bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Two Self‐Adhesive Cements on Marginal Adaptation and Strength of Esthetic Ceramic CAD/CAM Molar Crowns
Authors: Mörmann Werner , Wolf Daniel , Ender Andreas , Bindl Andreas , Göhring Till , Attin Thomas
Published: April 2009

Purpose: This study evaluated the effects of adhesive cements on marginal adaptation and fracture resistance of ceramic molar crowns.

Materials and Methods: Seventy‐five extracted maxillary molars were selected. The occlusal morphology of 15 molars (control) was scanned and transferred to the crowns in the test groups by CAD/CAM. Sixty molars received full‐coverage crown preparations with 6‐degree axial taper, 1.0‐mm shoulder, and 2.0‐mm occlusal reduction. They were assigned to four groups, and pulpal pressure was simulated. The 15 crowns in each test group were seated with resin‐based self‐adhesive cements, Rely‐X (RX) and Multilink (MS), one multistep bonded adhesive luting composite resin, Variolink (VL), and glass‐ionomer cement, Ketac Cem (KC). Test and control molars were subjected to thermal and mechanical fatigue stress (TMS: 12,000 × 5°C to 50°C; 2.4 million × 49 N) for 18 days in a masticator. Marginal adaptation [“continuous margin%” (CM%)] of the crowns was determined by scanning electron microscopy (200×). Finally, molars were occlusally loaded until fracture in a testing machine, and fracture load (N) was recorded. Marginal adaptation and strength data were statistically analyzed.

Results: TMS significantly (p < 0.001) reduced CM% in all groups. After TMS, CM% at the cement‐dentin interface was significantly (p < 0.001) higher for RX than for all other cements. At the crown‐cement interface both self‐adhesive cements MS and RX had significantly better CM% than VL (p < 0.05) and KC (p < 0.001). Fracture resistance of natural untreated molars was significantly (p < 0.001) higher than that of experimental crowns. Fracture resistance of RX cemented crowns was significantly (p < 0.05) higher than that of other crowns. Occlusal morphology significantly influenced fracture resistance (p < 0.05).

Conclusions: Self‐adhesive cement RX offers a valid alternative to multistep resin‐based luting composite with respect to marginal adaptation to dentin and fracture resistance. The latter is also influenced by occlusal morphology, necessitating careful monitoring of occlusal contacts.
Flexural Strength of Glass‐Infiltrated Zirconia/Alumina‐Based Ceramics and Feldspathic Veneering Porcelains
Authors: Bottino Marco Antonio , Salazar‐Marocho Susana M. , Leite Fabiola P.P. , Vásquez Vanessa C. , Valandro Luiz Felipe
Published: April 2009

Purpose: To compare the flexural strength of two glass‐infiltrated high‐strength ceramics and two veneering glass‐ceramics.

Materials and Methods: Four ceramic materials were tested: two glass‐infiltrated high‐strength ceramics used as framework in metal‐free restorations [In‐Ceram Zirconia IZ (Gr1) and In‐Ceram Alumina IA (Gr2)], and two glass‐ceramics used as veneering material in metal‐free restorations [Vita VM7 (Gr3) and Vitadur‐α (Gr4)]. Bar specimens (25 × 5 × 2 mm3) made from core ceramics, alumina, and zirconia/alumina composites were prepared and applied to a silicone mold, which rested on a base from a gypsum die material. The IZ and IA specimens were partially sintered in an In‐Ceram furnace according to the firing cycle of each material, and then were infiltrated with a low‐viscosity glass to yield bar specimens of high density and strength. The Vita VM7 and Vitadur‐α specimens were made from veneering materials, by vibration of slurry porcelain powder and condensation into a two‐part brass Teflon matrix (25 × 5 × 2 mm3). Excess water was removed with absorbent paper. The veneering ceramic specimens were then removed from the matrix and were fired as recommended by the manufacturer. Another ceramic application and sintering were performed to compensate the contraction of the feldspar ceramic. The bar specimens were then tested in a three‐point bending test.

Results: The core materials (Gr1: 436.1 ± 54.8; Gr2: 419.4 ± 83.8) presented significantly higher flexural strength (MPa) than the veneer ceramics (Gr3: 63.5 ± 9.9; Gr4: 57.8 ± 12.7).

Conclusion: In‐Ceram Alumina and Zirconia were similar statistically and more resistant than VM7 and Vitadur‐α.
Fatigue and Fluoride Corrosion on Streptococcus mutans Adherence to Titanium‐Based Implant/Component Surfaces
Authors: Correa Cassia Bellotto , Pires Juliana Rico , Fernandes‐Filho Romeu Belon , Sartori Rafael , Vaz Luis Geraldo
Published: April 2009

Purpose: The influence of fatigue and the fluoride ion corrosion process on Streptococcus mutans adherence to commercially pure Titanium (Cp Ti) implant/component set surfaces were studied.

Materials and Methods: Thirty Nobel implants and 30 Neodent implants were used. Each commercial brand was divided into three groups. Group A: control, Group B: sets submitted to fatigue (105 cycles, 15 Hz, 150 N), and Group C: sets submitted to fluoride (1500 ppm, pH 5.5) and fatigue, simulating a mean use of 5 years in the oral medium. Afterward, the sets were contaminated with standard strains of S. mutans (NTCC 1023) and analyzed by scanning electronic microscopy (SEM) and colony‐forming unit counts (CFU/mL).

Results: By SEM, bacterial adherence was verified only in group C in both brands. By CFU/mL counts, S. mutans was statistically higher in both brands in group C than in groups A and B (p < 0.05, ANOVA).

Conclusion: The process of corrosion by fluoride ions on Cp Ti implant/component sets allowed greater S. mutans adherence than in the absence of corrosion and with the fatigue process in isolation.
A Generalized Randomization Approach to Local Measures of Spatial Association
Authors: Lee Sang‐Il
Published: April 2009

This article establishes a unified randomization significance testing framework upon which various local measures of spatial association are commonly predicated. The generalized randomization approach presented is composed of two testing procedures, the extended Mantel test and the generalized vector randomization test. These two procedures employ different randomization assumptions, namely total and conditional randomization, according to the way in which they incorporate local measures. By properly specifying necessary matrices and vectors for a particular local measure of spatial association under a particular randomization assumption, the generalized randomization approach as a whole yields a reliable set of equations for expected values and variances, which then is confirmed by a Monte Carlo simulation utilizing random permutations.
Population Synthesis: Comparing the Major Techniques Using a Small, Complete Population of Firms
Authors: Ryan Justin , Maoh Hanna , Kanaroglou Pavlos
Published: April 2009

Recently, disaggregate modeling efforts that rely on microdata have received wide attention by scholars and practitioners. Synthetic population techniques have been devised and are used as a viable alternative to the collection of microdata that normally are inaccessible because of confidentiality concerns or incomplete because of high acquisition costs. The two most widely discussed synthetic techniques are the synthetic reconstruction method (IPFSR), which makes use of iterative proportional fitting (IPF) techniques, and the combinatorial optimization (CO) method. Both methods are described in this article and then evaluated in terms of their ability to recreate a known population of firms, using limited data extracted from the parent population of the firms. Testing a synthetic population against a known population is seldom done, because obtaining an entire population usually is too difficult. The case presented here uses a small, complete population of firms for the City of Hamilton, Ontario, for the year 1990; firm attributes compiled are number of employees, 3‐digit standard industrial classification, and geographic location. Results are summarized for experiments based upon various combinations of sample size and tabulation detail designed to maximize the accuracy of resulting synthetic populations while holding input data costs to a minimum. The output from both methods indicates that increases in sample size and tabulation detail result in higher quality synthetic populations, although the quality of the generated population is more sensitive to increases in tabular detail. Finally, most tests conducted with the created synthetic populations suggest that the CO method is superior to the IPFSR method.
Estimation of Living Stature from Selected Anthropometric (Soft Tissue) Measurements: Applications for Forensic Anthropology
Authors: Adams Bradley J. , Herrmann Nicholas P.
Published: April 2009

Abstract: Estimation of living stature has obvious utility in the identification process. Typically, anthropologists estimate stature from the measurement of long bone length. This type of analysis is traditionally conducted on skeletonized or badly decomposed remains, so collection of the necessary bone measurements is relatively simple. As the role of anthropologists expands into medical examiner offices and mass fatality incidents, the analysis of fleshed bodies and body parts is a more common scenario. For stature estimation in these types of cases (e.g., analysis of body portions recovered from an aircraft crash site or from intentional dismemberment), the presence of soft tissue on the human remains would usually necessitate dissection to expose skeletal elements to derive metric data for stature estimation. In order to circumvent this step, this paper provides various formulae that allow for standard anthropometric (i.e., soft tissue) measurements to be used in place of skeletal measurements. Data were compiled from several anthropometric studies (National Health and Nutrition Examination Survey [NHANES] and U.S. Army Anthropometric Survey [ANSUR]) and numerous regression models are presented. Results are compared between skeletal measurements and the anthropometric measurements from each study. It was found that the ANSUR models are similar to the skeletal models, while the NHANES models exhibit weaker correlation coefficients and higher standard errors. Overall, this study finds that stature estimates derived from anthropometric data provide good results and remove the necessity for dissection when working with fleshed body portions.
Development of an Antibody Hapten‐Chip System for Detecting the Residues of Multiple Antibiotic Drugs*
Authors: Chen Ailiang , Wang Guoqing , Cao Qin , Wang Yan , Zhang Zhaohui , Sun Yimin , Wang Hui , Xu Chaoyi , Zhou Qi , Han Pei , Liu Miao , Yang Yang , Xing Wanli , Mitchelson Keith R. , Cheng Jing
Published: April 2009

Abstract:  The abuse of antibiotic drugs during animal production remains a worldwide problem and the subsequent detection of the residues of various drugs present at low concentrations in complex biological matrices poses significant analytical challenges. The present study outlines a practical biochip assay system to identify antibiotic residues in different animal tissue extracts. The system uses a simple but efficient multiresidue sample extraction procedure to isolate the antibiotic residues which were then identified directly using high‐affinity monoclonal antibodies presented in a competitive immunoassay with conjugated antibiotic hapten‐chips. The hapten‐chip can analyze six samples each for eight antibiotics on a single chip within 3 h. The analytical results with both artificial positive standard samples and the incurred samples show that the antibody hapten‐chip system has a comparable accuracy and a similar sensitivity to a standard ultra performance liquid chromatography–mass spectrometry (MS)/MS assay. In conclusion, an effective analytical screening system based on antibody hapten‐chip was developed for detecting multiple antibiotic residues from multiple samples.
Forensic DNA Challenges: Replacing Numbers with Names of Fosse Ardeatine’s Victims*
Authors: Pietrangeli Ilenia , Caruso Vincenzo , Veneziano Liana , Spinella Aldo , Arcudi Giovanni , Giardina Emiliano , Novelli Giuseppe
Published: April 2009

Abstract:  The Fosse Ardeatine massacre was a mass execution carried out in Rome on March 24, 1944 by Nazi German occupation troops during the Second World War as a reprisal for a partisan attack conducted on the previous day in central Rome. The 335 civilians were taken to the “Cave Ardeatine” and they were shot. Only 323 corpses out of 335 have been identified. The aim of this work is the genetic and anthropological analysis of the remains exhumed from grave number 329 of Fosse Ardeatine’s Shrine to assess their identity. So far, such remains have been supposed to belong to MM but mitochondrial analysis excluded a biological relationship to two living maternal relatives. Our analysis indicated that remains recovered in grave number 329 do not belong to MM. This result suggests that genetic analysis of the remains should be also applied to the other 12 unknown corpses to elucidate their identity.
Handmade Guns in Trabzon, Turkey
Authors: Yilmaz Riza , Birincioğlu İsmail , Uner H. Bulent , Erkol Zerrin , Butun Celal , Acikgoz Dinc , Bulut Erkut R.
Published: April 2009

Abstract:  A wide variety of handmade firearms have been involved in criminal cases in the city of Trabzon, Turkey. Although they are often very similar to commercially manufactured firearms in terms of design, loading and locking mechanisms, and cocking and firing arrangements, these guns are constructed from cheap materials and are not safe for firing. Handmade firearms manufactured in the Black Sea region of Turkey, particularly in the city of Trabzon, are similar to pistols manufactured by Browning, Luger, Star, Smith and Wesson, Berretta, and MAB. A total of 201 handmade guns referred to the Criminal Police Laboratories for examination from 2003 to 2005 were evaluated with respect to type, number of barrels, size and caliber, rifling, design, mechanism, operability, legality, and similarity to commercial models. We found that most of these handmade guns resembled commercial models in several aspects.
A Carbon Dioxide Fatality from Dry Ice
Authors: Srisont Smith , Chirachariyavej Thamrong , Peonim A. V. M. Vichan
Published: April 2009

Abstract:  This report documents a rare case of carbon dioxide intoxication in a young healthy male. The deceased hid in a small plastic container, size 1.5 × 1 × 1 m, and within 5 min he was located suffering convulsions and was reported as dead within minutes. Scene investigation revealed dry ice in the container. Autopsy findings were unremarkable. The probable cause of the convulsions was carbon dioxide intoxication due to both the dry ice sublimation and the small confined space in which he was hiding. This report emphasizes the significance of scene investigation in establishing the cause of the death.
Camels and Arabian balîya and other forms of sacrifice: a review of archaeological and literary evidence
Authors: King Geoffrey
Published: April 2009

The paper surveys the recent archaeological information for the balîya immolation tradition of pre‐Islamic Arabia, whereby a camel or other valued animal was slaughtered to accompany a person of status in death so that they had an animal to ride or to maintain their status in the afterlife. In contrast to the dhibh immolation, which is prescribed in the Holy Qur’ân in memory of the sacrifice of the Prophet Ibrâhîm, the balîya is forbidden in Islam. Unlike the dhibh immolation, the balîya sacrifice was interred whole and provides precise archaeological information about the circumstances of its slaughter and burial. Information about such immolations derives largely from excavations in southern and eastern Arabia.
HDOR 410, a mid‐Holocene campsite (Hadramawt, Yemen) and the difficulty of determining cultural tradition
Authors: Crassard Rémy
Published: April 2009

Located in Wâdî Mikhfar, Yemen, the stratified site of HDOR 410 was excavated by the French Archaeological Mission in Jawf‐Hadramawt. The site illustrates the co‐existence of a form of expediency and a form of complexity in the production of lithics, revealing the presence of industries with low technological visibility (expedient production of flakes) at a time traditionally characterised by marked typological constraints (production of trihedral points).
Orofacial granulomatosis in childhood—a clinical entity that may indicate Crohn's disease as well as food allergy
Authors: Saalman Robert , Mattsson Ulf , Jontell Mats
Published: April 2009

Aim:  Orofacial granulomatosis (OFG) is a rare clinical entity with orofacial swelling in association with oral lesions such as mucosal oedema, ulcerations and mucosal tags. The aim of this prospective study was to evaluate the connection between OFG in childhood and systemic disease.

Methods:  During a 3‐year period, eight children (9–16 years old) who had been referred to the clinic of oral medicine were diagnosed solely with OFG. Thus, none of them had any known systemic disease or gastrointestinal symptoms at the time of referral. The children were then medically examined and followed up for 6–8 years at the department of paediatrics for systemic disease with specific emphasis on inflammatory disorders elsewhere in the gastrointestinal tract.

Results:  During follow‐up, four patients were diagnosed with Crohn's disease (CD). Further, one girl was found to have a food allergy‐induced OFG, with delayed‐type hypersensitivity to oats. One boy developed both diabetes and celiac disease during the follow‐up. Only two patients had no diagnosis of systemic disease at the end of the observation period.

Conclusion:  OFG in childhood seems to be frequently related to systemic disease, and children with OFG should be referred to a paediatrician for examination and follow‐up.
Allergic rhinitis: more than just a stuffy nose
Authors: Borres Magnus P
Published: April 2009

Allergic rhinitis is more than just sneezing and an itchy nose. Complications of this disease are numerous and can have a significant impact, both mentally and physically. That is why it is important not only to detect, investigate and treat allergic rhinitis but also to actively identify potential complications. Mental functions such as learning, sleep and activity levels can deteriorate, and the eustachian tubes, sinuses and airway functions can be affected. Otitis, sinusitis and asthma are overrepresented among individuals who suffer from allergic rhinitis.

This article highlights how allergic rhinitis can affect cognitive functions, and what consequences this can have on school performance, work and quality of life.

Conclusion:  Health professionals and school personnel need to increase their awareness of the ramifications of this disease and actively work to prevent deterioration in both academic achievement and workplace productivity.
Effects of 4‐week Treatment with Lithium and Olanzapine on Levels of Brain‐derived Neurotrophic Factor, B‐Cell CLL/Lymphoma 2 and Phosphorylated Cyclic Adenosine Monophosphate Response Element‐binding Protein in the Sub‐regions of the Hippocampus
Authors: Hammonds Michael D. , Shim Seong S.
Published: April 2009

Abstract:  A large body of evidence indicates that lithium, the prototype mood stabilizer in the treatment of bipolar disorder, has diverse neuroprotective and neurotrophic actions, and the actions are associated with its efficacy in treating bipolar disorder. It has been suggested that up‐regulation of neurotrophic and neuroprotective factors including brain‐derived neurotrophic factor (BDNF) and B‐cell CLL/lymphoma 2 (Bcl‐2) may underlie these neuroplastic actions of the drug. Olanzapine, an atypical anti‐psychotic drug, has been shown to be an effective mood stabilizer. Olanzapine also has neurotrophic and neuroprotective actions, and these actions may underlie the efficacy of the drug for bipolar disorder and schizophrenia. However, the molecular mechanism by which the drug produces the neuroplastic actions is poorly understood. To understand a common molecular mechanism underlying the neuroplastic actions of lithium and olanzapine, we assessed the effect of 4‐week lithium and olanzapine treatment on the levels of BDNF, Bcl‐2 and cyclic adenosine monophosphate response element‐binding protein (CREB), a transcription factor involved in expression of BDNF and Bcl‐2, in the dentate gyrus and hippocampal area CA1. Our results show that 4‐week treatment with both olanzapine and lithium increases the levels of Bcl‐2 and CREB in the dentate gyrus and hippocampal area CA1. Four‐week lithium treatment up‐regulates BDNF in the dentate gyrus, and 4‐week olanzapine treatment marginally did so. Neither drug altered BDNF levels in area CA1. These results suggest that the up‐regulation of Bcl‐2 and CREB may underlie the neuroplastic actions of olanzapine and lithium.
Leaf vascular dimensions associated with freeze tolerance in bahiagrass (Paspalum notatum)
Authors: Breman J.W. , Sinclair T.R. , Blount A.R. , Quesenberry K.H. , Brennan M.M.
Published: April 2009

Foliage damage as a result of individual freeze events is a major limitation to the expansion of bahiagrass (Paspalum notatum) pastures and hay production in Southeastern USA. Greater tolerance to such freeze events would allow production deeper into the fall and winter and allow expansion of this species into colder regions. While it has been reported that small cells are more tolerant to freeze damage, this possibility has not been explored in bahiagrass. Specifically, the hypothesis was examined that xylem vessels with smaller diameter in the midrib of leaves are associated with freeze tolerance among bahiagrass genotypes. Vascular bundle diameter was also measured as a possible index of xylem cell size. A total of eight bahiagrass genotypes were eventually studied representing four freeze‐sensitive and four freeze‐tolerant lines. There was a clear distinction in xylem cell size between the freeze‐sensitive and the freeze‐tolerant lines. The freeze‐tolerant genotypes had xylem element cells that were significantly smaller than the freeze‐sensitive genotypes. Averaged across three leaf positions and all genotypes, the xylem element diameter for the freeze‐sensitive lines was 222 μm and for the freeze‐tolerant lines was only 164 μm. A similar difference was observed in overall vascular bundle diameter with freeze‐sensitive lines having a mean of 1168 μm and the freeze‐tolerant lines a mean of 917 μm. These results indicated that the diameter of the xylem cells in the vascular midrib of bahiagrass may be an important variable influencing the sensitivity among genotypes to freeze damage.
C‐C Chemokine Receptor 2 Expression by Circulating Monocytes Influences Atherosclerosis in Patients on Chronic Hemodialysis
Authors: Okumoto Satoshi , Taniguchi Yoshihiko , Nakashima Ayumu , Masaki Takao , Ito Takafumi , Ogawa Takahiko , Takasugi Norihisa , Kohno Nobuoki , Yorioka Noriaki
Published: April 2009

Mortality from cardiovascular or cerebrovascular disease due to atherosclerosis is increased in patients on chronic hemodialysis. Monocyte chemoattractant protein‐1 and its receptor, C‐C chemokine receptor 2, play an important role in recruiting monocytes to atherosclerotic lesions. The relationship between atherosclerosis in hemodialysis patients and C‐C chemokine receptor 2 expression is unknown. Fifty‐six patients on chronic hemodialysis and 27 age‐ and sex‐matched controls were enrolled. Serum levels of monocyte chemoattractant protein‐1 and expression of C‐C chemokine receptor 2 by circulating monocytes were determined. Atherosclerosis was evaluated from the carotid intima‐media thickness and cardio‐ankle vascular index. Serum levels of monocyte chemoattractant protein‐1 and expression of C‐C chemokine receptor 2 by monocytes were significantly higher in the hemodialysis patients than the controls. Multiple regression analysis showed a positive correlation between receptor expression and both indexes of atherosclerosis. C‐C chemokine receptor 2 expression by circulating monocytes influences atherosclerosis in patients on chronic hemodialysis.
Marketing a Policy Idea: Elite Frame Selection and Development in Ballot Initiative Campaigns
Authors: FERRAIOLO KATHLEEN
Published: April 2009

The importance of issue framing is well documented in public opinion and policy literature. While many analyze the impact of frames at the policy subsystem or public opinion level, this article identifies factors that influence frame selection and development in drug policy reform initiative campaigns. This study investigates why policy entrepreneurs choose to sponsor and advance medical marijuana ballot initiatives and draws on campaign literature, advertisements, and interviews to analyze the role of three forces that affect elite frame development: receptivity of public opinion, access to financial and media resources, and availability and credibility of spokespersons. These conditions influenced medical marijuana proponents' emphasis on patient rights, treatment options, and compassion as well as opponents' arguments about lack of evidence of medical effectiveness, the broader agenda of advocates, and conflicts with federal law. The case of drug control policy lends insight into the factors that shape elite frame selection and dissemination and points to avenues for future research.
Mandeville's Paradox as Satire: The Moral Consequences of Being a Good Citizen in a Commercial Society
Authors: SCOTT KYLE
Published: April 2009

While most specialists have come to recognize that Bernard Mandeville wrote satirically, most nonspecialists have not. Moreover, even among those specialists who do recognize him as a satirist, their conclusions have not been made relevant to a political science audience nor have they successfully argued why some of his statements should be taken literally and others not. This essay tries to rectify both these deficiencies. Mandeville argues that in commercial societies, one cannot be a good person and a good citizen, since commercial societies require citizens to be motivated by greed and ambition, whereas being a good citizen requires the opposite: self‐denial and moderation. We must, as Mandeville does, consider the implications for a society that prefers vice to virtue and institutionalizes that preference.
The Curious Incident of the Dog that Didn't Bark in the Night‐Time: Structure and Agency in Britain's War with Iraq
Authors: KETTELL STEVE
Published: April 2009

As one of the most contentious and far‐reaching foreign policy decisions in Britain's political history, the Blair government's participation in the 2003 invasion of Iraq has attracted a considerable amount of analysis, commentary, and debate. To date, however, the focus of this debate has tended to attribute primary causality for the decision to invade Iraq to individual agency, and to downplay the role that was played by broader structural factors. Although the decision was driven by the attitudes, beliefs, and values of senior government figures, and principally, on the British side, by those of Tony Blair himself, the role of structures in shaping these subjective views, and in providing senior figures with the scope, freedom, and autonomy to pursue this policy goal, has been largely overlooked. This study argues that, in this regard, a key and defining influence was exerted by the contextual environment of the British political system.
Dynamic Particle Accumulation Structure due to Thermocapillary Effect in Noncylindrical Half‐Zone Liquid Bridge
Authors: Abe Yukiko , Ueno Ichiro , Kawamura Hiroshi
Published: April 2009

We focus on the dynamic particle accumulation structure (PAS) due to the thermocapillary effect in a half‐zone liquid bridge. In this study, by tracking particles in the liquid bridge and by measuring temperature on the free surface, we discuss the effects of a liquid bridge shape described by its volume ratio upon the shape of the PAS itself and motion of particle on the PAS. The variation of the liquid bridge volume ratio leads to a significant variation of the temperature gradient on the free surface, which results in difference of the shape of the PAS, especially width of the PAS blade. By considering the simply modeled particle motion, we explain that the width of the PAS blade is determined by several parameters, and we find that its variation is explained mainly by a drastic change of the axial velocity of the particle on the surface.
Detection of Advancing Edge and Length of Precursor Film Ahead of Macroscopic Contact Line of Droplet Spreading on Solid Substrate
Authors: Konisho Takumi , Ueno Ichiro
Published: April 2009

The authors carried out an experimental study with a special interest on the dynamics of the fluid near the boundary line of three phases: solid–liquid–gas interface. A spreading droplet on a solid substrate is accompanied by the movement of a visible boundary line called the macroscopic contact line. Previous studies by various research groups have indicated the existence of a thin liquid film known as a precursor film ahead of the macroscopic contact line of the droplet. The present authors focused on the early stage of spreading and dedicated their special effort to detect the advancing edge of the precursor film by applying an interferometer with a high‐speed camera and by noise cancellation of using time–frequency analysis of brightness variation. The authors estimated the precursor film length for comparison with theoretical predictions and investigated the effect of changing viscosity on the formation of the precursor film by using the method of detection described herein.
Growth and Characterization of High‐quality Protein Crystals for X‐ray Crystallography
Authors: Moreno Abel , Yokaichiya Fabiano , Dimasi Elaine , Stojanoff Vivian
Published: April 2009

Tetragonal hen egg white lysozyme is grown by the batch method in solution and gel media to study the influence of high magnetic fields on the quality of macromolecular crystals. The crystallographic quality of crystals grown in the absence and in the presence of 7‐ and 10‐T fields are analyzed in terms of mosaicity and high‐resolution X‐ray imaging methods. Crystals grown by the batch method from solution showed a remarkable enhancement of the crystallographic quality, although the overall crystal quality was higher for gel‐grown crystals than solution‐grown crystals. The observed improvement in crystal quality can be attributed to the suppression of convective transport during the crystal growth process and the control of the nucleation kinetics by the use of a magnetic force.
Pure and Doped Triglycine Sulfate Crystals
Authors: Alexandru H. V.
Published: April 2009

Triglycine sulfate (TGS) crystal is an important ferroelectric crystal used on a large spectrum of radiation detection. Crystals from this family are used as targeted vidicon materials. Pure, (L + D) and L‐ or D‐alanine doped TGS crystals in the ferro‐ and paraelectric phase, 3–4 cm long, were grown by slow solvent evaporation or temperature reduction. The alanine segregation coefficient, being K∼0.01 dopant concentrations in the crystals, was less than 1%. The L‐ or D‐alanine doped crystals presented mirror symmetry and unipolarity. Permittivity and losses were registered online as a function of temperature or at constant temperature versus time (1 kHz, HIOKI, RLC automatic bridge). Essential parameters permittivity, losses, positive and negative polarization components, coercive field components, and the bias field of the doped samples were measured versus temperature. Hysteresis loops and their derivatives were measured with a specially designed Sawyer–Tower device. Generally, doped crystals presented much smaller permittivity and losses and a higher pyroelectric coefficient. Pure TGS samples show nonreproducible permittivity values and its relaxation was studied at constant temperature in the ferroelectric phase. Dielectric parameters have been automatically recorded online every 10 s, during ∼7 days. It was found that the relaxation time is not a real constant on such large time intervals. In a semi‐log scale, permittivity shows three stages, probably related to several mechanisms of relaxation.
XRD Investigation of Binary Alloy Solidification
Authors: Montanari Roberto , Gauzzi Franco
Published: April 2009

The solidification of two binary alloys, In–10Sn and Sn–13Pb, has been investigated by X‐ray diffractometry (XRD) at high temperatures. The high‐temperature X‐ray camera, which was mounted on a diffractometer, had a sample holder suitable for molten metals and operated in a controlled Ar atmosphere. Melts were cooled down slowly and XRD spectra were recorded step by step in order to monitor the structural evolution of the liquid prior to and during solidification. Temperature was kept constant while the XRD data were collected. The radial distribution functions (RDFs) were then determined from the spectra for each temperature. Experiments showed that atomic clusters form in the melt immediately before the appearance of the first solid. The experimental problems encountered in real‐time monitoring of phase transformations involving liquid metals were looked at. To avoid convective motion in the liquid and to arrive at the best possible experimental conditions, we discussed the possibility of carrying out these studies at the reduced gravity found on the International Space Station.
Advances in Cardiovascular Fluid Mechanics: Bench to Bedside
Authors: Dasi Lakshmi P. , Sucosky Philippe , De Zelicourt Diane , Sundareswaran Kartik , Jimenez Jorge , Yoganathan Ajit P.
Published: April 2009

This paper presents recent advances in cardiovascular fluid mechanics that define the current state of the art. These studies include complex multimodal investigations with advanced measurement and simulation techniques. We first discuss the complex flows within the total cavopulmonary connection in Fontan patients. We emphasize the quantification of energy losses by studying the importance of caval offsets as well as the differences among various Fontan surgical protocols. In our studies of the fluid mechanics of prosthetic heart valves, we reveal for the first time the full three‐dimensional complexity of flow fields in the vicinity of bileaflet and trileaflet valves and the microscopic hinge flow dynamics. We also present results of these valves functioning in a patient‐specific native aorta geometry. Our in vitro mitral valve studies show the complex mechanism of the native mitral valve apparatus. We demonstrate that the different components of the mitral valve have independent and synergistically complex functions that allow the valve to operate efficiently. We also show how valve mechanics change under pathological and repair conditions associated with enlarged ventricles. Finally, our ex vivo studies on the interactions between the aortic valve and its surrounding hemodynamic environment are aimed at providing insights into normal valve function and valve pathology. We describe the development of organ‐ and tissue‐culture systems and the biological response of the tissue subjected to their respective simulated mechanical environment. The studies noted above have enhanced our understanding of the complex fluid mechanics associated with the cardiovascular system and have led to new translational technologies.
Computational and Ground‐Based Experimental Investigations of the Effects of Specified and Unspecified (Free) Pressure Conditions at the Condenser Exit for Condensing Flows in Terrestrial and Microgravity Environments
Authors: Narain Amitabh , Kulkarni Shantanu , Mitra Soumya , Kurita Jorge H. , Kivisalu Michael T.
Published: April 2009

Reported experimental and computational results confirm that both the flow features and heat transfer rates inside a condenser depend on the specification of inlet, wall, and exit conditions. The theoretical and experimental results presented in this paper allow us to propose important exit condition based categorization of these flows. Of these, category II flows are defined to be cases for which exit pressures are left unspecified. However it is shown here that steady flows under specified exit pressure conditions (category I flows) are more stable and can be more easily achieved under all conditions (normal or zero‐gravity). Existence of self‐selected exit pressure conditions for unspecified exit condition cases (category II flows) are more difficult to achieve and are often limited to gravity driven flows. In practice, however, special hardware arrangements are required for repeatable realization of both these categories of flow. If this is not so, one often has an inadvertent category I flow (flows with specified exit pressure) without the explicit knowledge of the exit pressure value. For microgravity situations, the remedy is to run condensers under suitably specified inlet and exit pressures (category I conditions) as well as a proper cooling strategy (i.e., proper wall temperature variations).
Calculation of the T‐X Phase Diagrams for Binary Mixtures of Cholestanyl Myristate–Cholesteryl Myristate and Cholestanyl Myristate–Cholesteryl Oleate
Authors: Yurtseven Hamit , Şen Sema
Published: April 2009

T‐X phase diagrams of binary mixtures of cholestanyl myristate (CnM)–cholesteryl myristate (CrM) and cholestanyl myristate (CnM)–cholesteryl oleate (CO) are calculated using the mean field theory. We expand the free energies for the phases of cholesteric, smectic, and solid solutions in terms of the order parameters for these binary mixtures (X is the concentration of CrM for CnM–CrM and the concentration of CnM for CnM–CO). From this expansion, we obtain the phase line equations for the transitions among the isotropic liquid, cholesteric, smectic, and solid solutions for both binary mixtures. Taking into account the temperature and concentration dependences of the coefficients in the free energy expansion, we fit our phase line equations to the experimentally measured T‐X phase diagrams for these two binary mixtures. Our calculated phase lines coincide with the measured T‐X phase diagrams, and the critical behavior of the thermodynamic quantities, including the order parameter, the specific heat, and the susceptibility, can be predicted from the mean field expansions.
Thermocapillary Convection during Subcooled Boiling in Reduced Gravity Environments
Authors: Raj Rishi , Kim Jungho
Published: April 2009

Complete understanding of the origin of thermocapillary convection during subcooled boiling remains elusive. Some recent studies have suggested that the presence of dissolved gas inside the vapor bubble leads to the formation of a localized concentration and temperature gradient along the liquid–vapor interface and thus to the onset of thermocapillary convection. These studies reported that the dissolved gas content determines the onset of thermocapillary convection and that no thermocapillary motion was observed for subcooled boiling with pure liquid. However, other experiments performed in reduced gravity suggest that the strength of the thermocapillary convection around the primary bubble in a gas‐saturated fluid is much weaker than that in a degassed fluid. This paper presents a qualitative study of the effects of dissolved gas content, bubble shape and size, and heat transfer coefficient on the strength of thermocapillary convection and offers possible explanations for the existing confusion. Owing to the presence of different complex and interrelated mechanisms, we decoupled the individual mechanisms to study their overall effect on thermocapillary convection. The results indicate that variations in the heat transfer coefficient and in the shape and the size of the bubble play a major role in the development of thermocapillary motion.
Gravitational Effects on Carbon Nano‐Materials Synthesized by Arc in Water
Authors: Kawanami Osamu , Sano Noriaki
Published: April 2009

The “arc‐in‐liquid” method is a simple and inexpensive technique for the synthesis of carbon nanotubes and related nano‐materials. In this paper, we report on the synthesis of carbon nanotubes by means of the arc‐in‐water method under microgravity and normal gravity conditions. The heat of convection and two‐phase flow caused by the arc plasma are suppressed under microgravity, so the heat and fluid flow are stabilized under such conditions and a single huge bubble is generated around the electrodes. From the images captured during the experiment of the arc‐in‐liquid method, it can be observed that the bubble contained a layer of water vapor at the gas–liquid interface under microgravity conditions, and this layer blocked the carbon vapor reaching the liquid phase. Owing to this unique phenomenon, it was determined that the synthesis of carbon nanotubes by the arc‐in‐water method is strongly affected by gravity.
Electrohydrodynamic Convective Heat Transfer in a Square Duct
Authors: Grassi Walter , Testi Daniele
Published: April 2009

Laminar to weakly turbulent forced convection in a square duct heated from the bottom is strengthened by ion injection from an array of high‐voltage points opposite the heated strip. Both positive and negative ion injection are activated within the working liquid HFE‐7100 (C4F9OCH3), with transiting electrical currents on the order of 0.1 mA. Local temperatures on the heated wall are measured by liquid crystal thermography. The tests are conducted in a Reynolds number range from 510 to 12,100. In any case, heat transfer is dramatically augmented, almost independently from the flow rate. The pressure drop increase caused by the electrohydrodynamically induced flow is also measured. A profitable implementation of the technique in the design of heat sinks and heat exchangers is foreseen; possible benefits are pumping power reduction, size reduction, and heat exchange capability augmentation.
Heat Transfer and Bubble Detachment in Subcooled Pool Boiling from a Downward‐Facing Microheater Array in a Nonuniform Electric Field
Authors: Liu Zan , Herman Cila , Kim Jungho
Published: April 2009

The effects of a nonuniform electric field on vapor bubble detachment and heat transfer in subcooled pool boiling from a microheater array are investigated. The heater array faced downward to simulate a −1 g gravity condition and to eliminate the dominant masking effect of the buoyancy force. Experiments were conducted at different subcooling levels for various wall temperatures and electric field magnitudes. A dielectric fluid, FC‐72, was used as the working fluid at ambient pressure. The array of 3 × 3 independently controlled microheaters was maintained at constant temperature and the rate of heat transfer from each heater was measured. Bubble images were recorded using a high‐speed camera. The electric field was applied between the horizontal downward‐facing microheater array, which was grounded, and a spherical, off‐axis electrode beneath it. Boiling heat transfer results with and without the electric field are presented in this study. In the absence of the nonuniform electric field, compared to the same bulk fluid temperature and wall superheat settings in the +1 g situation, a much larger primary bubble was formed on the heater array, due to the coalescence of the secondary bubbles that nucleated on the heater array. The vapor bubble remained on the heater array surface and no bubble detachment was observed. With the nonuniform electric field applied, bubbles were lifted and sheared off from the heater array surface. The electric field was able to break up the primary bubble into several smaller bubbles—considerably greater heat transfer enhancement was measured than under similar conditions in +1 g.
Numerical Investigation of Bubble‐induced Marangoni Convection
Authors: O'Shaughnessy Séamus M. , Robinson Anthony J.
Published: April 2009

The liquid motion induced by surface tension variation, termed the thermocapillary or Marangoni effect, and its contribution to boiling heat transfer has long been a very controversial issue. In the past this convection was not the subject of much attention because, under terrestrial conditions, it is superimposed by the strong buoyancy convection, which makes it difficult to obtain quantitative experimental results. The scenario under consideration in this paper may be applicable to the analysis of boiling heat transfer, specifically the bubble waiting period and, possibly, the bubble growth period. To elucidate the influence of Marangoni convection on local heat transfer, this work numerically investigates the presence of a hemispherical bubble of constant radius, Rb= 1.0 mm, situated on a heated wall immersed in a liquid silicone oil (Pr= 82.5) layer of constant depth H= 5.0 mm. A comprehensive description of the flow driven by surface tension gradients along the liquid–vapor interface required the solution of the nonlinear equations of free‐surface hydrodynamics. For this problem, the procedure involved solution of the coupled equations of fluid mechanics and heat transfer using the finite‐difference numerical technique. Simulations were carried out under zero‐gravity conditions for temperatures of 50, 40, 30, 20, 10, and 1 K, corresponding to Marangoni numbers of 915, 732, 550, 366, 183, and 18.3, respectively. The predicted thermal and flow fields have been used to describe the enhancement of the heat transfer as a result of thermocapillary convection around a stationary bubble maintained on a heated surface. It was found that the heat transfer enhancement, as quantified by both the radius of enhancement and the ratio of Marangoni heat transfer to that of pure molecular diffusion, increases asymptotically with increasing Marangoni number. For the range of Marangoni numbers tested, a 1.18‐fold improvement in the heat transfer was predicted within the region of Rb≤r≤ 7Rb.
Dispersion and Surface Characteristics of Nanosilica Suspensions
Authors: Kumar Ranganathan , Milanova Denitsa
Published: April 2009

Nanofluids consisting of nanometer‐sized particles dispersed in base liquids are known to be effective in extending the saturated boiling regime and critical heat flux in pool boiling. The heat transfer characteristics of nanosilica suspensions with particle sizes of 10 and 20 nm in pool boiling with a suspended heating Nichrome wire have been analyzed. The pH value of the nanosuspensions is important from the point of view that it determines the stability of the particles and their mutual interactions toward the suspended heated wire. When silica is suspended in water with no additives, the surface potential of the nanoparticles determines their movement toward the electrodes. Particles continuously deposit on the wire and extend the burnout heat flux, influenced by the chemical composition of the nanofluids. This agglomeration allows high heat transfer through interagglomerate pores, resulting in a nearly threefold increase in burnout heat flux. Particle size, zeta potential, and the burnout heat flux values under different volume concentrations are provided. The burnout heat flux of the wire does not increase monotonically with concentration, but depends on the agglomeration characteristics, particle shape, and the hydroxylated surface of the nanoparticles.