse crossbite owing to lateral deviation of the maxilla and nasal bone.
Dermis‐derived stem cells: a source of epidermal melanocytes and melanoma?
Authors: Zabierowski Susan E. , Fukunaga‐Kalabis Mizuho , Li Ling , Herlyn Meenhard
Published: March 2011

Human multipotent dermal stem cells (DSCs) have been isolated and propagated from the dermal region of neonatal foreskin. DSCs can self‐renew, express the neural crest stem cell markers NGFRp75 and nestin, and are capable of differentiating into a wide variety of cell types including mesenchymal and neuronal lineages and melanocytes, indicative of their neural crest origin. When placed in the context of reconstructed skin, DSCs migrate to the basement membrane zone and differentiate into melanocytes. These findings, combined with the identification of NGFRp75‐positive cells in the dermis of human foreskin, which are devoid of hair, suggest that DSCs may be a self‐renewing source of extrafollicular epidermal melanocytes. In this review, we discuss the properties of DSCs, the pathways required for melanocyte differentiation, and the value of 3D reconstructed skin to assess the behavior and contribution of DSCs in the naturalized environment of human skin. Potentially, DSCs provide a link to malignant melanoma by being a target of UVA‐induced transformation.
Arthroscopic treatment of meniscal cysts in the horse
Authors: SPARKS H. D. , NIXON A. J. , BOENING K. J. , POOL R. R.
Published: March 2011

Reasons for performing study:To describe the clinical symptoms, treatment, and outcome of meniscal cysts in horses. These structures have not been previously described in the literature as a potential cause of lameness in the horse.

Hypothesis:Meniscal cysts are an uncommon condition of the femorotibial joint but can be a significant cause of lameness. Symptoms can be resolved by arthroscopic excision.

Methods:Records of horses diagnosed with meniscal cysts and treated by cyst excision and meniscal debridement at 2 surgical practices were reviewed. Clinical outcome was determined by repeat veterinary examination and contact with owner.

Results:Seven cases of meniscal cyst were treated with arthroscopic cyst excision and meniscal debridement. Five of 7 horses had lameness attributable to femorotibial joint pathology, while the remaining 2 horses had meniscal cysts found incidentally during diagnostic arthroscopy for the treatment of osteochondritis dissecans of the lateral trochlear ridge of the femur. Five of 6 horses with long‐term follow‐up were sound and a 7th horse was improved 11 months after surgery.

Conclusions and potential relevance:Meniscal cysts, while uncommon, can be associated with progressive lameness in the horse. Surgical excision of the cysts results in resolution or improvement of symptoms, without evidence of recurrence on follow‐up examination.
Amelioration of cerebral infarction and improvement of neurological deficit by a Korean herbal medicine, modified Bo-Yang-Hwan-O-Tang
Authors: Choi Yookeum , Kim Seul-Ki , Choi In-Young , Ju Chung , Nam Kung-Woo , Hwang Sunyoung , Kim Byung-Woo , Yoon Min Ji , Won Moo-Ho , Park Yong-Ki , Kim Won-Ki
Published: March 2011

Objectives

Modified Bo-Yang-Hwan-O-Tang (mBHT) is an improved herbal formula of BHT, which has been widely used to treat ischaemic stroke in East Asia, by the addition of five herbs having anti-ischaemic properties. In this study, we investigated whether mBHT would reduce cerebral ischaemic injury in rats.

Methods

Sprague–Dawley rats were subjected to a 90-min middle cerebral artery occlusion (MCAO) and subsequent 22-h reperfusion. mBHT was administered either intraperitoneally twice 15 min before and 15 min after, or orally once 30 min or 120 min after the onset of MCAO (50 or 200 mg/kg each).

Key findings

Intraperitoneal administration of mBHT markedly reduced the cerebral infarct size and neurological deficit caused by MCAO/reperfusion. mBHT treatment also significantly improved long-term survival rate after cerebral ischaemic injury. Oral administration of mBHT 30 min after ischaemia also markedly reduced the infarct size after cerebral ischaemia. The anti-ischaemic effect of mBHT was significantly, but not fully, reduced when mBHT-induced hypothermia was abolished. In cultured cortical neurons, we further found that mBHT decreased oxygen-glucose deprivation/re-oxygenation-evoked neuronal injury by inhibiting production of reactive oxygen species, decrease in mitochondrial transmembrane potential, and activation of caspase-3. However, mBHT did not inhibit N-Methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity.

Conclusions

Taken together, our data suggest that mBHT has multiple anti-ischaemic properties and would be a good therapeutic herbal prescription for the treatment of cerebral ischaemic stroke.
Who we were and who we will be: The temporal context of women's in‐group stereotype content
Authors: Morton Thomas A. , Rabinovich Anna , Postmes Tom
Published: March 2011

Research has elaborated considerably on the dimensions of out‐group stereotype content and on the origins and functions of different content combinations. Less attention has been given to the origins and functions of in‐group stereotype content. We argue that in‐group stereotypes are likely to serve different social identity functions, and thus attract different content, dependent on individual differences in in‐group identification and on the temporal perspective of the perceiver. Two studies (Ns = 43 and 93) found that women's in‐group stereotype content varied as a function of gender group identification and temporal perspective. When the past was primed, highly identified women generated stereotypes that emphasized the warmth (but not competence) of their group. When the future was primed, highly identified women generated stereotypes that emphasized the competence (as well as warmth) of their group. These results are discussed in terms of the use of stereotypes for social creativity versus social change.
Role of feedforward geniculate inputs in the generation of orientation selectivity in the cat's primary visual cortex
Authors: Viswanathan Sivaram , Jayakumar Jaikishan , Vidyasagar Trichur R.
Published: March 2011

Non technical summary  Neurones of the mammalian primary visual cortex have the remarkable property of being selective for the orientation of visual contours. It has been controversial whether this selectivity arises purely from mechanisms within the cortex itself, from the special way afferents from the thalamus project to the cortex or from the sharpening of a bias for orientation that already exists in the retina and the thalamus. Our experiments support the last of these three hypotheses. We used a special protocol to study both inhibitory and excitatory interactions within the cortex as well as in the thalamus and we find that the orientation selectivity may depend upon multiple mechanisms – including the thalamic biases for orientation and intracortical inhibition and excitation.
Dehydroepiandrosterone protects against oxidative stress‐induced endothelial dysfunction in ovariectomized rats
Authors: Camporez João Paulo Gabriel , Akamine Eliana Hiromi , Davel Ana Paula , Franci Celso Rodrigues , Rossoni Luciana Venturini , de Oliveira Carvalho Carla Roberta
Published: March 2011

Non‐technical summary  It is well known that cardiovascular disease is more frequent in postmenopausal than in premenopausal women. Moreover, it has been shown that dehydroepiandrosterone (DHEA), a steroid hormone secreted by adrenal glands, reduces during ageing. Its reduced plasma level has been related to increased prevalence of obesity, insulin resistance and cardiovascular disease. We show that DHEA treatment in ovariectomized rats, an experimental model of menopause, reduces blood pressure and improves vascular function. Furthermore, DHEA reduced reactive oxygen species (ROS), correcting the reduced protein expression of Cu/Zn‐SOD, an antioxidant protein, and increased protein expression of NADPH oxidase, a pro‐oxidant protein. This work shows the potential effect of DHEA upon correction of endothelial dysfunction observed on oestrogen deprivation.
Modeling of Thermoelastic Stress Wave in Laser-Assisted Cell Direct Writing
Authors: Wang Wei , Lin Yafu , Huang Yong
Published: March 2011

Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, cell injury due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when vaporization and/or optical breakdown of coating materials is/are not available. It is found that a bipolar pressure pair, with peak magnitudes on the order of 1 MPa or higher, has been developed within a finite thin coating medium. Shorter duration laser pulses lead to higher thermoelastic stresses. This study will help to understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.
Real-Time Knee Adduction Moment Feedback for Gait Retraining Through Visual and Tactile Displays
Authors: Wheeler Jason W. , Shull Pete B. , Besier Thor F.
Published: March 2011

The external knee adduction moment (KAM) measured during gait is an indicator of tibiofemoral joint osteoarthritis progression and various strategies have been proposed to lower it. Gait retraining has been shown to be an effective, noninvasive approach for lowering the KAM. We present a new gait retraining approach in which the KAM is fed back to subjects in real-time during ambulation. A study was conducted in which 16 healthy subjects learned to alter gait patterns to lower the KAM through visual or tactile (vibration) feedback. Participants converged on a comfortable gait in just a few minutes by using the feedback to iterate on various kinematic modifications. All subjects adopted altered gait patterns with lower KAM compared with normal ambulation (average reduction of 20.7%). Tactile and visual feedbacks were equally effective for real-time training, although subjects using tactile feedback took longer to converge on an acceptable gait. This study shows that real-time feedback of the KAM can greatly increase the effectiveness and efficiency of subject-specific gait retraining compared with conventional methods.
Continuous Mode Laser Coating of Hydroxyapatite/Titanium Nanoparticles on Metallic Implants: Multiphysics Simulation and Experimental Verification
Authors: Zhang Martin Yi , Cheng Gary J.
Published: March 2011

A novel methodology of laser coating of mixture of bioceramic and titanium nanoparticles onto metal implants is developed in this work. Feasibility of this approach is demonstrated via both multiphysics simulation and experiments. Treating incident laser as an electromagnetic wave, an electromagnetic (EM) module is coupled with a heat transfer (HT) module. The EM-HT model analyzes the interaction between laser and nanoparticles and ends up with a temperature rise in the system. Hydroxyapatite (HAp) and titanium nanoparticles are coated on the Ti–6Al–4V substrate. Processing parameters such as laser power, beam radius, scan speed, and layer thickness are studied, and correlation between these parameters and the final temperature is presented. The effect of the HAp/Ti mixing ratio to the generated temperature is also examined. Experiments are carried out to verify the model. Good agreements have been found between the EM-HT model and experiments.
Order—Geometric Space Configuration of Momentum and Thermal Potential Energy
Authors: Huang Weimin
Published: March 2011

Maxwell had advanced the famous velocity distribution law for ideal gas and idea of momentum space. But he had also put the problem about “Maxwell demon” to oppugn that if should the space configuration of momentum exist? This paper defines the pressure resulting from elastic collision based on no-wall space model of ideal gas under the thermodynamic equilibrium. It lets the presupposition about Maxwell velocity space without any actions to be untenable. There are space configurations of momentum for ideal gas whatever in no-wall space or in box with solid wall that is a restriction for order relating space configuration of position of particle. The order and Boltzmann entropy should account for momentum space configuration. This paper proposes a statistic method for local certain region of non-localized particles of ideal gas. The pV and −TS are argued to be two kinds of potential energy. The −TS is the heat potential energy inside of an isolation system which change is equal to the heat exchanging between the system and surrounding.
A Large Eddy Simulation (LES) of Plate-Fin and Tube Heat Exchangers
Authors: Zhang Li-Zhi
Published: March 2011

Plate-fin and tube heat exchangers are extensively studied both experimentally and numerically. With a large eddy simulation technique (LES), this study performs a detailed investigation of the temporal oscillations of streamwise, spanwise and normal velocity components in the exchanger passage and their effects on heat transfer between fins and fluid. Focus is on the instability and transitional behavior of fluid flow in the exchanger. Temporal variations of instantaneous velocity found that even under very low frontal velocities, the fluid exhibits some degree of oscillations, which change from periodic, regular fluctuations to aperiodic, chaotic turbulence with increasing Reynolds numbers. Contrary to the vortex shedding in a bare tube bank, the flow in the exchanger is more like a duct flow, with steady vortexes formed behind each tube. A frequency spectrum analysis of velocity fluctuations further proves that vortex shedding is not the dominant mechanism for momentum and heat transfer. Rather, tube induced oscillations are the dominant factor.
An Estimation Method of Electric Field Forces on a Single Bubble
Authors: Song Yaozu , Chen Feng , Peng Yao
Published: March 2011

It has been well-known that externally imposed static electric fields have a significant effect on bubble dynamic behavior, especially on bubble departure behavior. With increasing electric field strength, bubble detachment volume decreases and bubble shape elongates along the electric field direction. It is electric field forces that change bubble behavior. The electric field forces can be calculated from theoretical formula for a simple electrode structure. However, for the complex electrode system, it is rather a tough thing to theoretically solve electric field forces. In this work a new method to experimentally estimate electric field forces exerted on a single bubble has been presented. Experimental estimation primarily depends upon decreasing in the buoyancy on the bubble. Furthermore, the calculations coming from theoretical formula have also been completed and the results show that experimental estimations agree well with theoretical calculations.
Numerical Analysis of Laminar Forced Convection in Sinusoidal-Wavy-, Rounded-Ellipse-, and Rounded-Vee-Shaped Corrugated-Plate Channels
Authors: Ferley Dean , Ormiston Scott J.
Published: March 2011

Numerical analysis of steady, two-dimensional, laminar forced convection in corrugated-plate channels is performed using a commercial CFD code: ANSYS CFX. The flow domain consists of six modules in each of three wall corrugations: sinusoidal-wavy-shaped (SWS), rounded-ellipse-shaped (RES), and rounded-vee-shaped (RVS). One ratio of minimum-to-maximum plate spacings and one module length-to-height ratio is considered. Fluid flow and heat transfer are repeating in the modules and the results are examined in a typical module in the fully-developed region for Reynolds numbers in the range of 25 to 300 for Prandtl numbers of 0.7 (air), 2.29 (water), and 34.6 (ethylene glycol). The RES corrugation produced the highest peak value of local Nusselt number as well as the highest friction factor. The SWS corrugation produced the highest average Nusselt number, except at a Prandtl number of 34.6 at higher Reynolds number where the RES corrugation had the highest value. The RVS corrugation had the lowest friction factor for the geometric configuration considered. The highest heat transfer rate per unit pumping power was found at the highest Prandtl number for the RES corrugation.
Pool Boiling Characteristics of Heat Transfer Surface With Micro Structures Created by Using MEMS Technology
Authors: Koizumi Yasuo , Ohtake Hiroyasu , Sato Takato
Published: March 2011

Pool nucleate boiling heat transfer experiments were performed for water by using well-controlled and -defined heat transfer surfaces. The silicon wafers of 0.200 mm thickness were used as the heat transfer surfaces. Artificial-cylindrical cavities, micro-straight-line grooves or micro-crossing-straight-line grooves (square pillars) were created on the silicon plate by utilizing the Micro-Electro Mechanical System (MEMS) technology. In the case of the straight-line grooves and the crossing-straight-line grooves, the grooves were wetted after the heat transfer surface experienced subcooling. Once the grooves were wetted, only small diameter cavities which were formed during the MEMS processing at the bottom of the grooves functioned at the inception of boiling. Thus, a large overshooting of the wall superheat at the inception of boiling was observed. In this point, the micro grooves and micro pillars are not advantageous to cooling a body that periodically generates heat such as MPUs and electro devices. In the fully developed nucleate boiling region, the general trend was similar to that of the usual heat transfer surface. In the case of the artificial-cylindrical cavities, nuclei were well preserved in cavities even after the heat transfer surface experienced subcooling. Thus, no overshooting of the wall superheat at the inception of boiling was observed. As the number of the artificial-cylindrical cavities was increased, the wall superheat shifted to a low wall superheat side. The boiling heat transfer coefficient of the heat transfer surface that had the artificial-cylindrical cavities of the 1 mm pitch was better than that of a usual copper heat transfer surface. The artificial-cylindrical cavities are advantageous to get reliable and better cooling efficiency.
Numerical and Experimental Study on Lift-Off Suppression Phenomenon of Subsonic Hydrogen Jet Diffusion Flame
Authors: Torii Shuichi
Published: March 2011

Experimental and numerical study is performed on subsonic hydrogen jet diffusion flame formed from the vertical circular nozzle. Emphasis is placed on the effect of the cavity height formed at the fuel injection nozzle tip on suppression of the flame lift-off. It is found that (i) an increase in the cavity height triggers and enhances a vacuum pressure, (ii) the air from the surroundings is transported naturally into the cavity to replenish the air entrained and consumed by the jet flame, and (iii) the vacuum pressure results in the mitigation of flame lift-off propensity.
Simulation of a Moving Porous Bed Reactor With a Two-Energy Equation Model
Authors: de Lemos Marcelo J. S. , Pivem Ana C.
Published: March 2011

Interface heat transfer in a moving porous bed is analyzed. This work proposes a set of transport equations for solving problems involving turbulent flow and heat transfer in a moving bed equipment. The device is modeled as a saturated porous matrix in which the solid phase moves with a steady imposed velocity. Additional drag terms appearing in the momentum equation, as well as interfacial heat transfer between phases, are assumed to be a function of the relative velocity between the fluid and solid phases. Results indicate that, as the phases attain velocities of equal order, heat transfer between solid and fluid occurs mainly by the conduction mechanism.
Experimental Performance of Novel Foam and Schwarz Surface Heat Sinks
Authors: Hernon Domhnaill
Published: March 2011

In this experimental investigation two novel heat sink designs that employ different flow phenomena for enhanced heat transfer are presented. Thermal and hydrodynamic performance comparisons are made for three foam heat sinks with and without fins and two heat sinks with zero-mean curvature based on the Schwarz minimal surface design. Results for a longitudinally-finned heat sink are presented as a baseline comparison against the complex foam and Schwarz “3D” heat sink designs. The heat sinks are manufactured using an investment casting process providing a means of fabricating complex designs as one monolithic piece with high thermal conductivity that would not be possible using traditional techniques. It is demonstrated that against pumping power and velocity parameters the foam structures perform reasonably well in the higher velocity range. It is shown that the pressure drop across the foam and Schwarz structures is significant and the application of these designs in real systems will depend on the design constraints of the system, e.g. the foams may work well in a fan mounted heat sink assembly but not in a typical telecommunications application where flow bypass is important.
Experimental Studies of Turbulent Flow Through Rectangular and Square Ducts With Axial Corrugation Roughness and Twisted Tapes With and Without Oblique Teeth
Authors: Saha Sujoy K.
Published: March 2011

The heat transfer and the pressure drop characteristics of turbulent flow of air through rectangular and square ducts with combined internal axial corrugations on all the surfaces of the ducts and with twisted-tape inserts with and without oblique teeth have been studied experimentally. The flow friction and thermal characteristics are governed by duct aspect ratio, corrugation angle, corrugation pitch, twist ratio, space ratio, length, tooth horizontal length and tooth angle of the twisted-tape, Reynolds number and Prandtl number. It has been found that up to fifty five per cent heat transfer coefficient increase occurs for the combined axial corrugation and regularly spaced twisted-tape elements inserts with oblique teeth case compared to without oblique teeth twisted-tape inserts cases in the measured experimental parameters space. The friction factor has been reduced up to forty seven per cent for the combined enhancement geometry than the individual enhancement geometries. However, full-length and short-length twisted-tapes with oblique teeth in combination with axial corrugations show only marginal improvements over the twisted tapes without oblique teeth.
Effects of Freestream on Thermally-Driven Boundary Layers Along a Heated Vertical Flat Plate
Authors: Abedin Mohammad Zoynal , Tsuji Toshihiro
Published: March 2011

Time-developing thermally-driven boundary layers created by imposing aiding and opposing freestreams on the natural-convection boundary layer in water along a heated vertical flat plate have been examined with a direct numerical simulation. The numerical results reveal that, with a slight increase in freestream velocity, the transition to turbulence delays for aiding flow and quickens for opposing flow. This fact is linked to the experimental results indicating that heat transfer rates of the turbulent combined-convection boundary layer decrease for aiding flow and increase for opposing flow with increasing freestream velocity. In response, turbulence statistics obtained for aiding flow such as the intensities of velocity and temperature fluctuations, Reynolds shear stress and turbulent heat fluxes become smaller than those for the pure natural-convection boundary layer suggesting the way to laminarization of the boundary layer, while those for opposing flow are not much different from the observations for the pure natural-convection boundary layer. To improve the significance of the present numerical results, the association of turbulence statistics between time- and space-developing flows has been also investigated. Consequently, the numerical results for time-developing flow are converted to those for space-developing flow through the integral thickness of the velocity boundary layer for pure natural convection, and thus the regimes of boundary layer flows in water can be quantitatively assessed. Moreover, by visualizing the flow field of the combined-convection boundary layers, it is found that the long-drawn high- and low-speed fluid motions with weak fluctuations for aiding flow and the large scale fluid motions for opposing flow are more apparent than those for the pure natural-convection boundary layer.
Modeling the Effect of Vesicle Traps on Mass Transfer and Traffic Jam Formation in Fast Axonal Transport
Authors: Kuznetsov Andrey V.
Published: March 2011

This paper simulates effects of structural changes in the microtubule (MT) system on mass transfer in an axon. Understanding this process is important for understanding the underlying reasons for many neurodegenerative diseases, such as Alzheimer’s disease. In particular, it is investigated how the degree of polar mismatching in an MT swirl affects organelle trap regions in the axon and inhibiting transport of organelles down the axon. The model is based on modified Smith-Simmons equations governing molecular-motor-assisted transport in neurons. It is established that the structure that develops as a result of a region with disoriented MTs (the MT swirl) consists of two organelle traps, the trap to the left of the swirl region accumulates plus-end oriented organelles and the trap to the right of this region accumulates minus-end oriented organelles. The presence of such a structure is shown to decrease the transport of organelles toward the synapse of the axon. Four cases with a different degree of polar mismatching in the swirl region are investigated; the results are compared with simulations for a healthy axon, in which case organelle traps are absent.
Cooling of an Isothermal Plate Using a Triangular Array of Swirling Air Jets
Authors: Rodriguez Sal B. , El-Genk Mohamed S.
Published: March 2011

Cooling with swirling jets is an effective means for enhancing heat transfer and improving spatial uniformity of the cooling rate in many applications. This paper investigates cooling a flat, isothermal plate at 1,000 K using a single and a triangular array of swirling air jets, and characterizes the resulting flow field and the air temperature above the plate. This problem was modeled using the Fuego computational fluid dynamics (CFD) code that is being developed at Sandia National Laboratories. The separation distance to jet diameter, L/D, varied from 3 to 12, Reynolds number, Re, varied from 5×103–5×104, and the swirl number, S varied from 0 to 2.49. The formation of the central recirculation zone (CRZ) and its impact on heat transfer were also investigated. For a hubless swirling jet, a CRZ was generated whenever S ≥ 0.67, in agreement with experimental data and our mathematical derivation for swirl (helicoid) azimuthal and axial velocities. On the other hand, for S ≤0.058, the velocity field closely approximated that of a conventional jet. With the azimuthal velocity of a swirling jet decaying as 1/z2, most mixing occurred only a few jet diameters from the jet nozzle. Highest cooling occurred when L/D = 3 and S = 0.12 to 0.79. Heat transfer enhancement increased as S or Re increased, or L/D decreased.
Decay of the Falling Wavy Liquids Films at Nonstationary Heat Release
Authors: Pavlenko Aleksandr N. , Surtaev Anton S. , Starodubtseva Irina P. , Volodin Oleg A. , Chernyavskiy Andrei N. , Tsoi Alexei N. , Pyatkov Aleksandr S.
Published: March 2011

This paper deals with investigation results on boiling up and crisis phenomena for nonstationary heat release in falling liquid films. According to the experimental results, in the studied range of irrigation degree alteration (Rein = 50–1300), parameters, characterizing decay of the falling liquid film with stepped heat release (distribution of time of boiling incipience along the liquid film, velocities of movable boundaries in the boiling-up and drying fronts), depend complexly on the Reynolds number, wave characteristics and heat flux density. Experiments were carried out with the use liquid nitrogen. Step-wise heat release was supplied on the vertical plane constantan foil of the 25-mkm thickness and 40-mm length. When loading impulses of high intensity, film decay is determined by dynamic characteristics of propagation of the self-maintained fronts of evaporation and the complex shape of structures, formed during its development. The effect of heat flux density on the time of boiling-up expectation and structures of evaporation fronts is shown for different Reynolds numbers. The experimental data obtained on the average propagation velocity of the self-maintained front of evaporation are compared with the simulation model results.