bluuebunny/crossref_metadata_2025 huggingface dataset:
Age at First Drink Moderates the Impact of Current Stressful Life Events on Drinking Behavior in Young Adults
Authors: Blomeyer Dorothea , Buchmann Arlette F. , Schmid Brigitte , Jennen‐Steinmetz Christine , Schmidt Martin H. , Banaschewski Tobias , Laucht Manfred
Published: March 2011

Background:  Recent evidence from animal experiments and studies in humans suggests that early age at first drink (AFD) may lead to higher stress‐induced drinking. The present study aimed to extend these findings by examining whether AFD interacted with stressful life events (SLE) and/or with daily hassles regarding the impact on drinking patterns among young adults.

Method:  In 306 participants of an epidemiological cohort study, AFD was assessed together with SLE during the past 3 years, daily hassles in the last month, and drinking behavior at age 22. As outcome variables, 2 variables were derived, reflecting different aspects of alcohol use: the amount of alcohol consumed in the last month and the drinking frequency, indicated by the number of drinking days in the last month.

Results:  Linear regression models revealed an interaction effect between the continuous measures of AFD and SLE on the amount of alcohol consumed. The earlier young adults had their first alcoholic drink and the higher the levels of SLE they were exposed to, the disproportionately more alcohol they consumed. Drinking frequency was not affected by an interaction of these variables, while daily hassles and their interaction with AFD were unrelated to drinking behavior.

Conclusions:  These findings highlight the importance of early age at drinking onset as a risk factor for later heavy drinking under high load of SLE. Prevention programs should aim to raise age at first contact with alcohol. Additionally, support in stressful life situations and the acquisition of effective coping strategies might prevent heavy drinking in those with earlier drinking onset.
No Longer Undertreated? Depression Diagnosis and Antidepressant Therapy in Elderly Long‐Stay Nursing Home Residents, 1999 to 2007
Authors: Gaboda Dorothy , Lucas Judith , Siegel Michele , Kalay Ece , Crystal Stephen
Published: March 2011

OBJECTIVES: To examine the evolution of depression identification and use of antidepressants in elderly long‐stay nursing home residents from 1999 through 2007 and the associated sociodemographic and facility characteristics.

DESIGN: Annual cross‐sectional analysis of merged resident assessment data from the Minimum Data Set (MDS) and facility characteristics from the Online Survey Certification and Reporting data.

SETTING: Nursing homes in eight states (5,445 facilities).

PARTICIPANTS: Long‐stay nursing home residents aged 65 and older (2,564,687 assessments).

MEASUREMENTS: Physician‐documented depression diagnoses recorded in the MDS were used to identify residents with depression; antidepressant use was measured using MDS information about residents' receipt of an antidepressant in the 7 days before assessment.

RESULTS: Diagnosis of depression and antidepressant therapy in residents diagnosed increased at a rapid rate. By 2007, 51.8% of residents were diagnosed with depression, 82.8% of whom received an antidepressant. Adjusted odds of treatment were higher for younger residents, whites, and those with moderate impairment of cognitive function.

CONCLUSION: This study demonstrates striking increases in depression diagnosis and treatment with antidepressant medications, but disparities persist without clear evidence about underlying mechanisms. More research is needed to assess effectiveness of antidepressant prescribing.
Racial Differences in Location Before Hospice Enrollment and Association with Hospice Length of Stay
Authors: Johnson Kimberly S. , Kuchibhatla Maragatha , Tulsky James A.
Published: March 2011

African Americans are less likely than Whites to enroll in hospice. In addition, patients are often referred to hospice very close to death, when they may not have time to take advantage of the full range of hospice services. Understanding how race and location before hospice enrollment are related to hospice length of stay (LOS) may inform the development of interventions to increase timely access to hospice care. Using data from a national hospice provider, African Americans and Whites admitted to routine home hospice care in a private residence between January 1, 2000, and December 31, 2003, were identified. Logistic regression was used to examine the association between race and hospice preadmission location (hospital vs other locations) and preadmission location and hospice LOS (≤7 days vs >7 days) after adjusting for demographic and hospice use variables. Of 43,869 enrollees, 15.3% were African American. One to 2 days before hospice enrollment, African Americans were more likely than Whites to be in the hospital than in all other locations (48.6% vs 32.3%, P<.001; adjusted odds ratio=1.83, 95% confidence interval=1.73–1.95). Regardless of race, those whose preadmission location was the hospital were more likely than those from other locations to die 7 days or less after hospice enrollment. Initiatives to improve end‐of‐life care should focus on increasing timely access to hospice referrals in settings outside of the hospital. Future research should examine whether racial differences in hospice preadmission location reflect differences in preferences for care or disparities in timely access to hospice referrals in non‐acute care settings.
Patients Treated with Catheter Ablation for Atrial Fibrillation Have Long‐Term Rates of Death, Stroke, and Dementia Similar to Patients Without Atrial Fibrillation
Authors: BUNCH T. JARED , CRANDALL BRIAN G. , WEISS J. PETER , MAY HEIDI T. , BAIR TAMI L. , OSBORN JEFFREY S. , ANDERSON JEFFREY L. , MUHLESTEIN JOSEPH B. , HORNE BENJAMIN D. , LAPPE DONALD L. , DAY JOHN D.
Published: March 2011

Outcomes in Patients With AF. Introduction: Atrial fibrillation (AF) adversely impacts mortality, stroke, heart failure, and dementia. AF ablation eliminates AF in most patients. We evaluated the long‐term impact of AF ablation on mortality, heart failure (HF), stroke, and dementia in a large system‐wide patient population.

Methods: A total of 4,212 consecutive patients who underwent AF ablation were compared (1:4) to 16,848 age/gender matched controls with AF (no ablation) and 16,848 age/gender matched controls without AF. Patients were enrolled from the large ongoing prospective Intermountain AF study and were followed for at least 3 years.

Results: Of the 37,908 patients, mean age 65.0 ± 13 years, 5,667 (14.9%) died, 1,296 (3.4%) had a stroke, and 1,096 (2.9%) were hospitalized for HF over >3 years of follow‐up. AF ablation patients were less likely to have diabetes, but were more likely to have hypertension, HF, and significant valvular heart disease. AF ablation patients had a lower risk of death and stroke in comparison to AF patients without ablation. Alzheimer's dementia occurred in 0.2% of the AF ablation patients compared to 0.9% of the AF no ablation patients and 0.5% of the no AF patients (P < 0.0001). Other forms of dementia were also reduced significantly in those treated with ablation. Compared to patients with no AF, AF ablation patients had similar long‐term rates of death, dementia, and stroke.

Conclusions: AF ablation patients have a significantly lower risk of death, stroke, and dementia in comparison to AF patients without ablation. AF ablation may eliminate the increased risk of death and stroke associated with AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 839‐845, August 2011)
Projected climate change causes loss and redistribution of genetic diversity in a model metapopulation of a medium‐good disperser
Authors: Cobben M. M. P. , Verboom J. , Opdam P. F. M. , Hoekstra R. F. , Jochem R. , Arens P. , Smulders M. J. M.
Published: March 2011

Climate change causes species ranges to shift geographically as individuals colonise new suitable temperature zones or fail to reproduce where climate conditions fall below tolerance levels. Little is known about the potential loss of genetic diversity in such dynamic ranges. We investigated the level and distribution of neutral genetic diversity in shifting metapopulations during three scenarios of temperature increase projected for this century and at various degrees of weather variability. We used an individual‐based and spatially explicit metapopulation model in which temperature zones were simulated to move across a fragmented landscape following different climate change scenarios. Although the connectivity between habitat patches allowed the species, modelled after the middle spotted woodpecker Dendrocopos medius, to move along with the shifting temperature range, existing neutral genetic diversity was lost under all three temperature increase scenarios. This was independent of the loss of individuals. The explanation for this effect is that only a part of the original genetic variation moved into the newly colonised habitat. Under increased weather variability the number of individuals and the number of alleles per locus were persistently lower. However, the pattern of changes in allele distributions under temperature zone shifts was the same under all weather variability levels. Genetic differentiation between populations had a tendency to increase at metapopulation range margins, but decreased again when population sizes increased in time. Increased weather variability led to increased variation around the mean genetic differentiation across the metapopulation. Our results illustrate the usefulness of more realistic models for studying the effects of climate change on metapopulations. They indicate that biodiversity monitoring indices based on species occurrence and abundance are not a good proxy for the trend in the level of genetic diversity. Further, the results underline the importance of conserving areas where species have existed for a long time as modern refugia for genetic diversity.
Revisiting the Flâneur in T. S. Eliot’s “Eeldrop and Appleplex – I”
Authors: Yang Carol L.
Published: March 2011

In the Little Review for May 1917, when Prufrock and Other Observations was first advertised, T. S. Eliot published “Eeldrop and Appleplex – I,” a prose piece that has been read as based on a conversation between himself and Ezra Pound. It is about the secret life of a bank clerk called Eeldrop (closely resembling Eliot himself) and his acquaintance Appleplex (possibly modeled after Ezra Pound), who indulge their taste for slumming in order to smell out evil with the “implacable curiosity of a master detective.” This article analyzes Eliot’s “Eeldrop and Appleplex – I” and explores Eliot’s writings on the experience of the city. I will examine Eliot’s urban poetics of flânerie, which are made up of a hermeneutic of seeing, as well as his marginal figures – such as the lonely Londoner, the flâneur, and the stranger – that populate the contested terrain of the city, or the fetish commodity of the market. I will argue that Eliot’s only piece of fiction, especially “Eeldrop and Appleplex – I,” presents his most prescient critique, his most intimate literary journalism of the problematic “public privacy,” especially of the so‐called virtual gaze of urban spectatorship. Instead of merely offering an indictment that focuses exclusively on the oppressive privacy and compartmentalization of urban life, Eliot’s piece attempts to read and write London as a text, with the flâneur as the key phenomenon to understanding the emergent metropolis of modernity, as well as providing a methodological apparatus to indulge in a kind of textual flânerie, a kind of double‐codedness of perspectives to upset any traditional narrative resolution. “Eeldrop and Appleplex – I” should not be read as a unique part of Eliot’s authorship, but should be viewed as a development and intensification of the speculative conception of urban experience that informs his philosophical, critical, and aesthetic writings.
Multiperspectivism in the Novels of the Spanish Civil War
Authors: Hansen Hans Lauge
Published: March 2011

Since the turn of the millennium, Spanish society has been engaged with an intense public and political debate about the Civil War and the post‐war period. The number of publications has exploded within all genres, and narrative fiction clearly participates in the negotiation of the cultural memory of this period. Taking its point of departure in Todorov’s concept of restorative narratives, this article investigates whether contemporary Spanish novels continue a Manichaean division between ‘us’ and ‘them’, and whether it is possible to detect a difference in narrative patterns before and after the turn of the millennium.
Late specialization: the key to success in centimeters, grams, or seconds (cgs) sports
Authors: Moesch K. , Elbe A.‐M. , Hauge M.‐L. T. , Wikman J. M.
Published: March 2011

A controversial question within elite sports is whether young athletes need to specialize early, as suggested by Ericsson et al., or if it is more beneficial to follow the path of early diversification proposed by Côté et al., which includes sampling different sport experiences during childhood and specializing later on during adolescence. Based on a Danish sample of 148 elite and 95 near‐elite athletes from cgs sports (sports measured in centimeters, grams, or seconds), the present study investigates group differences concerning accumulated practice hours during the early stages of the career, involvement in other sports, career development, as well as determining whether or not these variables predict membership in the elite group. The results clearly reveal that elite athletes specialized at a later age and trained less in childhood. However, elite athletes were shown to intensify their training regime during late adolescence more than their near‐elite peers. The involvement in other sports neither differs between the groups nor predicts success. It can be concluded that factors related to the organization of practice during the mid‐teens seem to be crucial for international success within cgs sports. Future research should adopt a longitudinal design with means of drawing causal inferences.
Erratum
Authors: Luoto R , Matomäki J , Isolauri E , Lehtonen L
Published: March 2011

‘Incidence of necrotizing enterocolitis in very‐low‐birth‐weight infants related to the use of Lactobacillus GG’ published in Acta Paediatrica (2010;99:1135–8)

Our recent article, examining retrospectively the incidence of necrotizing enterocolitis (NEC) in all five university hospital NICUs in Finland in relation to the use of LGG, demonstrated that the incidence of NEC was 4.6% vs. 3.3% vs. 1.8% in the prophylactic LGG group, the no probiotics group and the probiotics ‘on demand’ group, respectively; p = 0.0090, Chi‐Square. This is correctly presented in the result section of the manuscript. Unfortunately in the abstract the latter two groups, i.e. the no probiotics group and the probiotics ‘on demand’ group, were reported in wrong order.

We wish this type of error, kindly brought to our attention only recently by colleagues from Australia and Denmark, to be corrected. Further, we find this correction of most importance for the readers paying more attention to the abstracts than to the articles.

The conclusion of our paper remains, however, unchanged: more randomized clinical trials of the specific probiotic strains on the prevention of NEC in the premature infants is urgently needed.
Modulation of α‐synuclein aggregation by dopamine in the presence of MPTP and its metabolite
Authors: Jethva Prashant N. , Kardani Jay R. , Roy Ipsita
Published: March 2011

The neurotransmitter dopamine has been shown to inhibit fibrillation of α‐synuclein by promoting the formation of nonamyloidogenic oligomers. Fibrillation of α‐synuclein is accelerated in the presence of pesticides and the neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). The aim of this study was to determine whether dopamine continues to have an adverse effect on the fibrillation of α‐synuclein in the presence of MPTP and its metabolite 1‐methyl‐4‐phenylpyridinum ion (MPP+). We also attempted to answer the ambiguous question of whether conversion of MPTP to MPP+ is required for the fibrillation of α‐synuclein. For this, α‐synuclein was incubated in the presence of MPTP and MPP+ along with dopamine. The fibrillation of α‐synuclein was monitored by Thioflavin T fluorescence and immunoblotting. The morphology of the aggregates formed was observed using scanning electron microscopy. The concentrations of the neurotoxin and its metabolite were estimated by reverse phase HPLC. We found definitive evidence that the conversion of MPTP to MPP+ is not required for aggregation of α‐synuclein. MPP+ was found to accelerate the rate of α‐synuclein aggregation even in the absence of components of mitochondrial complex I. In contrast to the effect of dopamine on the aggregation of α‐synuclein alone, in the presence of MPTP or MPP+, the aggregates formed are Thioflavin T‐positive and amyloidogenic. Thus, the effect of dopamine on the nature of aggregates formed in case of α‐synuclein alone and in the presence of MPTP/MPP+ is different.
Vacuum‐assisted closure therapy leads to an increase in plasma fibronectin level
Authors: Arslan Emrah , Ozturk Ozlem Goruroglu , Aksoy Alper , Polat Gurbuz
Published: March 2011

An extensive research has been performed to investigate the mechanisms of action by which the application of subatmospheric pressure to wounds increases the rate of healing. Increased blood flow with vacuum‐assisted closure (VAC) use is the most popular aspect. Fibronectin, which is an adhesion molecule, has several functional domains mediating chemotaxis, adhesion and migration. This is thereby involved in differentiation, proliferation, inflammation and thus in wound healing. In this study, plasma fibronectin levels were measured before and after VAC in patients with wounds. The results showed that there was an increase in pre‐ and post‐VAC levels of plasma fibronectin. This statistically significant increase could be another explanation of how VAC therapy promotes wound healing.
Comparison of vacuum‐assisted closure device and conservative treatment for fasciotomy wound healing in ischaemia‐reperfusion syndrome: preliminary results
Authors: Saziye Karaca , Mustafa Cikirikcioglu , Ilker Uckay , Afksendyios Kalangos
Published: March 2011

Ischaemia‐reperfusion syndrome (IRS) is a condition that may require early fasciotomy. In the past, fasciotomies ultimately required prolonged hospitalisation. Vacuum‐assisted closure (VAC) therapy system is an innovative method which promotes wound healing by reducing wound oedema, increasing microcirculation, and stimulation of granulation tissue. The aim of this retrospective study was to compare the VAC treatment with the conservative treatment of the fasciotomy wound until definitive surgical closure. The researchers retrospectively identified 15 patients, 3 females and 12 males, with a mean age of 69 years, who underwent a fasciotomy between January 2003 and December 2009 at the University Hospital of Geneva. All of the fasciotomies performed on the patients were on account of IRS. Seven patients were subjected to wound treatment using the VAC‐system device and eight patients underwent treatment through the usual conservative method. The data were analysed by comparing the operative wound size, length of time for wound closure and duration of hospital stay in both groups. The number of days after fasciotomy until surgical wound closure in the VAC‐system group (n = 7) ranged from 8 to 13 days with a mean of 11 days. The wound size at the day of closure was decreased in length by a mean of 58% (range 29–67%) and in diameter by a mean of 56% (range 33–75%). The duration of hospital stay for this group ranged from 12 to 18 days with a mean of 14 days. No signs of infections were observed and no re‐operation was required after first closure. In the conservative group (n = 8), the time to wound closure ranged between 12 and 20 days with a mean of 15 days. The wound size was decreased in length by a mean of 40% (range 32–53%) and in diameter by a mean 46% (range 30–70%). The mean duration of hospital stay was 18·5 days. Three of the patients in the conservative treatment group manifested wound infection during the course of the treatment. VAC device could be a new standard for treatment of fasciotomy wound. VAC therapy is a recent innovation and becoming more and more a necessary complementary therapy to hasten wound healing. In our preliminary study, the VAC‐system device showed significantly reduction of the wound size, decreased tissue oedema, duration of hospital days and improvement of granulation tissue.
Morphological spectrum of primary epidermal laminae in the forehoof of Thoroughbred horses
Authors: FARAMARZI B.
Published: March 2011

Reasons for performing the study: Hoof health is a major concern of horse owners as well as the equine industry. However, many questions remain concerning regional variations of laminar junction and its potential to remodel.

Hypothesis: To examine regional variations in the morphology of the laminar junction and thickness of the hoof wall in Thoroughbred horses.

Methods: The forefeet of 25 Thoroughbred cadavers were examined. Each hoof was divided into 20 blocks through 4 proximodistal slices (below the coronary band, each 1 cm apart) and 5 circumferential positions (toe, medial and lateral quarters and heels). In each block, 25 central primary epidermal laminae (PEL) were considered. Orientation of each lamina in relation to the hoof wall (LO), degree of bending (IA) and the spaces between the adjacent laminae (LS) were measured. Thickness of the hoof wall and number of branched PEL were also measured. Data were analysed using a split‐block design in ANOVA.

Results: There were significant differences between the 2 proximal and 2 distal slices in LO and IA data, but not in LS data. Circumferentially, toe blocks were different from heel and quarters blocks. Lateral and medial heels as well as the quarters were mostly different. The hoof wall was slightly thicker laterally than medially. There were more branched PEL on the lateral side of the left hooves and on the medial side of the right hooves.

Conclusions: These data add to the circumstantial evidence supporting the hypothesis of adaptive remodelling in the laminar junction. Results of this study signify the capability of PEL to remodel in response to applied stress to the regions of the hoof.

Potential relevance: A deeper understanding of the gross and cellular processes of laminar remodelling may well prove to be complementary to an understanding of their failure in laminitis.
Descriptive results from a longitudinal study of airway inflammation in British National Hunt racehorses
Authors: CARDWELL J. M. , WOOD J. L. N. , SMITH K. C. , NEWTON J. R.
Published: March 2011

Reasons for performing study:Rates of airway inflammation in young racehorses decrease with time but it is not clear whether this is associated with increasing age or time exposed to the training environment. The structure of the British National Hunt (NH) population allowed closer examination of this relationship.

Objectives:To compare rates of inflammatory airway disease diagnosed by tracheal sampling (trIAD), and its components, in NH racehorses by age and training history and with published rates in young racehorses.

Methods:A prospective, longitudinal study was conducted on 5 NH yards over 2 years. Period sample prevalences of nasal discharge,tracheal mucus, airway neutrophilia and trIAD (defined by a combination of tracheal mucus and airway neutrophilia) were estimated and compared between horses with different ages and time in training.

Results:Horses new to training had twice the odds of visible tracheal mucus as ex‐flat trained horses (OR 2.0; 95% CI: 1.4–2.8; P<0.001) but no significantly increased odds of airway neutrophilia (OR 1.3; 95% CI: 0.8–1.9; P = 0.3) and inconclusive evidence of increased odds of trIAD (OR 1.8; CI: 0.9–3.5; P = 0.08). However, a lower median time in training was significantly associated with the presence of visible mucus (P<0.001), increased mucus (P = 0.005) and trIAD (P = 0.03). No disease measure varied significantly with age.

Conclusions:Tracheal mucus and trIAD, but not neutrophilia detected in tracheal wash samples, were less prevalent in horses that had been exposed to the training environment for longer, explaining previously reported associations with age.

Potential relevance:Neutrophil proportion in tracheal wash samples is not as useful a clinical tool as measures of visible tracheal mucus for identifying horses requiring treatment or changes in management. The inclusion of tracheal wash neutrophils in the assessment of equine airways, or at least their relative weighting in definitions of trIAD, should be re‐evaluated.
Enhanced IL‐6 transcriptional response to adenosine receptor ligands in horses with lower airway inflammation
Authors: ZHANG L. , FRANCHINI M. , WEHRLI ESER M. , DIP R.
Published: March 2011

Reasons for performing study: Accumulation of extracellular adenosine has been closely associated with human asthmatic responses. However, the relevance of adenosine signalling in equine airways has not previously been investigated.

Objectives: To determine the expression of adenosine receptors (AR) in bronchoalveolar lavage (BAL) cells and assess the reactivity of these cells to AR ligands ex vivo, employing IL‐6 as readout of adenosinergic inflammatory signalling.

Methods: Eight horses with varying degrees of lower airway inflammation and 10 healthy controls were analysed. Expression of AR‐subtypes in each BAL sample was determined by quantitative RT‐PCR and compared to that in 13 other tissues. Bronchoalveolar lavage cells were stimulated either with the adenosine analogue NECA, CGS‐21680 (A2AAR selective agonist) or with a combination of NECA and SCH‐58261 (A2AAR antagonist) and IL‐6 expression assessed.

Results: Bronchoalveolar lavage cells predominantly expressed A2BAR, with lower A2AAR levels and marginal A3AR expression; A1AR was not detected. This pattern was similar to that of PBMCs but different from the other tissues tested. No significant differences in AR expression in BAL cells from both groups were detected, although a trend for decreased A2BAR in airway‐compromised horses was observed. Treatment of BAL cells with the nonselective agonist NECA upregulated IL‐6 expression in cells from airway‐compromised horses, but levels remained unchanged in control animals. Furthermore, blockage of A2AAR with SCH‐58261 enhanced IL‐6 mRNA induction by NECA in both groups, with higher levels in airway‐compromised horses; the amplitude of this response correlated with neutrophil count.

Conclusions: These results demonstrate the presence of an adenosine/IL‐6 inflammatory axis in the bronchoalveolar milieu of airway‐compromised horses. While A2BAR is the predominant proinflammatory AR subtype expressed, A2AAR appears to modulate inflammatory signalling (IL‐6 expression) by adenosine.

Potential relevance: This study supports selective AR targeting as a potential therapeutic approach for the modulation of inflammation in the equine lower respiratory tract.
Early maladaptive schemas and child and adult attachment: A 15‐year longitudinal study
Authors: Simard Valérie , Moss Ellen , Pascuzzo Katherine
Published: March 2011

Objectives. To examine the relation between early maladaptive schemas (EMS), as defined in schema therapy, and both child and adult attachment.

Design. A 15‐year longitudinal design in which child attachment groups (secure, avoidant, ambivalent, and disorganized) were compared in early adulthood on their profile of scores across EMS domains. A similar strategy was used to examine EMS profiles as a function of adult attachment groups (secure, preoccupied, and fearful).

Methods. Sixty participants, recruited from Montreal day‐care centres, were assessed at 6 (Time 1) and 21 years of age (Time 2). Time 1 attachment was assessed using a separation–reunion procedure and Time 2 attachment, using the Experiences in Close Relationships questionnaire. EMS were evaluated with the Young Schema Questionnaire (Time 2).

Results. There were more signs of EMS among young adults with either an insecure ambivalent child attachment, or an insecure preoccupied adult attachment style, compared to their secure peers. These differences were not specific to one domain of EMS; they were reported for various EMS.

Conclusions. The results suggest that specific elements of representational models are more likely to be related to the development of EMS: high anxiety over abandonment, negative self‐view, and explicit manifestations of personal distress. Unmet childhood needs for secure attachment may lead to a large variety of EMS as defined in schema therapy.
Serration Design for a Gear Plunge Shaving Cutter
Authors: Hsu Ruei-Hung , Fong Zhang-Hua
Published: March 2011

The surface roughness of the work gear after plunge shaving is affected primarily by the arrangement of the serrations. Given the two possible shaving conditions—up cutting and down cutting—this surface roughness can be improved by arranging the serrations’ cutting edge to perform as much up cutting as possible. Hence, this paper provides guidance on choosing the serration helix and the displacement of the plunge shaving cutter and then validates these suggestions experimentally.
Time-Resolved Experimental Study of Silicon Carbide Ablation by Infrared Nanosecond Laser Pulses
Authors: Gao Yibo , Zhou Yun , Wu Benxin , Tao Sha , Jacobsen Ronald L. , Goodman Bill
Published: March 2011

Silicon carbide, due to its unique properties, has many promising applications in optics, electronics, and other areas. However, it is difficult to micromachine using mechanical approaches due to its brittleness and high hardness. Laser ablation can potentially provide a good solution for silicon carbide micromachining. However, previous studies of silicon carbide ablation by nanosecond laser pulses at infrared wavelengths are very limited on material removal mechanism, and the mechanism has not been well understood. In this paper, experimental study is performed for silicon carbide ablation by 1064 nm and 200 ns laser pulses through both nanosecond time-resolved in situ observation and laser-ablated workpiece characterization. This study shows that the material removal mechanism is surface vaporization, followed by liquid ejection (which becomes clearly observable at around 1 μs after the laser pulse starts). It has been found that the liquid ejection is very unlikely due to phase explosion. This study also shows that the radiation intensity of laser-induced plasma during silicon carbide ablation does not have a uniform spatial distribution, and the distribution also changes very obviously when the laser pulse ends.
The Preparation and Thermal Conductivities Enhacement of Nanofluids Containing Graphene Oxide Nanosheets
Authors: Yu Wei , Xie Huaqing , Chen Lifei , Li Yang , Li Dehui
Published: March 2011

The work presents a method to prepare stable nanofluids containing graphene oxide nanosheets (GO-EG nanofluid). The hydrophilic surfaces let graphene oxide nanosheets have good compatibility with ethylene glycol. The thermal conductivity of the nanofluids was measured by a short hot wire technique, and the result shows that the thermal conductivity of GO-EG nanofluids is almost constant within 7 days, and it reflects the high stability of GO-EG nanofluids. The thermal conductivity enhancement ratios of GO-EG nanofluids were almost constant with tested temperatures vary. GO-EG nanofluids have substantially higher thermal conductivities than the base fluids. When the loading is 5.0 vol.%, the enhancement ratios is up to 61%, much larger than those of metallic oxide. For 1.0 vol.% GO-EG nanofluid, the enhancement ratios is 10.5%, less than those of CNT with the same loading. The reason may be due to the defects, caused by the treatment with strong Oxidants. In our opinion, heat transport in the GO nanosheet is one of the major contributions to the increase of the effective thermal conductivity of nanofluids.
Forced Convective Boiling of Refrigerant HCFC123 in a Mini-Tube
Authors: Araga Koichi , Okamoto Keisuke , Murata Keiji
Published: March 2011

This paper presents an experimental investigation of the forced convective boiling of refrigerant HCFC123 in a mini-tube. The inner diameters of the test tubes, D, were 0.51 mm and 0.30 mm. First, two-phase frictional pressure drops were measured under adiabatic conditions and compared with the correlations for conventional tubes. The frictional pressure drop data were lower than the correlation for conventional tubes. However, the data were qualitatively in accord with those for conventional tubes and were correlated in the form φL2−1/Xtt. Next, heat transfer coefficients were measured under the conditions of constant heat flux and compared with those for conventional tubes and for pool boiling. The heat transfer characteristics for mini-tubes were different from those for conventional tubes and quite complicated. The heat transfer coefficients for D = 0.51 mm increased with heat flux but were almost independent of mass flux. Although the heat transfer coefficients were higher than those for a conventional tube with D = 10.3 mm and for pool boiling in the low quality region, they decreased gradually with increasing quality. The heat transfer coefficients for D = 0.30 mm were higher than those for D = 0.51 mm and were almost independent of both mass flux and heat flux.
Numerical Simulation for Outdoor Thermal Environment of High-Rise Building With Air-Conditioner
Authors: Zhang Zhen , Tong Lige , Wang Li
Published: March 2011

A large number of split-type air conditioner are widely used in high-rise residential or office buildings in China and the outdoor units of air-conditioner are often installed at the sidewalls or on the roofs in the confined space of a high-rise building. The factors affecting the performance of air-conditioner are the solar radiation, the heat released from the outdoor units, the ventilation of the confined installation space of a building where the outdoor units are installed and so on, which are investigated in this study. The air flow and temperature distribution under steady-state condition near the two outdoor units installed on the same storey in a building are simulated by software FLUENT, in which the porous model and DO radiation model are used. The optimum installation distance from the supporting wall is obtained. The average temperature of the exit surface without wind is 1.18% more than that with wind. The results show that the heat released from the outdoor units and the ventilation of the confined installation space where the outdoor units are installed are the main factors affecting the thermal environment in the confined installation space; The influence of the solar radiation can be neglected.
Enhanced Condensation of Ethylene Glycol on Three-Dimensional Pin-Fin Tubes
Authors: Ali Hafiz Muhammad , Ali Hassan , Briggs Adrian
Published: March 2011

New experimental data are reported for condensation of ethylene glycol at near atmospheric pressure and low velocity on six three-dimensional pin-fin tubes. Enhancements of the vapour-side, heat-transfer coefficients were found between 3 to 5.5 when compared to a plain tube at the same vapour-side temperature difference. Heat-transfer enhancement was found to be strongly dependent on the active surface area i.e. on the proportion of the tube and pin surface not covered by condensate retained by surface tension. For all the tubes, vapour-side, heat-transfer enhancements were found to be approximately 3 times the corresponding active-area enhancements. The best performing pin-fin tube gave a heat-transfer enhancement of up to 5.5; 17% higher than those obtained from ‘optimised’ two-dimensional fin-tubes reported in the literature and about 24% higher than the ‘equivalent’ two-dimensional integral-fin tube (i.e. with same fin root diameter, longitudinal fin spacing and thickness and fin height).
Experimental and Theoretical Study on Mixing Performance in Gas-Stirred Ladles With Throughflow Having Tap-Stream Addition of Particulates
Authors: Yang Wen-Jei , Torii Shuichi
Published: March 2011

An experimental study is performed to determine mixing performance in gas-ladles with throughflow having tap-addition of particles. Behavior of ascending gas bubbles in the plume and recirculating liquid-particle two-phase flow is visualized by means of direct photography aided by white light-sheet illumination. The path line profile and the history of ascending velocity of gas bubbles from the gas-injection nozzle installed at the ladle bottom are measured with the aid of the image processing method. It is disclosed that a rhythm is discovered in bubble detachment from the nozzle tip. This rhythm repeats by cycle and is characterized by two distinct patterns, forming the discrete bubbles regime and continuous jet regime for lower and higher air injection rates, respectively. Inspective of air injection rate, the growth of each bubble can be divided into the initial, intermediate, and final stages. Each stage has its own distinct bubble growth velocity, path line profile, and ascending velocity. The theoretical equation is derived to correlate experimental data on bubble path line.
Quantification of Nanoparticle Distribution in Tissue After Direct Injection Using MicroCT Imaging
Authors: Attaluri Anilchandra , Ma Ronghui , Zhu Liang
Published: March 2011

Magnetic nanoparticles have been used in clinical and animal studies to generate localized heating for tumor treatments when the particles are subjected to an external alternating magnetic field. One approach to deliver the nanoparticles is via directly injecting the nanoparticles in the extracellular space of the tumor. Its advantage is that multiple-site injections can be exploited to cover the entire target region in the case of an irregularly shaped tumor. Currently since most tissue is opaque, the detailed information of the nanoparticle spreading after the injection can not be visualized directly and it is often quantified by indirect methods such as temperature measurements to inversely determine the distribution. In this study, we use a high-resolution microCT imaging system to investigate the nanoparticle concentration distribution in a tissue equivalent agarose gel. The preliminary results are promising to obtain a 3-D distribution of the ferrofluid in tissue. The local density variations induced by the nanoparticles in the vicinity of the injection site can be detected and analyzed by the microCT system. Experiments are performed to study how the injection amount, gel concentration, and nanoparticle concentration in the ferrofluid affect nanoparticle spreading in the gel. The obtained quantified information is important for future studies of temperature elevations in opaque tumor to design optimized treatment protocols.
Vapor Embryo Nucleation in Near-Wall Region Under Pool Boiling Conditions
Authors: Bai Bofeng , Li Sijie
Published: March 2011

To construct a model of the microscopic near-wall region in a macroscopic pool boiling system, the present work introduced the effect of the solid wall at the bottom of the simulation system and the infinite liquid region outside it as extra potential. Molecular dynamics simulation results showed that thermodynamics properties of near-wall region was influenced by the interaction strength and deviated from the bulk liquid region. Vapor embryo nucleated at a position several nanometers away from the solid surface. With the increase of Hamaker constant, the vapor embryo occurred at a position farther away from the solid wall.
Analysis and Optimum for Air Cooling Thermal Module Using Dimple Vortex Generators
Authors: Yang Kai-Shing , Li Shu-Lin , Chen Ing Youn , Wang Chi-Chuan
Published: March 2011

This study examines the airside performance of heat sinks having fin patterns of plate fin (Type I), interrupted fin geometry (Type II), dense vortex generator (Type III), and loose vortex generator (Type IV). Test results indicate that the heat transfer performance is strongly related to the developing and fully developed flow characteristics. The augmentations via vortex generator are relatively effective when the flow is in the developing region whereas they become quite less effective in the fully developed region. This is especially pronounced when operated at a lower frontal velocity. Actually the plain fin geometry outperforms most of the enhanced fin patterns such as of type II and type III at the fully developed region. This is because a close spacing prevents the formation of vortex, and the presence of interrupted surface may also suffer from the degradation by constriction of conduction path. The results suggest that the vortex generators operated at a higher frontal velocity is more beneficial than that of plain fin geometry. In association with the VG-1 criteria (same pumping power and same heat transfer capacity), the results show that effective reduction of surface area can be achieved when the frontal velocities are at 3∼5 m/s and the fin patterns are triangular, triangular attack, or two-groups dimple. The result from the present experiment suggests that the asymmetric combination such as using loose vortex generator (Type IV) can be quite effective. The triangular attack vortex generator is regarded as the optimum enhancement design for it could reduce 12∼15% surface area at a frontal velocity around 3∼5 m/s. The asymmetric design is still applicable even when the fin pitch is reduced to 1 mm.
Electrical Initiation of Solidification and Preservation of Supercooled State for Sodium Acetate Trihydrate
Authors: Munakata Tetsuo , Nagata Shinichi
Published: March 2011

Electrical initiation of solidification from supercooled state and preservation of supercooled state of sodium acetate trihydrate solution, which is considered as a promising thermal energy storage material, are experimentally investigated with varying the configuration of electrodes and confirmed that the initiation of solidification and preservation of supercooled state are both possible by using the electric field. Further, effect of crystal growth direction on crystal growth rate is also investigated by using the newly developed electrical nucleation method. The result shows that the crystal growth rate, which growth direction is bottom to top, is slightly decreased compared with the direction of top to bottom at certain supercooling temperature range.
A Numerical Investigation of Nanofluids Forced Convection Flow in a Horizontal Smooth Tube
Authors: Demir Hakan , Dalkılıc¸ Ahmet Selim , Ku¨rekci Nuri Alpay , Keles¸og˘lu Bu¨lent , Wongwises Somchai
Published: March 2011

In this study, laminar and turbulent forced convection flows of a nanofluid consisting of water and Al2O3 in a horizontal smooth tube with constant wall temperature are investigated numerically. Studies that are related to the subject in the literature are reviewed. The determination of the nanofluid properties is calculated by means of the correlations of Palm et al. Two-dimensional elliptical governing equations are used to study the hydrodynamics and thermal behaviors of the nanofluid flow. A single-phase model is employed with either constant or temperature dependent properties. The investigation is performed for a constant particle size. The velocity and temperature vectors are presented in the entrance and fully developed region. Effects of nanoparticles concentration and Reynolds number on shear stress and pressure drop are presented. The Nusselt numbers and heat transfer coefficients of nanofluids are obtained for different nanoparticle concentrations. Numerical results show the heat transfer enhancement due to presence of the nanoparticles in the fluid. Heat transfer coefficient increases with increasing the particle volume concentration and also increasing wall shear stress values.
Forced Flow and Convective Heat Transfer of Phase Change Material Slurry in the Heat Exchangers
Authors: Zhang Peng , Ma Zhiwei , Wang Ruzhu
Published: March 2011

The application of phase change material slurry to the refrigeration and air conditioning system opens a new way for energy saving and reduction of the quantity of refrigerant in the system, because it can serve as both the energy storage and transportation media in the secondary loop which is responsible for distributing the cooling power. In the present study, the experimental investigations of the forced flow and heat transfer characteristics of Tetrabutylammonium Bromide (TBAB in abbreviation) clathrate hydrate slurry (CHS) in both the plate heat exchanger (PHE) and double-tube heat exchanger (DHE) are carried out. It is found out that the pressure drop in the PHE is about 5–50 kPa at the flow rate of 2–14 L/min and is about 2–30 kPa at the flow rate of 3–14 L/min, which is nearly 2 times of that of the chilled water. The overall heat transfer coefficient is in the range of 2500–5000 W/(m2K) for TBAB CHS in the PHE and is about 1500–3500 W/(m2K) in the DHE, which are both higher than that of TBAB aqueous solution flow because of the involvement of the phase change of TBAB CHS.
A Combined P1 and Monte Carlo Model for Radiative Transfer in Multi-Dimensional Anisotropically Scattering Media
Authors: Dombrovsky Leonid , Lipin´ski Wojciech
Published: March 2011

A combined two-step computational method incorporating (1) transport approximation of the scattering phase function, (2) P1 approximation and the finite element method for computing the radiation source function at the first step, and (3) the Monte Carlo method for computing radiative intensity at the second step, is developed. The accuracy of the combined method is examined for model problems involving two multi-dimensional configurations of an anisotropically scattering medium. A detailed analysis is performed for a medium with scattering phase function described by a family of the Henyey–Greenstein functions. The accuracy of the two-step method is assessed by comparing the distribution of the radiative flux leaving the medium to that obtained by a reference complete Monte Carlo method. This study confirms the main results of previous papers on the errors of the two-step solution method. The combined method leads to a significant reduction in computational time as compared to the reference method, by at least 1 order of magnitude. Finally, possible applications of the combined method are briefly discussed.
Convective Heat Transfer of Alumina Nanofluids in a Microchannel
Authors: Vafaei Saeid , Wen Dongsheng
Published: March 2011

This work reports an experimental study of convective heat transfer of aqueous alumina nanofluids in a horizontal microchannel under laminar flow condition. The variation of local heat transfer coefficients, in both entrance and developed flow regime, is obtained as a function of axial distance. The heat transfer coefficient of nanofluids is found to be dependent upon not only nanoparticle concentration but also mass flow rate. Different to the behavior in conventional-sized channels, the major heat transfer coefficient enhancement is observed in fully developed region in microchannels. Discussions of the results suggest that the heterogeneous nature of nanoparticle flow should be considered.