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Sample records for acute cbf drop

  1. Acute marijuana effects on rCBF and cognition: a PET study.

    PubMed

    O'Leary, D S; Block, R I; Flaum, M; Schultz, S K; Boles Ponto, L L; Watkins, G L; Hurtig, R R; Andreasen, N C; Hichwa, R D

    2000-11-27

    The effects of smoking marijuana on cognition and brain function were assessed with PET using H2(15)O. Regional cerebral blood flow (rCBF) was measured in five recreational users before and after smoking a marijuana cigarette, as they repeatedly performed an auditory attention task. Blood flow increased following smoking in a number of paralimbic brain regions (e.g. orbital frontal lobes, insula, temporal poles) and in anterior cingulate and cerebellum. Large reductions in rCBF were observed in temporal lobe regions that are sensitive to auditory attention effects. Brain regions showing increased rCBF may mediate the intoxicating and mood-related effects of smoking marijuana, whereas reduction of task-related rCBF in temporal lobe cortices may account for the impaired cognitive functions associated with acute intoxication.

  2. Acute effects of electroconvulsive therapy on regional cerebral blood flow (rCBF) in psychiatric disorders

    SciTech Connect

    Prohovnik, I.; Alderson, P.O.; Sackheim, H.A.; Decina, P.; Kahn, D.

    1984-01-01

    Electroconvulsive therapy (ECT) is frequently used in the treatment of major depression and other psychiatric disorders; its mechanism of action is not established, but previous evidence suggests that it is associated with postictal metabolic suppression. The authors have used measurements of rCBF as an index of cortical metabolic activity to study the acute effects of ECT. Measurements of rCBF were made in 32 cortical regions in 10 patients (pts) following one minute breathing of Xe-133 (5mCi/L); the measurements were performed 30min before and 50min after ECT. Bilateral ECT was administered to six pts (five diagnosed as major depressives and one schizophrenic) and unilateral ECT to four (all diagnosed as unipolar or bipolar affective disorder). The total rCBF material consists of 52 measurements in these pts, made before and after 16 bilateral and 10 unilateral treatments. ECT was found to cause significant reduction of rCBF. Mean hemispheric flows (using the Initial Slope Index to measure grey-matter flow) were reduced by about 5% in both hemispheres following bilateral treatment. Unilateral treatment caused a 9% reduction of flow in the treated hemisphere, but only 2% contralaterally. Regional patterns of flow decreases also differed between the two treatment modes: bilateral frontal reductions were found after bilateral treatment, whereas unilateral ECT caused a widespread flow reduction in the treated hemisphere, and almost no effect contralaterally. These results suggest that rCBF studies are useful for assessing ECT, and indicate that the acute cerebral effects of ECT vary with the mode of treatment.

  3. Acute bilateral isolated foot drop: Report of two cases

    PubMed Central

    Kertmen, H.; Gürer, B.; Yimaz, E. R.; Sekerci, Z.

    2015-01-01

    Foot drop is defined as the weakness of the foot and ankle dorsiflexion. Acute unilateral foot drop is a well-documented entity, whereas bilateral foot drop is rarely documented. Slowly progressing bilateral foot drop may occur with various metabolic causes, parasagittal intracranial pathologies, and cauda equina syndrome. Acute onset of bilateral foot drop due to disc herniation is extremely rare. Here we present two cases of acute bilateral foot drop due to disc herniation. The first patient was a 45-year-old man presented with acute bilateral foot drop, without any sign of the cauda equina syndrome. Lumbar magnetic resonance imaging of the patient revealed L4-5 disc herniation. To our knowledge, this is the first presented case of acute bilateral foot drop without any signs of cauda equina syndrome caused by L4-5 disc herniation. The second patient was a 50-year-old man who was also presented with acute bilateral foot drop, and had T12-L1 disc herniation with intradural extension. Also this is the first presented case of T12-L1 disc herniation with intradural extension causing acute bilateral foot drop. We performed emergent decompressive laminectomy to both of the patients and extrude disc materials were excised. Both of the patients were recovered with favorable outcome. PMID:25972945

  4. Core binding factor acute myeloid leukemia (CBF-AML) in México: a single institution experience.

    PubMed

    Ruiz-Delgado, Guillermo J; Macías-Gallardo, Julio; Lutz-Presno, Julia; Garcés-Eisele, Javier; Hernández-Arizpe, Ana; Montes-Montiel, Maryel; Ruiz-Argüelles, Guillermo J

    2011-01-01

    Twenty one patients with CBF-AML presented prospectively in the Centro de Hematología y Medicina Interna de Puebla (Puebla, México) between February 1995 and March 2010, 14 with the t(8;21)(q22;q22) and 7 with the inv(16)(p13;q22)/t(16;16)(p13;q22); they represent 13% of all cases of AML. The median age of the patients was 24 years (range 1 to 61). Seven of 14 patients with t(8;21)(q22;q22) had an M2 morphology whereas 3/7 with the inv(16) had an M4 morphology; in addition to the myeloid markers identified by flow-cytometry (surface CD13, surface CD33, and cytoplasmic myeloperoxidase) lymphoid markers were identified in the blast cells of 8/14 cases of the t(8;21) patients, but in no patient with the inv(16). Nineteen patients were treated with combined chemotherapy and 16 (84%) achieved a complete molecular remission. Seven patients were auto or allografted. Relapses presented in 10/16 patients. The median probability of overall survival (OS) has not been reached being above 165 months, whereas the 165-month probability of OS and leukemia-free survival was 52%; despite a tendency for a better outcome of patients with the t(8;21), there were no significant differences in survival of patients with either the t(8;21) or the inv(16). In this single institution experience in México, we found that the CBF variants of AML have a similar prevalence as compared with Caucasian populations, that the co-expression of lymphoid markers in the blast cells was frequent in the t(8;21) and that these two AML subtypes were associated with a relatively good long-term prognosis. Further studies are needed to describe with more detail the precise biological features of these molecular subtypes of acute leukemia.

  5. High prognostic value of minimal residual disease detected by flow-cytometry-enhanced fluorescence in situ hybridization in core-binding factor acute myeloid leukemia (CBF-AML).

    PubMed

    Wang, Libing; Gao, Lei; Xu, Sheng; Gong, Shenglan; Liu, Min; Qiu, Huiying; Xu, Xiaoqian; Ni, Xiong; Chen, Li; Lu, Shuqing; Chen, Jie; Song, Xianmin; Zhang, Weiping; Yang, Jianmin; Hu, Xiaoxia; Wang, Jianmin

    2014-10-01

    Acute myeloid leukemia (AML) is generally regarded as a disorder of stem cells, known as leukemic initiating cells (LICs), which initiate the disease and contribute to relapses. Although the phenotype of these cells remains unclear in most patients, they are enriched within the CD34(+)CD38(-) population. In core-binding factor (CBF) AML, the cytogenetic abnormalities also exist in LIC. The aim of this study was to determine the prognostic power of minimal residual disease (MRD) measured by fluorescence in situ hybridization (FISH) in CD34(+)CD38(-) cells sorted by flow cytometry at different periods during therapy. Thirty-six patients under 65 years of age with de novo CBF-AML treated with intensive chemotherapy were retrospectively included in this study. Correlations with relapse-free survival (RFS) and overall survival were evaluated with univariate and multivariate analyses. FISH efficiently identified LICs in the CD34(+)CD38(-) population. The presence of FISH(+)CD34(+)CD38(-) cells before consolidation was negatively associated with cumulative incidence of relapse (64 vs 18 %, P = .012), which showed prognostic value for RFS (12 vs 68 %, P = .008) and OS (11 vs 75 %, P = .0005), and retained prognostic significance for RFS in multivariate analysis. The detection of FISH(+)CD34(+)CD38(-) cells before consolidation therapy significantly correlated with long-term survival. Fluorescence-activated cell sorting (FACS)-FISH could be potentially adopted as a MRD monitor approach in clinical practice to identify CBF-AML patients at risk of treatment failure during therapy.

  6. Arabidopsis CBF1 and CBF3 have a different function than CBF2 in cold acclimation and define different gene classes in the CBF regulon

    PubMed Central

    Novillo, Fernando; Medina, Joaquín; Salinas, Julio

    2007-01-01

    The C-repeat-binding factor (CBF)/dehydration-responsive element-binding factor (DREB1) proteins constitute a small family of Arabidopsis transcriptional activators (CBF1/DREB1B, CBF2/DREB1C, and CBF3/DREB1A) that play a prominent role in cold acclimation. A fundamental question about these factors that remains to be answered is whether they are functionally equivalent. Recently, we reported that CBF2 negatively regulates CBF1 and CBF3 expression, and that CBFs are subjected to different temporal regulation during cold acclimation, which suggested this might not be the case. In this study, we have analyzed the expression of CBF genes in different tissues of Arabidopsis, during development and in response to low temperature, and characterized RNA interference (RNAi) and antisense lines that fail to accumulate CBF1 or/and CBF3 mRNAs under cold conditions. We found that CBF1 and CBF3 are regulated in a different way than CBF2. Moreover, in contrast to CBF2, CBF1 and CBF3 are not involved in regulating other CBF genes and positively regulate cold acclimation by activating the same subset of CBF-target genes. All these results demonstrate that CBF1 and CBF3 have different functions than CBF2. We also found that the CBF regulon is composed of at least two different kind of genes, one of them requiring the simultaneous expression of both CBF1 and CBF3 to be properly induced. This indicates that CBF1 and CBF3 have a concerted additive effect to induce the whole CBF regulon and the complete development of cold acclimation. PMID:18093929

  7. Homeopathic Ear Drops as an Adjunct in Reducing Antibiotic Usage in Children With Acute Otitis Media.

    PubMed

    Taylor, James A; Jacobs, Jennifer

    2014-01-01

    Objective. To determine if use of a homeopathic ear drop preparation reduces antibiotic use in children diagnosed with acute otitis media (AOM). Methods. Children 6 months to 11 years old, diagnosed with AOM and managed with a delayed antibiotic approach, were randomized to standard therapy alone or standard therapy plus a homeopathic ear drop preparation. The primary outcome was whether or not the antibiotic prescription given at the index visit was filled during a 12- to 15-day follow-up period. Results. Among 210 enrolled children, follow-up antibiotic data were collected on 206. During the 12- to 15-day follow-up period, fewer parents of children randomized to the homeopathic ear drops group filled the antibiotic prescription compared with those of children receiving standard therapy alone (26.9% and 41.2%, respectively, P = .032). Conclusion. Homeopathic ear drops may be effective in reducing the use of antibiotics in children with AOM managed with a delayed antibiotic approach.

  8. Homeopathic Ear Drops as an Adjunct in Reducing Antibiotic Usage in Children With Acute Otitis Media.

    PubMed

    Taylor, James A; Jacobs, Jennifer

    2014-01-01

    Objective. To determine if use of a homeopathic ear drop preparation reduces antibiotic use in children diagnosed with acute otitis media (AOM). Methods. Children 6 months to 11 years old, diagnosed with AOM and managed with a delayed antibiotic approach, were randomized to standard therapy alone or standard therapy plus a homeopathic ear drop preparation. The primary outcome was whether or not the antibiotic prescription given at the index visit was filled during a 12- to 15-day follow-up period. Results. Among 210 enrolled children, follow-up antibiotic data were collected on 206. During the 12- to 15-day follow-up period, fewer parents of children randomized to the homeopathic ear drops group filled the antibiotic prescription compared with those of children receiving standard therapy alone (26.9% and 41.2%, respectively, P = .032). Conclusion. Homeopathic ear drops may be effective in reducing the use of antibiotics in children with AOM managed with a delayed antibiotic approach. PMID:27335917

  9. Effect of oxymetazoline nose drops on acute sinusitis in the rabbit.

    PubMed

    Bende, M; Fukami, M; Arfors, K E; Mark, J; Stierna, P; Intaglietta, M

    1996-03-01

    This investigation was designed to evaluate the effect of the common topical nasal decongestant oxymetazoline hydrochloride on the early local tissue defense in an experimental bacterial infection. For that purpose, a bilateral infection of the maxillary sinus was induced in 14 rabbits. Nose drops (oxymetazoline) were instilled in one nasal cavity, and placebo in the other. After 48 hours, the degree of infection was judged by using a semiquantitative inflammatory score to evaluate histologic preparations of the maxillary sinuses. On the oxymetazoline-treated side, we found a significantly higher degree of inflammation. We conclude that oxymetazoline nose drops, commonly used in acute rhinitis and sinusitis, interfere with the normal defense mechanisms during bacterially induced sinusitis, possibly by a decrease in mucosal blood flow.

  10. Prospective long-term minimal residual disease monitoring using RQ-PCR in RUNX1-RUNX1T1-positive acute myeloid leukemia: results of the French CBF-2006 trial.

    PubMed

    Willekens, Christophe; Blanchet, Odile; Renneville, Aline; Cornillet-Lefebvre, Pascale; Pautas, Cécile; Guieze, Romain; Ifrah, Norbert; Dombret, Hervé; Jourdan, Eric; Preudhomme, Claude; Boissel, Nicolas

    2016-03-01

    In t(8;21)(q22;q22) acute myeloid leukemia, the prognostic value of early minimal residual disease assessed with real-time quantitative polymerase chain reaction is the most important prognostic factor, but how long-term minimal residual disease monitoring may contribute to drive individual patient decisions remains poorly investigated. In the multicenter CBF-2006 study, a prospective monitoring of peripheral blood and bone marrow samples was performed every 3 months and every year, respectively, for 2 years following intensive chemotherapy in 94 patients in first complete remission. A complete molecular remission was defined as a (RUNX1-RUNX1T1/ABL1)×100 ≤ 0.001%. After the completion of consolidation therapy, a bone marrow complete molecular remission was observed in 30% of the patients, but was not predictive of subsequent relapse. Indeed, 8 patients (9%) presented a positive bone marrow minimal residual disease for up to 2 years of follow-up while still remaining in complete remission. Conversely, a peripheral blood complete molecular remission was statistically associated with a lower risk of relapse whatever the time-point considered after the completion of consolidation therapy. During the 2-year follow-up, the persistence of peripheral blood complete molecular remission was associated with a lower risk of relapse (4-year cumulative incidence, 8.2%), while molecular relapse confirmed on a subsequent peripheral blood sample predicted hematological relapse (4-year cumulative incidence, 86.9%) within a median time interval of 3.9 months. In t(8;21)(q22;q22) acute myeloid leukemia, minimal residual disease monitoring on peripheral blood every 3 months allows for the prediction of hematological relapse, and to identify patients who could potentially benefit from intervention therapy. (ClinicalTrials.gov ID #NCT00428558).

  11. Assessment of cerebral blood flow autoregulation (CBF AR) with rheoencephalography (REG): studies in animals

    NASA Astrophysics Data System (ADS)

    Popovic, Djordje; Bodo, Michael; Pearce, Frederick; van Albert, Stephen; Garcia, Alison; Settle, Tim; Armonda, Rocco

    2013-04-01

    The ability of cerebral vasculature to regulate cerebral blood flow (CBF) in the face of changes in arterial blood pressure (SAP) or intracranial pressure (ICP) is an important guard against secondary ischemia in acute brain injuries, and official guidelines recommend that therapeutic decisions be guided by continuous monitoring of CBF autoregulation (AR). The common method for CBF AR monitoring, which rests on real-time derivation of the correlation coefficient (PRx) between slow oscillations in SAP and ICP is, however, rarely used in clinical practice because it requires invasive ICP measurements. This study investigated whether the correlation coefficient between SAP and the pulsatile component of the non-invasive transcranial bioimpedance signal (rheoencephalography, REG) could be used to assess the state and lower limit of CBF AR. The results from pigs and rhesus macaques affirm the utility of REG; however, additional animal and clinical studies are warranted to assess selectivity of automatic REG-based evaluation of CBF AR.

  12. Systematic Review of Compound Danshen Dropping Pill: A Chinese Patent Medicine for Acute Myocardial Infarction

    PubMed Central

    Xu, Hao; Chen, Keji

    2013-01-01

    Objective. This paper systematically evaluated the efficacy and safety of compound Danshen dropping pill (CDDP) in patients with acute myocardial infarction (AMI). Methods. Randomized controlled trials (RCTs), comparing CDDP with no intervention, placebo, or conventional western medicine, were retrieved. Data extraction and analyses were conducted in accordance with the Cochrane standards. We assessed risk of bias for each included study and evaluated the strength of evidence on prespecified outcomes. Results. Seven RCTs enrolling 1215 patients were included. CDDP was associated with statistically significant reductions in the risk of cardiac death and heart failure compared with no intervention based on conventional therapy for AMI. In addition, CDDP was associated with improvement of quality of life and impaired left ventricular ejection fraction. Nevertheless, the safety of CDDP was unproven for the limited data. The quality of evidence for each outcome in the main comparison (CDDP versus no intervention) was “low” or “moderate.” Conclusion. CDDP showed some potential benefits for AMI patients, such as the reductions of cardiac death and heart failure. However, the overall quality of evidence was poor, and the safety of CDDP for AMI patients was not confirmed. More evidence from high quality RCTs is warranted to support the use of CDDP for AMI patients. PMID:23843882

  13. Comparison of CBF1, CBF2, CBF3 and CBF4 expression in some grapevine cultivars and species under cold stress

    PubMed Central

    Karimi, Maryam; Ebadi, Ali; Mousavi, Seyed Amir; Salami, Seyed Alireza; Zarei, Abdolkarim

    2015-01-01

    Grapevine, an important horticultural crop in the world, is moderately tolerant to cold conditions and is subjected to the cold injuries at different regions. So studies on different aspects of tolerance mechanism to unexpected cold of late spring as well as winter freezing seems necessary about this vine. For this reason, study on genes responsible for acquiring cold tolerance is very important. Transcription factors are among regulatory proteins that are responsible for cold acclimation. In this research work, expression levels of CBF1, CBF2, CBF3, and CBF4 transcription factors were studied on two cvs of Vitis vinifera (“Khalili-Danedar” and “Shahroodi”) as well as one Vitis riparia at different times after treating at 4 °C. Results showed that two vinifera cultivars, “Khalili-Danedar” and “Shahroodi”, had similar trend for each transcription factor. Gene expression increased at the beginning of cold stress and then decreased. Expression of these TF started some minutes (CBF1) after cold treatment and continued for several hours (CBF2), even till the tenth day (CBF4). All together V. riparia which is endemic to the cold regions behaved stronger and showed higher expression for all studied transcription factors. Among two V. vinifera cultivars, “Khalili-Danedar” showed significantly higher expression compared with “Shahroodi”. The comparison of expression levels of these four transcription factors revealed that the least and the greatest expressions were recorded for CBF1 and CBF3 respectively, and two CBF2 and CBF4 had approximately the same expression levels. PMID:26973374

  14. Probability of Treatment Following Acute Drop in Lung Function in Children with Cystic Fibrosis is related to baseline pulmonary function

    PubMed Central

    Morgan, Wayne J.; Wagener, Jeffrey S.; Yegin, Ashley; Pasta, David J.; Millar, Stefanie J.; Konstan, Michael W.

    2014-01-01

    Objective To hypothesize whether the association between high forced expiratory volume in 1 second (FEV1) and increased rate of decline in FEV1 in children with cystic fibrosis could be due to less frequent intervention after acute drops (sudden decline events) in FEV1. Study design Patients with CF aged 6-17 years enrolled in ESCF were assessed for a sudden decline event, defined as a 10% relative drop in FEV1 % predicted from an average of 3 consecutive stable baseline spirometries. The likelihood of therapeutic intervention within 14 days before and 56 days after this event was then related to their baseline FEV1 % predicted age-specific decile using a logistic regression adjusting for age group (6-12y, 13-17y) and presence of Pseudomonas aeruginosa on respiratory culture. Results 10,888 patients had at least one sudden decline event in FEV1. Patients in the highest FEV1 decile were significantly less likely than those in the lowest decile to receive intravenous antibiotics (odds ratio [OR], 0.14; 95% confidence interval [CI], 0.11-0.18; P<.001) or be hospitalized (OR, 0.18; 95% CI, 0.14-0.23; P<.001) following decline. Conclusions Children and adolescents with high baseline lung function are less likely to receive a therapeutic intervention following an acute drop in FEV1, which may explain their greater rate of FEV1 decline. PMID:23810128

  15. The acute effect of drop jump protocols with different volumes and recovery time on countermovement jump performance.

    PubMed

    Chen, Zong-Rong; Wang, Yu-Han; Peng, Hsien-Te; Yu, Ching-Fang; Wang, Min-Hsien

    2013-01-01

    The aim of this study was to investigate the acute effect of (a) a drop jump (DJ) protocol with 1 set per 5 repetitions and (b) a DJ protocol with 2 sets per 5 repetitions on countermovement jump (CMJ) height performance in volleyball players at recovery times of (a) 2 minutes, (b) 6 minutes, and (c) 12 minutes. The subjects were 10 male Division I college volleyball players. They were instructed to perform a pretest of 3 CMJs and then randomly assigned to perform (a) a DJ protocol with 1 set per 5 repetitions and (b) a DJ protocol with 2 sets per 5 repetitions. After the DJ, 3 CMJs were completed in 2, 6, and 12 minutes. A 2-way repeated-measures analysis of variance was used to examine the differences between training volumes and recovery times in CMJ height (H(CMJ)) and maximum ground reaction force. Both DJ training volumes significantly increased the H(CMJ). The H(CMJ) at post 2 minutes was greater than those at the pretest (p = 0.008), post 6 minutes (p = 0.004), and post 12 minutes (p = 0.002). In addition, the H(CMJ) at post 6 minutes was significantly greater than that at post 12 minutes (p = 0.018). Drop jumps in lower volume (e.g., within 10 repetitions) and short recovery time (e.g., within 2 minutes) can produce a positive acute effect on CMJ performance. PMID:23249768

  16. Regulatory interrelations among topographic molecules CBF1, CBF2 and EphA3 in the developing chick retina.

    PubMed

    Yamagata, M; Mai, A; Pollerberg, G E; Noda, M

    1999-10-01

    It has been shown that topographic expression of two winged-helix transcription factors, CBF1/c-qin and CBF2, and a receptor tyrosine kinase EphA3 (Mek4/Cek4) play important roles in establishing the topographic retinotectal projection map along the rostrocaudal axis. The interrelationship among these topographic molecules in the chick retina was studied during development. The topographic expression of CBF1 and CBF2 preluded the graded expression of EphA3, but their precise expression profiles did not exactly fit together. However, interestingly, CBF1 and CBF2 were properly expressed, together with EphA3, in immortalized cell lines derived from the quail retina, which maintained position-specific characteristics. The expression of another topographic molecule SOHo-1, the sensory organ homeobox-1 transcription factor, was separate from EphA3 expression. Ectopic expression of CBF1 using in ovo electroporation repressed the expression of CBF2, and misexpression of CBF2 influenced the graded localization of EphA3 in the retina, albeit imperfectly. Taken together, it is suggested that retinal cells first begin to express CBF1 or CBF2 according to their topographic positions, generate cellular descendants in which the expression of CBF1 and CBF2 is maintained cell-autonomously, and then establish the nasotemporal gradient of EphA3 under the control of CBF2, although indirect.

  17. 103. (Credit CBF) Adding sections to the standpipe at the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    103. (Credit CBF) Adding sections to the standpipe at the corner of Texas and Hope streets. Date of photo unknown. The standpipe, 20 feet in diameter by 110 feet high, was originally erected in 1887. (Credit CBF and Grabill, photographer, Shreveport, Louisiana) - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  18. Foot Drop

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS NINDS Foot Drop Information Page Table of Contents (click to ... research is being done? Clinical Trials What is Foot Drop? Foot drop describes the inability to raise ...

  19. Mutational Evidence for the Critical Role of CBF Transcription Factors in Cold Acclimation in Arabidopsis.

    PubMed

    Zhao, Chunzhao; Zhang, Zhengjing; Xie, Shaojun; Si, Tong; Li, Yuanya; Zhu, Jian-Kang

    2016-08-01

    The three tandemly arranged CBF genes, CBF1, CBF2, and CBF3, are involved in cold acclimation. Due to the lack of stable loss-of-function Arabidopsis (Arabidopsis thaliana) mutants deficient in all three CBF genes, it is still unclear whether the CBF genes are essential for freezing tolerance and whether they may have other functions besides cold acclimation. In this study, we used the CRISPR/Cas9 system to generate cbf single, double, and triple mutants. Compared to the wild type, the cbf triple mutants are extremely sensitive to freezing after cold acclimation, demonstrating that the three CBF genes are essential for cold acclimation. Our results show that the three CBF genes also contribute to basal freezing tolerance. Unexpectedly, we found that the cbf triple mutants are defective in seedling development and salt stress tolerance. Transcript profiling revealed that the CBF genes regulate 414 cold-responsive (COR) genes, of which 346 are CBF-activated genes and 68 are CBF-repressed genes. The analysis suggested that CBF proteins are extensively involved in the regulation of carbohydrate and lipid metabolism, cell wall modification, and gene transcription. Interestingly, like the triple mutants, cbf2 cbf3 double mutants are more sensitive to freezing after cold acclimation compared to the wild type, but cbf1 cbf3 double mutants are more resistant, suggesting that CBF2 is more important than CBF1 and CBF3 in cold acclimation-dependent freezing tolerance. Our results not only demonstrate that the three CBF genes together are required for cold acclimation and freezing tolerance, but also reveal that they are important for salt tolerance and seedling development. PMID:27252305

  20. CBF2/DREB1C is a negative regulator of CBF1/DREB1B and CBF3/DREB1A expression and plays a central role in stress tolerance in Arabidopsis

    PubMed Central

    Novillo, Fernando; Alonso, José M.; Ecker, Joseph R.; Salinas, Julio

    2004-01-01

    CBF/DREB1 (C-repeat-binding factor/dehydration responsive element-binding factor 1) genes encode a small family of transcriptional activators that have been described as playing an important role in freezing tolerance and cold acclimation in Arabidopsis. To specify this role, we used a reverse genetic approach and identified a mutant, cbf2, in which the CBF2/DREB1C gene was disrupted. Here, we show that cbf2 plants have higher capacity to tolerate freezing than WT ones before and after cold acclimation and are more tolerant to dehydration and salt stress. All these phenotypes correlate with a stronger and more sustained expression of CBF/DREB1-regulated genes, which results from an increased expression of CBF1/DREB1B and CBF3/DREB1A in the mutant. In addition, we show that the expression of CBF1/DREB1B and CBF3/DREB1A in response to low temperature precedes that of CBF2/DREB1C. These results indicate that CBF2/DREB1C negatively regulates CBF1/DREB1B and CBF3/DREB1A, ensuring that their expression is transient and tightly controlled, which, in turn, guarantees the proper induction of downstream genes and the accurate development of Arabidopsis tolerance to freezing and related stresses. PMID:15004278

  1. 88. (Credit CBF) Twelve Mile Bayou Pumping Station and force ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. (Credit CBF) Twelve Mile Bayou Pumping Station and force main for pumping water over levee and into the canal (Blind Bayou), March 1913. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  2. Genetics Home Reference: core binding factor acute myeloid leukemia

    MedlinePlus

    ... acute myeloid leukemia core binding factor acute myeloid leukemia Enable Javascript to view the expand/collapse boxes. ... Close All Description Core binding factor acute myeloid leukemia (CBF-AML) is one form of a cancer ...

  3. Using an apple microarray to characterize the CBF-regulon in transgenic 'M.26' apple trees overexpressing a peach CBF gene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    CBF proteins belong to the CBF/DRE binding sub-family of the Apetala2-ethylene responsive factor (AP2/ERF) super family of transcription factors that bind to a cis-element containing a conserved CCGA core sequence. CBF genes have been shown to regulate a large number of cold-regulated genes that ar...

  4. Simultaneous Imaging of CBF Change and BOLD with Saturation-Recovery-T1 Method.

    PubMed

    Wang, Xiao; Zhu, Xiao-Hong; Zhang, Yi; Chen, Wei

    2015-01-01

    A neuroimaging technique based on the saturation-recovery (SR)-T1 MRI method was applied for simultaneously imaging blood oxygenation level dependence (BOLD) contrast and cerebral blood flow change (ΔCBF), which is determined by CBF-sensitive T1 relaxation rate change (ΔR1CBF). This technique was validated by quantitatively examining the relationships among ΔR1CBF, ΔCBF, BOLD and relative CBF change (rCBF), which was simultaneously measured by laser Doppler flowmetry under global ischemia and hypercapnia conditions, respectively, in the rat brain. It was found that during ischemia, BOLD decreased 23.1±2.8% in the cortical area; ΔR1CBF decreased 0.020±0.004s-1 corresponding to a ΔCBF decrease of 1.07±0.24 ml/g/min and 89.5±1.8% CBF reduction (n=5), resulting in a baseline CBF value (=1.18 ml/g/min) consistent with the literature reports. The CBF change quantification based on temperature corrected ΔR1CBF had a better accuracy than apparent R1 change (ΔR1app); nevertheless, ΔR1app without temperature correction still provides a good approximation for quantifying CBF change since perfusion dominates the evolution of the longitudinal relaxation rate (R1app). In contrast to the excellent consistency between ΔCBF and rCBF measured during and after ischemia, the BOLD change during the post-ischemia period was temporally disassociated with ΔCBF, indicating distinct CBF and BOLD responses. Similar results were also observed for the hypercapnia study. The overall results demonstrate that the SR-T1 MRI method is effective for noninvasive and quantitative imaging of both ΔCBF and BOLD associated with physiological and/or pathological changes.

  5. Isolation and characterization of a Chinese strain of Tembusu virus from Hy-Line Brown layers with acute egg-drop syndrome in Fujian, China.

    PubMed

    Chen, Shilong; Wang, Shao; Li, Zhaolong; Lin, Fengqiang; Cheng, Xiaoxia; Zhu, Xiaoli; Wang, Jingxiang; Chen, Shaoying; Huang, Meiqing; Zheng, Min

    2014-05-01

    Tembusu virus (TMUV) has been a causative agent of an acute egg-drop syndrome found in Chinese duck populations since at least 2010. In this paper, we report the characterization of a TMUV-like flavivirus (named CJD05) isolated from naturally infected egg-laying fowl. The virus was identified and then isolated from hens suffering from severe egg drop and fever in Fujian Province, China. The virus replicated well in MDEF and CEF cells, and its cytopathogenic effect (CPE) was apparent. Hemagglutinating activity (HA) was negative for this virus using erythrocytes from both chickens and pigeons. Viral particles were enveloped and approximately 45 nm in diameter, as observed by electron microscopy. Phylogenetic analysis of the full-length nucleotide sequence of CJD05 indicated that this virus is closely related to the duck-origin TMUV, belonging to Ntaya group of flavivirus. Most importantly, pathogenicity studies showed that CJD05 is highly virulent in 1-day-old chicks, 1-day-old Muscovy ducks, egg-laying chickens and shelducks. Our research highlights the increase in epidemic disease caused by avian TMUV, and subsequent outbreaks are becoming more complicated to treat. The pathogenic mechanisms of the virus are still not fully understood, further research is needed. PMID:24297489

  6. Copy number variation at the HvCBF4-HvCBF2 genomic segment is a major component of frost resistance in barley.

    PubMed

    Francia, Enrico; Morcia, Caterina; Pasquariello, Marianna; Mazzamurro, Valentina; Milc, Justyna Anna; Rizza, Fulvia; Terzi, Valeria; Pecchioni, Nicola

    2016-09-01

    A family of CBF transcription factors plays a major role in reconfiguring the plant transcriptome in response to low-freezing temperature in temperate cereals. In barley, more than 13 HvCBF genes map coincident with the major QTL FR-H2 suggesting them as candidates to explain the function of the locus. Variation in copy number (CNV) of specific HvCBFs was assayed in a panel of 41 barley genotypes using RT-qPCR. Taking advantage of an accurate phenotyping that combined Fv/Fm and field survival, resistance-associated variants within FR-H2 were identified. Genotypes with an increased copy number of HvCBF4 and HvCBF2 (at least ten and eight copies, respectively) showed greater frost resistance. A CAPS marker able to distinguish the CBF2A, CBF2B and CBF2A/B forms was developed and showed that all the higher-ranking genotypes in term of resistance harbour only CBF2A, while other resistant winter genotypes harbour also CBF2B, although at a lower CNV. In addition to the major involvement of the HvCBF4-HvCBF2 genomic segment in the proximal cluster of CBF elements, a negative role of HvCBF3 in the distal cluster was identified. Multiple linear regression models taking into account allelic variation at FR-H1/VRN-H1 explained 0.434 and 0.550 (both at p < 0.001) of the phenotypic variation for Fv/Fm and field survival respectively, while no interaction effect between CNV at the HvCBFs and FR-H1/VRN-H1 was found. Altogether our data suggest a major involvement of the CBF genes located in the proximal cluster, with no apparent involvement of the central cluster contrary to what was reported for wheat.

  7. 86. (Credit CBF) Canal between Twelve Mile Bayou and Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    86. (Credit CBF) Canal between Twelve Mile Bayou and Cross Bayou in the bed of Blind Bayou (constructed 1901-1903). Photo taken in November of 1911. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  8. Verbal Instructions Acutely Affect Drop Vertical Jump Biomechanics--Implications for Athletic Performance and Injury Risk Assessments.

    PubMed

    Khuu, Steven; Musalem, Lindsay L; Beach, Tyson A C

    2015-10-01

    Biomechanical quantities acquired during the drop vertical jump (DVJ) are used in the assessment of athletic performance and injury risk. The objective was to examine the impact of different verbal instructions on spatiotemporal, kinematic, and kinetic variables commonly included in such assessments. Ten men and 10 women from local varsity and club volleyball, basketball, figure skating, and track and field teams volunteered to participate. The athletes performed DVJs after given instructions to minimize ground contact time (CT), maximize jump height (HT), and synchronously extend the lower extremity joints (EX). Between the CT, HT, and EX conditions, body segment and joint angles were compared together with characteristics of vertical ground reaction force (GRF), whole-body power output, stiffness, and center-of-mass displacement time histories. Verbal instructions were found to influence nearly all of the spatiotemporal, body segment and joint kinematic, and kinetic variables that were statistically analyzed. Particularly noteworthy was the finding that athletic performance indices (e.g., jump height, power output, vertical stiffness, and reactive strength index) and lower extremity injury risk markers (e.g., peak vertical GRF and frontal plane knee angle) were significantly different (p ≤ 0.05) between the CT, HT, and EX conditions. The findings of this study suggest that verbal instructions should be controlled and/or clearly documented when using the DVJ to assess athletic performance potential and injury risk. Moreover, practitioners who devise performance enhancement and injury prevention strategies based on DVJ assessments are advised to consider that "coaching" or "cueing" during the task execution could impact conclusions drawn.

  9. Drop dynamics

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.

    1981-01-01

    The drop dynamics module is a Spacelab-compatible acoustic positioning and control system for conducting drop dynamics experiments in space. It consists basically of a chamber, a drop injector system, an acoustic positioning system, and a data collection system. The principal means of collecting data is by a cinegraphic camera. The drop is positioned in the center of the chamber by forces created by standing acoustic waves generated in the nearly cubical chamber (about 12 cm on a side). The drop can be spun or oscillated up to fission by varying the phse and amplitude of the acoustic waves. The system is designed to perform its experiments unattended, except for start-up and shutdown events and other unique events that require the attention of the Spacelab payload specialist.

  10. CBF gene expression in peach leaf and bark tissues is gated by a circadian clock

    Technology Transfer Automated Retrieval System (TEKTRAN)

    CBF transcription factors are part of the AP2/ERF domain family of DNA-binding proteins that recognize a C-repeat response cis-acting element that regulates a number of cold-responsive genes (CBF-regulon). In peach (Prunus persica), five CBF genes are situated in tandem on scaffold (Linkage Group) ...

  11. Ectopic expression of a novel peach (Prunus persica) CBF transcription factor in apple (Malus × domestica) results in short-day induced dormancy and increased cold hardiness.

    PubMed

    Wisniewski, Michael; Norelli, John; Bassett, Carole; Artlip, Timothy; Macarisin, Dumitru

    2011-05-01

    Low, non-freezing temperatures and/or short daylength (SD) regulates cold acclimation and dormancy in fruit trees. Regarding cold acclimation, C-repeat binding factor (CBF/DREB) transcriptional activator genes have the well-documented ability to induce the expression of a suite of genes associated with increased cold tolerance. We isolated a full-length cDNA of a peach CBF gene, designated PpCBF1 (GenBank Accession HM992943), and constitutively expressed it using an enhanced 35S promoter in apple. Unexpectedly, constitutive overexpression of the PpCBF1 in apple resulted in strong sensitivity to short daylength. Growth cessation and leaf senescence were induced in transgenic lines exposed to SD and optimal growth temperatures of 25°C over a 4-week period. Following 1-4 weeks of SD and 25°C trees were returned to LD and 25°C in the greenhouse. Control (untransformed) plants continued to grow while transgenic lines receiving two or more weeks of SD remained dormant and began to drop leaves. Constitutive overexpression of the PpCBF1 in apple resulted in a 4-6°C increase in freezing tolerance in both the non-acclimated and acclimated states, respectively, compared with untransformed M.26 trees. This is the first instance that constitutive overexpression of a CBF gene has resulted in SD-induction of dormancy and to our knowledge the first time apple has been shown to strongly respond to short daylength as a result of the insertion of a transgene.

  12. Ectopic expression of a novel peach (Prunus persica) CBF transcription factor in apple (Malus × domestica) results in short-day induced dormancy and increased cold hardiness.

    PubMed

    Wisniewski, Michael; Norelli, John; Bassett, Carole; Artlip, Timothy; Macarisin, Dumitru

    2011-05-01

    Low, non-freezing temperatures and/or short daylength (SD) regulates cold acclimation and dormancy in fruit trees. Regarding cold acclimation, C-repeat binding factor (CBF/DREB) transcriptional activator genes have the well-documented ability to induce the expression of a suite of genes associated with increased cold tolerance. We isolated a full-length cDNA of a peach CBF gene, designated PpCBF1 (GenBank Accession HM992943), and constitutively expressed it using an enhanced 35S promoter in apple. Unexpectedly, constitutive overexpression of the PpCBF1 in apple resulted in strong sensitivity to short daylength. Growth cessation and leaf senescence were induced in transgenic lines exposed to SD and optimal growth temperatures of 25°C over a 4-week period. Following 1-4 weeks of SD and 25°C trees were returned to LD and 25°C in the greenhouse. Control (untransformed) plants continued to grow while transgenic lines receiving two or more weeks of SD remained dormant and began to drop leaves. Constitutive overexpression of the PpCBF1 in apple resulted in a 4-6°C increase in freezing tolerance in both the non-acclimated and acclimated states, respectively, compared with untransformed M.26 trees. This is the first instance that constitutive overexpression of a CBF gene has resulted in SD-induction of dormancy and to our knowledge the first time apple has been shown to strongly respond to short daylength as a result of the insertion of a transgene. PMID:21274560

  13. Constitutive expression of DaCBF7, an Antarctic vascular plant Deschampsia antarctica CBF homolog, resulted in improved cold tolerance in transgenic rice plants.

    PubMed

    Byun, Mi Young; Lee, Jungeun; Cui, Li Hua; Kang, Yoonjee; Oh, Tae Kyung; Park, Hyun; Lee, Hyoungseok; Kim, Woo Taek

    2015-07-01

    Deschampsia antarctica is an Antarctic hairgrass that grows on the west coast of the Antarctic peninsula. In this report, we have identified and characterized a transcription factor, D. antarctica C-repeat binding factor 7 (DaCBF7), that is a member of the monocot group V CBF homologs. The protein contains a single AP2 domain, a putative nuclear localization signal, and the typical CBF signature. DaCBF7, like other monocot group V homologs, contains a distinct polypeptide stretch composed of 43 amino acids in front of the AP2 motif. DaCBF7 was predominantly localized to nuclei and interacted with the C-repeat/dehydration responsive element (CRT/DRE) core sequence (ACCGAC) in vitro. DaCBF7 was induced by abiotic stresses, including drought, cold, and salinity. To investigate its possible cellular role in cold tolerance, a transgenic rice system was employed. DaCBF7-overexpressing transgenic rice plants (Ubi:DaCBF7) exhibited markedly increased tolerance to cold stress compared to wild-type plants without growth defects; however, overexpression of DaCBF7 exerted little effect on tolerance to drought or salt stress. Transcriptome analysis of a Ubi:DaCBF7 transgenic line revealed 13 genes that were up-regulated in DaCBF7-overexpressing plants compared to wild-type plants in the absence of cold stress and in short- or long-term cold stress. Five of these genes, dehydrin, remorin, Os03g63870, Os11g34790, and Os10g22630, contained putative CRT/DRE or low-temperature responsive elements in their promoter regions. These results suggest that overexpression of DaCBF7 directly and indirectly induces diverse genes in transgenic rice plants and confers enhanced tolerance to cold stress.

  14. Cbfβ deletion in mice recapitulates cleidocranial dysplasia and reveals multiple functions of Cbfβ required for skeletal development

    PubMed Central

    Chen, Wei; Ma, Junqing; Zhu, Guochun; Jules, Joel; Wu, Mengrui; McConnell, Matthew; Tian, Fei; Paulson, Christie; Zhou, Xuedong; Wang, Lin; Li, Yi-Ping

    2014-01-01

    The pathogenesis of cleidocranial dysplasia (CCD) as well as the specific role of core binding factor β (Cbfβ) and the Runt-related transcription factor (RUNX)/Cbfβ complex in postnatal skeletogenesis remain unclear. We demonstrate that Cbfβ ablation in osteoblast precursors, differentiating chondrocytes, osteoblasts, and odontoblasts via Osterix-Cre, results in severe craniofacial dysplasia, skeletal dysplasia, abnormal teeth, and a phenotype recapitulating the clinical features of CCD. Cbfβf/fOsterix-Cre mice have fewer proliferative and hypertrophic chondrocytes, fewer osteoblasts, and almost absent trabecular bone, indicating that Cbfβ may maintain trabecular bone formation through its function in hypertrophic chondrocytes and osteoblasts. Cbfβf/fCollagen, type 1, alpha 1 (Col1α1)–Cre mice show decreased bone mineralization and skeletal deformities, but no radical deformities in teeth, mandibles, or cartilage, indicating that osteoblast lineage-specific ablation of Cbfβ results in milder bone defects and less resemblance to CCD. Activating transcription factor 4 (Atf4) and Osterix protein levels in both mutant mice are dramatically reduced. ChIP assays show that Cbfβ directly associates with the promoter regions of Atf4 and Osterix. Our data further demonstrate that Cbfβ highly up-regulates the expression of Atf4 at the transcriptional regulation level. Overall, our genetic dissection approach revealed that Cbfβ plays an indispensable role in postnatal skeletal development and homeostasis in various skeletal cell types, at least partially by up-regulating the expression of Atf4 and Osterix. It also revealed that CCD may result from functional defects of the Runx2/Cbfβ heterodimeric complex in various skeletal cells. These insights into the role of Cbfβ in postnatal skeletogenesis and CCD pathogenesis may assist in the development of new therapies for CCD and osteoporosis. PMID:24850862

  15. Pressure Drop

    NASA Technical Reports Server (NTRS)

    Lawson, Mike

    2010-01-01

    Mike Lawson briefly discussed pressure drop for aerospace applications and presented short stories about adventures experienced while working at NASA and General Dynamics, including exposure to technologies like the Crew and Equipment Translation Aid (CETA) cart and the SWME.

  16. Cbf11 and Cbf12, the fission yeast CSL proteins, play opposing roles in cell adhesion and coordination of cell and nuclear division

    SciTech Connect

    Prevorovsky, Martin; Grousl, Tomas; Stanurova, Jana; Rynes, Jan; Nellen, Wolfgang; Puta, Frantisek; Folk, Petr

    2009-05-01

    The CSL (CBF1/RBP-J{kappa}/Suppressor of Hairless/LAG-1) family is comprised of transcription factors essential for metazoan development, mostly due to their involvement in the Notch receptor signaling pathway. Recently, we identified two novel classes of CSL genes in the genomes of several fungal species, organisms lacking the Notch pathway. In this study, we characterized experimentally cbf11{sup +} and cbf12{sup +}, the two CSL genes of Schizosaccharomyces pombe, in order to elucidate the CSL function in fungi. We provide evidence supporting their identity as genuine CSL genes. Both cbf11{sup +} and cbf12{sup +} are non-essential; they have distinct expression profiles and code for nuclear proteins with transcription activation potential. Significantly, we demonstrated that Cbf11 recognizes specifically the canonical CSL response element GTG{sup A}/{sub G}GAA in vitro. The deletion of cbf11{sup +} is associated with growth phenotypes and altered colony morphology. Furthermore, we found that Cbf11 and Cbf12 play opposite roles in cell adhesion, nuclear and cell division and their coordination. Disturbed balance of the two CSL proteins leads to cell separation defects (sep phenotype), cut phenotype, and high-frequency diploidization in heterothallic strains. Our data show that CSL proteins operate in an organism predating the Notch pathway, which should be of relevance to the understanding of (Notch-independent) CSL functions in metazoans.

  17. Cold induction of Arabidopsis CBF genes involves multiple ICE (inducer of CBF expression) promoter elements and a cold-regulatory circuit that is desensitized by low temperature.

    PubMed

    Zarka, Daniel G; Vogel, Jonathan T; Cook, Daniel; Thomashow, Michael F

    2003-10-01

    The Arabidopsis CBF1, 2, and 3 genes (also known as DREB1b, c, and a, respectively) encode transcriptional activators that have a central role in cold tolerance. CBF1-3 are rapidly induced upon exposing plants to low temperature, followed by expression of CBF-targeted genes, the CBF regulon, resulting in an increase in plant freezing tolerance. At present, little is known about the cold-sensing mechanism that controls CBF expression. Results presented here indicate that this mechanism does not require a cold shock to bring about the accumulation of CBF transcripts, but instead, absolute temperature is monitored with a greater degree of input, i.e. lower temperature, resulting in a greater output, i.e. higher levels of CBF transcripts. Temperature-shift experiments also indicate that the cold-sensing mechanism becomes desensitized to a given low temperature, such as 4 degrees C, and that resensitization to that temperature requires between 8 and 24 h at warm temperature. Gene fusion experiments identified a 125-bp section of the CBF2 promoter that is sufficient to impart cold-responsive gene expression. Mutational analysis of this cold-responsive region identified two promoter segments that work in concert to impart robust cold-regulated gene expression. These sequences, designated ICEr1 and ICEr2 (induction of CBF expression region 1 or 2), were also shown to stimulate transcription in response to mechanical agitation and the protein synthesis inhibitor, cycloheximide.

  18. Complementary regulation of four Eucalyptus CBF genes under various cold conditions

    PubMed Central

    Navarro, M.; Marque, G.; Ayax, C.; Keller, G.; Borges, J. P.; Marque, C.; Teulières, C.

    2009-01-01

    CBF transcription factors play central roles in the control of freezing tolerance in plants. The isolation of two additional CBF genes, EguCBF1c and EguCBF1d, from E. gunnii, one of the cold-hardiest Eucalyptus species, is described. While the EguCBF1D protein sequence is very similar to the previously characterized EguCBF1A and EguCBF1B sequences, EguCBF1C is more distinctive, in particular in the AP2-DBD (AP2-DNA binding domain). The expression analysis of the four genes by RT-qPCR reveals that none of them is specific to one stress but they are all preferentially induced by cold, except for the EguCBF1c gene which is more responsive to salt. The calculation of the transcript copy number enables the quantification of constitutive CBF gene expression. This basal level, significant for the four genes, greatly influences the final EguCBF1 transcript level in the cold. A cold shock at 4 °C, as well as a progressive freezing which mimics a natural frost episode, trigger a fast and strong response of the EguCBF1 genes, while growth at acclimating temperatures results in a lower but more durable induction. The differential expression of the four EguCBF1 genes under these cold regimes suggests that there is a complementary regulation. The high accumulation of the CBF transcript, observed in response to the different types of cold conditions, might be a key for the winter survival of this evergreen broad-leaved tree. PMID:19457981

  19. Investigating intrinsic connectivity networks using simultaneous BOLD and CBF measurements.

    PubMed

    Mayhew, S D; Mullinger, K J; Bagshaw, A P; Bowtell, R; Francis, S T

    2014-10-01

    When the sensory cortex is stimulated and directly receiving afferent input, modulations can also be observed in the activity of other brain regions comprising spatially distributed, yet intrinsically connected networks, suggesting that these networks support brain function during task performance. Such networks can exhibit subtle or unpredictable task responses which can pass undetected by conventional general linear modelling (GLM). Additionally, the metabolic demand of these networks in response to stimulation remains incompletely understood. Here, we recorded concurrent BOLD and CBF measurements during median nerve stimulation (MNS) and compared GLM analysis with independent component analysis (ICA) for identifying the spatial, temporal and metabolic properties of responses in the primary sensorimotor cortex (S1/M1), and in the default mode (DMN) and fronto-parietal (FPN) networks. Excellent spatial and temporal agreement was observed between the positive BOLD and CBF responses to MNS detected by GLM and ICA in contralateral S1/M1. Values of the change in cerebral metabolic rate of oxygen consumption (Δ%CMRO2) and the Δ%CMRO2/Δ%CBF coupling ratio were highly comparable when using either GLM analysis or ICA to extract the contralateral S1/M1 responses, validating the use of ICA for estimating changes in CMRO2. ICA identified DMN and FPN network activity that was not detected by GLM analysis. Using ICA, spatially coincident increases/decreases in both BOLD and CBF signals to MNS were found in the FPN/DMN respectively. Calculation of CMRO2 changes in these networks during MNS showed that the Δ%CMRO2/Δ%CBF ratio is comparable between the FPN and S1/M1 but is larger in the DMN than in the FPN, assuming an equal value of the parameter M in the DMN, FPN and S1/M1. This work suggests that metabolism-flow coupling may differ between these two fundamental brain networks, which could originate from differences between task-positive and task-negative fMRI responses

  20. [Analysis of codon use features of CBF gene in Camellia sinensis].

    PubMed

    Guo, Xiu-Li; Wang, Yu; Yang, Lu-Cheng; Ding, Zhao-Tang

    2012-12-01

    CBF (C-repeat-binding factor) transcription factor exists widely in all kinds of plants. It is an important regulative factor in the process of plant resistance adversity. In this paper, Camellia sinensis CBF1 gene sequence was analyzed by Codon W, CHIPS, and CUSP programs online, and then compared with C. sinensis genes, genomes in other species, and CBF genes from 39 plant species. It is important to identify the codon usage of CsCBF1 gene and select appropriate expression systems. The results showed that CsCBF1 gene and selected 70 C. sinensis genes had distinct usage differences. CsCBF1 gene was bias toward the synonymous codons with G and C at the third codon position, but 70 C. sinensis genes were bias toward the synonymous codons with A and T. The differences in codon usage frequency between CsCBF1 gene and dicotyledons such as Arabidopsis thaliana and Nicotiana tobacum were less than monocotyledons such as wheat (Triticum aestivum) and corn (Zea mays). Therefore, A. thaliana and N. tobacum expression systems may be more suitable for the expression of CsCBF1 gene. The analysis results of CBF genes from 40 plant species also showed that most of the CBF genes were bias toward the synonymous codons with G and C at the third codon position. The reason of this phenomenon is possible due to special functions of these genes.

  1. Image presentation and normal SPECT rCBF

    SciTech Connect

    Devous, M.D. Sr.

    1991-12-31

    The appearance of images of normal regional cerebral blood flow (rCBF) obtained from single photon emission computed tomography (SPECT) is influenced by several factors, including (1) the environmental conditions at the time of administration of the radiotracer, (2) the characteristics of the subject (eg. age, gender, and handedness), (3) the format used for image presentation, (4) the quality of the tomographic device, (5) the choices of image-processing techniques, and (6) the radiopharmaceutical used. The first three of these topics are briefly reviewed here; topics 4, 5 and 6 are reviewed by others in this workshop summary. 27 refs.

  2. The cold response of CBF genes in barley is regulated by distinct signaling mechanisms.

    PubMed

    Marozsán-Tóth, Zsuzsa; Vashegyi, Ildikó; Galiba, Gábor; Tóth, Balázs

    2015-06-01

    Cold acclimation ability is crucial in the winter survival of cereals. In this process CBF transcription factors play key role, therefore understanding the regulation of these genes might provide useful knowledge for molecular breeding. In the present study the signal transduction pathways leading to the cold induction of different CBF genes were investigated in barley cv. Nure using pharmacological approach. Our results showed that the cold induced expression of CBF9 and CBF14 transcription factors is regulated by phospholipase C, phospholipase D pathways and calcium. On the contrary, these pathways have negative effect on the cold induction of CBF12 that is regulated by a different, as yet unidentified pathway. The diversity in the regulation of these transcription factors corresponds to their sequence based phylogenetic relationships suggesting that their evolutionary separation happened on structural, functional and regulational levels as well. On the CBF effector gene level, the signaling regulation is more complex, resultant effect of multiple pathways.

  3. Transcriptional profiling of Medicago truncatula under salt stress identified a novel CBF transcription factor MtCBF4 that plays an important role in abiotic stress responses

    PubMed Central

    2011-01-01

    Background Salt stress hinders the growth of plants and reduces crop production worldwide. However, different plant species might possess different adaptive mechanisms to mitigate salt stress. We conducted a detailed pathway analysis of transcriptional dynamics in the roots of Medicago truncatula seedlings under salt stress and selected a transcription factor gene, MtCBF4, for experimental validation. Results A microarray experiment was conducted using root samples collected 6, 24, and 48 h after application of 180 mM NaCl. Analysis of 11 statistically significant expression profiles revealed different behaviors between primary and secondary metabolism pathways in response to external stress. Secondary metabolism that helps to maintain osmotic balance was induced. One of the highly induced transcription factor genes was successfully cloned, and was named MtCBF4. Phylogenetic analysis revealed that MtCBF4, which belongs to the AP2-EREBP transcription factor family, is a novel member of the CBF transcription factor in M. truncatula. MtCBF4 is shown to be a nuclear-localized protein. Expression of MtCBF4 in M. truncatula was induced by most of the abiotic stresses, including salt, drought, cold, and abscisic acid, suggesting crosstalk between these abiotic stresses. Transgenic Arabidopsis over-expressing MtCBF4 enhanced tolerance to drought and salt stress, and activated expression of downstream genes that contain DRE elements. Over-expression of MtCBF4 in M. truncatula also enhanced salt tolerance and induced expression level of corresponding downstream genes. Conclusion Comprehensive transcriptomic analysis revealed complex mechanisms exist in plants in response to salt stress. The novel transcription factor gene MtCBF4 identified here played an important role in response to abiotic stresses, indicating that it might be a good candidate gene for genetic improvement to produce stress-tolerant plants. PMID:21718548

  4. Cerebral blood flow in volunteers measured by PET and Xe CT/CBF. A comparison.

    PubMed

    Bergholt, B; Ostergaard, L; von Oettingen, G; Johannsen, P; Poulsen, P H; Bundgaard, H; Asboe, H; Cold, G E; Gjedde, A; Gyldensted, C; Astrup, J

    2000-02-01

    Aim of this study was to compare two quantitative CBF methods. Seven young, healthy volunteers were studied with PET (15-0 labelled water) and afterwards with Xe CT/CBF (30% xenon in oxygen, 3 minutes wash-in, 5 minutes washout protocol). Xe CT/CBF showed greater differences between high and low flow areas than PET CBF. Correlation was found within subjects between ROI's, but no agreement or correlation between the methods could be demonstrated. The disagreement in this study could be due to changes in PCO2.

  5. Structure-function relationships of archaeal Cbf5 during in vivo RNA-guided pseudouridylation.

    PubMed

    Majumder, Mrinmoyee; Bosmeny, Michael S; Gupta, Ramesh

    2016-10-01

    In Eukarya and Archaea, in addition to protein-only pseudouridine (Ψ) synthases, complexes containing one guide RNA and four proteins can also produce Ψ. Cbf5 protein is the Ψ synthase in the complex. Previously, we showed that Ψ's at positions 1940, 1942, and 2605 of Haloferax volcanii 23S rRNA are absent in a cbf5-deleted strain, and a plasmid-borne copy of cbf5 can rescue the synthesis of these Ψ's. Based on published reports of the structure of archaeal Cbf5 complexed with other proteins and RNAs, we identified several potential residues and structures in H. volcanii Cbf5, which were expected to play important roles in pseudouridylation. We mutated these structures and determined their effects on Ψ production at the three rRNA positions under in vivo conditions. Mutations of several residues in the catalytic domain and certain residues in the thumb loop either abolished Ψ's or produced partial modification; the latter indicates a slower rate of Ψ formation. The universal catalytic aspartate of Ψ synthases could be replaced by glutamate in Cbf5. A conserved histidine, which is common to Cbf5 and TruB is not needed, but another conserved histidine of Cbf5 is required for the in vivo RNA-guided Ψ formation. We also identified a previously unreported novelty in the pseudouridylation activity of Cbf5 where a single stem-loop of a guide H/ACA RNA is used to produce two closely placed Ψ's and mutations of certain residues of Cbf5 abolished one of these two Ψ's. In summary, this first in vivo study identifies several structures of an archaeal Cbf5 protein that are important for its RNA-guided pseudouridylation activity.

  6. Structure-function relationships of archaeal Cbf5 during in vivo RNA-guided pseudouridylation.

    PubMed

    Majumder, Mrinmoyee; Bosmeny, Michael S; Gupta, Ramesh

    2016-10-01

    In Eukarya and Archaea, in addition to protein-only pseudouridine (Ψ) synthases, complexes containing one guide RNA and four proteins can also produce Ψ. Cbf5 protein is the Ψ synthase in the complex. Previously, we showed that Ψ's at positions 1940, 1942, and 2605 of Haloferax volcanii 23S rRNA are absent in a cbf5-deleted strain, and a plasmid-borne copy of cbf5 can rescue the synthesis of these Ψ's. Based on published reports of the structure of archaeal Cbf5 complexed with other proteins and RNAs, we identified several potential residues and structures in H. volcanii Cbf5, which were expected to play important roles in pseudouridylation. We mutated these structures and determined their effects on Ψ production at the three rRNA positions under in vivo conditions. Mutations of several residues in the catalytic domain and certain residues in the thumb loop either abolished Ψ's or produced partial modification; the latter indicates a slower rate of Ψ formation. The universal catalytic aspartate of Ψ synthases could be replaced by glutamate in Cbf5. A conserved histidine, which is common to Cbf5 and TruB is not needed, but another conserved histidine of Cbf5 is required for the in vivo RNA-guided Ψ formation. We also identified a previously unreported novelty in the pseudouridylation activity of Cbf5 where a single stem-loop of a guide H/ACA RNA is used to produce two closely placed Ψ's and mutations of certain residues of Cbf5 abolished one of these two Ψ's. In summary, this first in vivo study identifies several structures of an archaeal Cbf5 protein that are important for its RNA-guided pseudouridylation activity. PMID:27539785

  7. Structural and functional evidence of high specificity of Cbf5 for ACA trinucleotide

    SciTech Connect

    Zhou, Jing; Liang, Bo; Li, Hong

    2012-07-24

    Cbf5 is the catalytic subunit of the H/ACA small nucleolar/Cajal body ribonucleoprotein particles (RNPs) responsible for site specific isomerization of uridine in ribosomal and small nuclear RNA. Recent evidence from studies on archaeal Cbf5 suggests its second functional role in modifying tRNA U55 independent of guide RNA. In order to act both as a stand-alone and a RNP pseudouridine synthase, Cbf5 must differentiate features in H/ACA RNA from those in tRNA or rRNA. Most H/ACA RNAs contain a hallmark ACA trinucleotide downstream of the H/ACA motif. Here we challenged an archaeal Cbf5 (in the form of a ternary complex with its accessory proteins Nop10 and Gar1) with T-stem-loop RNAs with or without ACA trinucleotide in the stem. Although these substrates were previously shown to be substrates for the bacterial stand-alone pseudouridine synthase TruB, the Cbf5-Nop10-Gar1 complex was only able to modify those without ACA trinucleotide. A crystal structure of Cbf5-Nop10-Gar1 trimer bound with an ACA-containing T-stem-loop revealed that the ACA trinucleotide detracted Cbf5 from the stand-alone binding mode, thereby suggesting that the H/ACA RNP-associated function of Cbf5 likely supersedes its stand-alone function.

  8. CBF gene expression in peach leaf and bark tissues is gated by a circadian clock

    Technology Transfer Automated Retrieval System (TEKTRAN)

    CBFs regulate a host of genes (CBF-regulon) that respond to low temperature and play a role in cold acclimation. In peach, (Prunus persica) there are at least 4 CBF genes situated in tandem on scaffold 5 of the peach genome. This is in contrast to apple (Malus x domestica) where there are 5 comple...

  9. Depolarization of cell membrane is associated with an increase in ciliary beat frequency (CBF).

    PubMed

    Mao, H; Wong, L B

    1995-10-24

    We hypothesize that activation of muscarinic cholinergic receptors depolarizes the cell membrane of the mammalian ciliated cells which in turn causes an increase of CBF. To test this hypothesis, a di-8-ANEPPS fluorescence photon counting and nonstationary heterodyne laser light scattering system was developed to measure cell membrane potential (psi) and CBF in cultured ovine tracheal ciliated cells simultaneously. Carbachol dose dependently depolarized the cell membrane with a corresponding stimulation of CBF. The carbachol induced depolarization of cell membrane and increases of CBF were inhibited by prior application of either atropine or verapamil or amiloride. These novel data suggest that depolarization of the cell membrane and the corresponding stimulation of CBF caused by the activation of muscarinic receptors of the mammalian ciliated cells are dependent on the influx of either extracellular Ca2+ or Na+. PMID:7488025

  10. Transgenic barley lines prove the involvement of TaCBF14 and TaCBF15 in the cold acclimation process and in frost tolerance.

    PubMed

    Soltész, Alexandra; Smedley, Mark; Vashegyi, Ildikó; Galiba, Gábor; Harwood, Wendy; Vágújfalvi, Attila

    2013-04-01

    The enhancement of winter hardiness is one of the most important tasks facing breeders of winter cereals. For this reason, the examination of those regulatory genes involved in the cold acclimation processes is of central importance. The aim of the present work was the functional analysis of two wheat CBF transcription factors, namely TaCBF14 and TaCBF15, shown by previous experiments to play a role in the development of frost tolerance. These genes were isolated from winter wheat and then transformed into spring barley, after which the effect of the transgenes on low temperature stress tolerance was examined. Two different types of frost tests were applied; plants were hardened at low temperature before freezing, or plants were subjected to frost without a hardening period. The analysis showed that TaCBF14 and TaCBF15 transgenes improve the frost tolerance to such an extent that the transgenic lines were able to survive freezing temperatures several degrees lower than that which proved lethal for the wild-type spring barley. After freezing, lower ion leakage was measured in transgenic leaves, showing that these plants were less damaged by the frost. Additionally, a higher Fv/Fm parameter was determined, indicating that photosystem II worked more efficiently in the transgenics. Gene expression studies showed that HvCOR14b, HvDHN5, and HvDHN8 genes were up-regulated by TaCBF14 and TaCBF15. Beyond that, transgenic lines exhibited moderate retarded development, slower growth, and minor late flowering compared with the wild type, with enhanced transcript level of the gibberellin catabolic HvGA2ox5 gene.

  11. The unified ICE-CBF pathway provides a transcriptional feedback control of freezing tolerance during cold acclimation in Arabidopsis.

    PubMed

    Kim, Ye Seul; Lee, Minyoung; Lee, Jae-Hyung; Lee, Hyo-Jun; Park, Chung-Mo

    2015-09-01

    During cold acclimation, C-repeat binding factors (CBFs) activate downstream targets, such as cold-regulated genes, leading to the acquisition of freezing tolerance in plants. Inducer of CBF expression 1 (ICE1) plays a key role by activating CBF3 expression in shaping the cold-induced transcriptome. While the ICE1-CBF3 regulon constitutes a major cold acclimation pathway, gene regulatory networks governing the CBF signaling are poorly understood. Here, we demonstrated that ICE1 and its paralog ICE2 induce CBF1, CBF2, and CBF3 by binding to the gene promoters. ICE2, like ICE1, was ubiquitinated by the high expression of osmotically responsive gene 1 (HOS1) E3 ubiquitin ligase. Whereas ICE2-defective ice2-2 mutant did not exhibit any discernible freezing-sensitive phenotypes, ice1-2 ice2-2/+ plant, which is defective in ICE1 and has a heterozygotic ice2 mutation, exhibited significantly reduced freezing tolerance. Accordingly, all three CBF genes were markedly down-regulated in the ice1-2 ice2-2/+ plant, indicating that ICE1 and ICE2 are functionally redundant with different implementations in inducing CBF genes. Together with the negative regulation of CBF3 by CBF2, we propose that the unified ICE-CBF pathway provides a transcriptional feedback of freezing tolerance to sustain plant development and survival during cold acclimation.

  12. CBF measured by Xe-CT: Approach to analysis and normal values

    SciTech Connect

    Yonas, H.; Darby, J.M.; Marks, E.C.; Durham, S.R.; Maxwell, C. )

    1991-09-01

    Normal reference values and a practical approach to CBF analysis are needed for routine clinical analysis and interpretation of xenon-enhanced computed tomography (CT) CBF studies. The authors measured CBF in 67 normal individuals with the GE 9800 CT scanner adapted for CBF imaging with stable Xe. CBF values for vascular territories were systematically analyzed using the clustering of contiguous 2-cm circular regions of interest (ROIs) placed within the cortical mantle and basal ganglia. Mixed cortical flows averaged 51 {plus minus} 10ml.100g-1.min-1. High and low flow compartments, sampled by placing 5-mm circular ROIs in regions containing the highest and lowest flow values in each hemisphere, averaged 84 {plus minus} 14 and 20 {plus minus} 5 ml.100 g-1.min-1, respectively. Mixed cortical flow values as well as values within the high flow compartment demonstrated significant decline with age; however, there were no significant age-related changes in the low flow compartment. The clustering of systematically placed cortical and subcortical ROIs has provided a normative data base for Xe-CT CBF and a flexible and uncomplicated method for the analysis of CBF maps generated by Xe-enhanced CT.

  13. Transcriptional regulation of APOBEC3 antiviral immunity through the CBF-β/RUNX axis

    PubMed Central

    Anderson, Brett D.; Harris, Reuben S.

    2015-01-01

    A diverse set of innate immune mechanisms protects cells from viral infections. The APOBEC3 family of DNA cytosine deaminases is an integral part of these defenses. For instance, APOBEC3D, APOBEC3F, APOBEC3G, and APOBEC3H would have the potential to destroy HIV-1 complementary DNA replication intermediates if not for neutralization by a proteasomal degradation mechanism directed by the viral protein Vif. At the core of this complex, Vif heterodimerizes with the transcription cofactor CBF-β, which results in fewer transcription complexes between CBF-β and its normal RUNX partners. Recent studies have shown that the Vif/CBF-β interaction is specific to the primate lentiviruses HIV-1 and SIV (simian immunodeficiency virus), although related nonprimate lentiviruses still require a Vif-dependent mechanism for protection from host species’ APOBEC3 enzymes. We provide a molecular explanation for this evolutionary conundrum by showing that CBF-β is required for expression of the aforementioned HIV-1–restrictive APOBEC3 gene repertoire. Knockdown and knockout studies demonstrate that CBF-β is required for APOBEC3 mRNA expression in the nonpermissive T cell line H9 and in primary CD4+ T lymphocytes. Complementation experiments using CBF-β separation-of-function alleles show that the interaction with RUNX transcription factors is required for APOBEC3 transcriptional regulation. Accordingly, the infectivity of Vif-deficient HIV-1 increases in cells lacking CBF-β, demonstrating the importance of CBF-β/RUNX–mediated transcription in establishing the APOBEC3 antiviral state. These findings demonstrate a major layer of APOBEC3 gene regulation in lymphocytes and suggest that primate lentiviruses evolved to hijack CBF-β in order to simultaneously suppress this potent antiviral defense system at both transcriptional and posttranslational levels. PMID:26601257

  14. Involvement of CBF Transcription Factors in Winter Hardiness in Birch1[W][OA

    PubMed Central

    Welling, Annikki; Palva, E. Tapio

    2008-01-01

    Cold acclimation of plants involves extensive reprogramming of gene expression. In Arabidopsis (Arabidopsis thaliana), three cold-inducible transcriptional activators designated CBF1 to -3/DREB1a to -c have been shown to play an important regulatory role in this acclimation process. Similarly to Arabidopsis, boreal zone trees can increase their freezing tolerance (FT) in response to low temperature during the growing season. However, maximal FT of these trees requires short daylength-induced dormancy development followed by exposure to both low and freezing temperatures. To elucidate the molecular basis of FT in overwintering trees, we characterized the role of birch (Betula pendula) CBF transcription factors in the cold acclimation process. We identified four putative CBF orthologs in a birch expressed sequence tag collection designated BpCBF1 to -4. Ectopic expression of birch CBFs in Arabidopsis resulted in constitutive expression of endogenous CBF target genes and increased FT of nonacclimated transgenic plants. In addition, these plants showed stunted growth and delayed flowering, typical features for CBF-overexpressing plants. Expression analysis in birch showed that BpCBF1 to -4 are low temperature responsive but differentially regulated in dormant and growing plants, the expression being delayed in dormant tissues. Freeze-thaw treatment, simulating wintertime conditions in nature, resulted in strong induction of BpCBF genes during thawing, followed by induction of a CBF target gene, BpLTI36. These results suggest that in addition to their role in cold acclimation during the growing season, birch CBFs appear to contribute to control of winter hardiness in birch. PMID:18467468

  15. The absolute CBF response to activation is preserved during elevated perfusion: Implications for neurovascular coupling measures.

    PubMed

    Whittaker, Joseph R; Driver, Ian D; Bright, Molly G; Murphy, Kevin

    2016-01-15

    Functional magnetic resonance imaging (fMRI) techniques in which the blood oxygenation level dependent (BOLD) and cerebral blood flow (CBF) response to a neural stimulus are measured, can be used to estimate the fractional increase in the cerebral metabolic rate of oxygen consumption (CMRO2) that accompanies evoked neural activity. A measure of neurovascular coupling is obtained from the ratio of fractional CBF and CMRO2 responses, defined as n, with the implicit assumption that relative rather than absolute changes in CBF and CMRO2 adequately characterise the flow-metabolism response to neural activity. The coupling parameter n is important in terms of its effect on the BOLD response, and as potential insight into the flow-metabolism relationship in both normal and pathological brain function. In 10 healthy human subjects, BOLD and CBF responses were measured to test the effect of baseline perfusion (modulated by a hypercapnia challenge) on the coupling parameter n during graded visual stimulation. A dual-echo pulsed arterial spin labelling (PASL) sequence provided absolute quantification of CBF in baseline and active states as well as relative BOLD signal changes, which were used to estimate CMRO2 responses to the graded visual stimulus. The absolute CBF response to the visual stimuli were constant across different baseline CBF levels, meaning the fractional CBF responses were reduced at the hyperperfused baseline state. For the graded visual stimuli, values of n were significantly reduced during hypercapnia induced hyperperfusion. Assuming the evoked neural responses to the visual stimuli are the same for both baseline CBF states, this result has implications for fMRI studies that aim to measure neurovascular coupling using relative changes in CBF. The coupling parameter n is sensitive to baseline CBF, which would confound its interpretation in fMRI studies where there may be significant differences in baseline perfusion between groups. The absolute change in

  16. 76. (Credit CBF) Inside of laboratory at McNeil Street Station, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    76. (Credit CBF) Inside of laboratory at McNeil Street Station, c1912. Laboratory located over clear water well at this time. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  17. Vaccine Potential and Diversity of the Putative Cell Binding Factor (CBF, NMB0345/NEIS1825) Protein of Neisseria meningitidis

    PubMed Central

    Akoto, Charlene; Hill, Alison; Tan, Wei-Ming; Heckels, John Edward; Christodoulides, Myron

    2016-01-01

    The cbf gene from Neisseria meningitidis strain MC58 encoding the putative Cell Binding Factor (CBF, NMB0345/NEIS1825) protein was cloned into the pRSETA system and a ~36-kDa recombinant (r)CBF protein expressed in Escherichia coli and purified by metal affinity chromatography. High titres of rCBF antibodies were induced in mice following immunization with rCBF-saline, rCBF-Al(OH)3, rCBF-Liposomes or rCBF-Zwittergent (Zw) 3–14 micelles, both with and without incorporated monophosphoryl lipid A (MPLA) adjuvant. Anti-rCBF sera reacted in western blots of meningococcal lysates with a single protein band of molecular mass ~29.5 kDa, indicative of mature CBF protein, but did not react with a lysate of a Δnmb0345 mutant (CBF-), demonstrating specificity of the murine immune responses. CBF protein was produced by all strains of meningococci studied thus far and the protein was present on the surface of MC58 (CBF+) bacteria, but absent on Δnmb0345 mutant (CBF-) bacteria, as judged by FACS reactivity of anti-rCBF sera. Analysis of the NEIS1825 amino acid sequences from 6644 N. meningitidis isolates with defined Alleles in the pubmlst.org/Neisseria database showed that there were 141 ST types represented and there were 136 different allelic loci encoding 49 non-redundant protein sequences. Only 6/6644 (<0.1%) of N. meningitidis isolates lacked the nmb0345 gene. Amongst serogroup B isolates worldwide, ~68% and ~20% expressed CBF encoded by Allele 1 and 18 respectively, with the proteins sharing >99% amino acid identity. Murine antisera to rCBF in Zw 3–14 micelles + MPLA induced significant serum bactericidal activity (SBA) against homologous Allele 1 and heterologous Allele 18 strains, using both baby rabbit serum complement and human serum complement (h)SBA assays, but did not kill strains expressing heterologous protein encoded by Alelle 2 or 3. Furthermore, variable bactericidal activity was induced by murine antisera against different meningococcal strains in the h

  18. Vaccine Potential and Diversity of the Putative Cell Binding Factor (CBF, NMB0345/NEIS1825) Protein of Neisseria meningitidis.

    PubMed

    Humbert, María Victoria; Hung, Miao-Chiu; Phillips, Renee; Akoto, Charlene; Hill, Alison; Tan, Wei-Ming; Heckels, John Edward; Christodoulides, Myron

    2016-01-01

    The cbf gene from Neisseria meningitidis strain MC58 encoding the putative Cell Binding Factor (CBF, NMB0345/NEIS1825) protein was cloned into the pRSETA system and a ~36-kDa recombinant (r)CBF protein expressed in Escherichia coli and purified by metal affinity chromatography. High titres of rCBF antibodies were induced in mice following immunization with rCBF-saline, rCBF-Al(OH)3, rCBF-Liposomes or rCBF-Zwittergent (Zw) 3-14 micelles, both with and without incorporated monophosphoryl lipid A (MPLA) adjuvant. Anti-rCBF sera reacted in western blots of meningococcal lysates with a single protein band of molecular mass ~29.5 kDa, indicative of mature CBF protein, but did not react with a lysate of a Δnmb0345 mutant (CBF-), demonstrating specificity of the murine immune responses. CBF protein was produced by all strains of meningococci studied thus far and the protein was present on the surface of MC58 (CBF+) bacteria, but absent on Δnmb0345 mutant (CBF-) bacteria, as judged by FACS reactivity of anti-rCBF sera. Analysis of the NEIS1825 amino acid sequences from 6644 N. meningitidis isolates with defined Alleles in the pubmlst.org/Neisseria database showed that there were 141 ST types represented and there were 136 different allelic loci encoding 49 non-redundant protein sequences. Only 6/6644 (<0.1%) of N. meningitidis isolates lacked the nmb0345 gene. Amongst serogroup B isolates worldwide, ~68% and ~20% expressed CBF encoded by Allele 1 and 18 respectively, with the proteins sharing >99% amino acid identity. Murine antisera to rCBF in Zw 3-14 micelles + MPLA induced significant serum bactericidal activity (SBA) against homologous Allele 1 and heterologous Allele 18 strains, using both baby rabbit serum complement and human serum complement (h)SBA assays, but did not kill strains expressing heterologous protein encoded by Alelle 2 or 3. Furthermore, variable bactericidal activity was induced by murine antisera against different meningococcal strains in the h

  19. An apple rootstock overexpressing a peach CBF gene alters growth and flowering in the scion but does not impact cold hardiness or dormancy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The C-repeat Binding Factor (CBF) transcription factor is involved in responses to low temperature and water deficit in many plant species. Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhibition in many species. The overexpression of a peach CBF (PpCBF1) gene in a t...

  20. Characterization and expression analysis of three CBF/DREB1 transcriptional factor genes from mangrove Avicennia marina.

    PubMed

    Peng, Ya-Lan; Wang, You-Shao; Cheng, Hao; Sun, Cui-Ci; Wu, Peng; Wang, Li-Ying; Fei, Jiao

    2013-09-15

    Three CBF/DREB1 (C-repeat binding factor/dehydration responsive element-binding factor 1) homologues were isolated from mangrove Avicennia marina and designated AmCBF1, 2 and 3. Multiple sequence analysis showed that the three deduced proteins all contain an AP2 DNA-binding domain and two CBF signature sequences. According to the phylogenetic analysis, these proteins belong to the A-1 subgroup of the DREB subfamily. Expression analyses based on quantitative real-time PCR revealed that the AmCBF2 displayed relatively high expression under normal conditions, with the highest level in stems, while both AmCBF1 and 3 were weakly expressed without stress. The three genes also showed different responses to various environmental stimuli. The AmCBF2 was inducible by cold, drought, high salinity, heavy metals, as well as abscisic acid (ABA), and exhibited much stronger induction by cold, drought, Pb(2+) or Zn(2+) than by NaCl, ABA or Cd(2+). In contrast, both AmCBF1 and AmCBF3 displayed insignificant changes under these stimuli. These results indicate that the three AmCBF genes play different roles in A. marina and the AmCBF2 might be involved in the signaling pathway of cold, drought and heavy metal stress response.

  1. Alternate drop pulse polarography

    USGS Publications Warehouse

    Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

    1976-01-01

    The new technique of alternate drop pulse polarography is presented. An experimental evaluation of alternate drop pulse polarography shows complete compensation of the capacitative background due to drop expansion. The capillary response phenomenon was studied in the absence of faradaic reaction and the capillary response current was found to depend on the pulse width to the -0.72 power. Increased signal-to-noise ratios were obtained using alternate drop pulse polarography at shorter drop times.

  2. The cbfs triple mutants reveal the essential functions of CBFs in cold acclimation and allow the definition of CBF regulons in Arabidopsis.

    PubMed

    Jia, Yuxin; Ding, Yanglin; Shi, Yiting; Zhang, Xiaoyan; Gong, Zhizhong; Yang, Shuhua

    2016-10-01

    In Arabidopsis, the C-repeat binding factors (CBFs) have been extensively studied as key transcription factors in the cold stress response. However, their exact functions in the cold response remains unclear due to the lack of a null cbf triple mutant. In this study, we used CRISPR/Cas9 technology to mutate CBF1 or CBF1/CBF2 in a cbf3 T-DNA insertion mutant to generate cbf1,3 double and cbf1 cbf2 cbf3 (cbfs) triple mutants. The response of the cbfs triple mutants to chilling stress is impaired. Furthermore, no significant difference in freezing tolerance was observed between the wild-type and the cbf1,3 and cbfs mutants without cold acclimation. However, the cbfs mutants were extremely sensitive to freezing stress after cold acclimation, and freezing sensitivity ranking was cbfs > cbf1,3 > cbf3. RNA-Seq analysis showed that 134 genes were CBF regulated, of which 112 were regulated positively and 22 negatively by CBFs. Our study reveals the essential functions of CBFs in chilling stress response and cold acclimation, as well as defines a set of genes as CBF regulon. It also provides materials for the genetic dissection of components in CBF-dependent cold signaling. PMID:27353960

  3. Pseudouridine-guide RNAs and other Cbf5p-associated RNAs in Euglena gracilis.

    PubMed

    Russell, Anthony G; Schnare, Murray N; Gray, Michael W

    2004-07-01

    In eukaryotes, box H/ACA small nucleolar RNAs (snoRNAs) guide sites of pseudouridine (Psi) formation in rRNA. These snoRNAs reside in RNP complexes containing the putative Psi synthase, Cbf5p. In this study we have identified Cbf5p-associated RNAs in Euglena gracilis, an early diverging eukaryote, by immunoprecipitating Cbf5p-containing complexes from cellular extracts. We characterized one box H/ACA-like RNA which, however, does not appear to guide Psi formation in rRNA. We also identified four single Psi-guide box AGA RNAs. We determined target sites for these putative Psi-guide RNAs and confirmed that the predicted Psi modifications do, in fact, occur at these positions in Euglena rRNA. The Cbf5p-associated snoRNAs appear to be encoded by multicopy genes, some of which are clustered in the genome together with methylation-guide snoRNA genes. These modification-guide snoRNAs and snoRNA genes are the first ones to be reported in euglenid protists, the evolutionary sister group to the kinetoplastid protozoa. Unexpectedly, we also found and have partially characterized a selenocysteine tRNA homolog in the anti-Cbf5p-immunoprecipitated sample.

  4. A novel role for the CBF3 kinetochore–scaffold complex in regulating septin dynamics and cytokinesis

    PubMed Central

    Gillis, Amethyst N.; Thomas, Scott; Hansen, Scott D.; Kaplan, Kenneth B.

    2005-01-01

    In budding yeast, the kinetochore scaffold complex centromere binding factor 3 (CBF3) is required to form kinetochores on centromere DNA and to allow proper chromosome segregation. We have previously shown that SKP1 and SGT1 balance the assembly and turnover of CBF3 complexes, a cycle that we suggest is independent of its role in chromosome segregation (Rodrigo-Brenni, M.C., S. Thomas, D.C. Bouck, and K.B. Kaplan. 2004. Mol. Biol. Cell. 15:3366–3378). We provide evidence that this cycle contributes to a second, kinetochore-independent function of CBF3. In this study, we show that inhibiting the assembly of CBF3 causes disorganized septins and defects in cell polarity that give rise to cytokinesis failures. Specifically, we show that septin ring separation and disassembly is delayed in anaphase, suggesting that CBF3 regulates septin dynamics. Only mutations that affect the CBF3 cycle, and not mutants in outer kinetochore subunits, cause defects in septins. These results demonstrate a novel role for CBF3 in regulating cytokinesis, a role that is reminiscent of passenger proteins. Consistent with this possibility, we find that CBF3 interacts with Bir1p, the homologue of the passenger protein Survivin. Mutants in Bir1p similarly affect septin organization, leading us to propose that CBF3 and Bir1p act as passenger proteins to coordinate chromosome segregation with cytokinesis. PMID:16330709

  5. Regional cerebral blood flow (rCBF) in man during perception of radiant warmth and heat pain.

    PubMed

    Ryding, E; Eriksson, M B; Rosén, I; Ingvar, D H

    1985-08-01

    The present study concerns the effects of experimental pain (radiant warmth and heat pain) on regional cerebral blood flow (rCBF) in pretrained subjects. The radiant warmth caused a general rCBF increase. However, if anxiety was avoided, heat pain caused the general rCBF level to return towards the level at rest. Thus, pain sensation per se may not cause a larger rCBF (and metabolic) response than that of the localized tactile stimulation, provided that the element of psychic apprehension and anxiety is eliminated or controlled.

  6. Reassessing the clinical efficacy of two MR quantitative DSC PWI CBF algorithms following cross-calibration with PET images

    NASA Astrophysics Data System (ADS)

    Chen, Jean J.; Frayne, Richard; Smith, Michael R.

    2005-03-01

    Clinical cerebral blood flow (CBF) maps generated through dynamic- susceptibility contrast (DSC) magnetic resonance (MR) perfusion imaging are currently cross-calibrated with PET studies. The cross-calibration is achieved by rescaling the MR CBF values so that normal white matter CBF corresponds to 22 ml/100 g/min. Examples are provided in this paper to show how this rescaling procedure changes both the clinical interpretation of CBF maps and the manner by which the performance of a given deconvolution algorithm should be assessed. (i) Singular-value decomposition-based (SVD) algorithms produce absolute CBF estimates that are inherently under-estimated for all tissue mean transit times (MTT) but, after rescaling, will generate CBF maps that are over-estimated for MTT >4.8 s. (ii) In principle, frequency-domain modelling techniques are expected to be inherently less sensitive to contrast recirculation biases than the time-domain SVD algorithms. However, it is shown that both CBF algorithms become greatly less sensitive to distortions from recirculation after clinical cross-calibration through rescaling has been performed. It is concluded that, when rescaling procedures are employed, it is relatively more important to develop deconvolution algorithms that produce CBF estimates with accuracies that vary little with MTT than to produce algorithms that provide inherently more accurate CBF estimates, but whose relative accuracy varies significantly with MTT. A portion of this work was presented at the 2004 Annual Scientific Meeting of the ISMRM, 15-21 May, Kyoto, Japan.

  7. Association genetics and expression patterns of a CBF4 homolog in Populus under abiotic stress.

    PubMed

    Li, Ying; Xu, Baohua; Du, Qingzhang; Zhang, Deqiang

    2015-06-01

    New strategies for prevention and treatment of abiotic stress require an improved understanding of stress responses. Here, we examined response differences of a C-repeat binding factor gene (PsCBF4) between five species in the genus Populus. We also used a candidate gene-based approach to identify single nucleotide polymorphisms (SNPs) within PsCBF4 that were associated with physiological and biochemical traits in a natural population (528 unrelated individuals) of Populus simonii. We first isolated a 1,044-bp PsCBF4 cDNA encoding a polypeptide of 256 amino acids. Expression profiling revealed that CBF4 is differentially expressed under cold, heat, drought, and salt conditions among five Populus species. Cold stress is the most significant interspecific difference, and PsCBF4 transcript levels ranged from 6.5 to 379.5 times higher than in unstressed controls. A natural population of P. simonii showed high nucleotide diversity (π T = 0.00880, θ w = 0.01192) and low linkage disequilibrium (r (2) ≥ 0.1, within 700 bp) across PsCBF4. Association analysis showed that nine SNPs (false discovery rate Q < 0.10) and two haplotypes (Q < 0.10) were significantly associated with six physiological and biochemical traits, with each marker explaining 3.36-6.12 % of the phenotypic variance in the corresponding trait. Transcript analysis further detected significant differences among genotypic classes for all significant SNPs. Identification of these significant associations will help reveal the molecular bases of physiological and biochemical differences and provide a starting point for marker-assisted selection for traits involved in stress tolerance in P. simonii.

  8. Ternary drop collisions

    NASA Astrophysics Data System (ADS)

    Hinterbichler, Hannes; Planchette, Carole; Brenn, Günter

    2015-10-01

    It has been recently proposed to use drop collisions for producing advanced particles or well-defined capsules, or to perform chemical reactions where the merged drops constitute a micro-reactor. For all these promising applications, it is essential to determine whether the merged drops remain stable after the collision, forming a single entity, or if they break up. This topic, widely investigated for binary drop collisions of miscible and immiscible liquid, is quite unexplored for ternary drop collisions. The current study aims to close this gap by experimentally investigating collisions between three equal-sized drops of the same liquid arranged centri-symmetrically. Three drop generators are simultaneously operated to obtain controlled ternary drop collisions. The collision outcomes are observed via photographs and compared to those of binary collisions. Similar to binary collisions, a regime map is built, showing coalescence and bouncing as well as reflexive and stretching separation. Significant differences are observed in the transitions between these regimes.

  9. Dilating Eye Drops

    MedlinePlus

    ... Conditions Most Common Searches Adult Strabismus Amblyopia Cataract Conjunctivitis Corneal Abrasions Dilating Eye Drops Lazy eye (defined) ... Loading... Most Common Searches Adult Strabismus Amblyopia Cataract Conjunctivitis Corneal Abrasions Dilating Eye Drops Lazy eye (defined) ...

  10. Attracting Water Drops

    NASA Video Gallery

    Astronauts Cady Coleman and Ron Garan perform the Attracting Water Drops experiment from Chabad Hebrew Academy in San Diego, Calif. This research determines if a free-floating water drop can be att...

  11. The CBF1-dependent low temperature signalling pathway, regulon and increase in freeze tolerance are conserved in Populus spp.

    PubMed

    Benedict, Catherine; Skinner, Jeffrey S; Meng, Rengong; Chang, Yongjian; Bhalerao, Rishikesh; Huner, Norman P A; Finn, Chad E; Chen, Tony H H; Hurry, Vaughan

    2006-07-01

    The meristematic tissues of temperate woody perennials must acclimate to freezing temperatures to survive the winter and resume growth the following year. To determine whether the C-repeat binding factor (CBF) family of transcription factors contributing to this process in annual herbaceous species also functions in woody perennials, we investigated the changes in phenotype and transcript profile of transgenic Populus constitutively expressing CBF1 from Arabidopsis (AtCBF1). Ectopic expression of AtCBF1 was sufficient to significantly increase the freezing tolerance of non-acclimated leaves and stems relative to wild-type plants. cDNA microarray experiments identified genes up-regulated by ectopic AtCBF1 expression in Populus, demonstrated a strong conservation of the CBF regulon between Populus and Arabidopsis and identified differences between leaf and stem regulons. We studied the induction kinetics and tissue specificity of four CBF paralogues identified from the Populus balsamifera subsp. trichocarpa genome sequence (PtCBFs). All four PtCBFs are cold-inducible in leaves, but only PtCBF1 and PtCBF3 show significant induction in stems. Our results suggest that the central role played by the CBF family of transcriptional activators in cold acclimation of Arabidopsis has been maintained in Populus. However, the differential expression of the PtCBFs and differing clusters of CBF-responsive genes in annual (leaf) and perennial (stem) tissues suggest that the perennial-driven evolution of winter dormancy may have given rise to specific roles for these 'master-switches' in the different annual and perennial tissues of woody species.

  12. Characterization and expression analysis of a gene encoding CBF/DREB1 transcription factor from mangrove Aegiceras corniculatum.

    PubMed

    Peng, Ya-Lan; Wang, You-Shao; Cheng, Hao; Wang, Li-Ying

    2015-10-01

    Several transcription factors play important roles in survival of plants under cold, drought and salt stresses by serving as master regulator of sets of downstream stress-responsive genes. A gene encoding CBF/DREB1 transcription factor (C-repeat binding factor/dehydration responsive element-binding factor 1) was isolated from mangrove Aegiceras corniculatum and designated AcCBF1. The full-length cDNA of AcCBF1 was 896 bp containing 618 bp ORF encoding a protein of 205 amino acids. Multiple sequence analysis showed that the corresponding protein had 100 % identity to AmCBF1 (KC776908) from mangrove Avicennia marina, and contains an AP2/ERE DNA-binding domain and two CBF signature sequences. Expression analyses based on quantitative real-time PCR revealed that the AcCBF1 gene was expressed in all tissues of A. corniculatum under normal condition with the highest expression level detected in leaves. When exposed to abiotic stresses, AcCBF1 gene showed different expression patterns in different tissues. Generally, AcCBF1 gene could be rapidly and strongly induced by cold and drought, while slightly induced by abscisic acid and salinity. Furthermore, light could positively regulate the cold-induction level of AcCBF1. These results suggest that the AcCBF1 may be playing important role in the signaling pathway of cold stress and also involved in the cross-talk among abiotic stresses. Further studies focusing on the promotors and downstream stress-responsive genes of AcCBF1 will help to better understand the regulatory mechanisms of mangrove A. corniculatum under abiotic stresses. PMID:25976917

  13. Characterization and expression analysis of a gene encoding CBF/DREB1 transcription factor from mangrove Aegiceras corniculatum.

    PubMed

    Peng, Ya-Lan; Wang, You-Shao; Cheng, Hao; Wang, Li-Ying

    2015-10-01

    Several transcription factors play important roles in survival of plants under cold, drought and salt stresses by serving as master regulator of sets of downstream stress-responsive genes. A gene encoding CBF/DREB1 transcription factor (C-repeat binding factor/dehydration responsive element-binding factor 1) was isolated from mangrove Aegiceras corniculatum and designated AcCBF1. The full-length cDNA of AcCBF1 was 896 bp containing 618 bp ORF encoding a protein of 205 amino acids. Multiple sequence analysis showed that the corresponding protein had 100 % identity to AmCBF1 (KC776908) from mangrove Avicennia marina, and contains an AP2/ERE DNA-binding domain and two CBF signature sequences. Expression analyses based on quantitative real-time PCR revealed that the AcCBF1 gene was expressed in all tissues of A. corniculatum under normal condition with the highest expression level detected in leaves. When exposed to abiotic stresses, AcCBF1 gene showed different expression patterns in different tissues. Generally, AcCBF1 gene could be rapidly and strongly induced by cold and drought, while slightly induced by abscisic acid and salinity. Furthermore, light could positively regulate the cold-induction level of AcCBF1. These results suggest that the AcCBF1 may be playing important role in the signaling pathway of cold stress and also involved in the cross-talk among abiotic stresses. Further studies focusing on the promotors and downstream stress-responsive genes of AcCBF1 will help to better understand the regulatory mechanisms of mangrove A. corniculatum under abiotic stresses.

  14. Heterology expression of the sweet pepper CBF3 gene confers elevated tolerance to chilling stress in transgenic tobacco.

    PubMed

    Yang, Sha; Tang, Xian-Feng; Ma, Na-Na; Wang, Li-Yan; Meng, Qing-Wei

    2011-10-15

    Various studies have confirmed that the CBF (C-repeat binding factor) family of transcription factors has a key role in regulating many plants' responses to cold stress. Here we isolated CBF3 from sweet pepper (Capsicum frutescens). Green fluorescent protein (GFP) fusion protein of CfCBF3 was targeted to the nucleus of the onion epidermis cell. RNA gel blot analysis indicated that CfCBF3 was expressed in leaves of sweet pepper and the expression was induced by low temperature, drought and salinity stresses but not by ABA. Overexpression of CfCBF3 under the control of the CaMV35S promoter in tobacco induced expression of orthologs of CBF3-targeted genes and increased chilling tolerance without a dwarf phenotype. Indeed it also led to multiple biochemical and physiological changes associated with chilling stress. Higher levels of proline (Pro) and soluble sugars and lower content of reactive oxygen species (ROS) were observed in transgenic plants. Our results demonstrated that the increase in total unsaturated fatty acids, especially in phosphatidylglycerol (PG) was detected by overexpression of CfCBF3. During exposure to chilling stress, the transgenic lines were less susceptible to chilling-induced photoinhibition than wild-type (WT) plants. These results suggest that overexpression of CfCBF3 led to modification of the fatty acid unsaturation and alleviated the injuries under chilling stress.

  15. Archaeal proteins Nop10 and Gar1 increase the catalytic activity of Cbf5 in pseudouridylating tRNA.

    PubMed

    Kamalampeta, Rajashekhar; Kothe, Ute

    2012-01-01

    Cbf5 is a pseudouridine synthase that usually acts in a guide RNA-dependent manner as part of H/ACA small ribonucleoproteins; however archaeal Cbf5 can also act independently of guide RNA in modifying uridine 55 in tRNA. This guide-independent activity of Cbf5 is enhanced by proteins Nop10 and Gar1 which are also found in H/ACA small ribonucleoproteins. Here, we analyzed the specific contribution of Nop10 and Gar1 for Cbf5-catalyzed pseudouridylation of tRNA. Interestingly, both Nop10 and Gar1 not only increase Cbf5's affinity for tRNA, but they also directly enhance Cbf5's catalytic activity by increasing the k(cat) of the reaction. In contrast to the guide RNA-dependent reaction, Gar1 is not involved in product release after tRNA modification. These results in conjunction with structural information suggest that Nop10 and Gar1 stabilize Cbf5 in its active conformation; we hypothesize that this might also be true for guide-RNA dependent pseudouridine formation by Cbf5.

  16. 9. (Credit CBF) The McNeil Street Station from the northwest, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. (Credit CBF) The McNeil Street Station from the northwest, March 1913. The low service pump room is on the right, the clear water well (installed c1900) and filter house are on the left. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  17. 10. (Credit CBF) The McNeil Street Station from the west, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. (Credit CBF) The McNeil Street Station from the west, March 1913. The low service pump room is on the left. The 'coal shed' which housed the laboratory (after 1908), the alum and lime rooms, and chemical storage is on the right. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  18. 62. (Credit CBF) Operating floor of filter room, c1912. The ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    62. (Credit CBF) Operating floor of filter room, c1912. The remodeled New York horizontal pressure filters (now gravity filters) are in the foreground; the remodelled Hyatt tub filters are in the background. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  19. Vif determines the requirement for CBF-β in APOBEC3 degradation

    PubMed Central

    Yoshikawa, Rokusuke; Takeuchi, Junko S.; Yamada, Eri; Nakano, Yusuke; Ren, Fengrong; Tanaka, Hiroshi; Münk, Carsten; Harris, Reuben S.; Miyazawa, Takayuki; Koyanagi, Yoshio

    2015-01-01

    APOBEC3 (apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3) proteins are cellular DNA deaminases that restrict a broad spectrum of lentiviruses. This process is counteracted by Vif (viral infectivity factor) of lentiviruses, which binds APOBEC3s and promotes their degradation. CBF-β (core binding factor subunit β) is an essential co-factor for the function of human immunodeficiency virus type 1 Vif to degrade human APOBEC3s. However, the requirement for CBF-β in Vif-mediated degradation of other mammalian APOBEC3 proteins is less clear. Here, we determined the sequence of feline CBFB and performed phylogenetic analyses. These analyses revealed that mammalian CBFB is under purifying selection. Moreover, we demonstrated that CBF-β is dispensable for feline immunodeficiency virus Vif-mediated degradation of APOBEC3s of its host. These findings suggested that primate lentiviruses have adapted to use CBF-β, an evolutionary stable protein, to counteract APOBEC3 proteins of their hosts after diverging from other lentiviruses. PMID:25516542

  20. 32. (Credit CBF) Boilers in the McNeil Street Station, November ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. (Credit CBF) Boilers in the McNeil Street Station, November 1911: two 100 hp Atlas boilers and one Chattanooga boiler. The Atlas boilers were installed c1892, the Chattanooga boiler c1897. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  1. Evaluation of MRI Models in the Measurement of CMRO2 and Its Relationship With CBF

    PubMed Central

    Lin, Ai-Ling; Fox, Peter T.; Yang, Yihong; Lu, Hanzhang; Tan, Li-Hai; Gao, Jia-Hong

    2008-01-01

    The aim of this study was to investigate the various MRI biophysical models in the measurements of local cerebral metabolic rate of oxygen (CMRO2) and the corresponding relationship with cerebral blood flow (CBF) during brain activation. This aim was addressed by simultaneously measuring the relative changes in CBF, cerebral blood volume (CBV), and blood oxygen level dependent (BOLD) MRI signals in the human visual cortex during visual stimulation. A radial checkerboard delivered flash stimulation at five different frequencies. Two MRI models, the single-compartment model (SCM) and the multi-compartment model (MCM), were used to determine the relative changes in CMRO2 using three methods: [1] SCM with parameters identical to those used in a prior MRI study (M = 0.22; α = 0.38); [2] SCM with directly measured parameters (M from hypercapnia and α from measured δCBV and δCBF); and [3] MCM. The magnitude of relative changes in CMRO2 and the nonlinear relationship between CBF and CMRO2 obtained with Methods [2] and [3] were not in agreement with those obtained using Method [1]. However, the results of Methods [2] and [3] were aligned with positron emission tomography findings from the literature. Our results indicate that if appropriate parameters are used, the SCM and MCM models are equivalent for quantifying the values of CMRO2 and determining the flow-metabolism relationship. PMID:18666102

  2. Drag on Sessile Drops

    NASA Astrophysics Data System (ADS)

    Milne, Andrew J. B.; Fleck, Brian; Nobes, David; Sen, Debjyoti; Amirfazli, Alidad; University of Alberta Mechanical Engineering Collaboration

    2013-11-01

    We present the first ever direct measurements of the coefficient of drag on sessile drops at Reynolds numbers from the creeping flow regime up to the point of incipient motion, made using a newly developed floating element differential drag sensor. Surfaces of different wettabilities (PMMA, Teflon, and a superhydrophobic surface (SHS)), wet by water, hexadecane, and various silicone oils, are used to study the effects of drop shape, and fluid properties on drag. The relation between drag coefficient and Reynolds number (scaled by drop height) varies slightly with liquid-solid system and drop volume with results suggesting the drop experiences increased drag compared to similar shaped solid bodies due to drop oscillation influencing the otherwise laminar flow. Drops adopting more spherical shapes are seen to experience the greatest force at any given airspeed. This indicates that the relative exposed areas of drops is an important consideration in terms of force, with implications for the shedding of drops in applications such as airfoil icing and fuel cell flooding. The measurement technique used in this work can be adapted to measure drag force on other deformable, lightly adhered objects such as dust, sand, snow, vesicles, foams, and biofilms. The authours acknowledge NSERC, Alberta Innovates Technology Futures, and the Killam Trusts.

  3. Ectopic overexpression of SsCBF1, a CRT/DRE-binding factor from the nightshade plant Solanum lycopersicoides, confers freezing and salt tolerance in transgenic Arabidopsis.

    PubMed

    Zhang, Lili; Li, Zhenjun; Li, Jingfu; Wang, Aoxue

    2014-01-01

    The C-repeat (CRT)/dehydration-responsive element (DRE) binding factor (CBF/DREB1) transcription factors play a key role in cold response. However, the detailed roles of many plant CBFs are far from fully understood. A CBF gene (SsCBF1) was isolated from the cold-hardy plant Solanum lycopersicoides. A subcellular localization study using GFP fusion protein indicated that SsCBF1 is localized in the nucleus. We delimited the SsCBF1 transcriptional activation domain to the C-terminal segment comprising amino acid residues 193-228 (SsCBF1(193-228)). The expression of SsCBF1 could be dramatically induced by cold, drought and high salinity. Transactivation assays in tobacco leaves revealed that SsCBF1 could specifically bind to the CRT cis-elements in vivo to activate the expression of downstream reporter genes. The ectopic overexpression of SsCBF1 conferred increased freezing and high-salinity tolerance and late flowering phenotype to transgenic Arabidopsis. RNA-sequencing data exhibited that a set of cold and salt stress responsive genes were up-regulated in transgenic Arabidopsis. Our results suggest that SsCBF1 behaves as a typical CBF to contribute to plant freezing tolerance. Increased resistance to high-salinity and late flowering phenotype derived from SsCBF1 OE lines lend more credence to the hypothesis that plant CBFs participate in diverse physiological and biochemical processes related to adverse conditions.

  4. The Indeterminate Domain Protein ROC1 Regulates Chilling Tolerance via Activation of DREB1B/CBF1 in Rice

    PubMed Central

    Dou, Mingzhu; Cheng, Shuai; Zhao, Baotian; Xuan, Yuanhu; Shao, Minglong

    2016-01-01

    Abiotic stress, including salinity, drought and cold, severely affect diverse aspects of plant development and production. Rice is an important crop that does not acclimate to cold; therefore, it is relatively sensitive to low temperature stress. Dehydration-responsive element-binding protein 1s (DREB1s)/C-repeat binding factors (CBFs) are well known for their function in cold tolerance, but the transcriptional regulation of CBFs remains elusive, especially in rice. Here, we performed a yeast one-hybrid assay using the promoter of CBF1, a cold-induced gene, to isolate transcriptional regulators of CBF1. Among the seven candidates identified, an indeterminate domain (IDD) protein named ROC1 (a regulator of CBF1) was further analyzed. The ROC1 transcript was induced by exogenously-treated auxin, while it was not altered by cold or ABA stimuli. ROC1-GFP was localized at the nucleus, and ROC1 showed trans-activation activity in yeast. The electrophoretic mobility shift assay (EMSA) and ChIP analyses revealed that ROC1 directly bound to the promoter of CBF1. Furthermore, ROC1 mutants exhibited chilling-sensitive symptoms and inhibited cold-mediated induction of CBF1 and CBF3, indicating that ROC1 is a positive regulator of cold stress responses. Taken together, this study identified the CBF1 regulator, and the results are important for rice plant adaptation to chilling stress. PMID:26927068

  5. Detection of the chromosome 16 CBF beta-MYH11 fusion transcript in myelomonocytic leukemias.

    PubMed

    Poirel, H; Radford-Weiss, I; Rack, K; Troussard, X; Veil, A; Valensi, F; Picard, F; Guesnu, M; Leboeuf, D; Melle, J

    1995-03-01

    Karyotypic detection of chromosomal 16 abnormalities classically associated with AML M4Eo can be difficult. Characterization of the two genes involved in the inv(16)(p13q22), CBF beta and MYH11, has allowed the detection of fusion transcripts by reverse-transcriptase polymerase chain reaction (RT-PCR). We have analyzed CBF beta-MYH11 fusion transcripts by RT-PCR in myelomonocytic leukemias, with or without eosinophilia, to determine whether their presence correlates with morphology. Fifty-three cases (11 AML M4Eo; 1 AML M4 with atypical abnormal eosinophils (AML M4 "Eo"); 29 AML M4; 8 AML M5; 3 CMML; and 1 AML M2 with eosinophilia) were analyzed. All 11 typical AML M4Eo were CBF beta-MYH11 positive. The single case of AML M4 with distinctive eosinophil abnormalities was negative by karyotype, RT-PCR and fluorescent in situ hybridization (FISH). Three of 29 (10%) AML M4 without abnormal eosinophils were CBF beta-MYH11 positive, 1 of which did not show any apparent chromosome 16 abnormalities by classical metaphase analysis (2 not tested). Both cases tested also showed MYH11 genomic rearrangement. None of the other leukemias were RT-PCR positive. Follow-up of three patient showed residual positivity in apparent complete remission. These data show that CBF beta-MYH11 fusion transcripts occur not only in the vast majority of typical AML M4Eo, but also in approximately 10% of AML M4 without eosinophilic abnormalities, a much higher incidence than the sporadic reports of chromosome 16 abnormalities in AML M4 would suggest. Taken together with the detection of CBF beta-MYH11 transcripts in the absence of apparent chromosome 16 abnormalities by classical banding techniques, these data show that additional screening by either RT-PCR or FISH should be performed in all AML M4, regardless of morphologic features, to allow accurate evaluation of the prognostic importance of this fusion transcript.

  6. Oil palm EgCBF3 conferred stress tolerance in transgenic tomato plants through modulation of the ethylene signaling pathway.

    PubMed

    Ebrahimi, Mortaza; Abdullah, Siti Nor Akmar; Abdul Aziz, Maheran; Namasivayam, Parameswari

    2016-09-01

    CBF/DREB1 is a group of transcription factors that are mainly involved in abiotic stress tolerance in plants. They belong to the AP2/ERF superfamily of plant-specific transcription factors. A gene encoding a new member of this group was isolated from ripening oil palm fruit and designated as EgCBF3. The oil palm fruit demonstrates the characteristics of a climacteric fruit like tomato, in which ethylene has a major impact on the ripening process. A transgenic approach was used for functional characterization of the EgCBF3, using tomato as the model plant. The effects of ectopic expression of EgCBF3 were analyzed based on expression profiling of the ethylene biosynthesis-related genes, anti-freeze proteins (AFPs), abiotic stress tolerance and plant growth and development. The EgCBF3 tomatoes demonstrated altered phenotypes compared to the wild type tomatoes. Delayed leaf senescence and flowering, increased chlorophyll content and abnormal flowering were the consequences of overexpression of EgCBF3 in the transgenic tomatoes. The EgCBF3 tomatoes demonstrated enhanced abiotic stress tolerance under in vitro conditions. Further, transcript levels of ethylene biosynthesis-related genes, including three SlACSs and two SlACOs, were altered in the transgenic plants' leaves and roots compared to that in the wild type tomato plant. Among the eight AFPs studied in the wounded leaves of the EgCBF3 tomato plants, transcript levels of SlOSM-L, SlNP24, SlPR5L and SlTSRF1 decreased, while expression of the other four, SlCHI3, SlPR1, SlPR-P2 and SlLAP2, were up-regulated. These findings indicate the possible functions of EgCBF3 in plant growth and development as a regulator of ethylene biosynthesis-related and AFP genes, and as a stimulator of abiotic stress tolerance. PMID:27513726

  7. Oil palm EgCBF3 conferred stress tolerance in transgenic tomato plants through modulation of the ethylene signaling pathway.

    PubMed

    Ebrahimi, Mortaza; Abdullah, Siti Nor Akmar; Abdul Aziz, Maheran; Namasivayam, Parameswari

    2016-09-01

    CBF/DREB1 is a group of transcription factors that are mainly involved in abiotic stress tolerance in plants. They belong to the AP2/ERF superfamily of plant-specific transcription factors. A gene encoding a new member of this group was isolated from ripening oil palm fruit and designated as EgCBF3. The oil palm fruit demonstrates the characteristics of a climacteric fruit like tomato, in which ethylene has a major impact on the ripening process. A transgenic approach was used for functional characterization of the EgCBF3, using tomato as the model plant. The effects of ectopic expression of EgCBF3 were analyzed based on expression profiling of the ethylene biosynthesis-related genes, anti-freeze proteins (AFPs), abiotic stress tolerance and plant growth and development. The EgCBF3 tomatoes demonstrated altered phenotypes compared to the wild type tomatoes. Delayed leaf senescence and flowering, increased chlorophyll content and abnormal flowering were the consequences of overexpression of EgCBF3 in the transgenic tomatoes. The EgCBF3 tomatoes demonstrated enhanced abiotic stress tolerance under in vitro conditions. Further, transcript levels of ethylene biosynthesis-related genes, including three SlACSs and two SlACOs, were altered in the transgenic plants' leaves and roots compared to that in the wild type tomato plant. Among the eight AFPs studied in the wounded leaves of the EgCBF3 tomato plants, transcript levels of SlOSM-L, SlNP24, SlPR5L and SlTSRF1 decreased, while expression of the other four, SlCHI3, SlPR1, SlPR-P2 and SlLAP2, were up-regulated. These findings indicate the possible functions of EgCBF3 in plant growth and development as a regulator of ethylene biosynthesis-related and AFP genes, and as a stimulator of abiotic stress tolerance.

  8. Youth Crime Drop. Report.

    ERIC Educational Resources Information Center

    Butts, Jeffrey A.

    This report examines the recent drop in violent crime in the United States, discussing how much of the decrease seen between 1995-99 is attributable to juveniles (under age 18 years) and older youth (18-24 years). Analysis of current FBI arrest data indicates that not only did America's violent crime drop continue through 1999, but falling youth…

  9. Drop Tower Physics

    ERIC Educational Resources Information Center

    Dittrich, William A.

    2014-01-01

    The drop towers of yesteryear were used to make lead shot for muskets, as described in "The Physics Teacher" in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at…

  10. Axisymmetric Liquid Hanging Drops

    ERIC Educational Resources Information Center

    Meister, Erich C.; Latychevskaia, Tatiana Yu

    2006-01-01

    The geometry of drops hanging on a circular capillary can be determined by numerically solving a dimensionless differential equation that is independent on any material properties, which enables one to follow the change of the height, surface area, and contact angle of drops hanging on a particular capillary. The results show that the application…

  11. Sessile Rayleigh drop instability

    NASA Astrophysics Data System (ADS)

    Steen, Paul; Bostwick, Josh

    2012-11-01

    Rayleigh (1879) determined the mode shapes and frequencies of the inviscid motion of a free drop held by surface tension. We study the inviscid motions of a sessile Rayleigh drop - a drop which rests on a planar solid and whose contact-line is free to move. Linear stability analysis gives the modes and frequencies of the droplet motions. In this talk, we focus on the ``walking instability,'' an unstable mode wherein the drop moves across a planar substrate in an inviscid rocking-like motion. The mode shape is non-axisymmetric. Although the experimental literature has hinted at such a mode, this is the first prediction from linear stability analysis, as far as we are aware. The ``walking instability'' of the drop converts energy stored in the liquid shape into the energy of liquid motion - which represents a heretofore unknown pathway of energy conversion of potentially wide significance for a broad range of applications.

  12. Combination of dynamic and integral methods for generating reproducible functional CBF images

    SciTech Connect

    Lammertsma, A.A.; Cunningham, V.J.; Deiber, M.P.; Heather, J.D.; Bloomfield, P.M.; Nutt, J.; Frackowiak, R.S.; Jones, T. )

    1990-09-01

    A new method to measure regional CBF is presented, applying both dynamic and integral analyses to a dynamic sequence of positron emission tomographic scans collected during and following the administration of H2(15)O (inhalation of C15O2). The dynamic analysis is used to correct continuously monitored arterial whole-blood activity for delay and dispersion relative to tissue scans. An integral analysis including corrections for this delay and dispersion is then used to calculate CBF on a pixel-by-pixel basis. Normal values and reproducibility over a 2-h period are presented, together with the results of validation and simulation studies. The results indicate that the single-tissue compartment model adequately describes the distribution of H2(15)O in the brain, without recourse to postulating a nonexchanging water pool.

  13. Assessment of the fetal PO2 changes by cerebral and umbilical Doppler on lamb fetuses during acute hypoxia.

    PubMed

    Arbeille, P; Maulik, D; Fignon, A; Stale, H; Berson, M; Bodard, S; Locatelli, A

    1995-01-01

    The objective of the present study was to validate one or a combination of fetal Doppler parameters in order to assess acute fetal hypoxia in an ovine model. Acute hypoxia was induced by reducing umbilical, or maternal aortic flow (approx. 70%). A CW Doppler probe was fixed on the fetal cervical skin, facing the internal carotid artery and the fetal abdominal skin adjacent to the umbilical arteries. (The angle between Doppler beam and flow vector remained constant.) A "Doptek 3000" spectrum analyser was used to measure the maximal and mean Doppler frequencies. Heart rate (HR), umbilical blood flow (UBF), carotid blood flow (CBF), umbilical RI (URI), cerebral RI (CRI) and cerebroplacental ratio (CPR = CRI/URI) were calculated in real time. A catheter was inserted into the fetal femoral artery, for blood gas (PO2, PCO2 pH) and blood pressure (BP) measurements. After 1 min of aorta compression (70% aortic flow reduction), the URI increased by 10% (P < 0.05), and the UBF decreased by 10% (P < 0.05), but the CRI decreased by 20% (P < 0.02), and the CBF did not change significantly. Fetal PO2 and CPR fell down after 1 min (59% and 38%, respectively; P < 0.001), although strong fetal heart rate decelerations were observed. The blood pressure, PCO2 and pH did not change significantly during this test. Throughout the 12 min of cord compression (70% umbilical flow reduction) the URI increased (70% to 80% P < 0.001), and the UBF decreased (approx. 60%; P < 0.001), but the CRI decreased (approx. 25%; P < 0.01), and the CBF remained constant (+/- 5%; ns). Fetal PO2 and CPR all decreased during the compression (30% to 44% and 40% to 60%, respectively; P < 0.001). HR, pH and PCO2 did not change significantly. During cord compression the blood pressure did not change significantly. In both cases, the CPR decreased significantly (P < 0.001) with the PO2 in the same direction and with a comparable amplitude (-30% to -50%). Nevertheless, the drop in CPR was greater during cord

  14. 61. (Credit CBF) Operating floor of filter room, c1912. A ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. (Credit CBF) Operating floor of filter room, c1912. A remodeled Hyatt pressure filter, now operating as a tub, gravity, rapid sand filter, is in the foreground (the remodeling took place c1908-1909). The remodeled New York horizontal pressure filters (installed 01900, remodeled c1908-1909) are in the background. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  15. Genome-wide characterization of the CBF/DREB1 gene family in Brassica rapa.

    PubMed

    Lee, Sang-Choon; Lim, Myung-Ho; Yu, Jae-Gyeong; Park, Beom-Seok; Yang, Tae-Jin

    2012-12-01

    The C-repeat/dehydration-responsive element binding transcription factors (CBF/DREBs) are important proteins in involved in responses to abiotic stress in plants. We identified ten BrDREB1 genes belonging to the CBF/DREB1 gene family in the Brassica rapa whole genome sequence, whereas six genes are found in the Arabidopsis thaliana genome. The deduced amino acid sequences of the B. rapa genes showed conserved motifs shared with other known plant CBF/DREB1s. Comparative analysis revealed that nine of the BrDREB1 genes were derived from the recent genome triplication in the tribe Brassiceae and the other one was translocated. The nine genes were located in seven of the 12 macrosyntenic blocks that are triplicated counterparts of four Arabidopsis macrosyntenic blocks harboring six CBF/DREB1 genes: one gene on each of three blocks and three tandemly arrayed genes on another block. We inspected the expression patterns of eight BrDREB1 genes by RT-PCR and microarray database searches. All eight genes were highly up-regulated during cold (4 °C) treatment, and some of them were also responsive to salt (250 mM NaCl), drought (air drying), and ABA (100 μM) treatment. Microarray data for plant developmental stages revealed that BrDREB1C2 was highly expressed during a period of cold treatment for vernalization, similar to abiotic stress-inducible genes homologous to Bn28a, Bn47, Bn115, and BoRS1, but almost opposite of BrFLC genes. Taken together, the number of BrDREB1 genes increased to 10 by genome triplication and reorganization, providing additional functions in B. rapa abiotic stress responses and development, as distinct from their Arabidopsis homologs.

  16. 12. (Credit CBF) West end of McNeil Street Station in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. (Credit CBF) West end of McNeil Street Station in November 1911. The settling basins are visible on the far right. In the foreground is a pile of filter sand and several barrels of chemicals (probably lime or alum). The box car is delivering chemicals to storage in the west wing of the station. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  17. Genome-wide characterization of the CBF/DREB1 gene family in Brassica rapa.

    PubMed

    Lee, Sang-Choon; Lim, Myung-Ho; Yu, Jae-Gyeong; Park, Beom-Seok; Yang, Tae-Jin

    2012-12-01

    The C-repeat/dehydration-responsive element binding transcription factors (CBF/DREBs) are important proteins in involved in responses to abiotic stress in plants. We identified ten BrDREB1 genes belonging to the CBF/DREB1 gene family in the Brassica rapa whole genome sequence, whereas six genes are found in the Arabidopsis thaliana genome. The deduced amino acid sequences of the B. rapa genes showed conserved motifs shared with other known plant CBF/DREB1s. Comparative analysis revealed that nine of the BrDREB1 genes were derived from the recent genome triplication in the tribe Brassiceae and the other one was translocated. The nine genes were located in seven of the 12 macrosyntenic blocks that are triplicated counterparts of four Arabidopsis macrosyntenic blocks harboring six CBF/DREB1 genes: one gene on each of three blocks and three tandemly arrayed genes on another block. We inspected the expression patterns of eight BrDREB1 genes by RT-PCR and microarray database searches. All eight genes were highly up-regulated during cold (4 °C) treatment, and some of them were also responsive to salt (250 mM NaCl), drought (air drying), and ABA (100 μM) treatment. Microarray data for plant developmental stages revealed that BrDREB1C2 was highly expressed during a period of cold treatment for vernalization, similar to abiotic stress-inducible genes homologous to Bn28a, Bn47, Bn115, and BoRS1, but almost opposite of BrFLC genes. Taken together, the number of BrDREB1 genes increased to 10 by genome triplication and reorganization, providing additional functions in B. rapa abiotic stress responses and development, as distinct from their Arabidopsis homologs. PMID:23148914

  18. Focal hyperemia followed by spreading oligemia and impaired activation of rCBF in classic migraine

    SciTech Connect

    Olesen, J.; Larsen, B.; Lauritzen, M.

    1981-04-01

    Regional cerebral blood flow (rCBF) was measured in 254 areas of a hemisphere with the xenon 133 intraarterial injection method. Six cases of classic migraine were followed from the normal state into the prodromal phase, and in 3 cases further into the headache phase. One patient with common migraine was similarly followed during his only classic attack. The attacks were initiated by focal hyperemia in 3 patients. During prodromes all patients displayed occipitoparietal rCBF reduction (oligemia), but in only 1 case did the reduction approach critical values. Oligemia gradually spread anteriorly in the course of 15 to 45 minutes. In 4 patients a global oligemia was observed. In 4 patients severe headache was present concomitantly with oligemia and with no sign of hyperemia or nonhomogeneous brain perfusion. The normal rCBF increase during cortical activity (hand movement, speech, and similar activities) was impaired in 6 patients. The results indicate that the vasospastic model of the migraine attack is too simplistic.

  19. CbCBF from Capsella bursa-pastoris enhances cold tolerance and restrains growth in Nicotiana tabacum by antagonizing with gibberellin and affecting cell cycle signaling.

    PubMed

    Zhou, Mingqi; Xu, Ming; Wu, Lihua; Shen, Chen; Ma, Hong; Lin, Juan

    2014-06-01

    Plant cells respond to cold stress via a regulatory mechanism leading to enhanced cold acclimation accompanied by growth retardation. The C-repeat binding factor (CBF) signaling pathway is essential for cold response of flowering plants. Our previously study documented a novel CBF-like gene from the cold-tolerant Capsella bursa-pastoris named CbCBF, which was responsive to chilling temperatures. Here, we show that CbCBF expression is obviously responsive to chilling, freezing, abscisic acid, gibberellic acid (GA), indoleacetic acid or methyl jasmonate treatments and that the CbCBF:GFP fusion protein was localized to the nucleus. In addition, CbCBF overexpression conferred to the cold-sensitive tobacco plants enhanced tolerance to chilling and freezing, as well as dwarfism and delayed flowering. The leaf cells of CbCBF overexpression tobacco lines attained smaller sizes and underwent delayed cell division with reduced expression of cyclin D genes. The dwarfism of CbCBF transformants can be partially restored by GA application. Consistently, CbCBF overexpression reduced the bioactive gibberellin contents and disturbed the expression of gibberellin metabolic genes in tobacco. Meanwhile, cold induced CbCBF expression and cold tolerance in C. bursa-pastoris are reduced by GA. We conclude that CbCBF confers cold resistance and growth inhibition to tobacco cells by interacting with gibberellin and cell cycle pathways, likely through activation of downstream target genes.

  20. In vivo imaging of hemodynamics and oxygen metabolism in acute focal cerebral ischemic rats with laser speckle imaging and functional photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Deng, Zilin; Wang, Zhen; Yang, Xiaoquan; Luo, Qingming; Gong, Hui

    2012-08-01

    Stroke is a devastating disease. The changes in cerebral hemodynamics and oxygen metabolism associated with stroke play an important role in pathophysiology study. But the changes were difficult to describe with a single imaging modality. Here the changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and oxygen saturation (SO2) were yielded with laser speckle imaging (LSI) and photoacoustic microscopy (PAM) during and after 3-h acute focal ischemic rats. These hemodynamic measures were further synthesized to deduce the changes in oxygen extraction fraction (OEF). The results indicate that all the hemodynamics except CBV had rapid declines within 40-min occlusion of middle cerebral artery (MCAO). CBV in arteries and veins first increased to the maximum value of 112.42±36.69% and 130.58±31.01% by 15 min MCAO; then all the hemodynamics had a persistent reduction with small fluctuations during the ischemic. When ischemia lasted for 3 h, CBF in arteries, veins decreased to 17±14.65%, 24.52±20.66%, respectively, CBV dropped to 62±18.56% and 59±18.48%. And the absolute SO2 decreased by 40.52±22.42% and 54.24±11.77%. After 180-min MCAO, the changes in hemodynamics and oxygen metabolism were also quantified. The study suggested that combining LSI and PAM provides an attractive approach for stroke detection in small animal studies.

  1. Liquid Metal Drop Impingement

    NASA Astrophysics Data System (ADS)

    Che, Judy; Han, Jaehoon; Tryggvason, Gretar; Ceccio, Steven

    1996-11-01

    "Ballistic Partical Manufacturing" is a process in which individual drops are layered to form a part. We examine how metal drops deform and solidify, and how the solidification rate affects the material microstructure using both numerical simulations and experiments. A single set of equations governing the conservation of mass, energy, and momentum are written for all phases involved, and the phase boundary is treated as an imbedded interface by adding the appropriate source terms. We have simulated single drops colliding with a surface using a simple model which assumes that a melt solidifies below the melting point. Although simple, this model captures many aspects of the fluid flow and solidification. The experimental apparatus creates a single drop of prescribed size and propels it toward a cooled substrate. Favorable comparisons of experimental and numerical results have been achieved.

  2. Drop Tower Workshop

    NASA Technical Reports Server (NTRS)

    Urban, David

    2013-01-01

    Ground based microgravity facilities are an important proving ground for space experiments, ground-based research and space hardware risk mitigation. An overview of existing platforms will be discussed with an emphasis on drop tower capabilities. The potential for extension to partial gravity conditions will be discussed. Input will be solicited from attendees for their potential to use drop towers in the future and the need for enhanced capabilities (e.g. partial gravity)

  3. Rain Drop Charge Sensor

    NASA Astrophysics Data System (ADS)

    S, Sreekanth T.

    begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge

  4. Liquid metal drop ejection

    NASA Technical Reports Server (NTRS)

    Khuri-Yakub, B. T.

    1993-01-01

    The aim of this project was to demonstrate the possibility of ejecting liquid metals using drop on demand printing technology. The plan was to make transducers for operation in the 100 MHz frequency range and to use these transducers to demonstrate the ability to eject drops of liquid metals such as gallium. Two transducers were made by indium bonding piezoelectric lithium niobate to quartz buffer rods. The lithium niobate plates were thinned by mechanical polishing to a thickness of 37 microns for operation at 100 MHz. Hemispherical lenses were polished in the opposite ends of the buffer rods. The lenses, which focus the sound waves in the liquid metal, had an F-number equals 1. A mechanical housing was made to hold the transducers and to allow precise control over the liquid level above the lens. We started by demonstrating the ability to eject drops of water on demand. The drops of water had a diameter of 15 microns which corresponds to the wavelength of the sound wave in the water. A videotape of this ejection was made. We then used a mixture of Gallium and Indium (used to lower the melting temperature of the Gallium) to demonstrate the ejection of liquid metal drops. This proved to be difficult because of the oxide skin which forms on the surface of the liquid. In some instances, we were able to eject metal drops, however, this was not consistent and reproducible. An experiment was set up at NASA-Lewis to stabilize the process of drop on demand liquid metal ejection. The object was to place the transducer and liquid metal in a vacuum station so that no oxide would form on the surface. We were successful in demonstrating that liquid metals could be ejected on demand and that this technology could be used for making sheet metal in space.

  5. Functional Analysis of the Maize C-Repeat/DRE Motif-Binding Transcription Factor CBF3 Promoter in Response to Abiotic Stress

    PubMed Central

    Liu, Jinliang; Wang, Fengting; Yu, Gang; Zhang, Xianghui; Jia, Chengguo; Qin, Jianchun; Pan, Hongyu

    2015-01-01

    The ZmCBF3 gene is a member of AP2/ERF transcription factor family, which is a large family of plant-specific transcription factors that share a well-conserved DNA-binding domain. To understand the regulatory mechanism of ZmCBF3 gene expression, we isolated and characterized the ZmCBF3 promoter (PZmCBF3). Three deletion fragments of PZmCBF3 were generated, C1–C3, from the translation start codon at position −1079, −638, and −234, and fused to the GUS reporter gene. Each deletion construct was analyzed by Agrobacterium-mediated stable transformation and expression in Arabidopsis thaliana. GUS expression assays indicated that the PZmCBF3 exhibited root-specific expression activity. A 234-bp fragment upstream of the ZmCBF3 gene conferred a high level of GUS activity in Arabidopsis. Some cis-acting elements involved in the down-regulation of gene expression were detected in the promoter, encompassing positions −1079 to −234. PZmCBF3 was activated by cold stress. The MYCCONSENSUSAT elements (CANNTG) were responsible for the ability of PZmCBF3 to respond to cold stress. The results of the present study suggest that PZmCBF3 might play a role in cold tolerance in maize. PMID:26030672

  6. Drying drops of blood

    NASA Astrophysics Data System (ADS)

    Brutin, David; Sobac, Benjamin; Loquet, Boris; Sampol, José.

    2010-11-01

    The drying of a drop of human blood is fascinating by the complexity of the physical mechanisms that occur as well as the beauty of the phenomenon which has never been previously evidenced in the literature. The final stage of full blood evaporation reveals for a healthy person the same regular pattern with a good reproducibility. Other tests on anemia and hyperlipidemic persons were performed and presented different patterns. By means of digital camera, the influence of the motion of red blood cells (RBCs) which represent about 50% of the blood volume, is revealed as well as its consequences on the final stages of drying. The mechanisms which lead to the final pattern of dried blood drops are presented and explained on the basis of fluid and solid mechanics in conjunction with the principles of hematology. Our group is the first to evidence that the specific regular patterns characteristic of a healthy individual do not appear in a dried drop of blood from a person with blood disease. Blood is a complex colloidal suspension for which the flow motion is clearly non-Newtonian. When drops of blood evaporate, all the colloids are carried by the flow motion inside the drop and interact.

  7. Overexpression of the CBF2 transcriptional activator in Arabidopsis suppresses the responsiveness of leaf tissue to the stress hormone ethylene.

    PubMed

    Sharabi-Schwager, M; Samach, A; Porat, R

    2010-07-01

    The plant hormone ethylene affects myriad developmental processes ranging from seed germination to organ senescence, and plays a crucial role in plant resistance to environmental stresses. The C-repeat/dehydration-responsive element binding factor genes (CBF1-3) are transcriptional activators involved in plant low-temperatures responses; their overexpression enhances frost tolerance, but also has various pleiotropic effects on growth and development, mainly growth retardation and delay of flowering and senescence. We found that overexpression of CBF2 in Arabidopsis suppressed leaf tissue responsiveness to ethylene as compared with wild-type plants, as manifested in significantly delayed senescence and chlorophyll degradation. In wild-type plants, exposure to ethylene at 0.1 microl.l(-1) for 48 h caused 50% reduction in chlorophyll levels as compared to leaves held in air alone, whereas CBF2-overexpressing plants required an ethylene concentration of 10.0 microl.l(-1) to cause the same effect. Furthermore, continuous exposure to ethylene at 1.0 microl.l(-1) reduced chlorophyll content in wild-type leaves by 50% after 42 h but took 72 h in CBF2-overexpressing plants. Transcript profiling of ethylene receptors and signal transduction genes in leaves of wild-type and CBF2-overexpressing plants, by means of the Affymetrix ATH1 genome array, revealed only minor differences in gene expression patterns - insufficient to explain the observed responsiveness differences. Nevertheless, we found that overexpression of CBF2 significantly increased transcript levels of 17 ABA biosynthetic and responsive genes and, thus, may have affected leaf responsiveness to ethylene via contrasting interactions with other hormones, mainly ABA. Overall, the current findings suggest that overexpression of the CBF2 transcriptional activator in Arabidopsis may, at least in part, contribute to the observed delay of leaf senescence and enhanced plant fitness by suppressing leaf responsiveness to

  8. How do drops evaporate?

    NASA Astrophysics Data System (ADS)

    Murisic, Nebojsa; Kondic, Lou

    2007-11-01

    The problem of evaporating drops with non-pinned contact line, although seemingly trivial, so far lacks satisfactory theoretical description. In particular, there has been much discussion regarding appropriate evaporative mass flux model. We make an attempt to resolve this issue by comparing our experimental data with the results of several mathematical models for evaporating drops. After describing experimental procedure, we propose several models for mass flux and develop a governing equation for evolution of drop's thickness. Two-dimensional numerical results are then compared to the experimental results, and the most appropriate mass flux model is identified. Finally, we propose the governing equation for the full 3D system and present some new numerical results related to curious phenomena, where so-called ``octopus-shaped'' instabilities appear ahead of the contact line of volatile dropsootnotetextY. Gotkis, I. Ivanov, N. Murisic, L. Kondic, Phys. Rev. Lett. 97, 186101 (2006)..

  9. 14. (Credit CBF) The McNeil Street Pumping Station c1926, after ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. (Credit CBF) The McNeil Street Pumping Station c1926, after substantial enlargement, from the front of the new combination main high service-low service pumping room. On the left, located over the old clear water well, is a circular building which housed both the laboratory and the chlorination room (it was added c1911). The tank above the lab-chlorination room is the filter wash water tank (new). From: South-West Waterworks Association Convention, Shreveport, Louisiana, October 1926, Souvenir Booklet, p.19) - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  10. Drum drop test report

    SciTech Connect

    McBeath, R.S.

    1995-02-28

    Testing was performed to determine actual damage to drums when dropped from higher than currently stacked elevations. The drum configurations were the same as they are placed in storage; single drums and four drums banded to a pallet. Maximum drop weights were selected based on successful preliminary tests. Material was lost from each of the single drum tests while only a small amount of material was lost from one of the pelletized drums. The test results are presented in this report. This report also provides recommendations for further testing to determine the appropriate drum weight which can be stored on a fourth tier.

  11. Neuronal activation induced BOLD and CBF responses upon acetazolamide administration in patients with steno-occlusive artery disease.

    PubMed

    Siero, Jeroen C W; Hartkamp, Nolan S; Donahue, Manus J; Harteveld, Anita A; Compter, Annette; Petersen, Esben T; Hendrikse, Jeroen

    2015-01-15

    Blood-oxygenation-level-dependent (BOLD) MRI is widely used for inferring neuronal activation and is becoming increasingly popular for assessing cerebrovascular reactivity (CVR) when combined with a vasoactive stimulus. The BOLD signal contains changes in cerebral blood flow (CBF) and thus information regarding neurovascular coupling and CVR. The BOLD signal, however, is also modulated by changes in cerebral blood volume (CBV) and cerebral metabolic rate of oxygen (CMRO2), as well as changes in the physiological baseline state. Here, we measured BOLD and CBF responses upon neuronal (visual) activation, before and after a vasodilatory challenge (acetazolamide, ACZ) in patients with vertebrobasilar steno-occlusive disease. After ACZ, the neuronal activation induced BOLD response was reduced or even negative (3 out of 8 subjects), whereas the CBF response remained similar. We show that BOLD alone cannot correctly assess the neuronal activation and underlying neurovascular coupling. The generally assumed positive relationship between BOLD and CBF responses may be severely compromised under changes in the physiological baseline state. Accompanying CBF measurements contain crucial information, and simulations suggest an altered flow-metabolism coupling in these patients.

  12. Uncoupling cognitive workload and prefrontal cortical physiology: a PET rCBF study.

    PubMed

    Goldberg, T E; Berman, K F; Fleming, K; Ostrem, J; Van Horn, J D; Esposito, G; Mattay, V S; Gold, J M; Weinberger, D R

    1998-05-01

    Working memory is a fundamental cognitive building block involved in the short-term maintenance and transformation of information. In neuropsychological studies, working memory has been shown to be of limited capacity; however, the neurophysiological concomitants of this capacity limitation have not been explored. In this study we used the [15O] water PET rCBF technique and statistical parametric mapping to examine normal subjects while they performed two cognitive tasks, both individually and simultaneously. One task was the Wisconsin Card Sorting Test, a complex reasoning task involving working memory, and the other was a rapidly paced auditory verbal shadowing task. When both tasks were performed simultaneously, there were significant decrements in performance compared with the individual task performance scores, indicating that cognitive workload had been increased. Analysis of the rCBF maps showed that when the two tasks were performed together, in contrast to when they were performed separately, there was less prefrontal activation. These results suggest that increases in cognitive workload do not necessarily recruit and then sustain cortical neurophysiological resources to a maximum, but rather may actually be accompanied by a diminution in cortical activity.

  13. Genetic and Molecular Analyses of Natural Variation Indicate CBF2 as a Candidate Gene for Underlying a Freezing Tolerance Quantitative Trait Locus in Arabidopsis1[w

    PubMed Central

    Alonso-Blanco, Carlos; Gomez-Mena, Concepción; Llorente, Francisco; Koornneef, Maarten; Salinas, Julio; Martínez-Zapater, José M.

    2005-01-01

    Natural variation for freezing tolerance is a major component of adaptation and geographic distribution of plant species. However, little is known about the genes and molecular mechanisms that determine its naturally occurring diversity. We have analyzed the intraspecific freezing tolerance variation existent between two geographically distant accessions of Arabidopsis (Arabidopsis thaliana), Cape Verde Islands (Cvi) and Landsberg erecta (Ler). They differed in their freezing tolerance before and after cold acclimation, as well as in the cold acclimation response in relation to photoperiod conditions. Using a quantitative genetic approach, we found that freezing tolerance differences after cold acclimation were determined by seven quantitative trait loci (QTL), named FREEZING TOLERANCE QTL 1 (FTQ1) to FTQ7. FTQ4 was the QTL with the largest effect detected in two photoperiod conditions, while five other FTQ loci behaved as photoperiod dependent. FTQ4 colocated with the tandem repeated genes C-REPEAT BINDING FACTOR 1 (CBF1), CBF2, and CBF3, which encode transcriptional activators involved in the cold acclimation response. The low freezing tolerance of FTQ4-Cvi alleles was associated with a deletion of the promoter region of Cvi CBF2, and with low RNA expression of CBF2 and of several CBF target genes. Genetic complementation of FTQ4-Cvi plants with a CBF2-Ler transgene suggests that such CBF2 allelic variation is the cause of CBF2 misexpression and the molecular basis of FTQ4. PMID:16244146

  14. Identification of SFR6, a key component in cold acclimation acting post-translationally on CBF function.

    PubMed

    Knight, Heather; Mugford, Sarah G; Ulker, Bekir; Gao, Dahai; Thorlby, Glenn; Knight, Marc R

    2009-04-01

    The sfr6-1 mutant of Arabidopsis thaliana was identified previously on the basis of its failure to undergo acclimation to freezing temperatures following exposure to low positive temperatures. This failure is attributed to a defect in the pathway leading to cold on-regulated (COR) gene expression via CBF (C-box binding factor) transcription factors. We identified a region of chromosome 4 containing SFR6 by positional mapping. Fine mapping of the sfr6-1 mutation proved impossible as the locus resides very close to the centromere. Therefore, we screened 380 T-DNA lines with insertions in genes within the large region to which sfr6-1 mapped. This resulted in the identification of two further mutant alleles of SFR6 (sfr6-2 and sfr6-3); like the original sfr6-1 mutation, these disrupt freezing tolerance and COR gene expression. To determine the protein sequence, we cloned an SFR6 cDNA based on the predicted coding sequence, but this offered no indication as to the mechanism by which SFR6 acts. The SFR6 gene itself is not strongly regulated by cold, thus discounting regulation of SFR6 activity at the transcriptional level. We show that over-expression of CBF1 or CBF2 transcription factors, which constitutively activate COR genes in the wild-type, cannot do so in sfr6-1. We demonstrate that CBF protein accumulates to wild-type levels in response to cold in sfr6-1. These results indicate a role for the SFR6 protein in the CBF pathway -downstream of CBF translation. The fact that the SFR6 protein is targeted to the nucleus may suggest a direct role in modulating gene expression.

  15. Numerical Simulations of Drop Collisions

    NASA Technical Reports Server (NTRS)

    Nobari, M. R. H.; Tryggvason, G.

    1994-01-01

    Three-dimensional simulations of the off-axis collisions of two drops are presented. The full Navier-Stokes equations are solved by a Front-Tracking/Finite-Difference method that allows a fully deformable fluid interface and the inclusion of surface tension. The drops are accelerated towards each other by a body force that is turned off before the drops collide. Depending on whether the interface between the drops is ruptured or not, the drops either bounce or coalesce. For drops that coalesce, the impact parameter, which measures how far the drops are off the symmetry line, determines the eventual outcome of the collision. For low impact parameters, the drops coalesce permanently, but for higher impact parameters, a grazing collision, where the drops coalesce and then stretch apart again is observed. The results are in agreement with experimental observations.

  16. Drop tube technical tasks

    NASA Technical Reports Server (NTRS)

    Workman, G. L.

    1986-01-01

    Criteria, using fundamental thermochemical dynamics, were developed to assist a scientist using the Drop Tube Facility in designing a good experiment. The types of parameters involved in designing the experiments include the type of furnace, the type of atmosphere, and in general which materials are better behaved than others as determined by past experience in the facility. One of the major advantages of the facility lies in its ability to provide large undercoolings in the cooling curve during the drops. A beginning was to consider the effect of oxygen and other gases upon the amount of undercooling observed. The starting point of the thermochemistry was given by Ellingham and later transformed into what is known as the Richardson Chart. The effect of surface oxidations upon the nucleation phenomena can be observed in each specimen.

  17. Exploding Water Drops

    NASA Astrophysics Data System (ADS)

    Reich, Gary

    2016-01-01

    Water has the unusual property that it expands on freezing, so that ice has a specific gravity of 0.92 compared to 1.0 for liquid water. The most familiar demonstration of this property is ice cubes floating in a glass of water. A more dramatic demonstration is the ice bomb shown in Fig. 1. Here a cast iron flask is filled with water and tightly stoppered. The flask is then cooled, either by leaving it outdoors in winter or by immersing it in a cryogenic fluid, until the water freezes. As the water freezes and expands, the pressure inside the flask increases dramatically, eventually becoming sufficient to fracture the metal walls of the enclosure. A related, but much less familiar, phenomenon is the explosive fracturing of small water drops upon freezing. That water drops can fracture in this way has been known for many years, and the phenomenon has been described in detail in the atmospheric sciences literature, where it is seen as relevant to the freezing of raindrops as they fall through cold air. Carefully controlled experiments have been done documenting how the character and frequency of fracture is affected by such variables as drop size, rate of cooling, chemistry of dissolved gases, etc. Here I describe instead a simple demonstration of fracture suitable for video analysis and appropriate for study at the introductory physics level. Readers may also be interested in other characteristics of freezing and fragmenting water drops, for example, charge separation upon fracture and the appearance of spikes and bulges on the surface.

  18. Encapsulating Ellipsoids in Drops

    NASA Astrophysics Data System (ADS)

    Norton, Michael; Brugarolas, Teresa; Chou, Jonathan; Bau, Haim; Lee, Daeyeon

    2012-11-01

    Large aspect ratio particles were produced by embedding spherical polystyrene particles within a polymer film and subsequently heating and stretching the film. Particles were released by dissolving the film. Using a flow-focusing device, the elongated particles were partially encapsulated within droplets of fluid A, such as water, surrounded by an immiscible fluid B, such as oil. Drop volumes were controlled by adjusting the flow rates of fluids A and B. The contact angle was adjusted indirectly by varying the amount of surfactant adsorbed to the particle surface. The encapsulation process was visualized with a high-speed video camera. We observed cases ranging from partial to complete encapsulation and examined experimentally and theoretically the shape of the interface between fluid A and fluid B as a function of the drop volume. The numerically predicted position of the pinning line and the shape of the drop were compared to experimentally produced conformations and agreed favorably. This work was supported by ITMAT (UL1RR024134 from the NCRR) and the Penn MRSEC (NSF DMR-1120901).

  19. The yeast nucleolar protein Cbf5p is involved in rRNA biosynthesis and interacts genetically with the RNA polymerase I transcription factor RRN3.

    PubMed Central

    Cadwell, C; Yoon, H J; Zebarjadian, Y; Carbon, J

    1997-01-01

    Yeast Cbf5p was originally isolated as a low-affinity centromeric DNA binding protein (W. Jiang, K. Middleton, H.-J. Yoon, C. Fouquet, and J. Carbon, Mol. Cell. Biol. 13:4884-4893, 1993). Cbf5p also binds microtubules in vitro and interacts genetically with two known centromere-related protein genes (NDC10/CBF2 and MCK1). However, Cbf5p was found to be nucleolar and is highly homologous to the rat nucleolar protein NAP57, which coimmunoprecipitates with Nopp140 and which is postulated to be involved in nucleolar-cytoplasmic shuttling (U. T. Meier, and G. Blobel, J. Cell Biol. 127:1505-1514, 1994). The temperature-sensitive cbf5-1 mutant demonstrates a pronounced defect in rRNA biosynthesis at restrictive temperatures, while tRNA transcription and pre-rRNA and pre-tRNA cleavage processing appear normal. The cbf5-1 mutant cells are deficient in cytoplasmic ribosomal subunits at both permissive and restrictive temperatures. A high-copy-number yeast genomic library was screened for genes that suppress the cbf5-1 temperature-sensitive growth phenotype. SYC1 (suppressor of yeast cbf5-1) was identified as a multicopy suppressor of cbf5-1 and subsequently was found to be identical to RRN3, an RNA polymerase I transcription factor. A cbf5delta null mutant is not rescued by plasmid pNOY103 containing a yeast 35S rRNA gene under the control of a Pol II promoter, indicating that Cbf5p has one or more essential functions in addition to its role in rRNA transcription. PMID:9315678

  20. Saving every drop of water

    NASA Astrophysics Data System (ADS)

    Jinyu, J.

    2012-04-01

    Since the beginning of 2011 there has been extremely low rainfall, which has resulted in drought conditions that have affected several provinces in China. The situation of the acute water shortage requires people to make many changes in the little things they do in their daily life. Saving every drop of water and forming good habits of using water is of the utmost importance. Based on this need, our students, organized by our teachers, reached out into to the communities. By visiting, observing and issuing questionnaires, the students identified unreasonable water usage in the communities. The results of the research showed that the ratio of secondary treatment of domestic waste is very low, especially the ratio of collecting wastewater from washing, greywater, to flush the toilet. In order to solve this problem, students themselves designed a set of water saving facilities by collecting greywater to flush the toilet. They successfully installed these facilities in residential houses in the XiYinLi community, which achieved satisfactory results regarding saving water.

  1. Functional connectivity in BOLD and CBF data: similarity and reliability of resting brain networks.

    PubMed

    Jann, Kay; Gee, Dylan G; Kilroy, Emily; Schwab, Simon; Smith, Robert X; Cannon, Tyrone D; Wang, Danny J J

    2015-02-01

    Resting-state functional connectivity (FC) fMRI (rs-fcMRI) offers an appealing approach to mapping the brain's intrinsic functional organization. Blood oxygen level dependent (BOLD) and arterial spin labeling (ASL) are the two main rs-fcMRI approaches to assess alterations in brain networks associated with individual differences, behavior and psychopathology. While the BOLD signal is stronger with a higher temporal resolution, ASL provides quantitative, direct measures of the physiology and metabolism of specific networks. This study systematically investigated the similarity and reliability of resting brain networks (RBNs) in BOLD and ASL. A 2 × 2 × 2 factorial design was employed where each subject underwent repeated BOLD and ASL rs-fcMRI scans on two occasions on two MRI scanners respectively. Both independent and joint FC analyses revealed common RBNs in ASL and BOLD rs-fcMRI with a moderate to high level of spatial overlap, verified by Dice Similarity Coefficients. Test-retest analyses indicated more reliable spatial network patterns in BOLD (average modal Intraclass Correlation Coefficients: 0.905 ± 0.033 between-sessions; 0.885 ± 0.052 between-scanners) than ASL (0.545 ± 0.048; 0.575 ± 0.059). Nevertheless, ASL provided highly reproducible (0.955 ± 0.021; 0.970 ± 0.011) network-specific CBF measurements. Moreover, we observed positive correlations between regional CBF and FC in core areas of all RBNs indicating a relationship between network connectivity and its baseline metabolism. Taken together, the combination of ASL and BOLD rs-fcMRI provides a powerful tool for characterizing the spatiotemporal and quantitative properties of RBNs. These findings pave the way for future BOLD and ASL rs-fcMRI studies in clinical populations that are carried out across time and scanners.

  2. Draft Genome Sequence of Pseudomonas putida CBF10-2, a Soil Isolate with Bioremediation Potential in Agricultural and Industrial Environmental Settings

    PubMed Central

    Damania, Ashish

    2016-01-01

    Pseudomonas putida CBF10-2 is a microorganism isolated from farmland soil in Fairchild, TX, found to degrade high-impact xenobiotics, including organophosphate insecticides, petroleum hydrocarbons, and both monocyclic and polycyclic aromatics. The versatility of CBF10-2 makes it useful for multipurpose bioremediation of contaminated sites in agricultural and industrial environments. PMID:27417844

  3. Functional Characterization of Hevea brasiliensis CRT/DRE Binding Factor 1 Gene Revealed Regulation Potential in the CBF Pathway of Tropical Perennial Tree.

    PubMed

    Cheng, Han; Cai, Haibin; Fu, Haitian; An, Zewei; Fang, Jialin; Hu, Yanshi; Guo, Dianjing; Huang, Huasun

    2015-01-01

    Rubber trees (Hevea brasiliensis) are susceptible to low temperature and therefore are only planted in the tropical regions. In the past few decades, although rubber trees have been successfully planted in the northern margin of tropical area in China, they suffered from cold injury during the winter. To understand the physiological response under cold stress, we isolated a C-repeat binding factor 1 (CBF1) gene from the rubber tree. This gene (HbCBF1) was found to respond to cold stress but not drought or ABA stress. The corresponding HbCBF1 protein showed CRT/DRE binding activity in gel shift experiment. To further characterize its molecular function, the HbCBF1 gene was overexpressed in Arabidopsis. The HbCBF1 over expression (OE) line showed enhanced cold resistance and relatively slow dehydration, and the expression of Arabidopsis CBF pathway downstream target genes, e.g. AtCOR15a and AtRD29a, were significantly activated under non-acclimation condition. These data suggest HbCBF1 gene is a functional member of the CBF gene family, and may play important regulation function in rubber tree. PMID:26361044

  4. Draft Genome Sequence of Pseudomonas putida CBF10-2, a Soil Isolate with Bioremediation Potential in Agricultural and Industrial Environmental Settings.

    PubMed

    Iyer, Rupa; Damania, Ashish

    2016-01-01

    Pseudomonas putida CBF10-2 is a microorganism isolated from farmland soil in Fairchild, TX, found to degrade high-impact xenobiotics, including organophosphate insecticides, petroleum hydrocarbons, and both monocyclic and polycyclic aromatics. The versatility of CBF10-2 makes it useful for multipurpose bioremediation of contaminated sites in agricultural and industrial environments. PMID:27417844

  5. Drop foot corrective device

    NASA Technical Reports Server (NTRS)

    Deis, B. C. (Inventor)

    1986-01-01

    A light weight, economical device to alleviate a plurality of difficulties encountered in walking by a victim suffering from a drop foot condition is discussed. A legband girdles the leg below the knee and above the calf providing an anchor point for the upper end of a ligament having its lower end attached to a toe of a shoe or a toe on the foot. The ligament is of such length that the foot is supported thereby and retained in a normal position during walking.

  6. Liquid drops impacting superamphiphobic coatings.

    PubMed

    Deng, Xu; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

    2013-06-25

    The dynamics of liquid drops impacting superamphiphobic coatings is studied by high-speed video microscopy. Superamphiphobic coatings repel water and oils. The coating consists of a fractal-like hydrophobized silica network. Mixtures of ethanol-water and glycerin-water are chosen to investigate the influence of interfacial tension and viscosity on spreading and retraction dynamics. Drop spreading is dominated by inertia. At low impact velocity, the drops completely rebound. However, the contact time increases with impact velocity, whereas the restitution coefficient decreases. We suggest that the drop temporarily impales the superamphiphobic coating, although the drop completely rebounds. From an estimate of the pressure, it can be concluded that impalement is dominated by depinning rather than sagging. With increasing velocity, the drops partially pin, and an increasing amount of liquid remains on the coating. A time-resolved study of the retraction dynamics reveals two well-separated phases: a fast inertia-dominated phase followed by a slow decrease of the contact diameter of the drop. The crossover occurs when the diameter of the retracting drop matches the diameter of the drop before impact. We suggest that the depth of impalement increases with impact velocity, where impalement is confined to the initial impact zone of the drop. If the drop partially pins on the coating, the depth of impalement exceeds a depth, preventing the whole drop from being removed during the retraction phase.

  7. The Cbf5-Nop10 Complex is a Molecular Bracket that Organizes Box H/ACA RNPs

    SciTech Connect

    Hamma, Tomoko; Reichow, Steve L.; Varani, Gabriele; Ferre-D'Amare, Adrian R.

    2005-12-01

    Box H/ACA ribonucleoprotein particles (RNPs) catalyze RNA pseudouridylation and direct processing of ribosomal RNA, and are essential architectural components of vertebrate telomerases. H/ACA RNPs comprise four proteins and a multihelical RNA. Two proteins, Cbf5 and Nop10, suffice for basal enzymatic activity in an archaeal in vitro system. We now report their cocrystal structure at 1.95-A resolution. We find that archaeal Cbf5 can assemble with yeast Nop10 and with human telomerase RNA, consistent with the high sequence identity of the RNP componenets between archaea and eukarya. Thus, the Cbf5-Nop10 architecture is phylogenetically conserved. The structure shows how Nop10 buttresses the active site of Cbf5, and it reveals two basic troughs that bidirectionally extend the active site cleft. Mutagenesis results implicate an adjacent basic patch in RNA binding. This tripartite RNA-binding surface may function as a molecular bracket that organizes the multihelical H/ACA and telomerase RNAs.

  8. Coalescence of Liquid Drops

    NASA Technical Reports Server (NTRS)

    Yao, Wei-Jun

    2003-01-01

    When two liquid drops come into contact, a neck forms between them and grows rapidly. We are interested in the very early stage of the coalescence process, which can be characterized by the time dependence of the radius of the neck. The functional dependence of the size of the neck on time depends on the properties of the liquid. Experimentally, we are investigating a liquid in Stokes flow regime where the viscosity provides the principal retarding force to the surface tension. Recently, it has been predicted that the neck radius should change as t ln|t| in this regime. Theoretically, we have studied the situation when the velocity at each point on the surface is proportional to the local curvature and directed normal to the surface. This is the case that should be applicable to superfluid helium at low temperature when the mean free path of the thermal excitations are comparable to the size of liquid drops. For this system, the radius of the neck is found to be proportional to t(sup 1/3). We are able to find a simple expression for the shape of the interface in the vicinity of the neck.

  9. PpCBF3 from Cold-Tolerant Kentucky Bluegrass Involved in Freezing Tolerance Associated with Up-Regulation of Cold-Related Genes in Transgenic Arabidopsis thaliana.

    PubMed

    Zhuang, Lili; Yuan, Xiuyun; Chen, Yu; Xu, Bin; Yang, Zhimin; Huang, Bingru

    2015-01-01

    Dehydration-Responsive Element Binding proteins (DREB)/C-repeat (CRT) Binding Factors (CBF) have been identified as transcriptional activators during plant responses to cold stress. The objective of this study was to determine the physiological roles of a CBF gene isolated from a cold-tolerant perennial grass species, Kentucky bluegrass (Poa pratensis L.), which designated as PpCBF3, in regulating plant tolerance to freezing stress. Transient transformation of Arabidopsis thaliana mesophyll protoplast with PpCBF3-eGFP fused protein showed that PpCBF3 was localized to the nucleus. RT-PCR analysis showed that PpCBF3 was specifically induced by cold stress (4°C) but not by drought stress [induced by 20% polyethylene glycol 6000 solution (PEG-6000)] or salt stress (150 mM NaCl). Transgenic Arabidopsis overexpressing PpCBF3 showed significant improvement in freezing (-20°C) tolerance demonstrated by a lower percentage of chlorotic leaves, lower cellular electrolyte leakage (EL) and H2O2 and O2.- content, and higher chlorophyll content and photochemical efficiency compared to the wild type. Relative mRNA expression level analysis by qRT-PCR indicated that the improved freezing tolerance of transgenic Arabidopsis plants overexpressing PpCBF3 was conferred by sustained activation of downstream cold responsive (COR) genes. Other interesting phenotypic changes in the PpCBF3-transgenic Arabidopsis plants included late flowering and slow growth or 'dwarfism', both of which are desirable phenotypic traits for perennial turfgrasses. Therefore, PpCBF3 has potential to be used in genetic engineering for improvement of turfgrass freezing tolerance and other desirable traits. PMID:26177510

  10. Use of a stress inducible promoter to drive ectopic AtCBF expression improves potato freezing tolerance while minimizing negative effects on tuber yield.

    PubMed

    Pino, María-Teresa; Skinner, Jeffrey S; Park, Eung-Jun; Jeknić, Zoran; Hayes, Patrick M; Thomashow, Michael F; Chen, Tony H H

    2007-09-01

    Solanum tuberosum is a frost-sensitive species incapable of cold acclimation. A brief exposure to frost can significantly reduce its yields, while hard frosts can completely destroy entire crops. Thus, gains in freezing tolerance of even a few degrees would be of considerable benefit relative to frost damage. The S. tuberosum cv. Umatilla was transformed with three Arabidopsis CBF genes (AtCBF1-3) driven by either a constitutive CaMV35S or a stress-inducible Arabidopsis rd29A promoter. AtCBF1 and AtCBF3 over-expression via the 35S promoter increased freezing tolerance about 2 degrees C, whereas AtCBF2 over-expression failed to increase freezing tolerance. Transgenic plants of AtCBF1 and AtCBF3 driven by the rd29A promoter reached the same level of freezing tolerance as the 35S versions within a few hours of exposure to low but non-freezing temperatures. Constitutive expression of AtCBF genes was associated with negative phenotypes, including smaller leaves, stunted plants, delayed flowering, and reduction or lack of tuber production. While imparting the same degree of freezing tolerance, control of AtCBF expression via the stress-inducible promoter ameliorated these negative phenotypic effects and restored tuber production to levels similar to wild-type plants. These results suggest that use of a stress-inducible promoter to direct CBF transgene expression can yield significant gains in freezing tolerance without negatively impacting agronomically important traits in potato.

  11. PpCBF3 from Cold-Tolerant Kentucky Bluegrass Involved in Freezing Tolerance Associated with Up-Regulation of Cold-Related Genes in Transgenic Arabidopsis thaliana

    PubMed Central

    Chen, Yu; Xu, Bin; Yang, Zhimin; Huang, Bingru

    2015-01-01

    Dehydration-Responsive Element Binding proteins (DREB)/C-repeat (CRT) Binding Factors (CBF) have been identified as transcriptional activators during plant responses to cold stress. The objective of this study was to determine the physiological roles of a CBF gene isolated from a cold-tolerant perennial grass species, Kentucky bluegrass (Poa pratensis L.), which designated as PpCBF3, in regulating plant tolerance to freezing stress. Transient transformation of Arabidopsis thaliana mesophyll protoplast with PpCBF3-eGFP fused protein showed that PpCBF3 was localized to the nucleus. RT-PCR analysis showed that PpCBF3 was specifically induced by cold stress (4°C) but not by drought stress [induced by 20% polyethylene glycol 6000 solution (PEG-6000)] or salt stress (150 mM NaCl). Transgenic Arabidopsis overexpressing PpCBF3 showed significant improvement in freezing (-20°C) tolerance demonstrated by a lower percentage of chlorotic leaves, lower cellular electrolyte leakage (EL) and H2O2 and O2.- content, and higher chlorophyll content and photochemical efficiency compared to the wild type. Relative mRNA expression level analysis by qRT-PCR indicated that the improved freezing tolerance of transgenic Arabidopsis plants overexpressing PpCBF3 was conferred by sustained activation of downstream cold responsive (COR) genes. Other interesting phenotypic changes in the PpCBF3-transgenic Arabidopsis plants included late flowering and slow growth or ‘dwarfism’, both of which are desirable phenotypic traits for perennial turfgrasses. Therefore, PpCBF3 has potential to be used in genetic engineering for improvement of turfgrass freezing tolerance and other desirable traits. PMID:26177510

  12. Mechanically-Excited Sessile Drops

    NASA Astrophysics Data System (ADS)

    Chang, Chun-Ti; Bostwick, Joshua; Daniel, Susan; Steen, Paul

    2010-11-01

    The volume and contact-line mobility of a sessile drop determine the frequency response of the drop to mechanical excitation. A useful signature of the drop is its response to a sweep of frequency. At particular frequencies the drop exhibits standing wave patterns of different mode numbers and/or azimuthal, spinning motion. We report observations of the spectrum of standing wave patterns and compare to predictions of a linear stability theory. On the side of application, the results suggest how to tune the pinning-unpinning of a sessile drop in order to maximize its translation.

  13. Evidence that the negative BOLD response is neuronal in origin: a simultaneous EEG-BOLD-CBF study in humans.

    PubMed

    Mullinger, K J; Mayhew, S D; Bagshaw, A P; Bowtell, R; Francis, S T

    2014-07-01

    Unambiguous interpretation of changes in the BOLD signal is challenging because of the complex neurovascular coupling that translates changes in neuronal activity into the subsequent haemodynamic response. In particular, the neurophysiological origin of the negative BOLD response (NBR) remains incompletely understood. Here, we simultaneously recorded BOLD, EEG and cerebral blood flow (CBF) responses to 10 s blocks of unilateral median nerve stimulation (MNS) in order to interrogate the NBR. Both negative BOLD and negative CBF responses to MNS were observed in the same region of the ipsilateral primary sensorimotor cortex (S1/M1) and calculations showed that MNS induced a decrease in the cerebral metabolic rate of oxygen consumption (CMRO2) in this NBR region. The ∆CMRO2/∆CBF coupling ratio (n) was found to be significantly larger in this ipsilateral S1/M1 region (n=0.91±0.04, M=10.45%) than in the contralateral S1/M1 (n=0.65±0.03, M=10.45%) region that exhibited a positive BOLD response (PBR) and positive CBF response, and a consequent increase in CMRO2 during MNS. The fMRI response amplitude in ipsilateral S1/M1 was negatively correlated with both the power of the 8-13 Hz EEG mu oscillation and somatosensory evoked potential amplitude. Blocks in which the largest magnitude of negative BOLD and CBF responses occurred therefore showed greatest mu power, an electrophysiological index of cortical inhibition, and largest somatosensory evoked potentials. Taken together, our results suggest that a neuronal mechanism underlies the NBR, but that the NBR may originate from a different neurovascular coupling mechanism to the PBR, suggesting that caution should be taken in assuming the NBR simply represents the neurophysiological inverse of the PBR. PMID:24632092

  14. Controlling charge on levitating drops.

    PubMed

    Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M

    2007-08-01

    Levitation technologies are used in containerless processing of materials, as microscale manipulators and reactors, and in the study of single drops and particles. Presented here is a method for controlling the amount and polarity of charge on a levitating drop. The method uses single-axis acoustic levitation to trap and levitate a single, initially neutral drop with a diameter between 400 microm and 2 mm. This drop is then charged in a controllable manner using discrete packets of charge in the form of charged drops produced by a piezoelectric drop-on-demand dispenser equipped with a charging electrode. The magnitude of the charge on the dispensed drops can be adjusted by varying the voltage applied to the charging electrode. The polarity of the charge on the added drops can be changed allowing removal of charge from the trapped drop (by neutralization) and polarity reversal. The maximum amount of added charge is limited by repulsion of like charges between the drops in the trap. This charging scheme can aid in micromanipulation and the study of charged drops and particles using levitation. PMID:17580951

  15. Cortical blood flow in controlled hypotension as measured by thermal diffusion 1

    PubMed Central

    Carter, L. Philip; Atkinson, James R.

    1973-01-01

    A thermal diffusion flow probe which gave a continuous, dynamic, quantitative record of cortical blood flow (CBF) was used to assess CBF in experimental animals with controlled hypotension. Acute hypotension was produced by trimethaphan camsylate, halothane, and sodium nitroprusside. Halothane produced less reduction in CBF per drop in blood pressure than the other two agents. Images PMID:4772724

  16. [The abdominal drop flap].

    PubMed

    Bodin, F; Liverneaux, P; Seigle-Murandi, F; Facca, S; Bruant-Rodier, C; Dissaux, C; Chaput, B

    2015-08-01

    The skin between the mastectomy scar and the future infra-mammary fold may be managed in different ways in delayed breast reconstruction using a DIEP (deep inferior epigastric perforator). Conserving this skin and positioning the flap skin paddle in the middle of the breast usually highlights skin color disparity because of two visible transition zones. Resection of the entire skin under the scar may be more aesthetic but limits direct closure possibility in case of flap failure. In order to benefit from both aesthetic result and safe surgical method, we propose the abdominal drop flap. The inferior thoracic skin flap is detached from the thoracic wall beyond the future infra-mammary fold, preserved and pushed under the breast.

  17. Limited Reliability of CT perfusion acute infarct volume measurements compared to DWI in anterior circulation stroke

    PubMed Central

    Schaefer, Pamela W.; Souza, Leticia; Kamalian, Shervin; Hirsch, Joshua A.; Yoo, Albert J.; Kamalian, Shahmir; Gonzalez, R. Gilberto; Lev, Michael H.

    2015-01-01

    Background and Purpose DWI can reliably identify critically ischemic tissue (CIT) shortly after stroke onset. We tested if thresholded CT-CBF and CT-CBV maps are sufficiently accurate to substitute for DWI for estimating CIT volume. Methods Ischemic volumes of 55 patients with acute anterior circulation stroke were assessed on DWI by visual segmentation, and CT-CBF and CT-CBV with segmentation using 15% and 30% thresholds, respectively. The contrast-to-noise ratios (CNR) of ischemic regions on the DWI and CTP images were measured. Correlation and Bland-Altman analyses were used to assess reliability of CTP. Results Mean CNRs for DWI, CT-CBF and CT-CBV were 4.3, 0.9 and 0.4, respectively. CTP and DWI lesion volumes were highly correlated (R2=0.87 for CT-CBF; R2=0.83 for CT-CBV; p<0.001). Bland-Altman analyses revealed little systemic bias (−2.6 ml) but high measurement variability (95% CI ±56.7 ml) between mean CT-CBF and DWI lesion volumes, and systemic bias (−26 ml) and high measurement variability (95% CI ±64.0 ml) between mean CT-CBV and DWI lesion volumes. A simulated treatment study demonstrated that using CTP-CBF instead of DWI for detecting a statistically significant effect would require at least twice as many patients. Conclusions The poor CNRs of CT-CBV and CT-CBF compared to DWI result in large measurement error making it problematic to substitute CTP for DWI in selecting individual acute stroke patients for treatment. CTP could be used for treatment studies of patient groups, but the number of patients needed to identify a significant effect is much higher than if DWI is used. PMID:25550366

  18. The Vitis vinifera C-repeat binding protein 4 (VvCBF4) transcriptional factor enhances freezing tolerance in wine grape

    PubMed Central

    Tillett, Richard L.; Wheatley, Matthew D.; Tattersall, Elizabeth A.R.; Schlauch, Karen A.; Cramer, Grant R.; Cushman, John C.

    2014-01-01

    Summary Chilling and freezing can reduce significantly vine survival and fruit set in Vitis vinifera wine grape. To overcome such production losses, a recently identified grapevine C-repeat binding factor (CBF) gene, VvCBF4, was overexpressed in grape vine cv. “Freedom” and found to improve freezing survival and reduced freezing-induced electrolyte leakage by up to 2°C in non-cold-acclimated vines. In addition, overexpression of this transgene caused a reduced growth phenotype similar to that observed for CBF overexpression in Arabidopsis and other species. Both freezing tolerance and reduced growth phenotypes were manifested in a transgene dose-dependent manner. To understand the mechanistic basis of VvCBF4 transgene action, one transgenic line (9–12) was genotyped using microarray-based mRNA expression profiling. Forty-seven and 12 genes were identified in unstressed transgenic shoots with either a greater than 1.5-fold increase or decrease in mRNA abundance, respectively. Comparison of mRNA changes with characterized CBF regulons in woody and herbaceous species revealed partial overlaps suggesting that CBF-mediated cold acclimation responses are widely conserved. Putative VvCBF4-regulon targets included genes with functions in cell wall structure, lipid metabolism, epicuticular wax formation, and stress-responses suggesting that the observed cold tolerance and dwarf phenotypes are the result of a complex network of diverse functional determinants. PMID:21914113

  19. Investigations of levitated helium drops

    NASA Astrophysics Data System (ADS)

    Whitaker, Dwight Lawrence

    1999-11-01

    We report on the development of two systems capable of levitating drops of liquid helium. Helium drops of ˜20 mum have been levitated with the radiation pressure from two counter-propagating Nd:YAG laser beams. Drops are produced with a submerged piezoelectric transducer, and could be held for up to three minutes in our optical trap. Calculations show that Brillouin and Raman scattering of the laser light in the liquid helium produces a negligible rate of evaporation of the drop. Evaporation caused by the enhanced vapor pressure of the curved drop surfaces appears to be a significant effect limiting the drop lifetimes. Helium drops as large as 2 cm in diameter have been suspended in the earth's gravitational field with a magnetic field. A commercial superconducting solenoid provides the necessary field, field-gradient product required to levitate the drops. Drops are cooled to 0.5 K with a helium-3 refrigerator, and can be held in the trap indefinitely. We have found that when two or more drops are levitated in the same magnetic trap, the drops often remain in a state of apparent contact without coalescing. This effect is a result of the evaporation of liquid from between the two drops, and is found to occur only for normal fluid drops. We can induce shape oscillations in charged, levitated drops with an applied ac electric field. We have measured the resonance frequencies and damping rates for the l = 2 mode of oscillation as function of temperature. We have also developed a theory to describe the small amplitude shape oscillations of a He II drop surrounded by its saturated vapor. In our theory, we have considered two sets of boundary conditions---one where the drop does not evaporate and another in which the liquid and vapor are in thermodynamic equilibrium. We have found that both solutions give a frequency that agrees well with experiment, but that the data for the damping rate agree better with the solution without evaporation.

  20. Apfel's superheated drop detector

    NASA Astrophysics Data System (ADS)

    D'Errico, Francesco

    2001-05-01

    The introduction of new approaches for radiation dosimetry is rare. A similar breakthrough occurred in 1979, when Robert Apfel invented the superheated drop detector, a miniature relative of the bubble chamber. A fundamental in high-energy particle physics, the bubble chamber utilizes a liquid briefly brought to a transient, radiation-sensitive superheated state by reducing its pressure. Mass boiling of the liquid is prevented by cyclic pressurization, drastically limiting the detection efficiency. In Apfel's detector, the liquid is kept in a steady superheated state by fractionating it into droplets and dispersing them in an immiscible host fluid, a perfectly smooth and clean container. The approach extends the lifetime of the metastable droplets to the point that practical application in radiation dosimetry is possible. Bubble formation is measured from the volume of vapor or by detecting individual vaporizations acoustically. Various halocarbons are employed and this permits a wide range of applications. Moderately superheated halocarbons are used for neutron measurements, since they are only nucleated by energetic neutron recoil particles. Highly superheated halocarbons nucleate with much smaller energy deposition and are used to detect photons and electrons. This paper reviews the radiation physics of superheated emulsions and their manifold applications.

  1. Identification of CBF14 and NAC2 Genes in Aegilops tauschii Associated with Resistance to Freezing Stress.

    PubMed

    Masoomi-Aladizgeh, Farhad; Aalami, Ali; Esfahani, Masoud; Aghaei, Mohamad Jaafar; Mozaffari, Khadijeh

    2015-06-01

    Low temperature as one of the most important environmental factors limits the productivity of plants across the world. Aegilops, as a wild species of Poaceae, contains low temperature-responsive genes. In this study, we analyzed morphological (wilting, chlorosis, and recovery) and physiological (ion leakage) characteristics to identification of a cold-tolerant genotype. In this experiment, we introduced two transcription factors (TFs) in Aegilops species for the first time. Bioinformatics analysis demonstrated that our nucleotide sequences have high similarity with CBF14 (C-repeat-binding factor) and NAC2 (NAM, ATAF, and CUC) in Triticum aestivum. Based on the physiological and morphological data, one genotype (Aladizgeh) was identified as the most resistant genotype which was selected for further gene expression analysis. The real-time PCR results indicated that the CBF14 gene was not expressed 3 h following cold treatment, but the highest expression was observed after 6, 12, and 24 h of cold treatment; however, a sudden decrease was observed in its expression after 30 h. The NAC2 gene also was not expressed 3 h after cold stress, but the highest expression was at 24 h and similar to the CBF14 gene; its expression suddenly decreased after 30 h. Our results indicated that this genotype can tolerate -4 °C for 3 h, but the CBF14 and NAC2 genes were activated when treated for longer durations. Expression of TFs studied in this experiment had decreased after 30 h, in which cell death seems to be the important reason.

  2. Gas Pressure-Drop Experiment

    ERIC Educational Resources Information Center

    Luyben, William L.; Tuzla, Kemal

    2010-01-01

    Most chemical engineering undergraduate laboratories have fluid mechanics experiments in which pressure drops through pipes are measured over a range of Reynolds numbers. The standard fluid is liquid water, which is essentially incompressible. Since density is constant, pressure drop does not depend on the pressure in the pipe. In addition, flow…

  3. Hanging drop crystal growth apparatus

    NASA Technical Reports Server (NTRS)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  4. Improvement in Regional CBF by L-Serine Contributes to Its Neuroprotective Effect in Rats after Focal Cerebral Ischemia

    PubMed Central

    Jiang, Zheng-Lin; Wang, Guo-Hua; Sun, Li; Jiang, Rui; Zhao, Guang-Wei; Han, Le-Yang

    2013-01-01

    To investigate the mechanisms underlying the neuroprotective effect of L-serine, permanent focal cerebral ischemia was induced by occlusion of the middle cerebral artery while monitoring cerebral blood flow (CBF). Rats were divided into control and L-serine-treated groups after middle cerebral artery occlusion. The neurological deficit score and brain infarct volume were assessed. Nissl staining was used to quantify the cortical injury. L-serine and D-serine levels in the ischemic cortex were analyzed with high performance liquid chromatography. We found that L-serine treatment: 1) reduced the neurological deficit score, infarct volume and cortical neuron loss in a dose-dependent manner; 2) improved CBF in the cortex, and this effect was inhibited in the presence of apamin plus charybdotoxin while the alleviation of both neurological deficit score and infarct volume was blocked; and 3) increased the amount of L-serine and D-serine in the cortex, and inhibition of the conversion of L-serine into D-serine by aminooxyacetic acid did not affect the reduction of neurological deficit score and infarct volume by L-serine. In conclusion, improvement in regional CBF by L-serine may contribute to its neuroprotective effect on the ischemic brain, potentially through vasodilation which is mediated by the small- and intermediate-conductance Ca2+-activated K+ channels on the cerebral blood vessel endothelium. PMID:23825613

  5. Potato plants ectopically expressing Arabidopsis thaliana CBF3 exhibit enhanced tolerance to high-temperature stress.

    PubMed

    Dou, Haiou; Xv, Kunpeng; Meng, Qingwei; Li, Gang; Yang, Xinghong

    2015-01-01

    CBF3, a known cold-inducible gene that encodes a transcription factor, was isolated from Arabidopsis thaliana and introduced into the potato (Solanum tuberosum cv. 'luyin NO.1') under the control of the CaMV35S promoter or the rd29A promoter. Our results revealed that temperature of 40 °C or higher can significantly induce AtCBF3 expression. After heat stress, the net photosynthetic rate (Pn ), the maximal photochemical efficiency of photosystem II (PSII) (Fv /Fm ) and the accumulation of the D1 protein were higher in the transgenic lines than in the wild-type (WT) line. Moreover, compared with the WT line, O2 (●-) and H2 O2 accumulation in the transgenic lines were reduced. A Q-PCR assay of a subset of the genes involved in photosynthesis and antioxidant defence further verified the above results. Interestingly, under heat stress conditions, the accumulation of heat-shock protein 70 (HSP70) increased in the WT line but decreased in the transgenic lines. These results suggest that potato plants ectopically expressing AtCBF3 exhibited enhanced tolerance to high temperature, which is associated with improved photosynthesis and antioxidant defence via induction of the expression of many stress-inducible genes. However, this mechanism may not depend upon the regulatory pathways in which HSP70 is involved. PMID:24811248

  6. Cloning and characterization of Arabidopsis thaliana AtNAP57--a homologue of yeast pseudouridine synthase Cbf5p.

    PubMed

    Maceluch, J; Kmieciak, M; Szweykowska-Kulińska, Z; Jarmołowski, A

    2001-01-01

    Rat Nap57 and its yeast homologue Cbf5p are pseudouridine synthases involved in rRNA biogenesis, localized in the nucleolus. These proteins, together with H/ACA class of snoRNAs compose snoRNP particles, in which snoRNA guides the synthase to direct site-specific pseudouridylation of rRNA. In this paper we present an Arabidopsis thaliana protein that is highly homologous to Cbf5p (72% identity and 85% homology) and NAP57 (67% identity and 81% homology). Moreover, the plant protein has conserved structural motifs that are characteristic features of pseudouridine synthases of the TruB class. We have named the cloned and characterized protein AtNAP57 (Arabidopsis thaliana homologue of NAP57). AtNAP57 is a 565 amino-acid protein and its calculated molecular mass is 63 kDa. The protein is encoded by a single copy gene located on chromosome 3 of the A. thaliana genome. Interestingly, the AtNAP57 gene does not contain any introns. Mutations in the human DKC1 gene encoding dyskerin (human homologue of yeast Cbf5p and rat NAP57) cause dyskeratosis congenita a rare inherited bone marrow failure syndrome characterized by abnormal skin pigmentation, nail dystrophy and mucosal leukoplakia.

  7. Exogenous application of molybdenum affects the expression of CBF14 and the development of frost tolerance in wheat.

    PubMed

    Al-Issawi, Mohammed; Rihan, Hail Z; Woldie, Wondwossen Abate; Burchett, Stephen; Fuller, Michael P

    2013-02-01

    Wheat is able to cold acclimate in response to low temperatures and thereby increase its frost tolerance and the extent of this acclimation is greater in winter genotypes compared to spring genotypes. Such up-regulation of frost tolerance is controlled by Cbf transcription factors. Molybdenum (Mo) application has been shown to enhance frost tolerance of wheat and this study aimed to investigate the effect of Mo on the development of frost tolerance in winter and spring wheat. Results showed that Mo treatment increased the expression of Cbf14 in wheat under non-acclimating condition but did not alter frost tolerance. However, when Mo was applied in conjunction with exposure of plants to low temperature, Mo increased the expression of Cbf14 and enhanced frost tolerance in both spring and winter genotypes but the effect was more pronounced in the winter genotype. It was concluded that the application of Mo could be useful in situations where enhanced frost resistance is required. Further studies are proposed to elucidate the effect of exogenous of applications of Mo on frost resistance in spring and winter wheat at different growth stages.

  8. Binary drop coalescence in liquids

    NASA Astrophysics Data System (ADS)

    Kim, Jungyong

    Experiments on binary drop collisions within an index-matched liquid were conducted for Weber numbers (We) of 1-50 and collision angles of 15-80° below the horizontal. Drop pairs of water/glycerin mixture were injected into silicone oil and, due to gravitational effects, traveled on downward trajectories before colliding. A dual-field high-speed PIV measurement system was employed to quantify drop trajectories and overall collision conditions while simultaneously examining detailed velocity fields near the collision interface. In the We range examined, for equal size drops, both rebounding and coalescing behavior occurred. The drops coalesced for We > 10 and rebounded for We < 10, and this boundary was found to be insensitive to collision angle. Coalescence was found to result from a combination of vortical flow within drops and strong drop deformation characteristic of higher We. Flow through the centers of opposing ring vortices, strengthened by drop deformation, enhanced drainage of the thin film in the impact region, leading to film rupture and coalescence. The collision angle affected the eventual location of film rupture, with the rupture location moving higher in the thin film region as the collision angle increased. The film rupture location correlated closely with the location of maximum downward velocity in the thin film. The time between collision and rupture increases with We until We = 30. For We > 30, the time decreases as We increases. Unequal size drop collisions with drop size ratios (Ds/D L) of 0.7 and 0.5 were also examined. Coalescence occurs above We* = 11 similar to equal size drops. As drop size ratio decreases, the intervening film deforms more. If the velocity ratio uL/u s < 1, the deformed interface becomes flat before coalescence. The rupture location varies due to the asymmetry of the drops. As collision offset increases (B > 0), the film rupture time is shortened and mixing of the fluid from both drops is enhanced after coalescence

  9. Optimization of methods for quantification of rCBF using high-resolution [15O]H2O PET images

    NASA Astrophysics Data System (ADS)

    Walker, M. D.; Feldmann, M.; Matthews, J. C.; Anton-Rodriguez, J. M.; Wang, S.; Koepp, M. J.; Asselin, M.-C.

    2012-04-01

    This study aimed to derive accurate estimates of regional cerebral blood flow (rCBF) from noisy dynamic [15O]H2O PET images acquired on the high-resolution research tomograph, while retaining as much as possible the high spatial resolution of this brain scanner (2-3 mm) in parametric maps of rCBF. The PET autoradiographic method and generalized linear least-squares (GLLS), with fixed or extended to include spatially variable estimates of the dispersion of the measured input function, were compared to nonlinear least-squares (NLLS) for rCBF estimation. Six healthy volunteers underwent two [15O]H2O PET scans with continuous arterial blood sampling. rCBF estimates were obtained from three image reconstruction methods (one analytic and two iterative, of which one includes a resolution model) to which a range of post-reconstruction filters (3D Gaussian: 2, 4 and 6 mm FWHM) were applied. The optimal injected activity was estimated to be around 11 MBq kg-1 (800 MBq) by extrapolation of patient-specific noise equivalent count rates. Whole-brain rCBF values were found to be relatively insensitive to the method of reconstruction and rCBF quantification. The grey and white matter rCBF for analytic reconstruction and NLLS were 0.44 ± 0.03 and 0.15 ± 0.03 mL min-1 cm-3, respectively, in agreement with literature values. Similar values were obtained from the other methods. For generation of parametric images using GLLS or the autoradiographic method, a filter of ⩾4 mm was required in order to suppress noise in the PET images which otherwise produced large biases in the rCBF estimates.

  10. CIR, a corepressor of CBF1, binds to PAP-1 and effects alternative splicing

    SciTech Connect

    Maita, Hiroshi; Kitaura, Hirotake; Ariga, Hiroyoshi . E-mail: hiro@pharm.hokudai.ac.jp; Iguchi-Ariga, Sanae M.M.

    2005-02-15

    We have reported that PAP-1, a product of a causative gene for autosomal retinitis pigmentosa, plays a role in splicing. In this study, CIR, a protein originally identified as a CBF1-interacting protein and reported to act as a transcriptional corepressor, was identified as a PAP-1 binding protein and its function as a splicing factor was investigated. In addition to a basic lysine and acidic serine-rich (BA) domain and a zinc knuckle-like motif, CIR has an arginine/serine dipeptide repeat (RS) domain in its C terminal region. The RS domain has been reported to be present in the superfamily of SR proteins, which are involved in splicing reactions. We generated CIR mutants with deletions of each BA and RS domain and studied their subcellular localizations and interactions with PAP-1 and other SR proteins, including SC35, SF2/ASF, and U2AF{sup 35}. CIR was found to interact with U2AF{sup 35} through the BA domain, with SC35 and SF2/ASF through the RS domain, and with PAP-1 outside the BA domain in vivo and in vitro. CIR was found to be colocalized with SC35 and PAP-1 in nuclear speckles. Then the effect of CIR on splicing was investigated using the E1a minigene as a reporter in HeLa cells. Ectopic expression of CIR with the E1a minigene changed the ratio of spliced isoforms of E1a that were produced by alternative selection of 5'-splice sites. These results indicate that CIR is a member of the family of SR-related proteins and that CIR plays a role in splicing regulation.

  11. Instant freezing of impacting wax drops

    NASA Astrophysics Data System (ADS)

    Ponomarenko, Alexandre; Virot, Emmanuel; Rubinstein, Shmuel

    2015-11-01

    We present the impact of hot liquid drops of wax on surfaces whose temperature is below the solidifying temperature of the drops. During the fall the drops remain mostly liquid, but upon impact, their temperature quickly decreases resulting in the solidification of the drop. Depending on the impact energy, drops size and the temperature difference between the drop and the surface this results in plethora of solid shapes: simple lenses, triangular drops, spherical caps and popped popcorn shapes.

  12. Pool impacts of Leidenfrost drop

    NASA Astrophysics Data System (ADS)

    Darbois Texier, Baptiste; Maquet, Laurent; Dorbolo, Stephane; Dehandschoewercker, Eline; Pan, Zhao; Truscott, Tadd

    2015-11-01

    This work concerns the impact of a droplet made of a volatile liquid (typically HFE) on a pool of an other liquid (typically silicone oil) which temperature is above the boiling point of the drop. Depending on the properties of the two liquids and the impacting conditions, four different regimes are observed. For low impacting speeds, the droplet bounces on the surface of the bath and finally levitates above it in a Leidenfrost state. Such a regime occurs as soon as the pool temperature exceeds the boiling point of the drop. This observation means that there is no threshold in temperature for a Leidenfrost effect on a liquid surface contrary to the case of a solid substrate. For intermediate impacting velocities, the pinch-off of the surface of the pool entraps the drop in the liquid bulk. The entrapped drop is separated from the pool by a layer of its own vapour in a similar way of antibulles. For increasing impacting speeds, the vapour layer between the drop and the pool does not hold during the pinch-off event. The contact of the drop with the hot liquid provokes a sudden and intense evaporation. At very large impacting speeds, the drop rapidely contacts the pool, spreads and finally induces a hemi-spherical cavity. In the end, these four different regimes are summarized in a Froud-Weber diagram which boundaries are discussed.

  13. Electrokinetics of isolated electrified drops.

    PubMed

    Pillai, Rohit; Berry, Joseph D; Harvie, Dalton J E; Davidson, Malcolm R

    2016-04-14

    Using a recently developed multiphase electrokinetic model, we simulate the transient electrohydrodynamic response of a liquid drop containing ions, to both small and large values of electric field. The temporal evolution is found to be governed primarily by two dimensionless groups: (i) Ohnesorge number (Oh), a ratio of viscous to inertio-capillary effects, and (ii) inverse dimensionless Debye length (κ), a measure of the diffuse regions of charge that develop in the drop. The effects of dielectric polarization dominate at low Oh, while effects of separated charge gain importance with increase in Oh. For small values of electric field, the deformation behaviour of a drop is shown to be accurately described by a simple analytical expression. At large electric fields, the drops are unstable and eject progeny drops. Depending on Oh and κ this occurs via dripping or jetting; the regime transitions are shown by a Oh-κ phase map. In contrast to previous studies, we find universal scaling relations to predict size and charge of progeny drops. Our simulations suggest charge transport plays a significant role in drop dynamics for 0.1 ≤ Oh ≤ 10, a parameter range of interest in microscale flows.

  14. CBF mediates adenovirus Ela trans-activation by interaction at the C-terminal promoter targeting domain of conserved region 3.

    PubMed

    Agoff, S N; Wu, B

    1994-12-01

    Genetic and biochemical evidence suggest that conserved region 3 (CR3) of the adenovirus Ela polypeptide can provide two distinct and separable functions: an N-terminal transcriptional activation region and a C-terminal promoter targeting region. It is thought that the promoter targeting region of Ela CR3 interacts with promoter-specific transcription factors, thereby bringing the activation region of Ela CR3 in proximity of the promoter. Here we report that CBF, a CCAAT-box-binding factor that regulates hsp70 gene expression and mediates Ela trans-activation in vivo, interacts with the promoter targeting region of Ela CR3 in vitro. Point mutations in Ela CR3 that are defective in stimulating transcription from the hsp70 promoter are also defective in stimulating transcription directed by a synthetic activator, GAL-CBF, composed of the DNA-binding domain of yeast GAL4 fused to CBF. These mutations fall into two classes with respect to their abilities to interact with CBF in vitro. Mutations in the transcriptional activation region of Ela CR3 do not affect binding to CBF, but mutation of the promoter targeting region of Ela CR3 prevents association with CBF in vitro.

  15. Large deletions in the CBF gene cluster at the Fr-B2 locus are associated with reduced frost tolerance in wheat

    PubMed Central

    Pearce, Stephen; Zhu, Jie; Boldizsár, Ákos; Vágújfalvi, Attila; Burke, Adrienne; Garland-Campbell, Kimberley; Galiba, Gábor; Dubcovsky, Jorge

    2016-01-01

    Wheat plants which are exposed to periods of low temperatures (cold acclimation) exhibit increased survival rates when they are subsequently exposed to freezing temperatures. This process is associated with large-scale changes in the transcriptome which are modulated by a set of tandemly duplicated CBF (C-repeat Binding Factor) transcription factors located at the Fr-2 (Frost Resistance-2) locus. While Arabidopsis has three tandemly duplicated CBF genes, the CBF family in wheat has undergone an expansion and at least 15 CBF genes have been identified, eleven of which are present at the Fr-2 loci on homoeologous group 5 chromosomes. We report here the discovery of three large deletions which eliminate six, nine, and all eleven CBF genes from the Fr-B2 locus in tetraploid and hexaploid wheat. In wild emmer wheat, the Fr-B2 deletions were found only among the accessions from the southern sub-populations. Among cultivated wheats, the Fr-B2 deletions were more common among varieties with a spring growth habit than among those with a winter growth habit. Replicated freezing tolerance experiments showed that both the deletion of nine CBF genes in tetraploid wheat and the complete Fr-B2 deletion in hexaploid wheat are associated with significant reductions in survival after exposure to freezing temperatures. Our results suggest that selection for the wild type Fr-B2 allele may be beneficial for breeders selecting for varieties with improved frost tolerance. PMID:23884601

  16. Leidenfrost drops: Effect of gravity

    NASA Astrophysics Data System (ADS)

    Maquet, L.; Brandenbourger, M.; Sobac, B.; Biance, A.-L.; Colinet, P.; Dorbolo, S.

    2015-04-01

    A specific experimental set-up has been installed in a large centrifuge facility in order to study different aspects of Leidenfrost drops under high-gravity conditions (5, 10, 15 and 20 times the Earth gravity). In particular, the drop lifetime and more precisely the variations of drop diameter vs. time have shown to be in good agreement with previous experiments and scaling analysis (Biance A.-L. et al., Phys. Fluids, 15 (2003) 1632). Moreover, so-called chimneys are expectedly observed in the large puddles, the distance between two chimneys depending linearly on the capillary length. Finally, the Leidenfrost point, i.e. the temperature above which the Leidenfrost effect takes place, was unexpectedly found to increase slightly with gravity. A qualitative explanation based on a refined model (Sobac B. et al., Phys. Rev. E, 90 (2014) 053011) recognizing the non-trivial shape of the vapor film under the drop is proposed to explain this observation.

  17. Orion Capsule Mockup is Dropped

    NASA Video Gallery

    An Orion capsule mockup is dropped from a plane 25,000 feet above the Arizona desert to test its parachute design. Orion will return to Earth at speeds faster than previous human spacecraft, and wi...

  18. Involvement of a common progenitor cell in core binding factor acute myeloid leukaemia associated with mastocytosis.

    PubMed

    Cornet, Edouard; Dumézy, Florent; Roumier, Christophe; Lepelley, Pascale; Jouy, Nathalie; Philippe, Nathalie; Renneville, Aline; Berthon, Céline; Nelken, Brigitte; Quesnel, Bruno; Preudhomme, Claude

    2012-11-01

    In core binding factor (CBF) acute myeloid leukaemia (AML), realtime quantitative PCR is useful to quantify the fusion transcript ratio (CBFβ-MYH11 and AML1-ETO, in case of inv(16) and t(8;21) respectively) in peripheral blood and bone marrow during the courses of chemotherapy, in order to monitor minimal residual disease (MRD). In two cases of CBF AML associated with systemic mastocytosis (SM), the persistence of mast cells and the detection of a high ratio of fusion transcript, in bone marrow, during the courses of chemotherapy, led us to determine whether the mast cell component of the disease carried the same molecular alterations as leukaemic blasts. We demonstrate that sorted mast cells carried CBF abnormality. These observations point out the lack of specificity of MRD monitoring by RQ-PCR in these exceptional AML cases with SM. Moreover, this suggests that leukaemic blasts and mast cells derive from a common malignant progenitor.

  19. Computational analysis of drop-on-demand drop formation

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Basaran, Osman A.

    2007-10-01

    Motivated by the desire to improve the theoretical understanding of drop-on-demand (DOD) ink-jet printing, a computational analysis is carried out to simulate the formation of liquid drops of incompressible Newtonian fluids from a simple capillary tube by imposing a transient flow rate upstream of the nozzle exit. Since the flow in a typical ink-jet nozzle is toward the nozzle outlet during part of the time and away from the nozzle outlet at other times, an inflow rate is adopted here that captures the essential physics and is given in dimensionless form by Q =(π√We /2)sinΩt, where We is the Weber number (inertial/surface tension force), Ω is the frequency, and t is time. The dynamics are studied as functions of We, Ω, and the Ohnesorge number Oh (viscous/surface tension force). For a common ink forming from a nozzle of 10μm radius, Oh =0.1. For this typical case, a phase or operability diagram in (We,Ω)-space is developed that shows that three regimes of operation are possible. In the first regime, where We is low, breakup does not occur, and drops remain pendant from the nozzle and undergo time periodic oscillations. Thus, the simulations show that fluid inertia, and hence We, must be large enough if a DOD drop is to form, in accord with intuition. A sufficiently large We causes both drop elongation and onset of drop necking, but flow reversal is also necessary for the complete evacuation of the neck and capillary pinching. In the other two regimes, at a given Ω, We is large enough to cause drop breakup. In the first of these two regimes, where Wec1drops do form but have negative velocities, i.e., they would move toward the nozzle upon breakup, which is undesirable. In the second breakup regime, where We >Wec2, not only are DOD drops formed, but they do so with positive velocities.

  20. Electrostatic Liquid-Drop-Levitation System

    NASA Technical Reports Server (NTRS)

    Rhim, Won Kyu; Chung, San Kun; Hyson, Michael T.; Elleman, Daniel D.

    1988-01-01

    Electrostatic levitator has levitated drops of liquid up to 4 mm in diameter while maintaining spherical drop shapes. Stable levitation of spherical drops valuable in experiments involving super-cooling, solidification, and crystal growth.

  1. Effect of simulated weightlessness on the expression of Cbfα1 induced by fluid shear stress in MG-63 osteosarcoma cells.

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Zhang, S.; Wang, B.; Sun, X. Q.

    Objective The role of mechanical load in the functional regulation of osteoblasts becomes an emphasis in osseous biomechanical researches recently This study was aim to explore the effect of flow shear stress on the expression of Cbf alpha 1 in human osteosarcoma cells and to survey its functional alteration in simulated weightlessness Method After cultured for 72 h in two different gravitational environments i e 1G terrestrial gravitational condition and simulated weightlessness condition human osteosarcoma cells MG-63 were treated with 0 5 Pa or 1 5 Pa fluid shear stress FSS in a flow chamber for 15 30 60 min respectively The total RNA in cells was isolated Transcription PCR analysis was made to examine the gene expression of Cbf alpha 1 And the total protein of cells was extracted and the expression of Cbf alpha 1 protein was detected by means of Western Blotting Results MG-63 cultured in 1G condition reacted to FSS treatment with an enhanced expression of Cbf alpha 1 Compared with no FSS control group Cbf alpha 1 mRNA and protein expression increased significantly at 30 and 60 min with the treatment of FSS P 0 01 And there was remarkable difference on the Cbf alpha 1 mRNA and protein expression between the treatments of 0 5 Pa and 1 5 Pa FSS at 30 min or 60 min P 0 01 As to the osteoblasts cultured in simulated weightlessness by using clinostat the expression of Cbf alpha 1 was significantly different between 1G and simulated weightlessness conditions at each test time P 0 05 Compared with no FSS

  2. A C-Repeat Binding Factor Transcriptional Activator (CBF/DREB1) from European Bilberry (Vaccinium myrtillus) Induces Freezing Tolerance When Expressed in Arabidopsis thaliana

    PubMed Central

    Oakenfull, Rachael J.; Baxter, Robert; Knight, Marc R.

    2013-01-01

    Freezing stress affects all plants from temperate zones to the poles. Global climate change means such freezing events are becoming less predictable. This in turn reduces the ability of plants to predict the approaching low temperatures and cold acclimate. This has consequences for crop yields and distribution of wild plant species. C-repeat binding factors (CBFs) are transcription factors previously shown to play a vital role in the acclimation process of Arabidopsis thaliana, controlling the expression of hundreds of genes whose products are necessary for freezing tolerance. Work in other plant species cements CBFs as key determinants in the trait of freezing tolerance in higher plants. To test the function of CBFs from highly freezing tolerant plants species we cloned and sequenced CBF transcription factors from three Vaccinium species (Vaccinium myrtillus, Vaccinium uliginosum and Vaccinium vitis-idaea) which we collected in the Arctic. We tested the activity of CBF transcription factors from the three Vaccinium species by producing transgenic Arabidopsis lines overexpressing them. Only the Vaccinium myrtillus CBF was able to substantially activate COR (CBF-target) gene expression in the absence of cold. Correspondingly, only the lines expressing the Vaccinium myrtillus CBF were constitutively freezing tolerant. The basis for the differences in potency of the three Vaccinium CBFs was tested by observing cellular localisation and protein levels. All three CBFs were correctly targeted to the nucleus, but Vaccinium uliginosum CBF appeared to be relatively unstable. The reasons for lack of potency for Vaccinium vitis-idaea CBF were not due to stability or targeting, and we speculate that this was due to altered transcription factor function. PMID:23349799

  3. Analyzing the Expression Profile of AREB/ABF and DREB/CBF Genes under Drought and Salinity Stresses in Grape (Vitis vinifera L.).

    PubMed

    Zandkarimi, Hana; Ebadi, Ali; Salami, Seyed Alireza; Alizade, Houshang; Baisakh, Niranjan

    2015-01-01

    Expression patterns of four candidate AREB/ABF genes and four DREB/CBF genes were evaluated in leaf and root tissues of five grape varieties ('Qalati', 'Kaj Angoor', 'Sabz Angoor', 'Siahe Zarghan', 'Bidane Safid') with differential response to drought stress. Among the AREB/ABF genes, AREB1 and ABF2 showed up-regulation in response to drought stress in leaf and root tissues of all varieties while AREB2 and ABF1 showed down-regulation in both leaf and root tissues of the sensitive variety 'Bidane Sefid' in response to drought and salt stress. Among the DREB/CBF genes, CBF4 was the most responsive to drought stress in both leaf and root tissues. CBF2 and CBF3 showed up-regulation in all varieties in response to drought stress in leaf except in 'Bidane Sefid'. Under salinity stress, AREB2 and ABF2 showed up-regulation in response to the increasing level of salinity in the leaf tissues but in the root tissues ABF2 was up-regulated in response to increasing NaCl concentration while AREB2 was down-regulated. Therefore, it seems AREB2 has tissue-specific response to salinity stress. All CBF genes were up-regulated in response to salinity stress in the leaf and root tissues. Expression data suggested that CBF2 is more responsive to NaCl stress. Among all four promising and stress tolerant varieties 'Siah Zarghan' and 'Kaj Angoor' were more tolerant than 'Qalati' and 'Sabz Angoor' to drought and salinity.

  4. Analyzing the Expression Profile of AREB/ABF and DREB/CBF Genes under Drought and Salinity Stresses in Grape (Vitis vinifera L.)

    PubMed Central

    Zandkarimi, Hana; Ebadi, Ali; Salami, Seyed Alireza; Alizade, Houshang; Baisakh, Niranjan

    2015-01-01

    Expression patterns of four candidate AREB/ABF genes and four DREB/CBF genes were evaluated in leaf and root tissues of five grape varieties (‘Qalati’, ‘Kaj Angoor’, ‘Sabz Angoor’, ‘Siahe Zarghan’, ‘Bidane Safid’) with differential response to drought stress. Among the AREB/ABF genes, AREB1 and ABF2 showed up-regulation in response to drought stress in leaf and root tissues of all varieties while AREB2 and ABF1 showed down-regulation in both leaf and root tissues of the sensitive variety ‘Bidane Sefid’ in response to drought and salt stress. Among the DREB/CBF genes, CBF4 was the most responsive to drought stress in both leaf and root tissues. CBF2 and CBF3 showed up-regulation in all varieties in response to drought stress in leaf except in ‘Bidane Sefid’. Under salinity stress, AREB2 and ABF2 showed up-regulation in response to the increasing level of salinity in the leaf tissues but in the root tissues ABF2 was up-regulated in response to increasing NaCl concentration while AREB2 was down-regulated. Therefore, it seems AREB2 has tissue-specific response to salinity stress. All CBF genes were up-regulated in response to salinity stress in the leaf and root tissues. Expression data suggested that CBF2 is more responsive to NaCl stress. Among all four promising and stress tolerant varieties ‘Siah Zarghan’ and ‘Kaj Angoor’ were more tolerant than ‘Qalati’ and ‘Sabz Angoor’ to drought and salinity. PMID:26230273

  5. Forced Oscillations of Supported Drops

    NASA Technical Reports Server (NTRS)

    Wilkes, Edward D.; Basaran, Osman A.

    1996-01-01

    Oscillations of supported liquid drops are the subject of wide scientific interest, with applications in areas as diverse as liquid-liquid extraction, synthesis of ceramic powders, growing of pure crystals in low gravity, and measurement of dynamic surface tension. In this research, axisymmetric forced oscillations of arbitrary amplitude of viscous liquid drops of fixed volume which are pendant from or sessile on a rod with a fixed or moving contact line and surrounded by an inviscid ambient gas are induced by moving the rod in the vertical direction sinusiodally in time. In this paper, a preliminary report is made on the computational analysis of the oscillations of supported drops that have 'clean' interfaces and whose contact lines remain fixed throughout their motions. The relative importance of forcing to damping can be increased by either increasing the amplitude of rod motion A or Reynolds number Re. It is shown that as the ratio of forcing to damping rises, for drops starting from an initial rest state a sharp increase in deformation can occur when they are forced to oscillate in the vicinity of their resonance frequencies, indicating the incipience of hysteresis. However, it is also shown that the existence of a second stable limit cycle and the occurrence of hysteresis can be observed if the drop is subjected to a so-called frequency sweep, where the forcing frequency is first increased and then decreased over a suitable range. Because the change in drop deformation response is abrupt in the vicinity of the forcing frequencies where hysteresis occurs, it should be possible to exploit the phenomenon to accurately measure the viscosity and surface tension of the drop liquid.

  6. Solidification of Drops in the MSFC Drop Tube

    NASA Technical Reports Server (NTRS)

    Brush, Lucien N.

    1998-01-01

    Silver drops (99.9%, 7 mm diameter) were levitated, melted, and released to fall through the Marshall Space Flight Center's 105 m drop tube in an He-6% H atmosphere at 170 degrees superheat. The extent of solidification during the approx. 4.6 s of free fall time prior to impact was measured experimentally and computed numerically using a newly developed solidification heat transfer model. Comparison of the experimental observation of the fraction of liquid transformed with the numerical solutions showed reasonable agreement. Possible modifications of the model, in an attempt to close the gap between the experiment and the model comparison are discussed.

  7. Review on drop towers and long drop tubes

    NASA Technical Reports Server (NTRS)

    Bayuzick, R. J.; Hofmeister, W. H.; Robinson, M. B.

    1987-01-01

    A drop tube is an enclosure in which a molten sample can be solidified while falling; three such large tubes are currently in existence, all at NASA research facilities, and are engaged in combustion and fluid physics-related experiments rather than in materials research. JPL possesses smaller tubes, one of which can be cryogenically cooled to produce glass and metal microshells. A new small drop tube will soon begin operating at NASA Lewis that is equipped with four high-speed two-color pyrometers spaced equidistantly along the column.

  8. Static Magnetowetting of Ferrofluid Drops.

    PubMed

    Rigoni, Carlo; Pierno, Matteo; Mistura, Giampaolo; Talbot, Delphine; Massart, René; Bacri, Jean-Claude; Abou-Hassan, Ali

    2016-08-01

    We report results of a comprehensive study of the wetting properties of sessile drops of ferrofluid water solutions at various concentrations deposited on flat substrates and subjected to the action of permanent magnets of different sizes and strengths. The amplitude and the gradient of the magnetic field experienced by the ferrofluid are changed by varying the magnets and their distance to the surface. Magnetic forces up to 100 times the gravitational one and magnetic gradients up to 1 T/cm are achieved. A rich phenomenology is observed, ranging from flattened drops caused by the magnetic attraction to drops extended normally to the substrate because of the normal traction of the magnetic field. We find that the former effect can be conveniently described in terms of an effective Bond number that compares the effective drop attraction with the capillary force, whereas the drop's vertical elongation is effectively expressed by a dimensionless number S, which compares the pressure jump at the ferrofluid interface because of the magnetization with the capillary pressure.

  9. Static Magnetowetting of Ferrofluid Drops.

    PubMed

    Rigoni, Carlo; Pierno, Matteo; Mistura, Giampaolo; Talbot, Delphine; Massart, René; Bacri, Jean-Claude; Abou-Hassan, Ali

    2016-08-01

    We report results of a comprehensive study of the wetting properties of sessile drops of ferrofluid water solutions at various concentrations deposited on flat substrates and subjected to the action of permanent magnets of different sizes and strengths. The amplitude and the gradient of the magnetic field experienced by the ferrofluid are changed by varying the magnets and their distance to the surface. Magnetic forces up to 100 times the gravitational one and magnetic gradients up to 1 T/cm are achieved. A rich phenomenology is observed, ranging from flattened drops caused by the magnetic attraction to drops extended normally to the substrate because of the normal traction of the magnetic field. We find that the former effect can be conveniently described in terms of an effective Bond number that compares the effective drop attraction with the capillary force, whereas the drop's vertical elongation is effectively expressed by a dimensionless number S, which compares the pressure jump at the ferrofluid interface because of the magnetization with the capillary pressure. PMID:27385506

  10. Reliability comparison of spontaneous brain activities between BOLD and CBF contrasts in eyes-open and eyes-closed resting states.

    PubMed

    Zou, Qihong; Miao, Xinyuan; Liu, Dapeng; Wang, Danny J J; Zhuo, Yan; Gao, Jia-Hong

    2015-11-01

    Blood oxygenation level dependent (BOLD) and arterial spin labeling (ASL) are two predominant resting-state fMRI techniques in mapping spontaneous brain activities. At single voxel level, cerebral blood flow (CBF) measured by ASL and amplitude of low frequency fluctuations (ALFF) of BOLD have been recognized as useful indices to characterize brain function in health and disease. However, no study has directly compared the test-retest reliability between BOLD and CBF contrasts on the same group of subjects at single voxel level. Moreover, both eyes-open and eyes-closed conditions have been employed as resting states, but it is still not clear which state is more reliable. Here we collected BOLD and ASL data during eyes-open and eyes-closed states across three scanning visits on twenty-two healthy young subjects. CBF-mean, BOLD- and CBF-ALFF were computed to characterize corresponding brain activities at single voxel level. Seed-based functional connectivity (FC) with the posterior cingulate cortex (PCC) was further calculated for both BOLD and CBF data. Intra-class correlation was used as the index of long-term reliability between visits 1 and 2 (two months apart) and short-term reliability between visits 2 and 3 (on the same day). Both short- and long-term reliabilities for CBF-mean and BOLD-ALFF were high, but were lower for CBF-ALFF, BOLD- and CBF-FC in both eyes-open and eyes-closed states. Direct comparisons showed that brain regions with the highest reliability of CBF-mean were mainly in the gray matter. The reliability of CBF-ALFF and BOLD-FC was lower than that of BOLD-ALFF, and the reliability of CBF-FC was lower than those of both CBF-ALFF and BOLD-FC. Furthermore, we observed that reliabilities of the eyes-open state were higher than those of the eyes-closed state for both imaging contrasts, though the effect size was small. Voxel-wise comparisons demonstrated that the long-term reliability of BOLD-ALFF was significantly higher with eyes open in the

  11. Effects of background suppression on the sensitivity of dual-echo arterial spin labeling MRI for BOLD and CBF signal changes.

    PubMed

    Ghariq, Eidrees; Chappell, Michael A; Schmid, Sophie; Teeuwisse, Wouter M; van Osch, Matthias J P

    2014-12-01

    Dual-echo arterial spin labeling (DE-ASL) enables the simultaneous acquisition of BOLD and CBF fMRI data and is often used for calibrated BOLD and cerebrovascular CO2 reactivity measurements. DE-ASL, like all ASL techniques, suffers from a low intrinsic CBF SNR, which can be improved by suppressing the background signal via the inclusion of additional inversion pulses. However, until now this approach has been considered to be undesirable for DE-ASL, because the BOLD signal is extracted from the background signal and attenuating the background signal could decrease the sensitivity of DE-ASL scans for BOLD changes. In this study, the effect of background suppression on the sensitivity of DE-ASL MRI for BOLD and CBF signal changes with a visual stimulation paradigm was studied. Results showed that with an average background suppression level of 70% the BOLD sensitivity of DE-ASL MRI decreases slightly (15%), while the CBF sensitivity of the scans increased by almost a factor-of-two (81%). These findings support the conclusion that the gains in CBF sensitivity of DE-ASL MRI due to background suppression outweigh the slight decrease in sensitivity of these scans for BOLD changes, and thus that background suppression is highly recommended for DE-ASL.

  12. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.810 Section 178.810 Transportation... Drop test. (a) General. The drop test must be conducted for the qualification of all IBC design types... the drop test. (1) Metal, rigid plastic, and composite IBCs intended to contain solids must be...

  13. 49 CFR 178.1045 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.1045 Section 178.1045... Containers § 178.1045 Drop test. (a) General. The drop test must be conducted for the qualification of all... subpart. (b) Special preparation for the drop test. Flexible Bulk Containers must be filled to...

  14. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.965 Section 178.965 Transportation... Packagings § 178.965 Drop test. (a) General. The drop test must be conducted for the qualification of all...) Special preparation for the drop test. Large Packagings must be filled in accordance with § 178.960....

  15. 49 CFR 178.603 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.603 Section 178.603 Transportation... Packagings and Packages § 178.603 Drop test. (a) General. The drop test must be conducted for the... than flat drops, the center of gravity of the test packaging must be vertically over the point...

  16. Getting the Drop on Sediment

    ERIC Educational Resources Information Center

    Galindez, Peter

    1977-01-01

    In this exercise, students examine Aristotle's weight hypothesis by testing variously shaped marble chips. These chips are weighed and dropped down a water tube. Average fall times and weights are recorded and graphed. Students are asked to apply this information to rock and soil deposition by streams. (MA)

  17. Egg Drop: An Invention Workshop

    ERIC Educational Resources Information Center

    McCormack, Alan J.

    1973-01-01

    Describes an activity designed to stimulate elementary and junior high students to become actively engaged in thinking creatively rather than only analytically, convergently, or repetitively. The activity requires students to devise means of dropping an egg from a height without it breaking. (JR)

  18. ``Quantum'' interference with bouncing drops

    NASA Astrophysics Data System (ADS)

    Bohr, Tomas; Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens

    2013-11-01

    In a series of recent papers (most recently) Yves Couder and collaborators have explored the dynamics of walking drops on the surface of a vibrated bath of silicon oil and have demonstrated a close analogy to quantum phenomena. The bouncing drop together with the surface wave that it excites seems to be very similar to the pilot wave envisaged by de Broglie for quantum particles. In particular, have studied a double slit experiment with walking drops, where an interference pattern identical to the quantum version is found even though it is possible to follow the orbits of the drops and unambigously determine which slit it goes through, something which in quantum mechanics would be ruled out by the Heisenberg uncertainly relations. We have repeated the experiment and present a somewhat more complicated picture. Theoretically, we study a Schrödinger equation with a source term originating from a localised ``particle'' being simultaneously guided by the wave. We present simple solutions to such a field theory and discuss the fundamental difficulties met by such a theory in order to comply with quantum mechanics.

  19. Core binding factor beta (Cbfβ) controls the balance of chondrocyte proliferation and differentiation by upregulating Indian hedgehog (Ihh) expression and inhibiting parathyroid hormone-related protein receptor (PPR) expression in postnatal cartilage and bone formation.

    PubMed

    Tian, Fei; Wu, Mengrui; Deng, Lianfu; Zhu, Guochun; Ma, Junqing; Gao, Bo; Wang, Lin; Li, Yi-Ping; Chen, Wei

    2014-07-01

    Core binding factor beta (Cbfβ) is essential for embryonic bone morphogenesis. Yet the mechanisms by which Cbfβ regulates chondrocyte proliferation and differentiation as well as postnatal cartilage and bone formation remain unclear. Hence, using paired-related homeobox transcription factor 1-Cre (Prx1-Cre) mice, mesenchymal stem cell-specific Cbfβ-deficient (Cbfβ(f/f) Prx1-Cre) mice were generated to study the role of Cbfβ in postnatal cartilage and bone development. These mutant mice survived to adulthood but exhibited severe sternum and limb malformations. Sternum ossification was largely delayed in the Cbfβ(f/f) Prx1-Cre mice and the xiphoid process was noncalcified and enlarged. In newborn and 7-day-old Cbfβ(f/f) Prx1-Cre mice, the resting zone was dramatically elongated, the proliferation zone and hypertrophic zone of the growth plates were drastically shortened and disorganized, and trabecular bone formation was reduced. Moreover, in 1-month-old Cbfβ(f/f) Prx1-Cre mice, the growth plates were severely deformed and trabecular bone was almost absent. In addition, Cbfβ deficiency impaired intramembranous bone formation both in vivo and in vitro. Interestingly, although the expression of Indian hedgehog (Ihh) was largely reduced, the expression of parathyroid hormone-related protein (PTHrP) receptor (PPR) was dramatically increased in the Cbfβ(f/f) Prx1-Cre growth plate, indicating that that Cbfβ deficiency disrupted the Ihh-PTHrP negative regulatory loop. Chromatin immunoprecipitation (ChIP) analysis and promoter luciferase assay demonstrated that the Runx/Cbfβ complex binds putative Runx-binding sites of the Ihh promoter regions, and also the Runx/Cbfβ complex directly upregulates Ihh expression at the transcriptional level. Consistently, the expressions of Ihh target genes, including CyclinD1, Ptc, and Pthlh, were downregulated in Cbfβ-deficient chondrocytes. Taken together, our study reveals not only that Cbfβ is essential for chondrocyte

  20. The Stability of Two Connected Pendant Drops

    NASA Technical Reports Server (NTRS)

    Slobozhanin, Lev A.; Alexander, J. Iwan

    2004-01-01

    The stability of an equilibrium system of two drops suspended from circular holes is examined. The drop surfaces are disconnected surfaces of a connected liquid body. For holes of equal radii and identical pendant drops axisymmetric perturbations are always the most dangerous. The stability region for two identical drops differs considerably from that for a single drop. Loss of stability leads to a transition from a critical system of identical drops to a stable system of axisymmetric non-identical. This system of non-identical drops reaches its own stability limit (to isochoric or non-isochoric paturbations). For non-identical drops, loss of stability results in dripping or streaming from the holes. Critical volumes for non-identical drops have been calculated as functions of the Bond number, B. For unequal hole radii, stability regions have been constructed for a set of hole radius, K. The dependence of critical volumes on K and B is analyzed.

  1. Drop impact on a fiber

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Gil; Kim, Wonjung

    2016-04-01

    We present the results of a combined experimental and theoretical investigation of drop impact on a thin fiber. Using high-speed videography, we analyze the dynamics of droplet collision with a fiber. Based on the systematic experiments, we identify three outcomes of collision: capturing, single drop falling, and splitting. The outcomes are presented in a regime map, where the regime boundaries are explained through a scale analysis of forces. We also measure the liquid retention on the fiber after the droplet impact. By considering a liquid film on the fiber, we develop a mechanical model that predicts the residual water mass. Our model reveals that the residual mass depends critically on the fiber thickness and less on the impact speed. Our study can be extended to predicting the remaining droplet, critical problems in air filtration, water collection, and fiber coating.

  2. Thermocapillary motion of deformable drops

    NASA Technical Reports Server (NTRS)

    Haj-Hariri, Hossein; Shi, Qingping; Borhan, Ali

    1994-01-01

    The thermocapillary motion of initially spherical drops/bubbles driven by a constant temperature gradient in an unbounded liquid medium is simulated numerically. Effects of convection of momentum and energy, as well as shape deformations, are addressed. The method used is based on interface tracking on a base cartesian grid, and uses a smeared color or indicator function for the determination of the surface topology. Quad-tree adaptive refinement of the cartesian grid is implemented to enhance the fidelity of the surface tracking. It is shown that convection of energy results in a slowing of the drop, as the isotherms get wrapped around the front of the drop. Shape deformation resulting from inertial effects affect the migration velocity. The physical results obtained are in agreement with the existing literature. Furthermore, remarks are made on the sensitivity of the calculated solutions to the smearing of the fluid properties. Analysis and simulations show that the migration velocity depends very strongly on the smearing of the interfacial force whereas it is rather insensitive to the smearing of other properties, hence the adaptive grid.

  3. Piezoelectric Water Drop Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Al Ahmad, Mahmoud

    2014-02-01

    Piezoelectric materials convert mechanical deformation directly into electrical charges, which can be harvested and used to drive micropower electronic devices. The low power consumption of such systems on the scale of microwatts leads to the possibility of using harvested vibrational energy due to its almost universal nature. Vibrational energy harvested using piezoelectric cantilevers provides sufficient output for small-scale power applications. This work reports on vibrational energy harvesting from free-falling droplets at the tip of lead zirconate titanate piezoelectric-based cantilevers. The harvester incorporates a multimorph clamped-free cantilever made of lead zirconate titanate piezoelectric thick films. During the impact, the droplet's kinetic energy is transferred to the form of mechanical stress, forcing the piezoelectric structure to vibrate and thereby producing charges. Experimental results show an instantaneous drop-power of 2.15 mW cm-3 g-1. The scenario of a medium intensity of falling water drops, i.e., 200 drops per second, yielded a power of 0.48 W cm-3 g-1 per second.

  4. Selection of Reversions and Suppressors of a Mutation in the CBF Binding Site of a Lymphomagenic Retrovirus

    PubMed Central

    Martiney, Marita J.; Rulli, Karen; Beaty, Robert; Levy, Laura S.; Lenz, Jack

    1999-01-01

    The retrovirus SL3 induces T-cell lymphomas in mice. The transcriptional enhancer in the long terminal repeat (LTR) of SL3 contains two 72-bp repeats. Each repeat contains a binding site for the transcription factor CBF (also called AML1). The CBF binding sites are called core elements. SAA is a mutant that is identical to SL3 except for the presence of a single-base-pair substitution in each of the two core elements. This mutation significantly attenuates viral lymphomagenicity. Most lymphomas that occur in SAA-infected mice contain proviruses with reversions or second-site suppressor mutations within the core element. We examined the selective pressures that might account for the predominance of the reversions and suppressor mutations in tumor proviruses by analyzing when proviruses with altered core sequences became abundant during the course of lymphomagenesis. Altered core sequences were easily detected in thymus DNAs by 4 to 6 weeks after SAA infection of mice, well before lymphomas were grossly evident. This result is consistent with the hypothesis that viruses with the core sequence alterations emerged because they replicated more effectively in mice than SAA. The number of 72-bp tandem, repeats in the viral LTR was found to vary, presumably as a consequence of reverse transcriptase slippage during polymerization. Proviruses with two repeats predominated in the thymuses of SAA- and SL3-infected mice before lymphomas developed, although LTRs with one or three repeats were also present. This suggested that two was the optimal number of 72-bp repeats for viral replication. However, in lymphomas, proviruses with three or four repeats usually predominated. This suggested that a late step in the process of lymphomagenesis led to the abundance of proviruses with additional repeats. We hypothesize that proviruses with additional 72-bp repeats endowed the cells containing them with a selective growth advantage. PMID:10438850

  5. Ectopic AtCBF1 over-expression enhances freezing tolerance and induces cold acclimation-associated physiological modifications in potato.

    PubMed

    Pino, María-Teresa; Skinner, Jeffrey S; Jeknić, Zoran; Hayes, Patrick M; Soeldner, Alfred H; Thomashow, Michael F; Chen, Tony H H

    2008-04-01

    We studied the effect of ectopic AtCBF over-expression on physiological alterations that occur during cold exposure in frost-sensitive Solanum tuberosum and frost-tolerant Solanum commersonii. Relative to wild-type plants, ectopic AtCBF1 over-expression induced expression of COR genes without a cold stimulus in both species, and imparted a significant freezing tolerance gain in both species: 2 degrees C in S. tuberosum and up to 4 degrees C in S. commersonii. Transgenic S. commersonii displayed improved cold acclimation potential, whereas transgenic S. tuberosum was still incapable of cold acclimation. During cold treatment, leaves of wild-type S. commersonii showed significant thickening resulting from palisade cell lengthening and intercellular space enlargement, whereas those of S. tuberosum did not. Ectopic AtCBF1 activity induced these same leaf alterations in the absence of cold in both species. In transgenic S. commersonii, AtCBF1 activity also mimicked cold treatment by increasing proline and total sugar contents in the absence of cold. Relative to wild type, transgenic S. commersonii leaves were darker green, had higher chlorophyll and lower anthocyanin levels, greater stomatal numbers, and displayed greater photosynthetic capacity, suggesting higher productivity potential. These results suggest an endogenous CBFpathway is involved in many of the structural, biochemical and physiological alterations associated with cold acclimation in these Solanum species.

  6. Melatonin induces the transcripts of CBF/DREB1s and their involvement in both abiotic and biotic stresses in Arabidopsis.

    PubMed

    Shi, Haitao; Qian, Yongqiang; Tan, Dun-Xian; Reiter, Russel J; He, Chaozu

    2015-10-01

    Melatonin (N-acetyl-5-methoxytryptamine) is a naturally occurring small molecule that acts as an important secondary messenger in plant stress responses. However, the mechanism underlying the melatonin-mediated signaling pathway in plant stress responses has not been established. C-repeat-binding factors (CBFs)/Drought response element Binding 1 factors (DREB1s) encode transcription factors that play important roles in plant stress responses. This study has determined that endogenous melatonin and transcripts level of CBFs (AtCBF1, AtCBF2, and AtCBF3) in Arabidopsis leaves were significantly induced by salt, drought, and cold stresses and by pathogen Pseudomonas syringe pv. tomato (Pst) DC3000 infection. Moreover, both exogenous melatonin treatment and overexpression of CBFs conferred enhanced resistance to both abiotic and biotic stresses in Arabidopsis. Notably, AtCBFs and exogenous melatonin treatment positively regulated the mRNA expression of several stress-responsive genes (COR15A, RD22, and KIN1) and accumulation of soluble sugars content such as sucrose in Arabidopsis under control and stress conditions. Additionally, exogenous sucrose also conferred improved resistance to both abiotic and biotic stresses in Arabidopsis. Taken together, this study indicates that AtCBFs confer enhanced resistance to both abiotic and biotic stresses, and AtCBF-mediated signaling pathway and sugar accumulation may be involved in melatonin-mediated stress response in Arabidopsis, at least partially.

  7. Draft Genome Sequence of Stenotrophomonas maltophilia CBF10-1, an Organophosphate-Degrading Bacterium Isolated from Ranch Soil in Fairchilds, Texas

    PubMed Central

    Damania, Ashish

    2016-01-01

    Stenotrophomonas maltophilia CBF10-1 was isolated from a ranch in Fairchilds, Texas, USA. Its genome reveals a highly adaptable microorganism with a large complement of antibiotic and heavy metal resistance genes, efflux pumps, multidrug transporters, and xenobiotic degradation pathways. PMID:27174285

  8. The antimicrobial activity of Cbf-K16 against MRSA was enhanced by β-lactamantibiotics through cell wall non-integrity.

    PubMed

    Li, Bo; Kang, Wei; Liu, Hanhan; Wang, Yanrong; Yu, Changzhong; Zhu, Xinyi; Dou, Jie; Cai, Haibo; Zhou, Changlin

    2016-07-01

    Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as one of the most important pathogens both in health care and in community-onset infections. Cbf-K16, a cathelicidin-like antimicrobial peptide, presented broad antimicrobial activity during our previous studies. We evaluated the potential for synergy of Cbf-K16 with ceftazidime/ampicilin against MRSA, which was resistant to these two antibiotics with the minimum inhibitory concentration more than 64 μg/ml. The combinations showed a synergistic effect by a checkerboard assay with a fractional inhibitory concentration index ≤0.5. The killing curves of the combination treatment against MRSA showed that CFU counts decreased rapidly within 4 h by almost five logs, while single medication groups and the control group exhibited little inhibitory effect. In addition, in a mice bacteremia model, studies indicated that the combination treatment significantly prolonged the survival time of mice infected with MRSA, with a death protection rate of 80 %. Flow cytometry analysis and transmission electron microscopy indicated that combination-treated MRSA was completely ruptured with the cellular contents leaked out. The synergistic effect showed that Cbf-K16 selectively killed cells with non-integrity induced by cell wall inhibition antibiotics, suggesting that Cbf-K16 is a potential therapeutic agent and adjuvant for antimicrobial chemotherapy. PMID:27287456

  9. An apple rootstock overexpressing a peach CBF gene alters growth and flowering in the scion but does not impact cold hardiness or dormancy.

    PubMed

    Artlip, Timothy S; Wisniewski, Michael E; Arora, Rajeev; Norelli, John L

    2016-01-01

    The C-repeat binding factor (CBF) transcription factor is involved in responses to low temperature and water deficit in many plant species. Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhibition in many species. The overexpression of a peach CBF (PpCBF1) gene in a transgenic line of own-rooted apple (Malus×domestica) M.26 rootstock (T166) trees was previously reported to have additional effects on the onset of dormancy and time of spring budbreak. In the current study, the commercial apple cultivar 'Royal Gala' (RG) was grafted onto either non-transgenic M.26 rootstocks (RG/M.26) or transgenic M.26 (T166) rootstocks (RG/T166) and field grown for 3 years. No PpCBF1 transcript was detected in the phloem or cambium of RG scions grafted on T166 rootstocks indicating that no graft transmission of transgene mRNA had occurred. In contrast to own-rooted T166 trees, no impact of PpCBF1 overexpression in T166 rootstocks was observed on the onset of dormancy, budbreak or non-acclimated leaf-cold hardiness in RG/T166 trees. Growth, however, as measured by stem caliper, current-year shoot extension and overall height, was reduced in RG/T166 trees compared with RG/M.26 trees. Although flowering was evident in both RG/T166 and RG/M.26 trees in the second season, the number of trees in flower, the number of shoots bearing flowers, and the number of flower clusters per shoot was significantly higher in RG/M.26 trees than RG/T166 trees in both the second and third year after planting. Elevated levels of RGL (DELLA) gene expression were observed in RG/T166 trees and T166 trees, which may play a role in the reduced growth observed in these tree types. A model is presented indicating how CBF overexpression in a rootstock might influence juvenility and flower abundance in a grafted scion. PMID:26981253

  10. An apple rootstock overexpressing a peach CBF gene alters growth and flowering in the scion but does not impact cold hardiness or dormancy

    PubMed Central

    Artlip, Timothy S; Wisniewski, Michael E; Arora, Rajeev; Norelli, John L

    2016-01-01

    The C-repeat binding factor (CBF) transcription factor is involved in responses to low temperature and water deficit in many plant species. Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhibition in many species. The overexpression of a peach CBF (PpCBF1) gene in a transgenic line of own-rooted apple (Malus×domestica) M.26 rootstock (T166) trees was previously reported to have additional effects on the onset of dormancy and time of spring budbreak. In the current study, the commercial apple cultivar ‘Royal Gala’ (RG) was grafted onto either non-transgenic M.26 rootstocks (RG/M.26) or transgenic M.26 (T166) rootstocks (RG/T166) and field grown for 3 years. No PpCBF1 transcript was detected in the phloem or cambium of RG scions grafted on T166 rootstocks indicating that no graft transmission of transgene mRNA had occurred. In contrast to own-rooted T166 trees, no impact of PpCBF1 overexpression in T166 rootstocks was observed on the onset of dormancy, budbreak or non-acclimated leaf-cold hardiness in RG/T166 trees. Growth, however, as measured by stem caliper, current-year shoot extension and overall height, was reduced in RG/T166 trees compared with RG/M.26 trees. Although flowering was evident in both RG/T166 and RG/M.26 trees in the second season, the number of trees in flower, the number of shoots bearing flowers, and the number of flower clusters per shoot was significantly higher in RG/M.26 trees than RG/T166 trees in both the second and third year after planting. Elevated levels of RGL (DELLA) gene expression were observed in RG/T166 trees and T166 trees, which may play a role in the reduced growth observed in these tree types. A model is presented indicating how CBF overexpression in a rootstock might influence juvenility and flower abundance in a grafted scion. PMID:26981253

  11. An apple rootstock overexpressing a peach CBF gene alters growth and flowering in the scion but does not impact cold hardiness or dormancy.

    PubMed

    Artlip, Timothy S; Wisniewski, Michael E; Arora, Rajeev; Norelli, John L

    2016-01-01

    The C-repeat binding factor (CBF) transcription factor is involved in responses to low temperature and water deficit in many plant species. Overexpression of CBF genes leads to enhanced freezing tolerance and growth inhibition in many species. The overexpression of a peach CBF (PpCBF1) gene in a transgenic line of own-rooted apple (Malus×domestica) M.26 rootstock (T166) trees was previously reported to have additional effects on the onset of dormancy and time of spring budbreak. In the current study, the commercial apple cultivar 'Royal Gala' (RG) was grafted onto either non-transgenic M.26 rootstocks (RG/M.26) or transgenic M.26 (T166) rootstocks (RG/T166) and field grown for 3 years. No PpCBF1 transcript was detected in the phloem or cambium of RG scions grafted on T166 rootstocks indicating that no graft transmission of transgene mRNA had occurred. In contrast to own-rooted T166 trees, no impact of PpCBF1 overexpression in T166 rootstocks was observed on the onset of dormancy, budbreak or non-acclimated leaf-cold hardiness in RG/T166 trees. Growth, however, as measured by stem caliper, current-year shoot extension and overall height, was reduced in RG/T166 trees compared with RG/M.26 trees. Although flowering was evident in both RG/T166 and RG/M.26 trees in the second season, the number of trees in flower, the number of shoots bearing flowers, and the number of flower clusters per shoot was significantly higher in RG/M.26 trees than RG/T166 trees in both the second and third year after planting. Elevated levels of RGL (DELLA) gene expression were observed in RG/T166 trees and T166 trees, which may play a role in the reduced growth observed in these tree types. A model is presented indicating how CBF overexpression in a rootstock might influence juvenility and flower abundance in a grafted scion.

  12. Malignant paraganglioma, a rare presentation with foot drop: a case report.

    PubMed

    Asad, Sheikh; Peters-Willke, Jens; Nott, Louise

    2015-12-01

    Paragangliomas (or extra-adrenal paragangliomas) are rare neuroendocrine tumors that arise from the extra-adrenal autonomic paraganglia, small organs consisting mainly of neuroendocrine cells that are derived from the embryonic neural crest and have the ability to secrete catecholamines. This is in contrast to pheochromocytomas, where tumors occur in the adrenal gland. Malignant paraganglioma is a very rare presentation. We present a case report of a 56-year-old woman with acute foot drop with no previous significant background history. To the best of our knowledge, the current case represents the first case of malignant paraganglioma with acute foot drop presentation. PMID:27683685

  13. Malignant paraganglioma, a rare presentation with foot drop: a case report

    PubMed Central

    Peters-Willke, Jens; Nott, Louise

    2015-01-01

    Paragangliomas (or extra-adrenal paragangliomas) are rare neuroendocrine tumors that arise from the extra-adrenal autonomic paraganglia, small organs consisting mainly of neuroendocrine cells that are derived from the embryonic neural crest and have the ability to secrete catecholamines. This is in contrast to pheochromocytomas, where tumors occur in the adrenal gland. Malignant paraganglioma is a very rare presentation. We present a case report of a 56-year-old woman with acute foot drop with no previous significant background history. To the best of our knowledge, the current case represents the first case of malignant paraganglioma with acute foot drop presentation.

  14. Critical point wetting drop tower experiment

    NASA Technical Reports Server (NTRS)

    Kaukler, W. F.; Tcherneshoff, L. M.; Straits, S. R.

    1984-01-01

    Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

  15. Effect of Binghuang ear drop treatment on otitis externa in guinea pigs.

    PubMed

    Zhai, Suo-qiang; Yu, Ning; Guo, Wei-Wei; Zhang, Yue

    2014-12-01

    To investigate the pharmacodynamic effects of Binghuang ear drop on acute suppurative otitis externa in guinea pig model. Thirty guinea pigs were randomly divided into three groups, with ten animals in each group. Group A animals had normal ear canal and Binghuang ear drops (two drops, B.I.D) were applied in both ears for 7 days; Group B animals had induced otitis externa and received identical prescription as group A; Group C had normal ear canal and were treated with normal saline (two drops, B.I.D) for 7 days. After the treatments, the external morphology of ear canals was observed and the paraffin sections of external auditory canal were prepared and examined under the microscope. The inflammatory manifestation and cell infiltration into the skin of group B was significantly attenuated after the Binghuang ear drops treatment. In contrast, no allergy or side effects were produced by Binghuang ear drops application in the animals with normal ear canals. Binghuang ear drops could be used to treat acute otitis externa by eliciting anti-bacterial effects. PMID:25269771

  16. Genome-Wide Analysis of the AP2/ERF Family in Eucalyptus grandis: An Intriguing Over-Representation of Stress-Responsive DREB1/CBF Genes

    PubMed Central

    SanClemente, H.; Mounet, F.; Dunand, C.; Marque, G.; Marque, C.; Teulières, C.

    2015-01-01

    Background The AP2/ERF family includes a large number of developmentally and physiologically important transcription factors sharing an AP2 DNA-binding domain. Among them DREB1/CBF and DREB2 factors are known as master regulators respectively of cold and heat/osmotic stress responses. Experimental Approaches The manual annotation of AP2/ERF family from Eucalyptus grandis, Malus, Populus and Vitis genomes allowed a complete phylogenetic study for comparing the structure of this family in woody species and the model Arabidopsis thaliana. Expression profiles of the whole groups of EgrDREB1 and EgrDREB2 were investigated through RNAseq database survey and RT-qPCR analyses. Results The structure and the size of the AP2/ERF family show a global conservation for the plant species under comparison. In addition to an expansion of the ERF subfamily, the tree genomes mainly differ with respect to the group representation within the subfamilies. With regard to the E. grandis DREB subfamily, an obvious feature is the presence of 17 DREB1/CBF genes, the maximum reported to date for dicotyledons. In contrast, only six DREB2 have been identified, which is similar to the other plants species under study, except for Malus. All the DREB1/CBF and DREB2 genes from E. grandis are expressed in at least one condition and all are heat-responsive. Regulation by cold and drought depends on the genes but is not specific of one group; DREB1/CBF group is more cold-inducible than DREB2 which is mainly drought responsive. Conclusion These features suggest that the dramatic expansion of the DREB1/CBF group might be related to the adaptation of this evergreen tree to climate changes when it expanded in Australia. PMID:25849589

  17. Drag and drop display & builder

    SciTech Connect

    Bolshakov, Timofei B.; Petrov, Andrey D.; /Fermilab

    2007-12-01

    The Drag and Drop (DnD) Display & Builder is a component-oriented system that allows users to create visual representations of data received from data acquisition systems. It is an upgrade of a Synoptic Display mechanism used at Fermilab since 2002. Components can be graphically arranged and logically interconnected in the web-startable Project Builder. Projects can be either lightweight AJAX- and SVG-based web pages, or they can be started as Java applications. The new version was initiated as a response to discussions between the LHC Controls Group and Fermilab.

  18. Drop Tower and Aircraft Capabilities

    NASA Technical Reports Server (NTRS)

    Urban, David L.

    2015-01-01

    This presentation is a brief introduction to existing capabilities in drop towers and low-gravity aircraft that will be presented as part of a Symposium: Microgravity Platforms Other Than the ISS, From Users to Suppliers which will be a half day program to bring together the international community of gravity-dependent scientists, program officials and technologists with the suppliers of low gravity platforms (current and future) to focus on the future requirements and use of platforms other than the International Space Station (ISS).

  19. 14 CFR 91.15 - Dropping objects.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Dropping objects. 91.15 Section 91.15... AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES General § 91.15 Dropping objects. No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in...

  20. 49 CFR 572.102 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Drop test. 572.102 Section 572.102 Transportation..., DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Free Motion Headform § 572.102 Drop test. (a) When the headform is dropped from a height of 14.8 inches in accordance with paragraph (b)...

  1. 49 CFR 572.102 - Drop test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Drop test. 572.102 Section 572.102 Transportation..., DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Free Motion Headform § 572.102 Drop test. (a) When the headform is dropped from a height of 14.8 inches in accordance with paragraph (b)...

  2. 49 CFR 572.102 - Drop test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Drop test. 572.102 Section 572.102 Transportation..., DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Free Motion Headform § 572.102 Drop test. (a) When the headform is dropped from a height of 14.8 inches in accordance with paragraph (b)...

  3. Electrohydrodynamics of a particle-covered drop

    NASA Astrophysics Data System (ADS)

    Ouriemi, Malika; Vlahovska, Petia

    2014-11-01

    We study the dynamics of a drop nearly-completely covered with a particle monolayer in a uniform DC electric field. The weakly conducting fluid system consists of a silicon oil drop suspended in castor oil. A broad range of particle sizes, conductivities, and shapes is explored. In weak electric fields, the presence of particles increases drop deformation compared to a particle-free drop and suppresses the electrohydrodynamic flow. Very good agreement is observed between the measured drop deformation and the small deformation theory derived for surfactant-laden drops (Nganguia et al., 2013). In stronger electric fields, where drops are expected to undergo Quincke rotation (Salipante and Vlahovska, 2010), the presence of the particles greatly decreases the threshold for rotation and the stationary tilted drop configuration observed for clean drop is replaced by a spinning drop with either a wobbling inclination or a very low inclination. These behaviors resemble the predicted response of rigid ellipsoids in uniform electric fields. At even stronger electric fields, the particles can form dynamic wings or the drop implodes. The similar behavior of particle-covered and surfactant-laden drops provides new insights into understanding stability of Pickering emulsions. Supported by NSF-CBET 1437545.

  4. Electrohydrodynamics of a viscous drop with inertia.

    PubMed

    Nganguia, H; Young, Y-N; Layton, A T; Lai, M-C; Hu, W-F

    2016-05-01

    Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca_{E}. Below the critical Ca_{E}, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca_{E}, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca_{E}, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations. PMID:27300985

  5. Electrohydrodynamics of a viscous drop with inertia.

    PubMed

    Nganguia, H; Young, Y-N; Layton, A T; Lai, M-C; Hu, W-F

    2016-05-01

    Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca_{E}. Below the critical Ca_{E}, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca_{E}, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca_{E}, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations.

  6. The fate of electrospray drops

    NASA Astrophysics Data System (ADS)

    Basaran, Osman; Collins, Robert; Sambath, Krishnaraj; Harris, Michael

    2015-11-01

    Drops subjected to strong electric fields emit thin fluid jets from conical structures (Taylor cones) that form at their surfaces. Such behavior has practical, e.g. electrospray mass spectrometry, and fundamental, e.g. raindrops in thunderclouds, implications. Theoretical analysis of the temporal development of such EHD tip-streaming phenomena is challenging given the large disparity in length scales between the macroscopic drops and the microscopic jets. Furthermore, there exist conflicting theories and measurements on the size and charge of these small electrospray droplets. We use theory and simulation to show that conductivity can be tuned to yield three scaling regimes for droplet radius and charge, a finding missed by previous studies. The amount of charge Q that electrospray droplets carry determines whether they are coulombically stable and charged below the Rayleigh limit of stability R or are unstable and hence prone to further explosions once formed. Previous experiments reported droplet charge values ranging from 1/10th to in excess of R. Simulations unequivocally show that electrospray droplets are coulombically stable at the instant they are created and that there exists a universal scaling law for droplet charge, Q=0.44 R.

  7. Small drops from large nozzles

    NASA Astrophysics Data System (ADS)

    Castrejon-Pita, Alfonso Arturo; Said Mohamed, Ahmed; Castrejon-Pita, Jose Rafael; Herrada, Miguel Angel

    2015-11-01

    We report experimental and numerical results of the generation of drops which are significantly smaller than the nozzle from which they are generated. The system consists of a cylindrical reservoir and two endplates. One plate is a thin metal sheet with a small orifice in its centre which acts as the nozzle. The other end consists of a piston which moves by the action of an elecromechanical actuator which in turn is driven by sine-shape pull-mode pulses. The meniscus (formed at the nozzle) is thus first overturned, forming a cavity. This cavity collapses and a thin and fast jet emerges from its centre. Under appropriate conditions the tip of this jet breaks up and produces a single diminutive drop. A good agreement between the experimental and numerical results was found. Also, a series of experiments were performed in order to study the effects that the pulse amplitude and width, together with variations in the liquid properties, have over the final size of the droplet. Based on these experiments, a predictive law for the droplet size has been derived. This work was funded by the Royal Society (University Research Fellowship and Research Grant), the John Fell Fund (Oxford University Press), the Ministry of Science and Education (DPI2013-46485 Spain), and the Junta de Andalucia (P08-TEP-31704128 Spain).

  8. Peroneal nerve injury with foot drop complicating ankle sprain--a series of four cases with review of the literature.

    PubMed

    Brief, James M; Brief, Rochelle; Ergas, Enrique; Brief, L Paul; Brief, Andrew A

    2009-01-01

    Foot drop has many etiologies. One rarely mentioned and often neglected reason for foot drop is an acute inversion sprain of the ankle. Over the past 14 years, a collection of 32 cases of foot drop have been compiled in our orthopaedic and physiatric practices. All cases had appropriate evaluations, including electrodiagnostic studies (electromyography and nerve conduction studies) to determine the location and type of injury. Treatment and follow-up are also discussed. Of the 32 case studies, four were caused by a straightforward acute inversion sprain of the ankle. These cases are described with the electrodiagnostic evaluations, treatments, and outcomes. Proposed mechanisms for this type of foot drop are discussed, including traction and compression of the common peroneal nerve as it winds around the neck of the fibula, and possible compression by hematoma. Surgical versus conservative treatment is described. The functional impairment associated with foot drop is detailed.

  9. Channel drop filter for CWDM systems

    NASA Astrophysics Data System (ADS)

    Youcef Mahmoud, Mahmoud; Bassou, Ghaouti; de Fornel, Frédérique; Taalbi, Ahmed

    2013-10-01

    In this paper, a new design of channel drop filter (CDF) based on two-dimensional photonic crystal ring resonators (PCRRs) is provided by two-dimensional (2D) finite-difference time-domain (FDTD) simulations in triangular lattice photonic crystal (PC) silicon rods. 100% forward dropping efficiency and a quality factor of over 1000 can be achieved at maximum transfer efficiency while the operating wavelength is 1550 nm. Through this novel component, three channel drop operation with 100% dropping efficiencies at all output channels can be obtained. The proposed filter provides a possibility of channel drop filter and could be used in coarse wavelength division multiplexing (CWDM) systems.

  10. Charged drop levitators and their applications

    NASA Technical Reports Server (NTRS)

    Rhim, W. K.; Chung, S. K.; Hyson, M. T.; Elleman, D. D.

    1987-01-01

    An account is given of the charged drop levitation characteristics of two different devices: (1) a feedback-controlled electrostatic levitator able to lift a several mm-diameter drop in 1g conditions, which is applicable to drop dynamics, crystal growth, and supercooling/solidification experiments; and (2) a linear quadrupole levitator, whose advantages are demonstrated in light of the results obtained for the charged drop instability experiment. The cause of the premature drop burstings observed is suggested to be an electron avalanche in the surrounding gaseous medium rather than the Rayleigh limit.

  11. Effect of an acute increase in central blood volume on cerebral hemodynamics.

    PubMed

    Ogoh, Shigehiko; Hirasawa, Ai; Raven, Peter B; Rebuffat, Thomas; Denise, Pierre; Lericollais, Romain; Sugawara, Jun; Normand, Hervé

    2015-10-15

    Systemic blood distribution is an important factor involved in regulating cerebral blood flow (CBF). However, the effect of an acute change in central blood volume (CBV) on CBF regulation remains unclear. To address our question, we sought to examine the CBF and systemic hemodynamic responses to microgravity during parabolic flight. Twelve healthy subjects were seated upright and exposed to microgravity during parabolic flight. During the brief periods of microgravity, mean arterial pressure was decreased (-26 ± 1%, P < 0.001), despite an increase in cardiac output (+21 ± 6%, P < 0.001). During microgravity, central arterial pulse pressure and estimated carotid sinus pressure increased rapidly. In addition, this increase in central arterial pulse pressure was associated with an arterial baroreflex-mediated decrease in heart rate (r = -0.888, P < 0.0001) and an increase in total vascular conductance (r = 0.711, P < 0.001). The middle cerebral artery mean blood velocity (MCA Vmean) remained unchanged throughout parabolic flight (P = 0.30). During microgravity the contribution of cardiac output to MCA Vmean was gradually reduced (P < 0.05), and its contribution was negatively correlated with an increase in total vascular conductance (r = -0.683, P < 0.0001). These findings suggest that the acute loading of the arterial and cardiopulmonary baroreceptors by increases in CBV during microgravity results in acute and marked systemic vasodilation. Furthermore, we conclude that this marked systemic vasodilation decreases the contribution of cardiac output to CBF. These findings suggest that the arterial and cardiopulmonary baroreflex-mediated peripheral vasodilation along with dynamic cerebral autoregulation counteracts a cerebral overperfusion, which otherwise would occur during acute increases in CBV. PMID:26310936

  12. Drop short control of electrode gap

    DOEpatents

    Fisher, Robert W.; Maroone, James P.; Tipping, Donald W.; Zanner, Frank J.

    1986-01-01

    During vacuum consumable arc remelting the electrode gap between a consumable electrode and a pool of molten metal is difficult to control. The present invention monitors drop shorts by detecting a decrease in the voltage between the consumable electrode and molten pool. The drop shorts and their associated voltage reductions occur as repetitive pulses which are closely correlated to the electrode gap. Thus, the method and apparatus of the present invention controls electrode gap based upon drop shorts detected from the monitored anode-cathode voltage. The number of drop shorts are accumulated, and each time the number of drop shorts reach a predetermined number, the average period between drop shorts is calculated from this predetermined number and the time in which this number is accumulated. This average drop short period is used in a drop short period electrode gap model which determines the actual electrode gap from the drop short. The actual electrode gap is then compared with a desired electrode gap which is selected to produce optimum operating conditions and the velocity of the consumable error is varied based upon the gap error. The consumable electrode is driven according to any prior art system at this velocity. In the preferred embodiment, a microprocessor system is utilized to perform the necessary calculations and further to monitor the duration of each drop short. If any drop short exceeds a preset duration period, the consumable electrode is rapidly retracted a predetermined distance to prevent bonding of the consumable electrode to the molten remelt.

  13. Visual recovery using small dilating eye drops.

    PubMed

    Gray, R H; Franklin, S J; Reeves, B C

    1992-08-01

    It is well established that reduced size dilating eye drops of 1% tropicamide and 10% phenylephrine (micro drops) are effective for clinical purposes. Excellent pupil dilatation (mydriasis) is achieved and pupil constriction does not occur in response to light. In this study, the effect of micro drops of 1% tropicamide on distance and near visual recovery was compared with standard drops in a group of 20 healthy volunteers. For each person studied, one eye was selected at random to be tested first with the standard drop size, and then after a minimum of one week, the same eye was again tested using a drop of the same drug one fifth standard size. An iris photograph, Snellen visual acuity at 6 m, and reading visual acuity was obtained for each test procedure: before drop instillation and at 30 min, 1, 2 and 4 h after drug instillation. Use of the micro drops caused a small but statistically significant improvement in the rate of recovery of distance and near visual acuity. These findings, allied to the known beneficial effects of reduced systemic absorption using micro drops, lend further weight to the argument that mydriasis may be achieved more safely, with fewer side effects, and with earlier return of normal vision when reduced size drops are used. It is hoped that practical micro drop dispensers will be developed.

  14. Large charged drop levitation against gravity

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Chung, Sang Kun; Hyson, Michael T.; Trinh, Eugene H.; Elleman, Daniel D.

    1987-01-01

    A hybrid electrostatic-acoustic levitator that can levitate and manipulate a large liquid drop in one gravity is presented. To the authors' knowledge, this is the first time such large drops (up to 4 mm in diameter in the case of water) have been levitated against 1-gravity. This makes possible, for the first time, many new experiments both in space and in ground-based laboratories, such as 1)supercooling and superheating, 2) containerless crystal growth from various salt solutions or melts, 3) drop dynamics of oscillating or rotating liquid drops, 4) drop evaporation and Rayleigh bursting, and 5) containerless material processing in space. The digital control system, liquid drop launch process, principles of electrode design, and design of a multipurpose room temperature levitation chamber are described. Preliminary results that demonstrate drop oscillation and rotation, and crystal growth from supersaturated salt solutions are presented.

  15. Cystitis - acute

    MedlinePlus

    Uncomplicated urinary tract infection; UTI - acute; Acute bladder infection; Acute bacterial cystitis ... International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 ...

  16. Kaposi's sarcoma-associated herpesvirus viral interferon regulatory factor 4 (vIRF4/K10) is a novel interaction partner of CSL/CBF1, the major downstream effector of Notch signaling.

    PubMed

    Heinzelmann, Katharina; Scholz, Barbara A; Nowak, Agnes; Fossum, Even; Kremmer, Elisabeth; Haas, Juergen; Frank, Ronald; Kempkes, Bettina

    2010-12-01

    In cells infected with the Kaposi's sarcoma-associated herpesvirus (KSHV), CSL/CBF1 signaling is essential for viral replication and promotes the survival of KSHV-infected cells. CSL/CBF1 is a DNA adaptor molecule which recruits coactivator and corepressor complexes to regulate viral and cellular gene transcription and which is a major downstream effector molecule of activated Notch. The interaction of KSHV RTA and LANA with CSL/CBF1 has been shown to balance the lytic and latent viral life cycle. Here we report that a third KSHV protein, viral interferon regulatory factor 4 (vIRF4/K10), but none of the three other KSHV-encoded vIRFs, interacts with CSL/CBF1. Two regions of vIRF4 with dissimilar affinities contribute to CSL/CBF1 binding. Similar to Notch, vIRF4 targets the hydrophobic pocket in the beta trefoil domain of CSL/CBF1 through a short peptide motif which closely resembles a motif found in Notch but does not strictly follow the ΦWΦP consensus conserved in human and mouse Notch proteins. Our results suggest that vIRF4 might compete with Notch for CSL/CBF1 binding and signaling. PMID:20861242

  17. Kaposi's Sarcoma-Associated Herpesvirus Viral Interferon Regulatory Factor 4 (vIRF4/K10) Is a Novel Interaction Partner of CSL/CBF1, the Major Downstream Effector of Notch Signaling▿

    PubMed Central

    Heinzelmann, Katharina; Scholz, Barbara A.; Nowak, Agnes; Fossum, Even; Kremmer, Elisabeth; Haas, Juergen; Frank, Ronald; Kempkes, Bettina

    2010-01-01

    In cells infected with the Kaposi's sarcoma-associated herpesvirus (KSHV), CSL/CBF1 signaling is essential for viral replication and promotes the survival of KSHV-infected cells. CSL/CBF1 is a DNA adaptor molecule which recruits coactivator and corepressor complexes to regulate viral and cellular gene transcription and which is a major downstream effector molecule of activated Notch. The interaction of KSHV RTA and LANA with CSL/CBF1 has been shown to balance the lytic and latent viral life cycle. Here we report that a third KSHV protein, viral interferon regulatory factor 4 (vIRF4/K10), but none of the three other KSHV-encoded vIRFs, interacts with CSL/CBF1. Two regions of vIRF4 with dissimilar affinities contribute to CSL/CBF1 binding. Similar to Notch, vIRF4 targets the hydrophobic pocket in the beta trefoil domain of CSL/CBF1 through a short peptide motif which closely resembles a motif found in Notch but does not strictly follow the ΦWΦP consensus conserved in human and mouse Notch proteins. Our results suggest that vIRF4 might compete with Notch for CSL/CBF1 binding and signaling. PMID:20861242

  18. Dynamics of Aqueous Foam Drops

    NASA Technical Reports Server (NTRS)

    Akhatov, Iskander; McDaniel, J. Gregory; Holt, R. Glynn

    2001-01-01

    We develop a model for the nonlinear oscillations of spherical drops composed of aqueous foam. Beginning with a simple mixture law, and utilizing a mass-conserving bubble-in-cell scheme, we obtain a Rayleigh-Plesset-like equation for the dynamics of bubbles in a foam mixture. The dispersion relation for sound waves in a bubbly liquid is then coupled with a normal modes expansion to derive expressions for the frequencies of eigenmodal oscillations. These eigenmodal (breathing plus higher-order shape modes) frequencies are elicited as a function of the void fraction of the foam. A Mathieu-like equation is obtained for the dynamics of the higher-order shape modes and their parametric coupling to the breathing mode. The proposed model is used to explain recently obtained experimental data.

  19. Who is dropping your course?

    NASA Astrophysics Data System (ADS)

    Storrs, Alex; Ghent, C.; Labattaglia, R.

    2011-01-01

    We present an analysis of pre and post instruction instruments in a basic astronomy course. This analysis is built on the Light and Spectroscopy Concept Inventory (LSCI, Bardar et al. 2007). In addition to assessing our student's gain in knowledge of this fundamental topic, we have added some demographic questions. While the primary purpose is to compare the gain in knowledge during a semester of instruction to changes in instruction, we also look at the demographics of students who take the pretest but not the posttest. These students are usually excluded from this type of analysis. We look for trends in the demographic information among students who drop the course, and suggest ways to make the course more palatable. References: Bardar et al., 2007: "Development and Validation of the Light and Spectroscopy Concept Inventory", Astr. Ed. Rev. 5(2), 103-113

  20. Drop processes in natural clouds

    NASA Technical Reports Server (NTRS)

    Latham, J.

    1982-01-01

    A model of the diffusive mixing of dry and cloudy air, a process considered to be fundamental to the development of natural clouds, is presented. Water drops are formed at the cloud base by condensation upon nuclei and as they rise they grow by vapor diffusion in the slightly supersaturated environment of the clouds. Turbulent mixing between cloudy air and undersaturated air entrained from outside produces fluctuations in supersaturation, not linked to changes in vertical velocity, which cause broadening of the condensate spectrum and the rapid production of droplets large enough to engage in growth by coalescence. The probabilities of permanent union or the production of satellite droplets following the collision of a pair of raindrops is a sensitive function of several parameters. In some circumstances electrohydrodynamic bursting may influence the properties of clouds.

  1. Magnetically focused liquid drop radiator

    DOEpatents

    Botts, Thomas E.; Powell, James R.; Lenard, Roger

    1986-01-01

    A magnetically focused liquid drop radiator for application in rejecting rgy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.

  2. Magnetically focused liquid drop radiator

    DOEpatents

    Botts, T.E.; Powell, J.R.; Lenard, R.

    1984-12-10

    A magnetically focused liquid drop radiator for application in rejecting energy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.

  3. Micro-explosion of compound drops

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Kuei; Lin, Ta-Hui

    2014-08-01

    Introducing water into spray combustion systems, by either water-in-oil emulsification or supplementary water injection, is one of the major techniques for combustion improvement and NOx reduction. Plentiful researches are available on combustion of water-in-oil emulsion fuel drops. The emulsified liquid is a heterogeneous mixture of immiscible liquids. One component forms the continuous phase and the other component forms the discrete phase. The discrete phase consists of globules of the one fluid that are suspended in the continuous phase fluid. Water-in-oil emulsions are commonly considered for combustion applications because emulsions can result in micro-explosion, thereby reducing the average drop diameter to enhance liquid vaporization, and suppressing the formation of soot and NOx. However, the water addition generally does not exceed about 20% for smooth engine operations[!, 21. The combustion characteristics and micro-explosion of emulsion drop were studied by many researchers. The micro-explosion of water in fuel emulsion drops was caused by very fast growth of superheated water vapor bubbles, its superheat limits must be lower than the boiling point temperature of the fuel. These bubbles were primarily governed by the pressure difference between the superheated vapor and the liquid, and by the inertia imparted to the liquid by the motion of the bubble surface[3 6 In this study, we used a coaxial nozzle to generation the multi-component drop. The different type of water-in-oil fuel drops called the compound drops. Unlike an emulsion drop, a compound drop consists of a water core and a fuel shell, which can originate from the phase separation of emulsion[7, 81 or a water drop colliding with a fuel drop[9, 101 Burning and micro-explosion of compound drops have been found to be distinct from those of emulsion drops[9-111 Wang et al.[9 , 101 studied the combustion characteristics of collision merged alkane-water drops. The merged drops appeared in adhesive

  4. Planar Microfluidic Drop Splitting and Merging

    NASA Astrophysics Data System (ADS)

    Collignon, Sean; Friend, James; Yeo, Leslie; MAD-LAB Team

    2015-11-01

    Open drop microfluidic platforms offer attractive alternatives to closed microchannel devices, however, to be effective they require efficient schemes for planar drop transport and manipulation. While there are many methods that have been reported for drop transport, it is far more difficult to carry out drop operations of dispensing, merging and splitting. In this work, we introduce a novel alternative to merge and split drops using laterally-offset modulated surface acoustic waves (SAWs). To do so, the energy delivery into the drop is modulated to induce drop stretching. Upon removal of the SAW energy, capillary forces at the center of the elongated drop drain the capillary bridge region towards both ends, resulting in its collapse and consequential splitting of the drop. This occurs only below a critical Ohnesorge number, a balance between the viscous forces that retard the drainage and the sufficiently large capillary forces that cause the liquid bridge to pinch. By this scheme we show the possibility of both reliable symettric splitting of a drop with an average deviation in droplet volumes of only around 4%, and no greater than 10%, as well as asymmetric splitting, by tuning the input energy to the device--thus presenting a comparable alternative to electrowetting.

  5. Non-coalescence of oppositely charged drops.

    PubMed

    Ristenpart, W D; Bird, J C; Belmonte, A; Dollar, F; Stone, H A

    2009-09-17

    Electric fields induce motion in many fluid systems, including polymer melts, surfactant micelles and colloidal suspensions. Likewise, electric fields can be used to move liquid drops. Electrically induced droplet motion manifests itself in processes as diverse as storm cloud formation, commercial ink-jet printing, petroleum and vegetable oil dehydration, electrospray ionization for use in mass spectrometry, electrowetting and lab-on-a-chip manipulations. An important issue in practical applications is the tendency for adjacent drops to coalesce, and oppositely charged drops have long been assumed to experience an attractive force that favours their coalescence. Here we report the existence of a critical field strength above which oppositely charged drops do not coalesce. We observe that appropriately positioned and oppositely charged drops migrate towards one another in an applied electric field; but whereas the drops coalesce as expected at low field strengths, they are repelled from one another after contact at higher field strengths. Qualitatively, the drops appear to 'bounce' off one another. We directly image the transient formation of a meniscus bridge between the bouncing drops, and propose that this temporary bridge is unstable with respect to capillary pressure when it forms in an electric field exceeding a critical strength. The observation of oppositely charged drops bouncing rather than coalescing in strong electric fields should affect our understanding of any process involving charged liquid drops, including de-emulsification, electrospray ionization and atmospheric conduction. PMID:19759616

  6. Leidenfrost drops on a heated liquid pool

    NASA Astrophysics Data System (ADS)

    Maquet, L.; Sobac, B.; Darbois-Texier, B.; Duchesne, A.; Brandenbourger, M.; Rednikov, A.; Colinet, P.; Dorbolo, S.

    2016-09-01

    We show that a volatile liquid drop placed at the surface of a nonvolatile liquid pool warmer than the boiling point of the drop can be held in a Leidenfrost state even for vanishingly small superheats. Such an observation points to the importance of the substrate roughness, negligible in the case considered here, in determining the threshold Leidenfrost temperature. A theoretical model based on the one proposed by Sobac et al. [Phys. Rev. E 90, 053011 (2014), 10.1103/PhysRevE.90.053011] is developed in order to rationalize the experimental data. The shapes of the drop and of the liquid substrate are analyzed. The model notably provides scalings for the vapor film thickness profile. For small drops, these scalings appear to be identical to the case of a Leidenfrost drop on a solid substrate. For large drops, in contrast, they are different, and no evidence of chimney formation has been observed either experimentally or theoretically in the range of drop sizes considered in this study. Concerning the evaporation dynamics, the radius is shown to decrease linearly with time whatever the drop size, which differs from the case of a Leidenfrost drop on a solid substrate. For high superheats, the characteristic lifetime of the drops versus the superheat follows a scaling law that is derived from the model, but, at low superheats, it deviates from this scaling by rather saturating.

  7. Trapping of drops by wetting defects

    PubMed Central

    't Mannetje, Dieter; Ghosh, Somnath; Lagraauw, Rudy; Otten, Simon; Pit, Arjen; Berendsen, Christian; Zeegers, Jos; van den Ende, Dirk; Mugele, Frieder

    2014-01-01

    Controlling the motion of drops on solid surfaces is crucial in many natural phenomena and technological processes including the collection and removal of rain drops, cleaning technology and heat exchangers. Topographic and chemical heterogeneities on solid surfaces give rise to pinning forces that can capture and steer drops in desired directions. Here we determine general physical conditions required for capturing sliding drops on an inclined plane that is equipped with electrically tunable wetting defects. By mapping the drop dynamics on the one-dimensional motion of a point mass, we demonstrate that the trapping process is controlled by two dimensionless parameters, the trapping strength measured in units of the driving force and the ratio between a viscous and an inertial time scale. Complementary experiments involving superhydrophobic surfaces with wetting defects demonstrate the general applicability of the concept. Moreover, we show that electrically tunable defects can be used to guide sliding drops along actively switchable tracks—with potential applications in microfluidics. PMID:24721935

  8. A Different Cone: Bursting Drops in Solids

    NASA Astrophysics Data System (ADS)

    Zhao, Xuanhe

    2013-03-01

    Drops in fluids tend to be spheres--a shape that minimizes surface energy. In thunderstorm clouds, drops can become unstable and emit thin jets when charged beyond certain limits. The instability of electrified drops in gases and liquids has been widely studied and used in applications including ink-jet printing, electrospinning nano-fibers, microfluidics and electrospray ionization. Here we report a different scenario: drops in solids become unstable and burst under sufficiently high electric fields. We find the instability of drops in solids morphologically resembles that in liquids, but the critical electric field for the instability follows a different scaling due to elasticity of solids. Our observations and theoretical models not only advance the fundamental understanding of electrified drops but also suggest a new failure mechanism of high-energy-density dielectric polymers, which have diverse applications ranging from capacitors for power grids and electric vehicles to muscle-like transducers for soft robots and energy harvesting.

  9. Coalescence dynamics of viscous conical drops

    NASA Astrophysics Data System (ADS)

    Lu, Jiakai; Fang, Shengyang; Corvalan, Carlos M.

    2016-02-01

    When two oppositely charged drops come into light contact, a liquid meniscus bridge with double-cone geometry forms between the drops. Recent experiments have demonstrated the existence of a critical cone angle above which the meniscus bridge pinches off and the drops do not coalesce. This striking behavior—which has implications for processes ranging from the coarsening of emulsions to electrospray ionization in mass spectrometry—has been studied theoretically and experimentally for inertial liquid drops. Little is known, however, about the influence of the liquid viscosity on the critical cone angle. Here, we use high-fidelity numerical simulations to gain insight into the coalescence dynamics of conical drops at intermediate Reynolds numbers. The simulations, which account for viscous, inertial, and surface tension effects, predict that the critical cone angle increases as the viscosity of the drops decreases. When approaching the inertial regime, however, the predicted critical angle quickly stabilizes at approximately 27∘, as observed in experiments.

  10. Hydrodynamic instability and drop fragmentation modes

    NASA Astrophysics Data System (ADS)

    Girin, A. G.

    1985-05-01

    A linear analysis of the stability of the drop surface is employed to evaluate the dispersion parameters and to propose mechanisms for several types of degradation. The calculations show that in the Weber number range from 5 to 60 the drop is subjected to periodic perturbations whose wavelengths are larger than the initial drop diameter and comparable to the diameter of the deformed drop. The case where half-wavelength is approximately equal to the drop diameter corresponds to the formation of a parachute shape of the deformed drop; larger Weber numbers (and, correspondingly, smaller wavelengths) lead to the formation of a 'claviform'. A similar approach can be assumed to study the interphase interaction leading to degradation in other systems, such as bubble and film systems.

  11. Equilibrium shapes of acoustically levitated drops

    NASA Astrophysics Data System (ADS)

    Trinh, E. H.; Hsu, C.-J.

    1986-05-01

    The quantitative determination of the shape of liquid drops levitated in an ultrasonic standing wave has provided experimental data on the radiation pressure-induced deformations of freely suspended liquids. Within the limits of small deviations from the spherical shape and small drop diameter relative to the acoustic wavelength, an existing approximate theory yields a good agreement with experimental evidence. The data were obtained for millimeter and submillimeter drops levitated in air under 1 g, where g is the sea level gravitational acceleration.

  12. Surface-Controlled Drop Oscillations in Space

    NASA Technical Reports Server (NTRS)

    Holt, R. Glynn; Tian, Yuren; Janovsky, Joseph; Apfel, Robert E.

    1996-01-01

    Large liquid drops were deformed by an acoustic standing wave in a resonant air chanber called the Drop Physics Module, which was carried on Space Shuttle Columbia as part of the second United States Microgravity Laboratory mission. When this deforming force was suddenly reduced, the drops executed free oscillations about a perfect sherical equilibrium. Results are presented for pure water and aqueous solutions of soluble surfactants. [PACS: 43.25.U, 47.55Dz, 68.10.Cr, 83.10.-y].

  13. Rapid Drop Dynamics During Superhydrophobic Condensation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaodong; Boreyko, Jonathan; Chen, Chuan-Hua

    2008-11-01

    Rapid drop motion is observed on superhydrophobic surfaces during condensation; condensate drops with diameter of order 10 μm can move at above 100G and 0.1 m/s. When water vapor condenses on a horizontal superhydrophobic surface, condensate drops move in a seemingly random direction. The observed motion is attributed to the energy released through coalescence of neighboring condensate drops. A scaling analysis captured the initial acceleration and terminal velocity. Our work is a step forward in understanding the dynamics of superhydrophobic condensation occurring in both natural water-repellant plants and engineered dropwise condensers.

  14. Drop motion induced by vertical vibrations

    NASA Astrophysics Data System (ADS)

    Sartori, Paolo; Quagliati, Damiano; Varagnolo, Silvia; Pierno, Matteo; Mistura, Giampaolo; Magaletti, Francesco; Massimo Casciola, Carlo

    2015-11-01

    We have studied the motion of liquid drops on an inclined plate subject to vertical vibrations. The liquids comprised distilled water and different aqueous solutions of glycerol, ethanol and isopropanol spanning the range 1-39 mm2 s-1 in kinematic viscosities and 40-72 mN m-1 in surface tension. At sufficiently low oscillating amplitudes, the drops are always pinned to the surface. Vibrating the plate above a certain amplitude yields sliding of the drop. Further increasing the oscillating amplitude drives the drop upward against gravity. In the case of the most hydrophilic aqueous solutions, this motion is not observed and the drop only slides downward. Images taken with a fast camera show that the drop profile evolves in a different way during sliding and climbing. In particular, the climbing drop experiences a much bigger variation in its profile during an oscillating period. Complementary numerical simulations of 2D drops based on a diffuse interface approach confirm the experimental findings. The overall qualitative behavior is reproduced suggesting that the contact line pinning due to contact angle hysteresis is not necessary to explain the drop climbing.

  15. Impact force of a falling drop

    NASA Astrophysics Data System (ADS)

    Soto, Dan; Clanet, Cristophe; Quere, David; Xavier Boutillon Collaboration

    2012-11-01

    Controlling droplet deposition is crucial in many industrial processes such as spraying pesticides on crops, inkjet printing or spray coating. Therefore, the dynamics of drop impacts have been extensively studied for more than one century. However, few literature describe the impacting force of a drop on a solid flat surface, although it might be a way to measure the size distribution of a collection of falling drops. We investigated experimentally how the instantaneous force at impact depends on impact velocity and drop radius. We also propose a new model to understand our observations. Physique et Mecanique des Milieux Heterogenes, CNRS, ESPCI, Paris France & Ladhyx, CNRS, Ecole Polytechnique, Palaiseau, France.

  16. Molecular and physiological changes in response to salt stress in Citrus macrophylla W plants overexpressing Arabidopsis CBF3/DREB1A.

    PubMed

    Alvarez-Gerding, Ximena; Espinoza, Carmen; Inostroza-Blancheteau, Claudio; Arce-Johnson, Patricio

    2015-07-01

    Plant stress induced by high salinity has leading to an important reduction in crop yields. Due to their tropical origin, citrus fruits are highly sensitive to salts. Rootstocks are the root system of fruit trees, regulating ion uptake and transport to the canopy. Therefore, increasing their salt tolerance could improve the salt tolerance of the fruit tree. For this, we genetically-transformed an important rootstock for lemon, Citrus macrophylla W, to constitutively express the CBF3/DREB1A gene from Arabidopsis, a well-studied salinity tolerance transcription factor. Transgenic lines showed normal size, with no dwarfism. Under salt stress, some transgenic lines showed greater growth, similar accumulation of chloride and sodium in the leaves and better stomatal conductance, in comparison to wild-type plants. Quantitative real-time analyses showed a similar expression of several CBF3/DREB1A target genes, such as COR15A, LEA 4/5, INV, SIP1, P5CS, GOLS, ADC2 and LKR/SDH, in transgenic lines and wild type plants, with the exception of INV that shows increased expression in line 4C15. Under salt stress, all measured transcript increased in both wild type and transgenics lines, with the exception of INV. Altogether, these results suggest a higher salt tolerance of transgenic C. macrophylla plants induced by the overexpression of AtCBF3/DREB1A. PMID:25914135

  17. Polyethylene glygol conjugated superoxide dismutase (PEG-SOD) improves recovery of hypercapnia cerebral blood flow (CBF) reactivity following transient global ischemia in piglets

    SciTech Connect

    Traystman, R.J.; Kirsch, J.R.; Helfaer, M.A.; Haun, S.E. )

    1991-03-15

    This study tested the hypothesis that alteration in hypercapnic cerebral blood flow (CBF) reactivity is due to oxygen-derived free radical mediated vascular damage and therefore could be inhibited by treatment with PEG-SOD. Pentobarbital anesthetized piglets were mechanically ventilated and hemodynamically monitored. CBF was measured at PaCO{sub 2} of approximately 25, 40 and 55 mmHg. Reactivity was tested in all piglets prior to and 2 hours following reperfusion from global ischemia. Control piglets received PEG prior to ischemia and at reperfusion. Experimental piglets received either PEG-SOD prior to ischemia and PEG at reperfusion or PEG prior to ischemia and PEG-SOD at reperfusion. During reperfusion cerebral perfusion pressure was maintained constant between groups by intravenous infusion of epinephrine. Pre-ischemic hypercapnic reactivity was not different between groups. At 2 hr reperfusion hypercapnic CBF reactivity in control piglets was diminished to forebrain and brainstem but hypercapnic reactivity was not different than preischemic values in either group receiving PEG-SOD. The authors conclude that administration of PEG-SOD, either prior to or following transient global ischemia, improves recovery of post-ischemic hypercapnic reactivity in piglets. This implicates oxygen-derived free radicals as important mediators of reperfusion injury in brain.

  18. Molecular and physiological changes in response to salt stress in Citrus macrophylla W plants overexpressing Arabidopsis CBF3/DREB1A.

    PubMed

    Alvarez-Gerding, Ximena; Espinoza, Carmen; Inostroza-Blancheteau, Claudio; Arce-Johnson, Patricio

    2015-07-01

    Plant stress induced by high salinity has leading to an important reduction in crop yields. Due to their tropical origin, citrus fruits are highly sensitive to salts. Rootstocks are the root system of fruit trees, regulating ion uptake and transport to the canopy. Therefore, increasing their salt tolerance could improve the salt tolerance of the fruit tree. For this, we genetically-transformed an important rootstock for lemon, Citrus macrophylla W, to constitutively express the CBF3/DREB1A gene from Arabidopsis, a well-studied salinity tolerance transcription factor. Transgenic lines showed normal size, with no dwarfism. Under salt stress, some transgenic lines showed greater growth, similar accumulation of chloride and sodium in the leaves and better stomatal conductance, in comparison to wild-type plants. Quantitative real-time analyses showed a similar expression of several CBF3/DREB1A target genes, such as COR15A, LEA 4/5, INV, SIP1, P5CS, GOLS, ADC2 and LKR/SDH, in transgenic lines and wild type plants, with the exception of INV that shows increased expression in line 4C15. Under salt stress, all measured transcript increased in both wild type and transgenics lines, with the exception of INV. Altogether, these results suggest a higher salt tolerance of transgenic C. macrophylla plants induced by the overexpression of AtCBF3/DREB1A.

  19. Redox Signaling and CBF-Responsive Pathway Are Involved in Salicylic Acid-Improved Photosynthesis and Growth under Chilling Stress in Watermelon

    PubMed Central

    Cheng, Fei; Lu, Junyang; Gao, Min; Shi, Kai; Kong, Qiusheng; Huang, Yuan; Bie, Zhilong

    2016-01-01

    Salicylic acid (SA) plays an important role in plant response to abiotic stresses. This study investigated the potential role of SA in alleviating the adverse effects of chilling stress on photosynthesis and growth in watermelon (Citrullus lanatus). Chilling stress induced the simultaneous accumulation of free and conjugated SA in watermelon plants, and the chilling-induced SA production was attributed to the phenylalanine ammonia-lyase pathway. Applying SA at moderate concentrations induced chilling tolerance, whereas inhibition of SA biosynthesis by L-α-aminooxy-β-phenylpropionic acid (AOPP) increased the photooxidation of PS II under chilling stress in watermelon, resulting in reduced photosynthesis and growth. Chilling induced a transient increase in the ratios of reduced to oxidized glutathione and reduced ascorbate to dehydroascorbate. Then, the expression of antioxidant genes was upregulated, and the activities of antioxidant enzymes were enhanced. Furthermore, SA-induced chilling tolerance was associated with cellular glutathione and ascorbate homeostasis, which served as redox signals to regulate antioxidant metabolism under chilling stress. AOPP treatment stimulated the chilling-induced expression of cold-responsive genes, particularly via C-repeat binding factors CBF3 and CBF4. These results confirm the synergistic role of SA signaling and the CBF-dependent responsive pathway during chilling stress in watermelon. PMID:27777580

  20. Value of Dynamic Susceptibility Contrast Perfusion MRI in the Acute Phase of Transient Global Amnesia

    PubMed Central

    Förster, Alex; Al-Zghloul, Mansour; Kerl, Hans U.; Böhme, Johannes; Mürle, Bettina; Groden, Christoph

    2015-01-01

    Purpose Transient global amnesia (TGA) is a transitory, short-lasting neurological disorder characterized by a sudden onset of antero- and retrograde amnesia. Perfusion abnormalities in TGA have been evaluated mainly by use of positron emission tomography (PET) or single-photon emission computed tomography (SPECT). In the present study we explore the value of dynamic susceptibility contrast perfusion-weighted MRI (PWI) in TGA in the acute phase. Methods From a MRI report database we identified TGA patients who underwent MRI including PWI in the acute phase and compared these to control subjects. Quantitative perfusion maps (cerebral blood flow (CBF) and volume (CBV)) were generated and analyzed by use of Signal Processing In NMR-Software (SPIN). CBF and CBV values in subcortical brain regions were assessed by use of VOI created in FIRST, a model-based segmentation tool in the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FSL). Results Five TGA patients were included (2 men, 3 women). On PWI, no relevant perfusion alterations were found by visual inspection in TGA patients. Group comparisons for possible differences between TGA patients and control subjects showed significant lower rCBF values bilaterally in the hippocampus, in the left thalamus and globus pallidus as well as bilaterally in the putamen and the left caudate nucleus. Correspondingly, significant lower rCBV values were observed bilaterally in the hippocampus and the putamen as well as in the left caudate nucleus. Group comparisons for possible side differences in rCBF and rCBV values in TGA patients revealed a significant lower rCBV value in the left caudate nucleus. Conclusions Mere visual inspection of PWI is not sufficient for the assessment of perfusion changes in TGA in the acute phase. Group comparisons with healthy control subjects might be useful to detect subtle perfusion changes on PWI in TGA patients. However, this should be confirmed in

  1. Core binding factor acute myeloid leukaemia and c-KIT mutations.

    PubMed

    Riera, Ludovica; Marmont, Filippo; Toppino, Daniela; Frairia, Chiara; Sismondi, Francesca; Audisio, Ernesta; Di Bello, Cristiana; D'Ardia, Stefano; Di Celle, Paola Francia; Messa, Emanuela; Inghirami, Giorgio; Vitolo, Umberto; Pich, Achille

    2013-05-01

    Core binding factor (CBF) acute myeloid leukaemia (AML) represents 5-8% of all AMLs and has a relatively favourable prognosis. However, activating c-KIT mutations are reported to be associated with higher risk of relapse and shorter survival. To verify the incidence and prognostic value of c-KIT mutations in CBF AML, we retrospectively analysed bone marrow samples of 23 consecutive adult patients with de novo CBF AML [14 inv(16) and 9 t(8;21)] treated at a single institution from 2000 to 2011. All patients received standard induction chemotherapy with cytarabine, idarubicin and etoposide; 13 underwent allogeneic stem cell transplantation. c-KIT mutations in exons 8, 9, 10, 11, 13, 14 and 17 were assessed by PCR amplification in combination with direct sequencing. c-KIT mutations (3 in exon 10 and 4 in exon 17) were detected in 7/23 (30.4%) patients, 3 with t(8;21) and 4 with inv(16). No difference in c-KIT mutation status was observed between cases with inv(16) or t(8;21) alone and cases with additional cytogenetic abnormalities. No association between gender, age, white blood cell and platelet count, peripheral blood and bone marrow blast cells at diagnosis, achievement of complete remission, cytogenetic risk groups and Wilms tumour gene 1 (WT1) levels was found. On the contrary, lactate dehydrogenase (LDH) values were higher in mutated than in non-mutated patients (p=0.01). Overall survival (OS) rates were longer in CBF compared to the other types of AML and disease-free survival (DFS) was longer in inv(16) than in t(8;21) AML. OS and DFS were similar in mutated and non-mutated CBF AML patients. Our results confirm a better prognosis for CBF AML than all other AML categories, and for inv(16) than t(8;21) AML. However, no prognostic value for c-KIT mutational status was found in our series. The association between LDH levels and c-KIT mutation would indicate a more active proliferation for mutated CBF AML. PMID:23467883

  2. Arterial Transit Time Mapping Obtained by Pulsed Continuous 3D ASL Imaging with Multiple Post-Label Delay Acquisitions: Comparative Study with PET-CBF in Patients with Chronic Occlusive Cerebrovascular Disease

    PubMed Central

    Tsujikawa, Tetsuya; Kimura, Hirohiko; Matsuda, Tsuyoshi; Fujiwara, Yasuhiro; Isozaki, Makoto; Kikuta, Ken-ichiro; Okazawa, Hidehiko

    2016-01-01

    Arterial transit time (ATT) is most crucial for measuring absolute cerebral blood flow (CBF) by arterial spin labeling (ASL), a noninvasive magnetic resonance (MR) perfusion assessment technique, in patients with chronic occlusive cerebrovascular disease. We validated ASL-CBF and ASL-ATT maps calculated by pulsed continuous ASL (pCASL) with multiple post-label delay acquisitions in patients with occlusive cerebrovascular disease. Fifteen patients underwent MR scans, including pCASL, and positron emission tomography (PET) scans with 15O-water to obtain PET-CBF. MR acquisitions with different post-label delays (1.0, 1.5, 2.0, 2.5 and 3.0 sec) were also obtained for ATT correction. The theoretical framework of 2-compartmental model (2CM) was also used for the delay compensation. ASL-CBF and ASL-ATT were calculated based on the proposed 2CM, and the effect on the CBF values and the ATT correction characteristics were discussed. Linear regression analyses were performed both on pixel-by-pixel and region-of-interest bases in the middle cerebral artery (MCA) territory. There were significant correlations between ASL-CBF and PET-CBF both for voxel values (r = 0.74 ± 0.08, slope: 0.87 ± 0.22, intercept: 6.1 ± 4.9) and for the MCA territorial comparison in both affected (R2 = 0.67, y = 0.83x + 6.3) and contralateral sides (R2 = 0.66, y = 0.74x + 6.3). ASL-ATTs in the affected side were significantly longer than those in the contralateral side (1.51 ± 0.41 sec and 1.12 ± 0.30 sec, respectively, p <0.0005). CBF measurement using pCASL with delay compensation was feasible and fairly accurate even in altered hemodynamic states. PMID:27275779

  3. 49 CFR 178.603 - Drop test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...). Bags—single-ply without a side seam, or multi-ply Three—(two drops per bag) First drop: Flat on a wide... feet). (C) Packing Group III: SG × 0.67 m (2.2 feet). (f) Criteria for passing the test. A package...

  4. Drop Ejection From an Oscillating Rod

    NASA Technical Reports Server (NTRS)

    Wilkes, E. D.; Basaran, O. A.

    1999-01-01

    The dynamics of a drop of a Newtonian liquid that is pendant from or sessile on a solid rod that is forced to undergo time-periodic oscillations along its axis is studied theoretically. The free boundary problem governing the time evolution of the shape of the drop and the flow field inside it is solved by a method of lines using a finite element algorithm incorporating an adaptive mesh. When the forcing amplitude is small, the drop approaches a limit cycle at large times and undergoes steady oscillations thereafter. However, drop breakup is the consequence if the forcing amplitude exceeds a critical value. Over a wide range of amplitudes above this critical value, drop ejection from the rod occurs during the second oscillation period from the commencement of rod motion. Remarkably, the shape of the interface at breakup and the volume of the primary drop formed are insensitive to changes in forcing amplitude. The interface shape at times close to and at breakup is a multi-valued function of distance measured along the rod axis and hence cannot be described by recently popularized one-dimensional approximations. The computations show that drop ejection occurs without the formation of a long neck. Therefore, this method of drop formation holds promise of preventing formation of undesirable satellite droplets.

  5. Drops and Bubble in Materials Science

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1982-01-01

    The formation of extended p-n junctions in semiconductors by drop migration, mechanisms and morphologies of migrating drops and bubbles in solids and nucleation and corrections to the Volmer-Weber equations are discussed. Bubble shrinkage in the processing of glass, the formation of glass microshells as laser-fusion targets, and radiation-induced voids in nuclear reactors were examined.

  6. Mixing in colliding, ultrasonically levitated drops.

    PubMed

    Chainani, Edward T; Choi, Woo-Hyuck; Ngo, Khanh T; Scheeline, Alexander

    2014-02-18

    Lab-in-a-drop, using ultrasonic levitation, has been actively investigated for the last two decades. Benefits include lack of contact between solutions and an apparatus and a lack of sample cross-contamination. Understanding and controlling mixing in the levitated drop is necessary for using an acoustically levitated drop as a microreactor, particularly for studying kinetics. A pulsed electrostatic delivery system enables addition and mixing of a desired-volume droplet with the levitated drop. Measurement of mixing kinetics is obtained by high-speed video monitoring of a titration reaction. Drop heterogeneity is visualized as 370 nl of 0.25 M KOH (pH: 13.4) was added to 3.7 μL of 0.058 M HCl (pH: 1.24). Spontaneous mixing time is about 2 s. Following droplet impact, the mixed drop orbits the levitator axis at about 5 Hz during homogenization. The video's green channel (maximum response near 540 nm) shows the color change due to phenolphthalein absorption. While mixing is at least an order of magnitude faster in the levitated drop compared with three-dimensional diffusion, modulation of the acoustic waveform near the surface acoustic wave resonance frequency of the levitated drop does not substantially reduce mixing time. PMID:24460103

  7. [Nasal drops addiction--the case report].

    PubMed

    Korzeniowska, Katarzyna; Simon, Karolina; Jabłecka, Anna

    2012-01-01

    The article describes the case of 34-years old man, who has used nasal drops with xylomethazoline for three years. Health consequence of uncontrolled use of the drops and treatment were prescribed. Described problem confirms the need of physicians and pharmacists cooperation to limit the problem of drug-addiction. PMID:23421118

  8. Spatial Distribution of Large Cloud Drops

    NASA Technical Reports Server (NTRS)

    Marshak, A.; Knyazikhin, Y.; Larsen, M.; Wiscombe, W.

    2004-01-01

    By analyzing aircraft measurements of individual drop sizes in clouds, we have shown in a companion paper (Knyazikhin et al., 2004) that the probability of finding a drop of radius r at a linear scale l decreases as l(sup D(r)) where 0 less than or equal to D(r) less than or equal to 1. This paper shows striking examples of the spatial distribution of large cloud drops using models that simulate the observed power laws. In contrast to currently used models that assume homogeneity and therefore a Poisson distribution of cloud drops, these models show strong drop clustering, the more so the larger the drops. The degree of clustering is determined by the observed exponents D(r). The strong clustering of large drops arises naturally from the observed power-law statistics. This clustering has vital consequences for rain physics explaining how rain can form so fast. It also helps explain why remotely sensed cloud drop size is generally biased and why clouds absorb more sunlight than conventional radiative transfer models predict.

  9. University Drop-Out: An Italian Experience

    ERIC Educational Resources Information Center

    Belloc, Filippo; Maruotti, Antonello; Petrella, Lea

    2010-01-01

    University students' drop-out is a crucial issue for the universities' efficiency evaluation and funding. In this paper, we analyze the drop-out rate of the Economics and Business faculty of Sapienza University of Rome. We use administrative data on 9,725 undergraduates students enrolled in three-years bachelor programs from 2001 to 2007 and…

  10. Drop tower with no aerodynamic drag

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Jr.

    1981-01-01

    Cooling air accelerated to match velocity of falling object eliminates drag. 3 meter drop tower with suction fan and specific geometry causes air to accelerate downward at 1 g. Although cooling of molten material released from top is slow because surrounding air moves with it, drop remains nearly spherical.

  11. CPAS Preflight Drop Test Analysis Process

    NASA Technical Reports Server (NTRS)

    Englert, Megan E.; Bledsoe, Kristin J.; Romero, Leah M.

    2015-01-01

    Throughout the Capsule Parachute Assembly System (CPAS) drop test program, the CPAS Analysis Team has developed a simulation and analysis process to support drop test planning and execution. This process includes multiple phases focused on developing test simulations and communicating results to all groups involved in the drop test. CPAS Engineering Development Unit (EDU) series drop test planning begins with the development of a basic operational concept for each test. Trajectory simulation tools include the Flight Analysis and Simulation Tool (FAST) for single bodies, and the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) simulation for the mated vehicle. Results are communicated to the team at the Test Configuration Review (TCR) and Test Readiness Review (TRR), as well as at Analysis Integrated Product Team (IPT) meetings in earlier and intermediate phases of the pre-test planning. The ability to plan and communicate efficiently with rapidly changing objectives and tight schedule constraints is a necessity for safe and successful drop tests.

  12. Acute Bronchitis

    MedlinePlus

    ... tightness. There are two main types of bronchitis: acute and chronic. Most cases of acute bronchitis get better within several days. But your ... that cause colds and the flu often cause acute bronchitis. These viruses spread through the air when ...

  13. Electrolytic drops in an electric field: A numerical study of drop deformation and breakup

    NASA Astrophysics Data System (ADS)

    Pillai, R.; Berry, J. D.; Harvie, D. J. E.; Davidson, M. R.

    2015-07-01

    The deformation and breakup of an axisymmetric, conducting drop suspended in a nonconducting medium and subjected to an external electric field is numerically investigated here using an electrokinetic model. This model uses a combined level set-volume of fluid formulation of the deformable surfaces, along with a multiphase implementation of the Nernst-Planck equation for transport of ions, that allows for varying conductivity inside the drop. A phase diagram, based on a parametric study, is used to characterize the stability conditions. Stable drops with lower ion concentration are characterized by longer drop shapes than those achieved at higher ion concentrations. For higher drop ion concentration, greater charge accumulation is observed at drop tips. Consequently, such drops break up by pinching off rather than tip streaming. The charge contained in droplets released from unstable drops is shown to increase with drop ion concentration. These dynamic drop behaviors depend on the strength of the electric field and the concentration of ions in the drop and result from the interplay between the electric forces arising from the permittivity jump at the drop interface and the ions in the bulk.

  14. Pattern formation in evaporating drops

    NASA Astrophysics Data System (ADS)

    Li, Fang-I.

    The redistribution of organic solutes during drop evaporation is a nanoscale self assembly process with relevance to technologies ranging from inkjet printing of organic displays to synthesis of bio-smart interfaces for sensing and screening. Atomic force microscopy studies comparing the behavior of different generation dendrimers with different surface chemistry in two solvent alcohols on mica substrates confirm that the detailed morphologies of condensed dendrimer ring structures resulting from micro-droplet evaporation sensitively depend on the surface chemistry, the solute evaporation rate and the dendrimer generation. For the dilute concentration studied here the presence of periodically 'scalloped' molecular rings is ubiquitous. The instability wavelength of the scalloped rings is found to be proportional to the width of the ring, similar to observations of the rim instability in dewetting holes. The effect of the surface chemistry of the dendrimer molecules is obvious in the detailed structure of the self assembled rings. Varying the chain length of solvent alcohol leads to modification of ring patterns. The influence of dendrimer generation on ring structure primarily reflects the increase in dendrimer density with generation number. The evolution of G2-50%C12 -pentanol rings as a function of dendrimer concentration is also described. High surface mobility and phase transformation phenomena in condensed, micro-scale dendrimer structures are documented, again using atomic force microscopy. Stratified dendrimer rings undergo dramatic temperature, time and dendrimer generation dependent morphological changes associated with large-scale molecular rearrangements and partial melting. These transformations produce ring structures consisting of a highly stable first monolayer of the scalloped structure in equilibrium with spherical cap shaped dendrimer islands that form at the center of each pre-existing scallop (creating a 'pearl necklace' structure). Analysis of

  15. The Parkfield Stress Drop Controversy

    NASA Astrophysics Data System (ADS)

    Abercrombie, R. E.; Nadeau, R. M.

    2003-12-01

    Nadeau et al. (1995) found that the seismicity on the San Andreas fault at Parkfield is highly clustered. Individual clusters consist of a sequence of near periodically repeating small earthquakes of similar seismic moment. Nadeau and Johnston (1998) compared the moments and timing of these repeating earthquakes (Mw < 2), and some larger events, with the surface creep rate on the fault to estimate the slip and stress drop (Δ σ ). They obtained conventional values (0.1 to 10 MPa) for the larger earthquakes, but Δ σ increased with decreasing Mw to extremely high values (> 1000 MPa) for the small earthquakes (Mw < 2). Such values are just about physically possible, but they are much higher than those estimated by seismic methods for small earthquakes elsewhere (e. g. Abercrombie 1995). These controversial high Δ σ estimates have sparked a number of theoretical and laboratory studies (e. g. Sammis & Rice 2000, Anooshepoor & Brune 2001, Beeler 2001) aimed at investigating whether the observations could result from earthquakes with more normal Δ σ occurring within the unusual tectonic setting at Parkfield. Lane & Nadeau (2000, 2002) considered whether localized patches of high Δ σ would be resolvable by standard seismic methods. However, to date nobody has used seismic methods to determine source parameters for these controversial small earthquakes at Parkfield. We use closely located earthquakes of different sizes (for example, the sub-clusters of cluster CL14, Nadeau et al., 1995, Mw-0.2 to 1), recorded on the HRSN borehole network to analyse the source parameters. The smaller earthquakes are used as empirical Green's functions to resolve source processes of the larger events. Preliminary results from the earthquakes in cluster CL14 result in a source dimension of about 25 m and Δ σ of about 1 MPa for the Mw1 earthquakes, assuming that rupture velocity is the same as that for large earthquakes. We also resolve source-time functions for these earthquakes at

  16. Condensation on surface energy gradient shifts drop size distribution toward small drops.

    PubMed

    Macner, Ashley M; Daniel, Susan; Steen, Paul H

    2014-02-25

    During dropwise condensation from vapor onto a cooled surface, distributions of drops evolve by nucleation, growth, and coalescence. Drop surface coverage dictates the heat transfer characteristics and depends on both drop size and number of drops present on the surface at any given time. Thus, manipulating drop distributions is crucial to maximizing heat transfer. On earth, manipulation is achieved with gravity. However, in applications with small length scales or in low gravity environments, other methods of removal, such as a surface energy gradient, are required. This study examines how chemical modification of a cooled surface affects drop growth and coalescence, which in turn influences how a population of drops evolves. Steam is condensed onto a horizontally oriented surface that has been treated by silanization to deliver either a spatially uniform contact angle (hydrophilic, hydrophobic) or a continuous radial gradient of contact angles (hydrophobic to hydrophilic). The time evolution of number density and associated drop size distributions are measured. For a uniform surface, the shape of the drop size distribution is unique and can be used to identify the progress of condensation. In contrast, the drop size distribution for a gradient surface, relative to a uniform surface, shifts toward a population of small drops. The frequent sweeping of drops truncates maturation of the first generation of large drops and locks the distribution shape at the initial distribution. The absence of a shape change indicates that dropwise condensation has reached a steady state. Previous reports of heat transfer enhancement on chemical gradient surfaces can be explained by this shift toward smaller drops, from which the high heat transfer coefficients in dropwise condensation are attributed to. Terrestrial applications using gravity as the primary removal mechanism also stand to benefit from inclusion of gradient surfaces because the critical threshold size required for

  17. The Drop Tower Bremen -An Overview

    NASA Astrophysics Data System (ADS)

    von Kampen, Peter; Könemann, Thorben; Rath, Hans J.

    The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University of Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of ZARM`s drop tower began. Since its inau-guration in September 1990, the eye-catching Drop Tower Bremen with a height of 146m and its characteristic glass roof has become twice a landmark on the campus of the University of Bremen and the emblem of the technology park Bremen. As such an outstanding symbol of space science in Bremen the drop tower provides an european unique facility for experiments under conditions of high-quality weightlessness with residual gravitational accelerations in the microgravity regime. The period of maximum 4.74s of each freely falling experiment at the Drop Tower Bremen is only limited by the height of the drop tower vacuum tube, which was fully manufactured of steal and enclosed by an outer concrete shell. Thus, the pure free fall height of each microgravity drop experiment is approximately 110m. By using the later in-stalled catapult system established in 2004 ZARM`s short-term microgravity laboratory is able to nearly double the time of free fall. This world-wide inimitable capsule catapult system meets scientists` demand of extending the period of weightlessness. During the catapult operation the experiment capsule performs a vertical parabolic flight within the drop tower vacuum tube. In this way the time of microgravity can be extended to slightly over 9s. Either in the drop or in the catapult operation routine the repetition rates of microgravity experiments at ZARM`s drop tower facility are the same, generally up to 3 times per day. In comparison to orbital platforms the ground-based laboratory Drop Tower Bremen represents an economic alternative with a permanent access to weightlessness on earth. Moreover, the exceptional high quality of weightlessness in order of 1e-6 g (in the frequency range below 100

  18. Nonmonotonic Response of Drop Impacting Liquid Film

    NASA Astrophysics Data System (ADS)

    Tang, Xiaoyu; Saha, Abhishek; Zhu, Delin; Sun, Chao; Law, Chung K.

    2015-11-01

    Drop impact on liquid film is ubiquitous in both natural phenomena and industrial applications. The dynamics of the gas layer trapped between the drop and the deformed liquid surface play a crucial role in determining the impact outcomes. However, a quantitative measurement of this gas layer dynamics is extremely challenging because it is hidden behind the deformed liquid film. In this study, high-speed white light interferometry enables the measurement of the gas layer dynamics during the drop impact with high resolutions and is complemented by side view shadowgraphy to observe the penetration process below the liquid surface. Drop impacting with different inertia onto liquid film with various thicknesses is systematically studied to obtain a phase diagram of different outcomes in the h/R-We space, where h/R is the liquid thickness normalized by drop radius, and We is the drop Weber number. It is observed that there exists a critical WeC beyond which the drop always merges with the liquid film. However, for `subcritical' conditions, there exists a merging peninsula in otherwise globally bouncing region. Across this peninsula, as the liquid film thickness increases, the impact outcome transits from bouncing to merging and to bouncing again. The merging time within this peninsula is longer compared to its `supercritical' counterpart, indicating different merging mechanisms. Based on scaling analysis, the boundaries between different zones are identified and compared with experiments.

  19. Pattern formation in drying drops of blood

    NASA Astrophysics Data System (ADS)

    Brutin, D.; Sobac, B.; Loquet, B.; Sampol, J.

    2011-01-01

    The drying of a drop of human blood exhibits coupled physical mechanisms, such as Marangoni flow, evaporation and wettability. The final stage of a whole blood drop evaporation reveals regular patterns with a good reproducibility for a healthy person. Other experiments on anaemic and hyperlipidemic people were performed, and different patterns were revealed. The flow motion inside the blood drop is observed and analyzed with the use of a digital camera: the influence of the red blood cells (RBCs) motion is revealed at the drop periphery as well as its consequences on the final stage of drying. The mechanisms which lead to the final pattern of the dried blood drops are presented and explained on the basis of fluid mechanics in conjunction with the principles of haematology. The blood drop evaporation process is evidenced to be driven only by Marangoni flow. The same axisymetric pattern formation is observed, and can be forecast for different blood drop diameters. The evaporation mass flux can be predicted with a good agreement, assuming only the knowledge of the colloids mass concentration.

  20. Conically shaped drops in electric fields

    NASA Astrophysics Data System (ADS)

    Stone, Howard A.; Brenner, Michael P.; Lister, John R.

    1996-11-01

    When an electric field is applied to a dielectric liquid containing a suspended immiscible fluid drop, the drop deforms into a prolate ellipsoidal shape. Above a critical field strength the drop develops conical ends, as first observed by Zeleny [Phys. Rev. 10, 1 (1917)] and Wilson & Taylor [Proc. Camb. Phil. Soc. 22, 728 (1925)] for, respectively, the case of conducting drops and soap films in air. The case of two dielectric liquids was studied recently using a slender drop approximation by Li, Halsey & Lobkovsky [Europhys. Lett 27, 575 (1994)]. In this presentation we further develop the slender body approximation to obtain coupled ordinary differential equations for the electric field and the drop shape. Analytical formulae are derived which approximately give the cone angle as a function of the dielectric constant ratio between the two fluids, and the minimum applied electric field at which conical tips first form as a function of the dielectric constant ratio. Finally, drops shapes are calculated numerically and compared with the common prolate shape assumption.

  1. Drop rebound in clouds and precipitation

    NASA Technical Reports Server (NTRS)

    Ochs, H. T., III; Beard, K. V.

    1982-01-01

    The possibility of rebound for colliding cloud drops was measured by determining the collection efficiency. The collection efficiency for 17 size pairs of relatively uncharged drops in over 500 experimental runs was measured using two techniques. The collection efficiencies fall in a narrow range of 0.60 to 0.70 even though the collection drop was varied between 63 and 326 microns and the size ratio from 0.05 to 0.33. In addition the measured values of collection efficiencies (Epsilon) were below the computed values of collision efficiencies (E) for rigid spheres. Therefore it was concluded that rebound was occurring for these sizes since inferred coalescence (epsilon = Epsilon/E) efficiencies are about 0.6 yo 0.8. At a very small size ratio (r/R = p = 0.05, R = 326 microns) the coalescence efficiency inferred is in good agreement with the experimental findings for a supported collector drop. At somewhat large size ratios the inferred values of epsilon are well above results of supported drop experiments, but show a slight correspondence in collected drop size dependency to two models of drop rebound. At a large size ratio (p = 0.73, R = 275) the inferred coalescence efficiency is significantly different from all previous results.

  2. Mitomycin eye drops as treatment for pterygium.

    PubMed

    Singh, G; Wilson, M R; Foster, C S

    1988-06-01

    The authors used an antineoplastic-antibiotic agent, mitomycin, in the form of eye drops as adjunctive treatment for primary and recurrent pterygia after surgical excision. Sixteen primary and four recurrent pterygia were treated with 1.0 mg/ml mitomycin eye drops, 14 primary and 10 recurrent pterygia were treated with 0.4 mg/ml mitomycin eye drops, and 18 primary pterygia were treated with placebo eye drops. Postoperative follow-up for the eyes treated with mitomycin eye drops ranged from 3 to 34 weeks (mean, 23 weeks). One of 44 pterygia treated with mitomycin recurred after 5 months (recurrence rate, 2.3%), whereas 16 of 18 primary pterygia treated with placebo eye drops developed postoperative granulomas and recurrent pterygia with a mean postoperative period of 6 weeks (recurrence rate, 88.9%). Topical mitomycin (1.0 mg/ml) caused conjunctival irritation, excessive lacrimation, and mild superficial punctate keratitis. These topical side effects were minimized with the 0.4 mg/ml mitomycin dosage. No systemic toxicity was noted with either dosage. The authors believe that mitomycin eye drops is a safe and effective adjunct to surgical excision in the treatment of primary or recurrent pterygia, or both.

  3. Microjetting from wave focusing on oscillating drops

    NASA Astrophysics Data System (ADS)

    Thoroddsen, S. T.; Etoh, T. G.; Takehara, K.

    2007-05-01

    We present experimental observations of microjetting from an oscillating drop. The jet is generated by the focusing of axisymmetric capillary waves that overturn and collide at an apex of the drop. These jets are up to two orders of magnitude smaller than the original drops. We present two widely different configurations that produce such microjets. The first occurs on a satellite drop, produced by the pinch-off of a water drop from a vertical nozzle. The large oscillations following the contraction of the satellite bridge focus waves at the bottom, sending out a 30μm jet at 9.9m/s. The second jet arises when a water drop, containing surfactants, falls onto and passes through a hemispherical soap film. The gentle deformation of the drop creates a surface wave that focuses at its top, shooting out a tiny jet and entrapping a small bubble inside the drop. This jet is 16±5μm in diameter and emerges at 6.3m/s. In this configuration, the soap film wraps around the drop and acts as a sensor of the air flow, revealing that the liquid jet is preceded by a localized faster-moving air jet. The jetting in both configurations is quite robust and occurs even for slightly asymmetric conditions. These microjets appear for much lower values of the Reynolds and Weber numbers than previously observed, suggesting that free-surface jetting is not limited to the inviscid capillary-inertial regime, which has been the focus of much of the theoretical work.

  4. Condensation-induced jumping water drops.

    PubMed

    Narhe, R D; Khandkar, M D; Shelke, P B; Limaye, A V; Beysens, D A

    2009-09-01

    Water droplets can jump during vapor condensation on solid benzene near its melting point. This phenomenon, which can be viewed as a kind of micro scale steam engine, is studied experimentally and numerically. The latent heat of condensation transferred at the drop three phase contact line melts the substrate during a time proportional to R (the drop radius). The wetting conditions change and a spontaneous jump of the drop results in random direction over length approximately 1.5R , a phenomenon that increases the coalescence events and accelerates the growth. Once properly rescaled by the jump length scale, the growth dynamics is, however, similar to that on a solid surface. PMID:19905120

  5. Condensation-induced jumping water drops

    NASA Astrophysics Data System (ADS)

    Narhe, R. D.; Khandkar, M. D.; Shelke, P. B.; Limaye, A. V.; Beysens, D. A.

    2009-09-01

    Water droplets can jump during vapor condensation on solid benzene near its melting point. This phenomenon, which can be viewed as a kind of micro scale steam engine, is studied experimentally and numerically. The latent heat of condensation transferred at the drop three phase contact line melts the substrate during a time proportional to R (the drop radius). The wetting conditions change and a spontaneous jump of the drop results in random direction over length ˜1.5R , a phenomenon that increases the coalescence events and accelerates the growth. Once properly rescaled by the jump length scale, the growth dynamics is, however, similar to that on a solid surface.

  6. Condensation-induced jumping water drops.

    PubMed

    Narhe, R D; Khandkar, M D; Shelke, P B; Limaye, A V; Beysens, D A

    2009-09-01

    Water droplets can jump during vapor condensation on solid benzene near its melting point. This phenomenon, which can be viewed as a kind of micro scale steam engine, is studied experimentally and numerically. The latent heat of condensation transferred at the drop three phase contact line melts the substrate during a time proportional to R (the drop radius). The wetting conditions change and a spontaneous jump of the drop results in random direction over length approximately 1.5R , a phenomenon that increases the coalescence events and accelerates the growth. Once properly rescaled by the jump length scale, the growth dynamics is, however, similar to that on a solid surface.

  7. Rotation of ultrasonically levitated glycerol drops

    NASA Technical Reports Server (NTRS)

    Biswas, A.; Leung, E. W.; Trinh, E. H.

    1991-01-01

    Ultrasonic levitation is used to suspend single millimeter-size glycerol drops in a rectangular chamber. Audio-frequency laterally standing waves set up in the chamber are used to torque the suspended drops. The shape evolution of the drop under the combined effect of centrifugal forces and the acoustic radiation stress, along with its angular velocity are monitored, using video imaging and light scattering techniques. The results show good qualitative agreement with the theoretically predicted shape evolution as a function of angular velocity.

  8. Nanofluid Drop Evaporation: Experiment, Theory, and Modeling

    NASA Astrophysics Data System (ADS)

    Gerken, William James

    Nanofluids, stable colloidal suspensions of nanoparticles in a base fluid, have potential applications in the heat transfer, combustion and propulsion, manufacturing, and medical fields. Experiments were conducted to determine the evaporation rate of room temperature, millimeter-sized pendant drops of ethanol laden with varying amounts (0-3% by weight) of 40-60 nm aluminum nanoparticles (nAl). Time-resolved high-resolution drop images were collected for the determination of early-time evaporation rate (D2/D 02 > 0.75), shown to exhibit D-square law behavior, and surface tension. Results show an asymptotic decrease in pendant drop evaporation rate with increasing nAl loading. The evaporation rate decreases by approximately 15% at around 1% to 3% nAl loading relative to the evaporation rate of pure ethanol. Surface tension was observed to be unaffected by nAl loading up to 3% by weight. A model was developed to describe the evaporation of the nanofluid pendant drops based on D-square law analysis for the gas domain and a description of the reduction in liquid fraction available for evaporation due to nanoparticle agglomerate packing near the evaporating drop surface. Model predictions are in relatively good agreement with experiment, within a few percent of measured nanofluid pendant drop evaporation rate. The evaporation of pinned nanofluid sessile drops was also considered via modeling. It was found that the same mechanism for nanofluid evaporation rate reduction used to explain pendant drops could be used for sessile drops. That mechanism is a reduction in evaporation rate due to a reduction in available ethanol for evaporation at the drop surface caused by the packing of nanoparticle agglomerates near the drop surface. Comparisons of the present modeling predictions with sessile drop evaporation rate measurements reported for nAl/ethanol nanofluids by Sefiane and Bennacer [11] are in fairly good agreement. Portions of this abstract previously appeared as: W. J

  9. Electric field induced deformation of sessile drops

    NASA Astrophysics Data System (ADS)

    Corson, Lindsey; Tsakonas, Costas; Duffy, Brian; Mottram, Nigel; Brown, Carl; Wilson, Stephen

    2014-11-01

    The ability to control the shape of a drop with the application of an electric field has been exploited for many technological applications including measuring surface tension, producing an optical display device, and optimising the optical properties of microlenses. In this work we consider, both theoretically and experimentally, the deformation of pinned sessile drops with contact angles close to either 0° or 90° resting on the lower substrate inside a parallel plate capacitor due to an A.C. electric field. Using both asymptotic and numerical approaches we obtain predictive equations for the static and dynamic drop shape deformations as functions of the key experimental parameters (drop size, capacitor plate separation, electric field magnitude and contact angle). The asymptotic results agree well with the experimental results for a range of liquids. We gratefully acknowledge the financial support of EPSRC via research Grants EP/J009865 and EP/J009873.

  10. Rotating drops of axion dark matter

    NASA Astrophysics Data System (ADS)

    Davidson, Sacha; Schwetz, Thomas

    2016-06-01

    We consider how QCD axions produced by the misalignment mechanism could form galactic dark matter halos. We recall that stationary, gravitationally stable axion field configurations have the size of an asteroid with masses of order 10-13M⊙ (because gradient pressure is insufficient to support a larger object). We call such field configurations "drops." We explore whether rotating drops could be larger, and find that their mass could increase by a factor ˜10 . This mass is comparable to the mass of miniclusters generated from misalignment axions in the scenario where the axion is born after inflation. We speculate that misalignment axions today are in the form of drops, contributing to dark matter like a distribution of asteroids (and not as a coherent oscillating background field). We consider some observational signatures of the drops, which seem consistent with a galactic halo made of axion dark matter.

  11. Detachment of a single water drop

    NASA Astrophysics Data System (ADS)

    Chashechkin, Yu. D.; Prokhorov, V. E.

    2014-01-01

    The detachment process of a single water drop from a nozzle made of poorly wetted material is followed using high-speed video equipment. The formation and motion dynamics of various flow components are investigated. These are the drop itself; a liquid bridge (jumper), which connects the drop with the mother liquid; the primary satellite, which is formed from the jumper; and a microsatellite, which is thrown from the satellite and flies to the mother liquid. The strong influence of surface effects, under which the satellite initially moves upward and only at a certain time starts to fall along the ballistic trajectory, is established. Bounce of the microsatellite from the mother liquid, which precedes its absorption, is fixed. It is shown that a stable connection of the formation mechanism of satellites with the jumper dynamics opens the possibility of obtaining uniform-sized drops.

  12. Teen Birth Rates Drop, But Disparities Persist

    MedlinePlus

    ... Features Teen Birth Rates Drop, But Disparities Persist Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir The feature you selected is no longer available. In 10 seconds you will be automatically redirected to the CDC. ...

  13. Shapes of Bubbles and Drops in Motion.

    ERIC Educational Resources Information Center

    O'Connell, James

    2000-01-01

    Explains the shape distortions that take place in fluid packets (bubbles or drops) with steady flow motion by using the laws of Archimedes, Pascal, and Bernoulli rather than advanced vector calculus. (WRM)

  14. Sound field inside acoustically levitated spherical drop

    NASA Astrophysics Data System (ADS)

    Xie, W. J.; Wei, B.

    2007-05-01

    The sound field inside an acoustically levitated small spherical water drop (radius of 1mm) is studied under different incident sound pressures (amplitude p0=2735-5643Pa). The transmitted pressure ptr in the drop shows a plane standing wave, which varies mainly in the vertical direction, and distributes almost uniformly in the horizontal direction. The maximum of ptr is always located at the lowermost point of the levitated drop. Whereas the secondary maximum appears at the uppermost point if the incident pressure amplitude p0 is higher than an intermediate value (3044Pa), in which there exists a pressure nodal surface in the drop interior. The value of the maximum ptr lies in a narrow range of 2489-3173Pa, which has a lower limit of 2489Pa when p0=3044Pa. The secondary maximum of ptr is rather small and only remarkable at high incident pressures.

  15. Singular Jets and Bubbles in Drop Impact

    NASA Astrophysics Data System (ADS)

    Bartolo, Denis; Josserand, Christophe; Bonn, Daniel

    2006-03-01

    We show that when water droplets gently impact on a hydrophobic surface, the droplet shoots out a violent jet, the velocity of which can be up to 40 times the drop impact speed. As a function of the impact velocity, two different hydrodynamic singularities are found that correspond to the collapse of the air cavity formed by the deformation of the drop at impact. It is the collapse that subsequently leads to the jet formation. We show that the divergence of the jet velocity can be understood using simple scaling arguments. In addition, we find that very large air bubbles can remain trapped in the drops. The surprising occurrence of the bubbles for low-speed impact is connected with the nature of the singularities, and can have important consequences for drop deposition, e.g., in ink-jet printing.

  16. Drop size measurement of liquid aerosols

    NASA Astrophysics Data System (ADS)

    Liu, B. Y. H.; Pui, D. Y. H.; Xian-Qing, Wang

    The factor B = D/ D' relating the diameter D of a spherical liquid drop to the diameter, D˜, of the same drop collected on a microscope slide has been measured for DOP (di-octyl phthalate) and oleic acid aerosols. The microscope slide was coated with a fluorocarbon, oleophobic surfactant (L-1428, 3M Co., St. Paul, MN). The ratio was found to be independent of drop diameter in the 2-50 μm range and the mean value of B was found to be 0.700 for oleic acid and 0.690 for DOP. Similar measurements for oleic acid and DOP drops collected on a clean, uncoated slide resulted in the values of 0.419 and 0.303, respectively. The experimental values of B were compared with the theoretical values based on contact angle measurements. Good agreement was obtained.

  17. Proceedings of the Second International Colloquium on Drops and Bubbles

    NASA Technical Reports Server (NTRS)

    Lecroissette, D. H. (Editor)

    1982-01-01

    Applications of bubble and drop technologies are discussed and include: low gravity manufacturing, containerless melts, microballoon fabrication, ink printers, laser fusion targets, generation of organic glass and metal shells, and space processing. The fluid dynamics of bubbles and drops were examined. Thermomigration, capillary flow, and interfacial tension are discussed. Techniques for drop control are presented and include drop size control and drop shape control.

  18. Identification of determinants in the protein partners aCBF5 and aNOP10 necessary for the tRNA:Psi55-synthase and RNA-guided RNA:Psi-synthase activities.

    PubMed

    Muller, Sébastien; Fourmann, Jean-Baptiste; Loegler, Christine; Charpentier, Bruno; Branlant, Christiane

    2007-01-01

    Protein aNOP10 has an essential scaffolding function in H/ACA sRNPs and its interaction with the pseudouridine(Psi)-synthase aCBF5 is required for the RNA-guided RNA:Psi-synthase activity. Recently, aCBF5 was shown to catalyze the isomerization of U55 in tRNAs without the help of a guide sRNA. Here we show that the stable anchoring of aCBF5 to tRNAs relies on its PUA domain and the tRNA CCA sequence. Nonetheless, interaction of aNOP10 with aCBF5 can counterbalance the absence of the PUA domain or the CCA sequence and more generally helps the aCBF5 tRNA:Psi55-synthase activity. Whereas substitution of the aNOP10 residue Y14 by an alanine disturbs this activity, it only impairs mildly the RNA-guided activity. The opposite effect was observed for the aNOP10 variant H31A. Substitution K53A or R202A in aCBF5 impairs both the tRNA:Psi55-synthase and the RNA-guided RNA:Psi-synthase activities. Remarkably, the presence of aNOP10 compensates for the negative effect of these substitutions on the tRNA: Psi55-synthase activity. Substitution of the aCBF5 conserved residue H77 that is expected to extrude the targeted U residue in tRNA strongly affects the efficiency of U55 modification but has no major effect on the RNA-guided activity. This negative effect can also be compensated by the presence of aNOP10.

  19. Noninvasive Optical Measures of CBV, StO2, CBF Index, and rCMRO2 in Human Premature Neonates’ Brains in the First Six Weeks of Life

    PubMed Central

    Roche-Labarbe, Nadège; Carp, Stefan A.; Surova, Andrea; Patel, Megha; Boas, David A.; Grant, P. Ellen; Franceschini, Maria Angela

    2009-01-01

    With the causes of perinatal brain injuries still unclear and the probable role of hemodynamic instability in their etiology, bedside monitoring of neonatal cerebral hemodynamics with standard values as a function of age are needed. In this study, we combined quantitative frequency domain near infrared spectroscopy (FD-NIRS) measures of cerebral tissue oxygenation (StO2) and cerebral blood volume (CBV) with diffusion correlation spectroscopy (DCS) measures of a cerebral blood flow index (CBFix) to test the validity of the CBV-CBF relationship in premature neonates and to estimate cerebral metabolic rate of oxygen (rCMRO2) with or without the CBFix measurement. We measured 11 premature neonates (28–34 weeks gestational age) without known neurological issues, once a week from one to six weeks of age. In nine patients, cerebral blood velocities from the middle cerebral artery were collected by transcranial Doppler (TCD) and compared with DCS values. Results show a steady decrease in StO2 during the first six weeks of life while CBV remains stable, and a steady increase in CBFix. rCMRO2 estimated from FD-NIRS remains constant but shows wide interindividual variability. rCMRO2 calculated from FD-NIRS and DCS combined increased by 40% during the first six weeks of life with reduced interindividual variability. TCD and DCS values are positively correlated. In conclusion, FD-NIRS combined with DCS offers a safe and quantitative bedside method to assess CBV, StO2, CBF, and rCMRO2 in the premature brain, facilitating individual follow-up and comparison among patients. A stable CBV-CBF relationship may not be valid for premature neonates. PMID:19650140

  20. Total Gaussian curvature, drop shapes and the range of applicability of drop shape techniques.

    PubMed

    Saad, Sameh M I; Neumann, A Wilhelm

    2014-02-01

    Drop shape techniques are used extensively for surface tension measurement. It is well-documented that, as the drop/bubble shape becomes close to spherical, the performance of all drop shape techniques deteriorates. There have been efforts quantifying the range of applicability of drop techniques by studying the deviation of Laplacian drops from the spherical shape. A shape parameter was introduced in the literature and was modified several times to accommodate different drop constellations. However, new problems arise every time a new configuration is considered. Therefore, there is a need for a universal shape parameter applicable to pendant drops, sessile drops, liquid bridges as well as captive bubbles. In this work, the use of the total Gaussian curvature in a unified approach for the shape parameter is introduced for that purpose. The total Gaussian curvature is a dimensionless quantity that is commonly used in differential geometry and surface thermodynamics, and can be easily calculated for different Laplacian drop shapes. The new definition of the shape parameter using the total Gaussian curvature is applied here to both pendant and constrained sessile drops as an illustration. The analysis showed that the new definition is superior and reflects experimental results better than previous definitions, especially at extreme values of the Bond number.

  1. Total Gaussian curvature, drop shapes and the range of applicability of drop shape techniques.

    PubMed

    Saad, Sameh M I; Neumann, A Wilhelm

    2014-02-01

    Drop shape techniques are used extensively for surface tension measurement. It is well-documented that, as the drop/bubble shape becomes close to spherical, the performance of all drop shape techniques deteriorates. There have been efforts quantifying the range of applicability of drop techniques by studying the deviation of Laplacian drops from the spherical shape. A shape parameter was introduced in the literature and was modified several times to accommodate different drop constellations. However, new problems arise every time a new configuration is considered. Therefore, there is a need for a universal shape parameter applicable to pendant drops, sessile drops, liquid bridges as well as captive bubbles. In this work, the use of the total Gaussian curvature in a unified approach for the shape parameter is introduced for that purpose. The total Gaussian curvature is a dimensionless quantity that is commonly used in differential geometry and surface thermodynamics, and can be easily calculated for different Laplacian drop shapes. The new definition of the shape parameter using the total Gaussian curvature is applied here to both pendant and constrained sessile drops as an illustration. The analysis showed that the new definition is superior and reflects experimental results better than previous definitions, especially at extreme values of the Bond number. PMID:24373931

  2. Bubble, Drop and Particle Unit (BDPU)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This section of the Life and Microgravity Spacelab (LMS) publication includes the following articles entitled: (1) Oscillatory Thermocapillary Instability; (2) Thermocapillary Convection in Multilayer Systems; (3) Bubble and Drop Interaction with Solidification Front; (4) A Liquid Electrohydrodynamics Experiment; (5) Boiling on Small Plate Heaters under Microgravity and a Comparison with Earth Gravity; (6) Thermocapillary Migration and Interactions of Bubbles and Drops; and (7) Nonlinear Surface Tension Driven Bubble Migration

  3. On the Stability of Rotating Drops

    PubMed Central

    Nurse, A. K.; Coriell, S. R.; McFadden, G. B.

    2015-01-01

    We consider the equilibrium and stability of rotating axisymmetric fluid drops by appealing to a variational principle that characterizes the equilibria as stationary states of a functional containing surface energy and rotational energy contributions, augmented by a volume constraint. The linear stability of a drop is determined by solving the eigenvalue problem associated with the second variation of the energy functional. We compute equilibria corresponding to both oblate and prolate shapes, as well as toroidal shapes, and track their evolution with rotation rate. The stability results are obtained for two cases: (i) a prescribed rotational rate of the system (“driven drops”), or (ii) a prescribed angular momentum (“isolated drops”). For families of axisymmetric drops instabilities may occur for either axisymmetric or non-axisymmetric perturbations; the latter correspond to bifurcation points where non-axisymmetric shapes are possible. We employ an angle-arc length formulation of the problem which allows the computation of equilibrium shapes that are not single-valued in spherical coordinates. We are able to illustrate the transition from spheroidal drops with a strong indentation on the rotation axis to toroidal drops that do not extend to the rotation axis. Toroidal drops with a large aspect ratio (major radius to minor radius) are subject to azimuthal instabilities with higher mode numbers that are analogous to the Rayleigh instability of a cylindrical interface. Prolate spheroidal shapes occur if a drop of lower density rotates within a denser medium; these drops appear to be linearly stable. This work is motivated by recent investigations of toroidal tissue clusters that are observed to climb conical obstacles after self-assembly [Nurse et al., Journal of Applied Mechanics 79 (2012) 051013]. PMID:26958440

  4. La Gocciolina (The Little Drop of Water).

    ERIC Educational Resources Information Center

    Palandra, Maria

    This primary level reader in Italian intended for use in a bilingual education setting, is about the life cycle of a drop of water. The drop of water is personified and the story tells of its adventures as it travels from the top of the lake to the bottom, its meeting with the inhabitants of the lake, and its trip to the clouds. After deciding not…

  5. Misuse of xylometazoline nasal drops by inhalation.

    PubMed

    Anand, Jacek Sein; Salamon, Marek; Habrat, Boguslaw; Scinska, Anna; Bienkowski, Przemyslaw

    2008-12-01

    Six male prisoners who misused xylometazoline nasal drops by inhalation were interviewed by a prison physician in 2006. The prisoners received xylometazoline drops during regular visits in the prison ambulatory service. In order to get the medication, the subjects reported false symptoms of rhinosinusitis and allergic reactions. Psychoactive effects of inhaled xylometazoline were described as "stimulation," "excitation," and "feeling of strength." Although preliminary, our findings suggest that topical adrenergic decongestants can produce rewarding effects when administered by inhalation. PMID:19085441

  6. Blood drop patterns: Formation and applications.

    PubMed

    Chen, Ruoyang; Zhang, Liyuan; Zang, Duyang; Shen, Wei

    2016-05-01

    The drying of a drop of blood or plasma on a solid substrate leads to the formation of interesting and complex patterns. Inter- and intra-cellular and macromolecular interactions in the drying plasma or blood drop are responsible for the final morphologies of the dried patterns. Changes in these cellular and macromolecular components in blood caused by diseases have been suspected to cause changes in the dried drop patterns of plasma and whole blood, which could be used as simple diagnostic tools to identify the health of humans and livestock. However, complex physicochemical driving forces involved in the pattern formation are not fully understood. This review focuses on the scientific development in microscopic observations and pattern interpretation of dried plasma and whole blood samples, as well as the diagnostic applications of pattern analysis. Dried drop patterns of plasma consist of intricate visible cracks in the outer region and fine structures in the central region, which are mainly influenced by the presence and concentration of inorganic salts and proteins during drying. The shrinkage of macromolecular gel and its adhesion to the substrate surface have been thought to be responsible for the formation of the cracks. Dried drop patterns of whole blood have three characteristic zones; their formation as functions of drying time has been reported in the literature. Some research works have applied engineering treatment to the evaporation process of whole blood samples. The sensitivities of the resultant patterns to the relative humidity of the environment, the wettability of the substrates, and the size of the drop have been reported. These research works shed light on the mechanisms of spreading, evaporation, gelation, and crack formation of the blood drops on solid substrates, as well as on the potential applications of dried drop patterns of plasma and whole blood in diagnosis. PMID:26988066

  7. Hanging drop crystal growth apparatus and method

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor); Smith, Robbie E. (Inventor)

    1989-01-01

    An apparatus (10) is constructed having a cylindrical enclosure (16) within which a disc-shaped wicking element (18) is positioned. A well or recess (22) is cut into an upper side (24) of this wicking element, and a glass cover plate or slip (28) having a protein drop disposed thereon is sealably positioned on the wicking element (18), with drop (12) being positioned over well or recess (22). A flow of control fluid is generated by a programmable gradient former (16), with this control fluid having a vapor pressure that is selectively variable. This flow of control fluid is coupled to the wicking element (18) where control fluid vapor diffusing from walls (26) of the recess (22) is exposed to the drop (12), forming a vapor pressure gradient between the drop (12) and the control fluid vapor. Initially, this gradient is adjusted to draw solvent from the drop (12) at a relatively high rate, and as the critical supersaturation point is approached (the point at which crystal nucleation occurs), the gradient is reduced to more slowly draw solvent from the drop (12). This allows discrete protein molecules more time to orient themselves into an ordered crystalline lattice, producing protein crystals which, when processed by X-ray crystallography, possess a high degree of resolution.

  8. Electrohydrodynamics of a surfactant-covered drop

    NASA Astrophysics Data System (ADS)

    Oberlander, Andrew; Ouriemi, Malika; Vlahovska, Petia

    2014-11-01

    We present an experimental study of the behavior of a drop covered with insoluble surfactant in a uniform DC electric field. Steady drop shapes, drop evolution upon application of the field, and drop relaxation after the field is turned off are observed for a polybutadiene (PB) drop suspended in silicon oil (PDMS). The surfactant is generated at the drop interface by reaction between end-functionalized PB and PDMS. The experimental data is compared with the theory of Nganguia et al. (2013) for the steady shapes, and a new model developed by us which accounts for polarization relaxation. The latter effect turns to be significant for our system of very low conductivity fluids, for which the Maxwell-Wagner time is of the order of tens of seconds. We will discuss the complex interplay of shape deformation, surfactant redistribution, and interfacial charging in droplet electrohydrodynamics. Our results are important for understanding electrorheology of emulsions commonly found in the petroleum industry. Supported by NSF-CBET-1132614.

  9. Leidenfrost drops on liquid baths: theory

    NASA Astrophysics Data System (ADS)

    Sobac, Benjamin; Rednikov, Alexei; Maquet, Laurent; Darbois-Texier, Baptiste; Duchesne, Alexis; Brandenbourger, Martin; Dorbolo, Stéphane; Colinet, Pierre

    2015-11-01

    It is well known that a liquid drop released over a very hot surface generally does not contact the surface nor boils but rather levitates over a thin vapor film generated by its own evaporation (Leidenfrost effect). In particular, the case of a hot (and flat) solid substrate has been extensively studied in recent years. In contrast, we here focus on Leidenfrost drops over a superheated liquid bath, addressing the problem theoretically and comparing our predictions with experimental results, detailed in a separate talk. We predict the geometry of the drop and of the liquid bath, based on the hydrostatic Young-Laplace and lubrication equations. A good agreement is observed with the available experimental data concerning the deformation of the liquid bath. The modeling also yields a rather complete insight into the shape of the drop. As in the case of a solid substrate, the vapor layer generally appears to be composed of a vapor pocket surrounded by a circular neck. The influences of the superheat and of the drop size are parametrically investigated. A number of scaling laws are established. Unlike the case of a solid substrate, no chimney instability was found in the range of drop size studied.

  10. Electrochemistry in an acoustically levitated drop.

    PubMed

    Chainani, Edward T; Ngo, Khanh T; Scheeline, Alexander

    2013-02-19

    Levitated drops show potential as microreactors, especially when radicals are present as reactants or products. Solid/liquid interfaces are absent or minimized, avoiding adsorption and interfacial reaction of conventional microfluidics. We report amperometric detection in an acoustically levitated drop with simultaneous ballistic addition of reactant. A gold microelectrode sensor was fabricated with a lithographic process; active electrode area was defined by a photosensitive polyimide mask. The microdisk gold working electrode of radius 19 μm was characterized using ferrocenemethanol in aqueous buffer. Using cyclic voltammetry, the electrochemically active surface area was estimated by combining a recessed microdisk electrode model with the Randles-Sevcik equation. Computer-controlled ballistic introduction of reactant droplets into the levitated drop was developed. Chronoamperometric measurements of ferrocyanide added ballistically demonstrate electrochemical monitoring using the microfabricated electrode in a levitated drop. Although concentration increases with time due to drop evaporation, the extent of concentration is predictable with a linear evaporation model. Comparison of diffusion-limited currents in pendant and levitated drops show that convection arising from acoustic levitation causes an enhancement of diffusion-limited current on the order of 16%. PMID:23351154

  11. A spreading drop of shallow water

    NASA Astrophysics Data System (ADS)

    Jarecka, Dorota; Jaruga, Anna; Smolarkiewicz, Piotr K.

    2015-05-01

    The theoretical solutions and corresponding numerical simulations of Schär and Smolarkiewicz (1996) [3] are revisited. The original abstract problem of a parabolic, slab-symmetric drop of shallow water spreading under gravity is extended to three spatial dimensions, with the initial drop defined over an elliptical compact support. An axisymmetric drop is considered as a special case. The elliptical drop exhibits enticing dynamics, which may appear surprising at the first glance. In contrast, the evolution of the axisymmetric drop is qualitatively akin to the evolution of the slab-symmetric drop and intuitively obvious. Besides being interesting per se, the derived theoretical results provide a simple means for testing numerical schemes concerned with wetting-drying areas in shallow water flows. Reported calculations use the libmpdata++, a recently released free/libre and open-source software library of solvers for generalized transport equations. The numerical results closely match theoretical predictions, demonstrating strengths of the nonoscillatory forward-in-time integrators comprising the libmpdata++.

  12. Toroidal bubble entrapment under an impacting drop

    NASA Astrophysics Data System (ADS)

    Thoraval, Marie-Jean; Thoroddsen, Sigurdur T.; Takehara, Kohsei; Etoh, Takeharu Goji

    2012-11-01

    We use ultra-high-speed imaging and numerical simulations (GERRIS, http://gfs.sf.net) to observe and analyze the formation of up to 14 air tori when a water drop impacts on a thin liquid film of water or other miscible liquids. They form during the early contact between the drop and the pool by the vertical oscillations of the ejecta sheet. They then break in micro-bubble rings by the Rayleigh instability. Their formation is associated with the shedding of an axisymmetric vortex street into the liquid from the free surface. These vorticity structures and their dynamics are made apparent by the dynamics of the micro-bubbles, added seed particles and the difference of refractive index for different liquids in the drop and the pool. More robust entrapments are observed for a thin film of ethanol or methanol. We show that while the non-spherical drop shape is not responsible for the toroidal bubble entrapments, the number of rings is increasing for more oblate drops. Individual bubble entrapments are also observed from azimuthal destabilizations of the neck between the drop and the pool.

  13. Computational analysis of DOD drop formation

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Basaran, Osman

    2007-11-01

    A fundamental theoretical understanding of drop-on-demand (DOD) ink jet printing remains weak despite the widespread use of the method in practical applications for two decades. To overcome this deficiency, a computational analysis is carried out to simulate the formation of liquid drops of incompressible Newtonian fluids from a nozzle by imposing a transient flow rate upstream of the nozzle exit. The dynamics are studied as functions of the Ohnesorge number Oh (viscous/surface tension force) and the Weber number We (inertial/surface tension force). For a common ink forming from a nozzle of 10 micrometer radius, Oh=0.1. For this typical case, a phase or operability diagram is developed that shows that three regimes of operation are possible. In the first regime, where We is low, breakup does not occur, and drops remain pendant from the nozzle and undergo time periodic oscillations. Thus, the simulations show that sufficient fluid inertia, or a sufficiently large We, is required if a DOD drop is to form, in accord with intuition. At high We, two regimes exist. In the first of these two regimes, DOD drops do form but have negative velocities, i.e. they would move toward the nozzle upon breakup, which is undesirable. In the second breakup regime, not only are DOD drops formed but they do so with positive velocities.

  14. Airflows generated by an impacting drop.

    PubMed

    Bischofberger, Irmgard; Ray, Bahni; Morris, Jeffrey F; Lee, Taehun; Nagel, Sidney R

    2016-03-28

    A drop impacting a solid surface with sufficient velocity will splash and emit many small droplets. However, lowering the ambient air pressure suppresses splashing completely. This effect, robustly found for different liquid and substrate properties, raises the fundamental question of how air affects a spreading drop. In a combined experimental and numerical study we characterize the flow of air induced by the drop after it hits the substrate, using a modified Schlieren optics technique combined with high-speed video imaging and Lattice-Boltzmann simulations. Our experiments reveal the emergence of air structures on different length scales. On large scales, the airflow induced in the drop's wake leads to vortex structures due to interaction with the substrate. On smaller scales, we visualize a ring structure above the outer edge of the spreading liquid generated by the spreading of the drop. Our simulations reveal the interaction between the wake vorticity and the flows originating from the rapidly escaping air from below the impacting drop. We show that the vorticity is governed by a balance between inertial and viscous forces in the air, and is unrelated to the splashing threshold. PMID:26809314

  15. Airflows generated by an impacting drop.

    PubMed

    Bischofberger, Irmgard; Ray, Bahni; Morris, Jeffrey F; Lee, Taehun; Nagel, Sidney R

    2016-03-28

    A drop impacting a solid surface with sufficient velocity will splash and emit many small droplets. However, lowering the ambient air pressure suppresses splashing completely. This effect, robustly found for different liquid and substrate properties, raises the fundamental question of how air affects a spreading drop. In a combined experimental and numerical study we characterize the flow of air induced by the drop after it hits the substrate, using a modified Schlieren optics technique combined with high-speed video imaging and Lattice-Boltzmann simulations. Our experiments reveal the emergence of air structures on different length scales. On large scales, the airflow induced in the drop's wake leads to vortex structures due to interaction with the substrate. On smaller scales, we visualize a ring structure above the outer edge of the spreading liquid generated by the spreading of the drop. Our simulations reveal the interaction between the wake vorticity and the flows originating from the rapidly escaping air from below the impacting drop. We show that the vorticity is governed by a balance between inertial and viscous forces in the air, and is unrelated to the splashing threshold.

  16. Prognostic Significance of KIT Mutations in Core-Binding Factor Acute Myeloid Leukemia: A Systematic Review and Meta-Analysis.

    PubMed

    Chen, Wenlan; Xie, Hui; Wang, Hongxiang; Chen, Li; Sun, Yi; Chen, Zhichao; Li, Qiubai

    2016-01-01

    The prognostic significance of KIT mutations in core-binding factor acute myeloid leukemia (CBF-AML), including inv(16) and t(8;21) AML, is uncertain. We performed a systematic review and meta-analysis of the effect of KIT mutations on the complete remission (CR) and relapse rates and overall survival (OS) of CBF-AML. PubMed, Embase, Web of Science, and the Cochrane Library were searched and relevant studies were included. Negative effect was indicated on relapse risk of CBF-AML (RR [relative risk], 1.43; 95%CI [confidence interval], 1.20-1.70) and t(8;21) AML (RR, 1.70; 95% CI, 1.31-2.21), not on OS of CBF-AML (RR, 1.09; 95% CI, 0.97-1.23), CR (OR [odds ratio], 0.95; 95% CI, 0.52-1.74), relapse risk (RR, 1.12; 95% CI, 0.90-1.41) or OS (RR, 1.03; 95% CI, 0.90-1.18) of inv(16) AML. Subgroup analysis of t(8,21) AML showed negative effect of KIT mutations on CR (OR, 2.03; 95%CI: 1.02-4.05), relapse risk (RR, 1.89; 95%CI: 1.51-2.37) and OS (RR, 2.26; 95%CI: 1.35-3,78) of non-Caucasians, not on CR (OR, 0.61; 95%CI: 0.19-1.95) or OS (RR, 1.12; 95%CI: 0.90-1.40) of Caucasians. This study indicates KIT mutations in CBF-AML to be included in the initial routine diagnostic workup and stratification system of t(8,21) AML. Prospective large-scale clinical trials are warranted to evaluate these findings. PMID:26771376

  17. Prognostic Significance of KIT Mutations in Core-Binding Factor Acute Myeloid Leukemia: A Systematic Review and Meta-Analysis

    PubMed Central

    Wang, Hongxiang; Chen, Li; Sun, Yi; Chen, Zhichao; Li, Qiubai

    2016-01-01

    The prognostic significance of KIT mutations in core-binding factor acute myeloid leukemia (CBF-AML), including inv(16) and t(8;21) AML, is uncertain. We performed a systematic review and meta-analysis of the effect of KIT mutations on the complete remission (CR) and relapse rates and overall survival (OS) of CBF-AML. PubMed, Embase, Web of Science, and the Cochrane Library were searched and relevant studies were included. Negative effect was indicated on relapse risk of CBF-AML (RR [relative risk], 1.43; 95%CI [confidence interval], 1.20–1.70) and t(8;21) AML (RR, 1.70; 95% CI, 1.31–2.21), not on OS of CBF-AML (RR, 1.09; 95% CI, 0.97–1.23), CR (OR [odds ratio], 0.95; 95% CI, 0.52–1.74), relapse risk (RR, 1.12; 95% CI, 0.90–1.41) or OS (RR, 1.03; 95% CI, 0.90–1.18) of inv(16) AML. Subgroup analysis of t(8,21) AML showed negative effect of KIT mutations on CR (OR, 2.03; 95%CI: 1.02–4.05), relapse risk (RR, 1.89; 95%CI: 1.51–2.37) and OS (RR, 2.26; 95%CI: 1.35–3,78) of non-Caucasians, not on CR (OR, 0.61; 95%CI: 0.19–1.95) or OS (RR, 1.12; 95%CI: 0.90–1.40) of Caucasians. This study indicates KIT mutations in CBF-AML to be included in the initial routine diagnostic workup and stratification system of t(8,21) AML. Prospective large-scale clinical trials are warranted to evaluate these findings. PMID:26771376

  18. Lifetime of oil drops pressed by buoyancy against a planar interface: large drops.

    PubMed

    Rojas, Clara; García-Sucre, Máximo; Urbina-Villalba, Germán

    2010-11-01

    In a previous report [C. Rojas, G. Urbina-Villalba, and M. García-Sucre, Phys. Rev. E 81, 016302 (2010)] it was shown that emulsion stability simulations are able to reproduce the lifetime of micrometer-size drops of hexadecane pressed by buoyancy against a planar water-hexadecane interface. It was confirmed that small drops (r(i)< 10 μm) stabilized with β -casein behave as nondeformable particles, moving with a combination of Stokes and Taylor tensors as they approach the interface. Here, a similar methodology is used to parametrize the potential of interaction of drops of soybean oil stabilized with bovine serum albumin. The potential obtained is then employed to study the lifetime of deformable drops in the range 10 ≤ r(i) ≤ 1000 μm . It is established that the average lifetime of these drops can be adequately replicated using the model of truncated spheres. However, the results depend sensibly on the expressions of the initial distance of deformation and the maximum film radius used in the calculations. The set of equations adequate for large drops is not satisfactory for medium-size drops (10 ≤ r(i) ≤ 100 μm) , and vice versa. In the case of large particles, the increase in the interfacial area as a consequence of the deformation of the drops generates a very large repulsive barrier which opposes coalescence. Nevertheless, the buoyancy force prevails. As a consequence, it is the hydrodynamic tensor of the drops which determine the characteristic behavior of the lifetime as a function of the particle size. While the average values of the coalescence time of the drops can be justified by the mechanism of film thinning, the scattering of the experimental data of large drops cannot be rationalized using the methodology previously described. A possible explanation of this phenomenon required elaborate simulations which combine deformable drops, capillary waves, repulsive interaction forces, and a time-dependent surfactant adsorption.

  19. The Drop Tower Bremen -Experiment Operation

    NASA Astrophysics Data System (ADS)

    Könemann, Thorben; von Kampen, Peter; Rath, Hans J.

    The idea behind the drop tower facility of the Center of Applied Space Technology and Micro-gravity (ZARM) in Bremen is to provide an inimitable technical opportunity of a daily access to short-term weightlessness on earth. In this way ZARM`s european unique ground-based microgravity laboratory displays an excellent economic alternative for research in space-related conditions at low costs comparable to orbital platforms. Many national and international ex-perimentalists motivated by these prospects decide to benefit from the high-quality and easy accessible microgravity environment only provided by the Drop Tower Bremen. Corresponding experiments in reduced gravity could open new perspectives of investigation methods and give scientists an impressive potential for a future technology and multidisciplinary applications on different research fields like Fundamental Physics, Astrophysics, Fluid Dynamics, Combus-tion, Material Science, Chemistry and Biology. Generally, realizing microgravity experiments at ZARM`s drop tower facility meet new requirements of the experimental hardware and may lead to some technical constraints in the setups. In any case the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH) maintaining the drop tower facility is prepared to as-sist experimentalists by offering own air-conditioned laboratories, clean rooms, workshops and consulting engineers, as well as scientific personal. Furthermore, ZARM`s on-site apartment can be used for accommodations during the experiment campaigns. In terms of approaching drop tower experimenting, consulting of experimentalists is mandatory to successfully accomplish the pursued drop or catapult capsule experiment. For this purpose there will be a lot of expertise and help given by ZARM FAB mbH in strong cooperation to-gether with the experimentalists. However, in comparison to standard laboratory setups the drop or catapult capsule setup seems to be completely different at first view. While defining a

  20. Charge and Size Distributions of Electrospray Drops

    PubMed

    de Juan L; de la Mora JF

    1997-02-15

    The distributions of charge q and diameter d of drops emitted from electrified liquid cones in the cone-jet mode are investigated with two aerosol instruments. A differential mobility analyzer (DMA, Vienna type) first samples the spray drops, selects those with electrical mobilities within a narrow band, and either measures the associated current or passes them to a second instrument. The drops may also be individually counted optically and sized by sampling them into an aerodynamic size spectrometer (API's Aerosizer). For a given cone-jet, the distribution of charge q for the main electrospray drops is some 2.5 times broader than their distribution of diameters d, with qmax/qmin approximately 4. But mobility-selected drops have relative standard deviations of only 5% for both d and q, showing that the support of the (q, d) distribution is a narrow band centered around a curve q(d). The approximate one-dimensionality of this support region is explained through the mechanism of jet breakup, which is a random process with only one degree of freedom: the wavelength of axial modulation of the jet. The observed near constancy of the charge over volume ratio (q approximately d3) shows that the charge is frozen in the liquid surface at the time scale of the breakup process. The charge over volume ratio of the primary drops varies between 98 and 55% of the ratio of spray current I over liquid flow rate Q, and decreases at increasing Q. I/Q is therefore an unreliable measure of the charge density of these drops.

  1. Stress Drops for Potentially Induced Earthquake Sequences

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Beroza, G. C.; Ellsworth, W. L.

    2015-12-01

    Stress drop, the difference between shear stress acting across a fault before and after an earthquake, is a fundamental parameter of the earthquake source process and the generation of strong ground motions. Higher stress drops usually lead to more high-frequency ground motions. Hough [2014 and 2015] observed low intensities in "Did You Feel It?" data for injection-induced earthquakes, and interpreted them to be a result of low stress drops. It is also possible that the low recorded intensities could be a result of propagation effects. Atkinson et al. [2015] show that the shallow depth of injection-induced earthquakes can lead to a lack of high-frequency ground motion as well. We apply the spectral ratio method of Imanishi and Ellsworth [2006] to analyze stress drops of injection-induced earthquakes, using smaller earthquakes with similar waveforms as empirical Green's functions (eGfs). Both the effects of path and linear site response should be cancelled out through the spectral ratio analysis. We apply this technique to the Guy-Greenbrier earthquake sequence in central Arkansas. The earthquakes migrated along the Guy-Greenbrier Fault while nearby injection wells were operating in 2010-2011. Huang and Beroza [GRL, 2015] improved the magnitude of completeness to about -1 using template matching and found that the earthquakes deviated from Gutenberg-Richter statistics during the operation of nearby injection wells. We identify 49 clusters of highly similar events in the Huang and Beroza [2015] catalog and calculate stress drops using the source model described in Imanishi and Ellsworth [2006]. Our results suggest that stress drops of the Guy-Greenbrier sequence are similar to tectonic earthquakes at Parkfield, California (the attached figure). We will also present stress drop analysis of other suspected induced earthquake sequences using the same method.

  2. Self-Diffusion of Drops in a Dilute Sheared Emulsion

    NASA Technical Reports Server (NTRS)

    Loewenberg, Michael; Hinch, E. J.

    1996-01-01

    Self-diffusion coefficients that describe cross-flow migration of non-Brownian drops in a dilute sheared emulsion were obtained by trajectory calculations. A boundary integral formulation was used to describe pairwise interactions between deformable drops; interactions between undeformed drops were described with mobility functions for spherical drops. The results indicate that drops have large anisotropic self-diffusivities which depend strongly on the drop viscosity and modestly on the shear-rate. Pairwise interactions between drops in shear-flow do not appreciably promote drop breakup.

  3. A comprehensive protein-protein interactome for yeast PAS kinase 1 reveals direct inhibition of respiration through the phosphorylation of Cbf1.

    PubMed

    DeMille, Desiree; Bikman, Benjamin T; Mathis, Andrew D; Prince, John T; Mackay, Jordan T; Sowa, Steven W; Hall, Tacie D; Grose, Julianne H

    2014-07-15

    Per-Arnt-Sim (PAS) kinase is a sensory protein kinase required for glucose homeostasis in yeast, mice, and humans, yet little is known about the molecular mechanisms of its function. Using both yeast two-hybrid and copurification approaches, we identified the protein-protein interactome for yeast PAS kinase 1 (Psk1), revealing 93 novel putative protein binding partners. Several of the Psk1 binding partners expand the role of PAS kinase in glucose homeostasis, including new pathways involved in mitochondrial metabolism. In addition, the interactome suggests novel roles for PAS kinase in cell growth (gene/protein expression, replication/cell division, and protein modification and degradation), vacuole function, and stress tolerance. In vitro kinase studies using a subset of 25 of these binding partners identified Mot3, Zds1, Utr1, and Cbf1 as substrates. Further evidence is provided for the in vivo phosphorylation of Cbf1 at T211/T212 and for the subsequent inhibition of respiration. This respiratory role of PAS kinase is consistent with the reported hypermetabolism of PAS kinase-deficient mice, identifying a possible molecular mechanism and solidifying the evolutionary importance of PAS kinase in the regulation of glucose homeostasis.

  4. The Arabidopsis mediator complex subunits MED16, MED14, and MED2 regulate mediator and RNA polymerase II recruitment to CBF-responsive cold-regulated genes.

    PubMed

    Hemsley, Piers A; Hurst, Charlotte H; Kaliyadasa, Ewon; Lamb, Rebecca; Knight, Marc R; De Cothi, Elizabeth A; Steele, John F; Knight, Heather

    2014-01-01

    The Mediator16 (MED16; formerly termed SENSITIVE TO FREEZING6 [SFR6]) subunit of the plant Mediator transcriptional coactivator complex regulates cold-responsive gene expression in Arabidopsis thaliana, acting downstream of the C-repeat binding factor (CBF) transcription factors to recruit the core Mediator complex to cold-regulated genes. Here, we use loss-of-function mutants to show that RNA polymerase II recruitment to CBF-responsive cold-regulated genes requires MED16, MED2, and MED14 subunits. Transcription of genes known to be regulated via CBFs binding to the C-repeat motif/drought-responsive element promoter motif requires all three Mediator subunits, as does cold acclimation-induced freezing tolerance. In addition, these three subunits are required for low temperature-induced expression of some other, but not all, cold-responsive genes, including genes that are not known targets of CBFs. Genes inducible by darkness also required MED16 but required a different combination of Mediator subunits for their expression than the genes induced by cold. Together, our data illustrate that plants control transcription of specific genes through the action of subsets of Mediator subunits; the specific combination defined by the nature of the stimulus but also by the identity of the gene induced.

  5. A comprehensive protein–protein interactome for yeast PAS kinase 1 reveals direct inhibition of respiration through the phosphorylation of Cbf1

    PubMed Central

    DeMille, Desiree; Bikman, Benjamin T.; Mathis, Andrew D.; Prince, John T.; Mackay, Jordan T.; Sowa, Steven W.; Hall, Tacie D.; Grose, Julianne H.

    2014-01-01

    Per-Arnt-Sim (PAS) kinase is a sensory protein kinase required for glucose homeostasis in yeast, mice, and humans, yet little is known about the molecular mechanisms of its function. Using both yeast two-hybrid and copurification approaches, we identified the protein–protein interactome for yeast PAS kinase 1 (Psk1), revealing 93 novel putative protein binding partners. Several of the Psk1 binding partners expand the role of PAS kinase in glucose homeostasis, including new pathways involved in mitochondrial metabolism. In addition, the interactome suggests novel roles for PAS kinase in cell growth (gene/protein expression, replication/cell division, and protein modification and degradation), vacuole function, and stress tolerance. In vitro kinase studies using a subset of 25 of these binding partners identified Mot3, Zds1, Utr1, and Cbf1 as substrates. Further evidence is provided for the in vivo phosphorylation of Cbf1 at T211/T212 and for the subsequent inhibition of respiration. This respiratory role of PAS kinase is consistent with the reported hypermetabolism of PAS kinase–deficient mice, identifying a possible molecular mechanism and solidifying the evolutionary importance of PAS kinase in the regulation of glucose homeostasis. PMID:24850888

  6. Do Bacterial Symbionts Govern Aphid's Dropping Behavior?

    PubMed

    Lavy, Omer; Sher, Noa; Malik, Assaf; Chiel, Elad

    2015-06-01

    Defensive symbiosis is amongst nature's most important interactions shaping the ecology and evolution of all partners involved. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbors one obligatory bacterial symbiont and up to seven different facultative symbionts, some of which are known to protect the aphid from pathogens, natural enemies, and other mortality factors. Pea aphids typically drop off the plant when a mammalian herbivore approaches it to avoid incidental predation. Here, we examined whether bacterial symbionts govern the pea aphid dropping behavior by comparing the bacterial fauna in dropping and nondropping aphids of two A. pisum populations, using two molecular techniques: high-throughput profiling of community structure using 16 S reads sequenced on the Illumina platform, and diagnostic polymerase chain reaction (PCR). We found that in addition to the obligatory symbiont, Buchnera aphidicola, the tested colonies of A. pisum harbored the facultative symbionts Serratia symbiotica, Regiella insecticola and Rickettsia, with no significant differences in infection proportions between dropping and nondropping aphids. While S. symbiotica was detected by both techniques, R. insecticola and Rickettsia could be detected only by diagnostic PCR. We therefore conclude that A. pisum's dropping behavior is not affected by its bacterial symbionts and is possibly affected by other factors. PMID:26313964

  7. Computations of drop collision and coalescence

    NASA Technical Reports Server (NTRS)

    Tryggvason, Gretar; Juric, Damir; Nobari, Mohammed H. R.; Nas, Selman

    1994-01-01

    Computations of drops collision and coalescence are presented. The computations are made possible by a recently developed finite difference/front tracking technique that allows direct solutions of the Navier-Stokes equations for a multi-fluid system with complex, unsteady internal boundaries. This method has been used to examine the boundaries between the various collision modes for drops of equal size and two examples, one of a 'reflective' collision and another of a 'grazing' collision is shown. From drops of unequal size, coalescence can result in considerable mixing between the fluid from the small and the large drop. This problem is discussed and one example showed. In many cases it is necessary to account also for heat transfer along with the fluid mechanics. We show two preliminary results where we are using extensions of the method to simulate such a problem. One example shows pattern formation among many drops moving due to thermal migration, the other shows unstable evolution of a solidification front.

  8. Drop deployment system for crystal growth apparatus

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy H. (Inventor); Snyder, Robert S. (Inventor); Pusey, Marc L. (Inventor)

    1992-01-01

    This invention relates to a crystal growth apparatus (10) generally used for growing protein crystals wherein a vapor diffusion method is used for growing the crystals. In this apparatus, a precipitating solution and a solution containing dissolved crystalline material are stored in separate vials (12, 14), each having a resilient diaphragm (28) across one end and an opening (24) with a puncturable septum (26) thereacross at an opposite end. The vials are placed in receptacles (30) having a manifold (41) with a manifold diaphragm (42) in contact with the vial diaphragm at one end of the receptacle and a hollow needle (36) for puncturing the septum at the other end of the manifold. The needles of each vial communicate with a ball mixer (40) that mixes the precipitate and protein solutions and directs the mixed solution to a drop support (64) disposed in a crystal growth chamber (16), the drop support being a tube with an inner bevelled surface (66) that provides more support for the drop (68) than the tubes of the prior art. A sealable storage region (70) intermediate the drop support and mixer provides storage of the drop (68) and the grown crystals.

  9. Drops with non-circular footprints

    NASA Astrophysics Data System (ADS)

    Ravazzoli, Pablo D.; González, Alejandro G.; Diez, Javier A.

    2016-04-01

    In this paper we study the morphology of drops formed on partially wetting substrates, whose footprint is not circular. These drops are consequence of the breakup processes occurring in thin films when anisotropic contact line motions take place. The anisotropy is basically due to the hysteresis of the contact angle since there is a wetting process in some parts of the contact line, while a dewetting occurs in other parts. Here, we obtain a characteristic drop shape from the rupture of a long liquid filament sitting on a solid substrate. We analyze its shape and contact angles by means of goniometric and refractive techniques. We also find a non-trivial steady state solution for the drop shape within the long wave approximation (lubrication theory), and we compare most of its features with experimental data. This solution is presented both in Cartesian and polar coordinates, whose constants must be determined by a certain group of measured parameters. Besides, we obtain the dynamics of the drop generation from numerical simulations of the full Navier-Stokes equation, where we emulate the hysteretic effects with an appropriate spatial distribution of the static contact angle over the substrate.

  10. Drop splash on a smooth, dry surface

    NASA Astrophysics Data System (ADS)

    Riboux, Guillaume; Gordillo, Jose Manuel; Korobkin, Alexander

    2013-11-01

    It is our purpose here to determine the conditions under which a drop of a given liquid with a known radius R impacting against a smooth impermeable surface at a velocity V, will either spread axisymmetrically onto the substrate or will create a splash, giving rise to usually undesired star-shaped patterns. In our experimental setup, drops are generated injecting low viscosity liquids falling under the action of gravity from a stainless steel hypodermic needle. The experimental observations using two high speed cameras operating simultaneously and placed perpendicularly to each other reveal that, initially, the drop deforms axisymmetrically, with A (T) the radius of the wetted area. For high enough values of the drop impact velocity, a thin sheet of liquid starts to be ejected from A (T) at a velocity Vjet > V for instants of time such that T >=Tc . If Vjet is above a certain threshold, which depends on the solid wetting properties as well as on the material properties of both the liquid and the atmospheric gas, the rim of the lamella dewets the solid to finally break into drops. Using Wagner's theory we demonstrate that A (T) =√{ 3 RVT } and our results also reveal that Tc We - 1 / 2 =(ρV2 R / σ) - 1 / 2 and Vjet We 1 / 4 .

  11. Drop impact on inclined superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Choi, Wonjae; Leclear, Sani; Leclear, Johnathon; Abhijeet, .; Park, Kyoo-Chul

    We report an empirical study and dimensional analysis on the impact patterns of water drops on inclined superhydrophobic surfaces. While the classic Weber number determines the spreading and recoiling dynamics of a water drop on a horizontal / smooth surface, for a superhydrophobic surface, the dynamics depends on two distinct Weber numbers, each calculated using the length scale of the drop or of the pores on the surface. Impact on an inclined superhydrophobic surface is even more complicated, as the velocity that determines the Weber number is not necessarily the absolute speed of the drop but the velocity components normal and tangential to the surface. We define six different Weber numbers, using three different velocities (absolute, normal and tangential velocities) and two different length scales (size of the drop and of the texture). We investigate the impact patterns on inclined superhydrophobic surfaces with three different types of surface texture: (i) posts, (ii) ridges aligned with and (iii) ridges perpendicular to the impact direction. Results suggest that all six Weber numbers matter, but affect different parts of the impact dynamics, ranging from the Cassie-Wenzel transition, maximum spreading, to anisotropic deformation. We acknowledge financial support from the Office of Naval Research (ONR) through Contract 3002453812.

  12. Drop Testing Representative Multi-Canister Overpacks

    SciTech Connect

    Snow, Spencer D.; Morton, Dana K.

    2015-06-01

    The objective of the work reported herein was to determine the ability of the Multi- Canister Overpack (MCO) canister design to maintain its containment boundary after an accidental drop event. Two test MCO canisters were assembled at Hanford, prepared for testing at the Idaho National Engineering and Environmental Laboratory (INEEL), drop tested at Sandia National Laboratories, and evaluated back at the INEEL. In addition to the actual testing efforts, finite element plastic analysis techniques were used to make both pre-test and post-test predictions of the test MCOs structural deformations. The completed effort has demonstrated that the canister design is capable of maintaining a 50 psig pressure boundary after drop testing. Based on helium leak testing methods, one test MCO was determined to have a leakage rate not greater than 1x10-5 std cc/sec (prior internal helium presence prevented a more rigorous test) and the remaining test MCO had a measured leakage rate less than 1x10-7 std cc/sec (i.e., a leaktight containment) after the drop test. The effort has also demonstrated the capability of finite element methods using plastic analysis techniques to accurately predict the structural deformations of canisters subjected to an accidental drop event.

  13. Bubble and Drop Nonlinear Dynamics (BDND)

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Leal, L. Gary; Thomas, D. A.; Crouch, R. K.

    1998-01-01

    Free drops and bubbles are weakly nonlinear mechanical systems that are relatively simple to characterize experimentally in 1-G as well as in microgravity. The understanding of the details of their motion contributes to the fundamental study of nonlinear phenomena and to the measurement of the thermophysical properties of freely levitated melts. The goal of this Glovebox-based experimental investigation is the low-gravity assessment of the capabilities of a modular apparatus based on ultrasonic resonators and on the pseudo- extinction optical method. The required experimental task is the accurate measurements of the large-amplitude dynamics of free drops and bubbles in the absence of large biasing influences such as gravity and levitation fields. A single-axis levitator used for the positioning of drops in air, and an ultrasonic water-filled resonator for the trapping of air bubbles have been evaluated in low-gravity and in 1-G. The basic feasibility of drop positioning and shape oscillations measurements has been verified by using a laptop-interfaced automated data acquisition and the optical extinction technique. The major purpose of the investigation was to identify the salient technical issues associated with the development of a full-scale Microgravity experiment on single drop and bubble dynamics.

  14. Do Bacterial Symbionts Govern Aphid's Dropping Behavior?

    PubMed

    Lavy, Omer; Sher, Noa; Malik, Assaf; Chiel, Elad

    2015-06-01

    Defensive symbiosis is amongst nature's most important interactions shaping the ecology and evolution of all partners involved. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbors one obligatory bacterial symbiont and up to seven different facultative symbionts, some of which are known to protect the aphid from pathogens, natural enemies, and other mortality factors. Pea aphids typically drop off the plant when a mammalian herbivore approaches it to avoid incidental predation. Here, we examined whether bacterial symbionts govern the pea aphid dropping behavior by comparing the bacterial fauna in dropping and nondropping aphids of two A. pisum populations, using two molecular techniques: high-throughput profiling of community structure using 16 S reads sequenced on the Illumina platform, and diagnostic polymerase chain reaction (PCR). We found that in addition to the obligatory symbiont, Buchnera aphidicola, the tested colonies of A. pisum harbored the facultative symbionts Serratia symbiotica, Regiella insecticola and Rickettsia, with no significant differences in infection proportions between dropping and nondropping aphids. While S. symbiotica was detected by both techniques, R. insecticola and Rickettsia could be detected only by diagnostic PCR. We therefore conclude that A. pisum's dropping behavior is not affected by its bacterial symbionts and is possibly affected by other factors.

  15. Settling of copper drops in molten slags

    NASA Astrophysics Data System (ADS)

    Warczok, A.; Utigard, T. A.

    1995-02-01

    The settling of suspended metal and sulfide droplets in liquid metallurgical, slags can be affected by electric fields. The migration of droplets due to electrocapillary motion phenomena may be used to enhance the recovery of suspended matte/metal droplets and thereby to increase the recovery of pay metals. An experimental technique was developed for the purpose of measuring the effect of electric fields on the settling rate of metallic drops in liquid slags. Copper drops suspended in CaO-SiO2-Al2O3-Cu2O slags were found to migrate toward the cathode. Electric fields can increase the settling rate of 5-mm-diameter copper drops 3 times or decrease the settling until levitation by reversal of the electric field. The enhanced settling due to electric fields decreases with increasing Cu2O contents in the slag.

  16. Micro coulometric titration in a liquid drop.

    PubMed

    Kanyanee, Tinakorn; Fuekhad, Pongwasin; Grudpan, Kate

    2013-10-15

    Miniaturized coulometric titration in a liquid drop has been investigated. Assays of ascorbic acid and thiosulfate with iodine titration were chosen as models. Constant volumes of falling liquid drops containing sample or reagent are manipulated via gravimetrical force to move along a slope hydrophobic path and directed to stop or to move out from an electrode. Such manipulation is useful for delivery of sample and reagents, in a way of flow without tubing. Electrochemical generation of titrant, in this case, iodine, is started at the electrode and micro coulometric titration can be performed in a drop by applying constant current. Timing in the titration can be made via naked eye with a stopwatch or via recording with a webcam camera connecting to a computer to detect the change due to the blue color complex of the excess iodine and starch.

  17. Glaucoma eye drops adverse skin reactions.

    PubMed

    Cantisani, Carmen; Ambrifi, Marina; Frascani, Federica; Fazia, Gilda; Paolino, Giovanni; Lisi, Roberto; Calvieri, Stefano

    2014-01-01

    The term "Glaucoma" is used to describe a number of diseases of the eye characterized by a particular form of optic nerve damage that is often associated with high intraocular pressure (IOP). The open-angle glaucoma is the most common form that is also referred to as chronic glaucoma. This is described as an optic neuropathy with multifactorial nature in which there is a loss of characteristics of the optic nerve fibers. Therapeutic options for the treatment of this disease are different, you can take advantage of eye drops, laser therapy and conventional surgery or more combined treatments. Medicated eye drops are the most common way to treat glaucoma. Although eye drops are widely used, adverse reactions are not frequently observed and described. In particular, the adverse skin reactions are not frequently described in the literature, but often seen in dermatologic clinic, we reported their skin reactions and possible alternative treatments described in literature and their patent applications. PMID:25487259

  18. Ultrasonic characterization of single drops of liquids

    DOEpatents

    Sinha, Dipen N.

    1998-01-01

    Ultrasonic characterization of single drops of liquids. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities.

  19. Nonreciprocal photonic crystal add-drop filter

    NASA Astrophysics Data System (ADS)

    Tao, Keyu; Xiao, Jun-Jun; Yin, Xiaobo

    2014-11-01

    We present a versatile add-drop integrated photonic filter (ADF) consisting of nonreciprocal waveguides in which the propagation of light is restricted in one predetermined direction. With the bus and add/drop waveguides symmetrically coupled through a cavity, the four-port device allows each individual port to add and/or drop a signal of the same frequency. The scheme is general and we demonstrate the nonreciprocal ADF with magneto-optical photonic crystals. The filter is immune to waveguide defects, allowing straightforward implementation of multi-channel ADFs by cascading the four-port designs. The results should find applications in wavelength-division multiplexing and related integrated photonic techniques.

  20. Profiles of electrified drops and bubbles

    NASA Technical Reports Server (NTRS)

    Basaran, O. A.; Scriven, L. E.

    1982-01-01

    Axisymmetric equilibrium shapes of conducting drops and bubbles, (1) pendant or sessile on one face of a circular parallel-plate capacitor or (2) free and surface-charged, are found by solving simultaneously the free boundary problem consisting of the augmented Young-Laplace equation for surface shape and the Laplace equation for electrostatic field, given the surface potential. The problem is nonlinear and the method is a finite element algorithm employing Newton iteration, a modified frontal solver, and triangular as well as quadrilateral tessellations of the domain exterior to the drop in order to facilitate refined analysis of sharply curved drop tips seen in experiments. The stability limit predicted by this computer-aided theoretical analysis agrees well with experiments.

  1. Thermocapillary Convection in Bubbles and Drops

    NASA Technical Reports Server (NTRS)

    Balassubramaniam; Subramanian, R. Shankar

    2003-01-01

    When bubbles or drops are present in an immiscible liquid in reduced gravity and the temperature of the liquid is non-uniform, a thermocapillary stress is generated at the interface due to the variation of interfacial tension with temperature. The resulting flow propels the drop freely suspended in the liquid towards warmer regions, so as to minimize the interfacial energy. In this presentation, we will focus on the effect of convective transport of momentum and energy, that are characterized by the Reynolds number and the Marangoni number, respectively. The results of asymptotic analyses for the speed of the drop for low and large values of these parameters will be discussed. These predictions as well as those from numerical simulations will be compared with reduced gravity experimental results obtained from experiments performed aboard the space shuttle.

  2. Drop interaction with the ejecta sheet

    NASA Astrophysics Data System (ADS)

    Thoraval, M.-J.; Thoroddsen, S. T.; Takehara, K.; Etoh, T. G.; Ray, P.; Josserand, C.; Zaleski, S.

    2011-11-01

    We studied experimentally and numerically the dynamics of the ejecta sheet produced by a drop impacting on a deep pool of the same liquid at high Reynolds and Weber numbers. Ultra-high speed imaging revealed a diversity of evolutions by using different mixtures of water and glycerine, and different impact velocities. We observed a transition from a smooth ejecta sheet to a more irregular splashing for a Reynolds number of 3500. In this transition regime, the ejecta sheet interacts with the impacting drop. This interaction can pull the ejecta sheet towards the centre of the drop at lower splash parameters, or generate a bumping on the ejecta sheet moving outwards at higher splash parameters. The volume of fluid (VOF) code Gerris was used to reproduce numerically this peculiar dynamics in axisymmetric conditions. Very good agreement with the experiments was reached by using adaptive refinement and parallelization of the calculations.

  3. Micro coulometric titration in a liquid drop.

    PubMed

    Kanyanee, Tinakorn; Fuekhad, Pongwasin; Grudpan, Kate

    2013-10-15

    Miniaturized coulometric titration in a liquid drop has been investigated. Assays of ascorbic acid and thiosulfate with iodine titration were chosen as models. Constant volumes of falling liquid drops containing sample or reagent are manipulated via gravimetrical force to move along a slope hydrophobic path and directed to stop or to move out from an electrode. Such manipulation is useful for delivery of sample and reagents, in a way of flow without tubing. Electrochemical generation of titrant, in this case, iodine, is started at the electrode and micro coulometric titration can be performed in a drop by applying constant current. Timing in the titration can be made via naked eye with a stopwatch or via recording with a webcam camera connecting to a computer to detect the change due to the blue color complex of the excess iodine and starch. PMID:24054589

  4. Nonreciprocal photonic crystal add-drop filter

    SciTech Connect

    Tao, Keyu; Xiao, Jun-Jun; Yin, Xiaobo

    2014-11-24

    We present a versatile add-drop integrated photonic filter (ADF) consisting of nonreciprocal waveguides in which the propagation of light is restricted in one predetermined direction. With the bus and add/drop waveguides symmetrically coupled through a cavity, the four-port device allows each individual port to add and/or drop a signal of the same frequency. The scheme is general and we demonstrate the nonreciprocal ADF with magneto-optical photonic crystals. The filter is immune to waveguide defects, allowing straightforward implementation of multi-channel ADFs by cascading the four-port designs. The results should find applications in wavelength-division multiplexing and related integrated photonic techniques.

  5. Computer simulations of nematic drops: Coupling between drop shape and nematic order

    NASA Astrophysics Data System (ADS)

    Rull, L. F.; Romero-Enrique, J. M.; Fernandez-Nieves, A.

    2012-07-01

    We perform Monte Carlo computer simulations of nematic drops in equilibrium with their vapor using a Gay-Berne interaction between the rod-like molecules. To generate the drops, we initially perform NPT simulations close to the nematic-vapor coexistence region, allow the system to equilibrate and subsequently induce a sudden volume expansion, followed with NVT simulations. The resultant drops coexist with their vapor and are generally not spherical but elongated, have the rod-like particles tangentially aligned at the surface and an overall nematic orientation along the main axis of the drop. We find that the drop eccentricity increases with increasing molecular elongation, κ. For small κ the nematic texture in the drop is bipolar with two surface defects, or boojums, maximizing their distance along this same axis. For sufficiently high κ, the shape of the drop becomes singular in the vicinity of the defects, and there is a crossover to an almost homogeneous texture; this reflects a transition from a spheroidal to a spindle-like drop.

  6. Coalescing drops in microfluidic parking networks: A multifunctional platform for drop-based microfluidics

    PubMed Central

    Bithi, Swastika S.; Wang, William S.; Sun, Meng; Blawzdziewicz, Jerzy; Vanapalli, Siva A.

    2014-01-01

    Multiwell plate and pipette systems have revolutionized modern biological analysis; however, they have disadvantages because testing in the submicroliter range is challenging, and increasing the number of samples is expensive. We propose a new microfluidic methodology that delivers the functionality of multiwell plates and pipettes at the nanoliter scale by utilizing drop coalescence and confinement-guided breakup in microfluidic parking networks (MPNs). Highly monodisperse arrays of drops obtained using a hydrodynamic self-rectification process are parked at prescribed locations in the device, and our method allows subsequent drop manipulations such as fine-gradation dilutions, reactant addition, and fluid replacement while retaining microparticles contained in the sample. Our devices operate in a quasistatic regime where drop shapes are determined primarily by the channel geometry. Thus, the behavior of parked drops is insensitive to flow conditions. This insensitivity enables highly parallelized manipulation of drop arrays of different composition, without a need for fine-tuning the flow conditions and other system parameters. We also find that drop coalescence can be switched off above a critical capillary number, enabling individual addressability of drops in complex MPNs. The platform demonstrated here is a promising candidate for conducting multistep biological assays in a highly multiplexed manner, using thousands of submicroliter samples. PMID:25379078

  7. Unrecognized acute exertional compartment syndrome of the leg and treatment.

    PubMed

    Popovic, Nebojsa; Bottoni, Craig; Cassidy, Charles

    2011-04-01

    Acute-on-chronic exertional compartment syndrome is rare and may be easily missed without a high degree of awareness and clinical suspicion. We report a case of unrecognized acute-on-chronic exertional compartment syndrome in a recreational soccer player. The late sequela of this condition, foot drop, was successfully treated with transfer of the peroneus longus tendon.

  8. Drop deployment system for crystal growth apparatus

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy (Inventor); Snyder, Robert S. (Inventor); Pusey, Marc L. (Inventor)

    1990-01-01

    A crystal growth apparatus is presented. It utilizes a vapor diffusion method for growing protein crystals, and particularly such an apparatus wherein a ball mixer is used to mix the fluids that form a drop within which crystals are grown. Particular novelty of this invention lies in utilizing a ball mixer to completely mix the precipitate and protein solutions prior to forming the drop. Additional novelty lies in details of construction of the vials, the fluid deployment system, and the fluid storage system of the preferred embodiment.

  9. Monitoring of interfacial tensions by drop counting

    SciTech Connect

    Duerksen, W.K.; Boring, C.P.; McLaughlin, J.F.; Harless, D.P.

    1988-11-01

    A capillary tube device was shown to provide a rapid means of measuring the interfacial tension between water and Freon-113. The measurement technique is based on counting the number of drops that form when a fixed volume of water passes through the capillary tube into the bulk Freon. The interfacial tension is predicted to be proportional to the number of drops to the negative 2/3 power. Calibration curves were obtained for Freon-water samples containing known concentrations of a surfactant. A standard Gibbs adsorption curve was obtained. 5 refs., 3 figs., 2 tabs.

  10. Transformation of the bridge during drop separation

    NASA Astrophysics Data System (ADS)

    Chashechkin, Yu. D.; Prokhorov, V. E.

    2016-05-01

    The geometry of flows during separation of pendant drops of liquids with significantly different physical properties (alcohol, water, glycerin, oil) has been studied by high-speed video recording. The dynamics of the processes involving the formation of bridges of two characteristic shapes—slightly nonuniform in thickness and with thinning of the upper and lower ends—has been investigated. It has been shown that the shape change of the separated bridge has a number of stages determined by the properties of the liquid. As a result, the bridge is transformed into a small drop—a satellite drop.

  11. The new Drop Tower catapult system

    NASA Astrophysics Data System (ADS)

    von Kampen, Peter; Kaczmarczik, Ulrich; Rath, Hans J.

    2006-07-01

    The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of the "Drop Tower" began. Since then, the eye-catching tower with a height of 146 m and its characteristic glass roof has become the emblem of the technology centre in Bremen. The Drop Tower Bremen provides a facility for experiments under conditions of weightlessness. Items are considered weightless, when they are in "free fall", i.e. moving without propulsion within the gravity field of the earth. The height of the tower limits the simple "free fall" experiment period to max. 4.74 s. With the inauguration of the catapult system in December 2004, the ZARM is entering a new dimension. This world novelty will meet scientists' demands of extending the experiment period up to 9.5 s. Since turning the first sod on May 3rd, 1988, the later installation of the catapult system has been taken into account by building the necessary chamber under the tower. The catapult system is located in a chamber 10 m below the base of the tower. This chamber is almost completely occupied by 12 huge pressure tanks. These tanks are placed around the elongation of the vacuum chamber of the drop tube. In its centre there is the pneumatic piston that accelerates the drop capsule by the pressure difference between the vacuum inside the drop tube and the pressure inside the tanks. The acceleration level is adjusted by means of a servo hydraulic breaking system controlling the piston velocity. After only a quarter of a second the drop capsule achieves its lift-off speed of 175 km/h. With this exact speed, the capsule will rise up to the top of the tower and afterwards fall down again into the deceleration unit which has been moved under the drop tube in the meantime. The scientific advantages of the doubled experiment time are obvious: during almost 10 s of high

  12. Corners, Cusps, and Pearls in Running Drops

    SciTech Connect

    Podgorski, T.; Flesselles, J.-M.; Limat, L.

    2001-07-16

    Small drops sliding down a partially wetting substrate bifurcate between different shapes depending on their capillary number Ca . At low Ca , they are delimited by a rounded, smooth contact line. At intermediate values they develop a corner at the trailing edge, the angle of which evolves from flat to 60{sup o} with increasing velocity. Further up, they exhibit a cusped tail that emits smaller drops (''pearls''). These bifurcations may be qualitatively and quantitatively recovered by considering the dynamic contact angle along the contact line.

  13. Static shape of an acoustically levitated drop with wave-drop interaction

    NASA Astrophysics Data System (ADS)

    Lee, C. P.; Anilkumar, A. V.; Wang, T. G.

    1994-11-01

    The static shape of a drop levitated and flattened by an acoustic standing wave field in air is calculated, requiring self-consistency between the drop shape and the wave. The wave is calculated for a given shape using the boundary integral method. From the resulting radiation stress on the drop surface, the shape is determined by solving the Young-Laplace equation, completing an iteration cycle. The iteration is continued until both the shape and the wave converge. Of particular interest are the shapes of large drops that sustain equilibrium, beyond a certain degree of flattening, by becoming more flattened at a decreasing sound pressure level. The predictions for flattening versus acoustic radiation stress, for drops of different sizes, compare favorably with experimental data.

  14. Cecal drop reflects the chickens' cecal microbiome, fecal drop does not.

    PubMed

    Pauwels, J; Taminiau, B; Janssens, G P J; De Beenhouwer, M; Delhalle, L; Daube, G; Coopman, F

    2015-10-01

    Microbiota in the gastro-intestinal tract are closely related to both the intestinal and overall health of the host. Experimental chickens have always been euthanized in order to identify and quantify the bacteria in cecal content. In this study, quantification and identification of the microbial populations in cecal drop, cecal content and fecal drop samples from chickens showed that cecal drop contains a bacterial community that is very similar (concerning bacterial diversity, richness and species composition) to cecal content, as opposed to the bacterial community found in fecal drop. Cecal drop analysis thus allows for longitudinal experiments on chickens' cecal bacteria. The varying results in the analysis of fecal samples question the method's reliability in reflecting the true cecal microbiota in chickens. PMID:26264624

  15. Best Measuring Time for a Millikan Oil Drop Experiment

    ERIC Educational Resources Information Center

    Kapusta, J. I.

    1975-01-01

    In a Millikan oil drop experiment, there is a best measuring time for observing the drop, due to Brownian motion of the drop and the experimenter's reaction time. Derives an equation for the relative error in the measurement of the drop's excess charge, and obtains a formula for the best measuring time. (Author/MLH)

  16. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  17. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  18. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  19. 14 CFR 23.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reserve energy absorption drop test. 23.727... Construction Landing Gear § 23.727 Reserve energy absorption drop test. (a) If compliance with the reserve energy absorption requirement in § 23.723(b) is shown by free drop tests, the drop height may not be...

  20. Predicting Students Drop Out: A Case Study

    ERIC Educational Resources Information Center

    Dekker, Gerben W.; Pechenizkiy, Mykola; Vleeshouwers, Jan M.

    2009-01-01

    The monitoring and support of university freshmen is considered very important at many educational institutions. In this paper we describe the results of the educational data mining case study aimed at predicting the Electrical Engineering (EE) students drop out after the first semester of their studies or even before they enter the study program…

  1. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  2. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  3. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  4. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  5. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  6. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  7. Viscosity Measurement Using Drop Coalescence in Microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.; Ethridge, Edwin C.; Maxwell, Daniel; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    We present in here validation studies of a new method for application in microgravity environment which measures the viscosity of highly viscous undercooled liquids using drop coalescence. The method has the advantage of avoiding heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Homogeneous nucleation can also be avoided due to the rapidity of the measurement using this method. The technique relies on measurements from experiments conducted in near zero gravity environment as well as highly accurate analytical formulation for the coalescence process. The viscosity of the liquid is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity for two coalescing drops. Results are presented from two sets of validation experiments for the method which were conducted on board aircraft flying parabolic trajectories. In these tests the viscosity of a highly viscous liquid, namely glycerin, was determined at different temperatures using the drop coalescence method described in here. The experiments measured the free surface velocity of two glycerin drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The liquid viscosity was determined by adjusting the computed free surface velocity values to the measured experimental data. The results of these experiments were found to agree reasonably well with the known viscosity for the test liquid used.

  8. Reasons Students with Disabilities Drop Out.

    ERIC Educational Resources Information Center

    Bounds, M. Betsy; Gould, Albert

    2000-01-01

    Students with disabilities who dropped out of high school (n=60) cited more school factors (lack of academic success, suspension, peer problems) than personal factors (motivation, pregnancy, family problems) influencing dropout. Three-fourths suggested improved communication with teachers, flexible scheduling, and more relevance would decrease…

  9. Naphazoline nasal drops intoxication in children.

    PubMed

    Vitezić, D; Rozmanić, V; Franulović, J; Ahel, V; Matesić, D

    1994-03-01

    Naphazoline, a sympathomimetic and an imidazoline derivative, is used as 0.05-0.1% solution for local decongestion of the nasal and ocular mucosa. In excessive dosage, or if ingested by accident, may cause depression of the central nervous system (disturbances of consciousness progressing to coma), hypothermia, bradycardia and sweating. These naphazoline effects are particularly strongly pronounced in children. Anglo-Saxon pharmacotherapy excludes the application of naphazoline nasal drops in children younger than six years, whereas the Croatian pharmacotherapeutic literature (and practice) allows its use even in infancy. At the Kantrida Paediatric Clinic, Clinical Hospital Centre in Rijeka, 11 children with signs of intoxication with naphazoline nasal drops were hospitalized from 1990 to 1992. The symptoms pertaining to the central nervous system i.e. disturbances of consciousness in the form of somnolence were clearly marked in all children. Some children developed skin pallor, bradycardia, bradypnoea and hypothermia. Resolution occurred within 24 hours and the findings returned to normal values. Clinical picture followed by rapid resolution and normal findings, with a personal history of drug taking, is a safe indication for diagnosis. There are several reasons to account for intoxication (drops difficult to use with children, containers inadequate for proper dosage), but the major factor is the age of the patient--all hospitalized children were younger than six years. It is pointed out that administration of naphazoline drops at an early age is not advisable.

  10. Allergic Contact Dermatitis to Eye Drops

    PubMed Central

    Bhat, Yasmeen Jabeen; Zeerak, Sumaya; Hassan, Iffat

    2015-01-01

    Allergic contact dermatitis (ACD) occurs due to a milieu of allergens and involves different anatomical sites, including eyelids, and periorbital areas. Topically applied ophthalmic drugs are a potential cause of ACD of the periorbital region. Here we describe the report of a patient who developed ACD to eye drop preparations. PMID:26677304

  11. Understanding the Early Regime of Drop Spreading.

    PubMed

    Mitra, Surjyasish; Mitra, Sushanta K

    2016-09-01

    We present experimental data to characterize the spreading of a liquid drop on a substrate kept submerged in another liquid medium. They reveal that drop spreading always begins in a regime dominated by drop viscosity where the spreading radius scales as r ∼ t with a nonuniversal prefactor. This initial viscous regime either lasts in its entirety or switches to an intermediate inertial regime where the spreading radius grows with time following the well-established inertial scaling of r ∼ t(1/2). This latter case depends on the characteristic viscous length scale of the problem. In either case, the final stage of spreading, close to equilibrium, follows Tanner's law. Further experiments performed on the same substrate kept in ambient air reveal a similar trend, albeit with limited spatiotemporal resolution, showing the universal nature of the spreading behavior. It is also found that, for early times of spreading, the process is similar to coalescence of two freely suspended liquid drops, making the presence of the substrate and consequently the three-phase contact line insignificant. PMID:27513708

  12. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  13. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...: (i) Where the substances to be carried have a specific gravity not exceeding 1.2, the drop...

  14. Drop-Out Challenges: Pathways to Success

    ERIC Educational Resources Information Center

    Conner, Evguenia; McKee, Jan

    2008-01-01

    This article describes an action research at an alternative high school which explores drop-out prevention strategies with first-year students. Student retention is extremely challenging for alternative schools. Because their mission is to provide a second chance to students who could not succeed in a regular setting, those schools regularly must…

  15. Orion Parachute Drop Test, July 18

    NASA Video Gallery

    A C-17 plane dropped a test version of Orion from an altitude of 25,000 feet above the U.S. Army Yuma Proving Ground in southwestern Arizona on July 18, 2012. This test was the second to use an Ori...

  16. Acoustic forcing of a liquid drop

    NASA Technical Reports Server (NTRS)

    Lyell, M. J.

    1992-01-01

    The development of systems such as acoustic levitation chambers will allow for the positioning and manipulation of material samples (drops) in a microgravity environment. This provides the capability for fundamental studies in droplet dynamics as well as containerless processing work. Such systems use acoustic radiation pressure forces to position or to further manipulate (e.g., oscillate) the sample. The primary objective was to determine the effect of a viscous acoustic field/tangential radiation pressure forcing on drop oscillations. To this end, the viscous acoustic field is determined. Modified (forced) hydrodynamic field equations which result from a consistent perturbation expansion scheme are solved. This is done in the separate cases of an unmodulated and a modulated acoustic field. The effect of the tangential radiation stress on the hydrodynamic field (drop oscillations) is found to manifest as a correction to the velocity field in a sublayer region near the drop/host interface. Moreover, the forcing due to the radiation pressure vector at the interface is modified by inclusion of tangential stresses.

  17. Inverted drop testing and neck injury potential.

    PubMed

    Forrest, Stephen; Herbst, Brian; Meyer, Steve; Sances, Anthony; Kumaresan, Srirangam

    2003-01-01

    Inverted drop testing of vehicles is a methodology that has long been used by the automotive industry and researchers to test roof integrity and is currently being considered by the National Highway Traffic Safety Administration as a roof strength test. In 1990 a study was reported which involved 8 dolly rollover tests and 5 inverted drop tests. These studies were conducted with restrained Hybrid III instrumented Anthropometric Test Devices (ATD) in production and rollcaged vehicles to investigate the relationship between roof strength and occupant injury potential. The 5 inverted drop tests included in the study provided a methodology producing "repeatable roof impacts" exposing the ATDs to the similar impact environment as those seen in the dolly rollover tests. Authors have conducted two inverted drop test sets as part of an investigation of two real world rollover accidents. Hybrid-III ATD's were used in each test with instrumented head and necks. Both test sets confirm that reduction of roof intrusion and increased headroom can significantly enhance occupant protection. In both test pairs, the neck force of the dummy in the vehicle with less crush and more survival space was significantly lower. Reduced roof crush and dynamic preservation of the occupant survival space resulted in only minor occupant contact and minimal occupant loading, establishing a clear causal relationship between roof crush and neck injuries.

  18. Containerless undercooling and solidification in drop tubes

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Robinson, M. B.; Rathz, T. J.

    1981-01-01

    A containerless low-gravity environment, produced within a 32 m drop tube apparatus, has been used to undercool and solidify metals, alloys or glasses by eliminating crucible induced nucleation processes. Niobium droplets with diameters in the range of 2 to 5 mm have been undercooled by 525 K which corresponds to the maximum undercooling reported by Turnbull and others on fine dispersions of low melting point metals. Solidification at large undercooling resulted in single crystalline spheres with the formation of interdendritic shrinkage channels on the sample surface rather than interior shrinkage cavities. The grain refinement as observed for Ni samples undercooled and solidified in fused silica crucibles does not occur in free-falling drops of Nb. A calculated solidification speed of undercooled Nb is compared to Ni. A solidification speed of 320 m/s is found for the Nb drops. This solidification speed is greater than or comparable to the solidification speeds calculated in splat cooled samples. Thus, a drop tube apparatus can be useful in the preparation and study of high temperature metastable compounds or alloys in bulk form.

  19. A drop theorem without vector topology

    NASA Astrophysics Data System (ADS)

    Wong, Chi-Wing

    2007-05-01

    Danes' drop theorem is extended to bornological vector spaces. An immediate application is to establish Ekeland-type variational principle and its equivalence, Caristi fixed point theorem, in bornological vector spaces. Meanwhile, since every locally convex space becomes a convex bornological vector space when equipped with the canonical von Neumann bornology, Qiu's generalization of Danes' work to locally convex spaces is recovered.

  20. Sessile drop deformations under an impinging jet

    NASA Astrophysics Data System (ADS)

    Feng, James Q.

    2015-08-01

    The problem of steady axisymmetric deformations of a liquid sessile drop on a flat solid surface under an impinging gas jet is of interest for understanding the fundamental behavior of free surface flows as well as for establishing the theoretical basis in process design for the Aerosol direct-write technology. It is studied here numerically using a Galerkin finite-element method, by computing solutions of Navier-Stokes equations. For effective material deposition in Aerosol printing, the desired value of Reynolds number for the laminar gas jet is found to be greater than ~500. The sessile drop can be severely deformed by an impinging gas jet when the capillary number is approaching a critical value beyond which no steady axisymmetric free surface deformation can exist. Solution branches in a parameter space show turning points at the critical values of capillary number, which typically indicate the onset of free surface shape instability. By tracking solution branches around turning points with an arc-length continuation algorithm, critical values of capillary number can be accurately determined. Near turning points, all the free surface profiles in various parameter settings take a common shape with a dimple at the center and bulge near the contact line. An empirical formula for the critical capillary number for sessile drops with contact angle is derived for typical ranges of jet Reynolds number and relative drop sizes especially pertinent to Aerosol printing.

  1. Utah Drop-Out Drug Use Questionnaire.

    ERIC Educational Resources Information Center

    Governor's Citizen Advisory Committee on Drugs, Salt Lake City, UT.

    This questionnaire assesses drug use practices in high school drop-outs. The 79 items (multiple choice or apply/not apply) are concerned with demographic data and use, use history, reasons for use/nonuse, attitudes toward drugs, availability of drugs, and drug information with respect to narcotics, amphetamines, LSD, Marijuana, and barbiturates.…

  2. Sliding viscoelastic drops on slippery surfaces

    NASA Astrophysics Data System (ADS)

    Xu, H.; Clarke, A.; Rothstein, J. P.; Poole, R. J.

    2016-06-01

    We study the sliding of drops of constant-viscosity dilute elastic liquids (Boger fluids) on various surfaces caused by sudden surface inclination. For smooth or roughened hydrophilic surfaces, such as glass or acrylic, there is essentially no difference between these elastic liquids and a Newtonian comparator fluid (with identical shear viscosity, surface tension, and static contact angle). In contrast for embossed polytetrafluoroethylene superhydrophobic surfaces, profound differences are observed: the elastic drops slide at a significantly reduced rate and complex branch-like patterns are left on the surface by the drop's wake including, on various scales, beads-on-a-string like phenomena. Microscopy images indicate that the strong viscoelastic effect is caused by stretching filaments of fluid from isolated islands, residing at pinning sites on the surface pillars, of the order ˜30 μm in size. On this scale, the local strain rates are sufficient to extend the polymer chains, locally increasing the extensional viscosity of the solution, retarding the drop and leaving behind striking branch-like structures on much larger scales.

  3. Instabilities of volatile films and drops

    NASA Astrophysics Data System (ADS)

    Murisic, Nebojsa

    2008-12-01

    We report on instabilities during spreading of volatile liquids, with emphasis on the novel instability observed when isopropyl alcohol (IPA) is deposited on a monocrystalline silicon (Si) wafer. This instability is characterized by emission of drops ahead of the expanding front, with each drop followed by smaller, satellite droplets, forming the structures which we nickname "octopi" due to their appearance. A less volatile liquid, or a substrate of larger heat conductivity, suppress this instability. In addition, we examine the spreading of drops of water (DIW)-IPA mixtures on both Si wafers and plain glass slides, and describe the variety of contact line instabilities which appear. We find that the decrease of IPA concentration in mixtures leads to transition from "octopi" to mushroom-like instabilities. Through manipulation of our experimental set up, we also find that the mechanism responsible for these instabilities appears to be mostly insensitive to both the external application of convection to the gas phase, and the doping of the gas phase with vapor in order to create the saturated environment. In order to better understand the "octopi" instability, we develop a theoretical model for evaporation of a pure liquid drop on a thermally conductive solid substrate. This model includes all relevant physical effects, including evaporation, thermal conductivity in both liquid and solid, (thermocapillary) Marangoni effect, vapor recoil, disjoining pressure, and gravity. The crucial ingredient in this problem is the evaporation model, since it influences both the motion of the drop contact line, and the temperature profiles along the liquid-solid and liquid-gas interfaces. We consider two evaporation models: the equilibrium "lens" model and the non-equilibrium one-sided (NEOS) model. Along with the assumption of equilibrium at the liquid-gas interface, the "lens" model also assumes that evaporation proceeds in a (vapor) diffusion-limited regime, therefore bringing

  4. Annual Occurrence of Meteorite-Dropping Fireballs

    NASA Astrophysics Data System (ADS)

    Konovalova, Natalia; Jopek, Tadeusz J.

    2016-07-01

    The event of Chelyabinsk meteorite has brought about change the earlier opinion about limits of the sizes of potentially dangerous asteroidal fragments that crossed the Earth's orbit and irrupted in the Earth's atmosphere making the brightest fireball. The observations of the fireballs by fireball networks allows to get the more precise data on atmospheric trajectories and coordinates of predicted landing place of the meteorite. For the reason to search the periods of fireball activity is built the annual distribution of the numbers of meteorites with the known fall dates and of the meteorite-dropping fireballs versus the solar longitude. The resulting profile of the annual activity of meteorites and meteorite-dropping fireballs shows several periods of increased activity in the course of the year. The analysis of the atmospheric trajectories and physical properties of sporadic meteorite-dropping fireballs observed in Tajikistan by instrumental methods in the summer‒autumn periods of increased fireballs activity has been made. As a result the structural strength, the bulk density and terminal mass of the studied fireballs that can survive in the Earth atmosphere and became meteorites was obtained. From the photographic IAU MDC_2003 meteor database and published sources based on the orbit proximity as determined by D-criterion of Southworth and Hawkins the fireballs that could be the members of group of meteorite-dropping fireballs, was found. Among the near Earth's objects (NEOs) the searching for parent bodies for meteorite-dropping fireballs was made and the evolution of orbits of these objects in the past on a long interval of time was investigated.

  5. Simulations of Evaporating Multicomponent Fuel Drops

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Le Clercq, Patrick

    2005-01-01

    A paper presents additional information on the subject matter of Model of Mixing Layer With Multicomponent Evaporating Drops (NPO-30505), NASA Tech Briefs, Vol. 28, No. 3 (March 2004), page 55. To recapitulate: A mathematical model of a three-dimensional mixing layer laden with evaporating fuel drops composed of many chemical species has been derived. The model is used to perform direct numerical simulations in continuing studies directed toward understanding the behaviors of sprays of liquid petroleum fuels in furnaces, industrial combustors, and engines. The model includes governing equations formulated in an Eulerian and a Lagrangian reference frame for the gas and drops, respectively, and incorporates a concept of continuous thermodynamics, according to which the chemical composition of a fuel is described by use of a distribution function. In this investigation, the distribution function depends solely on the species molar weight. The present paper reiterates the description of the model and discusses further in-depth analysis of the previous results as well as results of additional numerical simulations assessing the effect of the mass loading. The paper reiterates the conclusions reported in the cited previous article, and states some new conclusions. Some new conclusions are: 1. The slower evaporation and the evaporation/ condensation process for multicomponent-fuel drops resulted in a reduced drop-size polydispersity compared to their single-component counterpart. 2. The inhomogeneity in the spatial distribution of the species in the layer increases with the initial mass loading. 3. As evaporation becomes faster, the assumed invariant form of the molecular- weight distribution during evaporation becomes inaccurate.

  6. Evaluation of the in vitro ocular toxicity of the fortified antibiotic eye drops prepared at the Hospital Pharmacy Departments.

    PubMed

    Fernández-Ferreiro, Anxo; González-Barcia, Miguel; Gil-Martínez, María; Santiago Varela, María; Pardo, María; Blanco-Méndez, José; Piñeiro-Ces, Antonio; Lamas Díaz, María Jesús; Otero-Espinar, Francisco J

    2016-09-01

    The use of parenteral antibiotic eye drop formulations with non-marketed compositions or concentrations, commonly called fortified antibiotic eye drops, is a common practice in Ophthalmology in the hospital setting. The aim of this study was to evaluate the in vitro ocular toxicity of the main fortified antibiotic eye drops prepared in the Hospital Pharmacy Departments. We have conducted an in vitro experimental study in order to test the toxicity of gentamicin, amikacin, cefazolin, ceftazidime, vancomycin, colistimethate sodium and imipenem-cilastatin eye drops; their cytotoxicity and acute tissue irritation have been evaluated. Cell-based assays were performed on human stromal keratocytes, using a cell-based impedance biosensor system [xCELLigence Real-Time System Cell Analyzer (RTCA)], and the Hen's Egg Test for the ocular irritation tests. All the eye drops, except for vancomycin and imipenem, have shown a cytotoxic effect dependent on concentration and time; higher concentrations and longer exposure times will cause a steeper decline in the population of stromal keratocytes. Vancomycin showed a major initial cytotoxic effect, which was reverted over time; and imipenem appeared as a non-toxic compound for stromal cells. The eye drops with the highest irritating effect on the ocular surface were gentamicin and vancomycin. Those antibiotic eye drops prepared at the Hospital Pharmacy Departments included in this study were considered as compounds potentially cytotoxic for the ocular surface; this toxicity was dependent on the concentration used.

  7. Evaluation of the in vitro ocular toxicity of the fortified antibiotic eye drops prepared at the Hospital Pharmacy Departments.

    PubMed

    Fernández-Ferreiro, Anxo; González-Barcia, Miguel; Gil-Martínez, María; Santiago Varela, María; Pardo, María; Blanco-Méndez, José; Piñeiro-Ces, Antonio; Lamas Díaz, María Jesús; Otero-Espinar, Francisco J

    2016-01-01

    The use of parenteral antibiotic eye drop formulations with non-marketed compositions or concentrations, commonly called fortified antibiotic eye drops, is a common practice in Ophthalmology in the hospital setting. The aim of this study was to evaluate the in vitro ocular toxicity of the main fortified antibiotic eye drops prepared in the Hospital Pharmacy Departments. We have conducted an in vitro experimental study in order to test the toxicity of gentamicin, amikacin, cefazolin, ceftazidime, vancomycin, colistimethate sodium and imipenem-cilastatin eye drops; their cytotoxicity and acute tissue irritation have been evaluated. Cell-based assays were performed on human stromal keratocytes, using a cell-based impedance biosensor system [xCELLigence Real-Time System Cell Analyzer (RTCA)], and the Hen's Egg Test for the ocular irritation tests. All the eye drops, except for vancomycin and imipenem, have shown a cytotoxic effect dependent on concentration and time; higher concentrations and longer exposure times will cause a steeper decline in the population of stromal keratocytes. Vancomycin showed a major initial cytotoxic effect, which was reverted over time; and imipenem appeared as a non-toxic compound for stromal cells. The eye drops with the highest irritating effect on the ocular surface were gentamicin and vancomycin. Those antibiotic eye drops prepared at the Hospital Pharmacy Departments included in this study were considered as compounds potentially cytotoxic for the ocular surface; this toxicity was dependent on the concentration used. PMID:27570987

  8. PEBP2-β/CBF-β–dependent phosphorylation of RUNX1 and p300 by HIPK2: implications for leukemogenesis

    PubMed Central

    Wee, Hee-Jun; Voon, Dominic Chih-Cheng; Bae, Suk-Chul

    2008-01-01

    The heterodimeric transcription factor RUNX1/PEBP2-β (also known as AML1/CBF-β) is essential for definitive hematopoiesis. Here, we show that interaction with PEBP2-β leads to the phosphorylation of RUNX1, which in turn induces p300 phosphorylation. This is mediated by homeodomain interacting kinase 2 (HIPK2), targeting Ser249, Ser273, and Thr276 in RUNX1, in a manner that is also dependent on the RUNX1 PY motif. Importantly, we observed the in vitro disruption of this phosphorylation cascade by multiple leukemogenic genetic defects targeting RUNX1/CBFB. In particular, the oncogenic protein PEBP2-β-SMMHC prevents RUNX1/p300 phosphorylation by sequestering HIPK2 to mislocalized RUNX1/β-SMMHC complexes. Therefore, phosphorylation of RUNX1 appears a critical step in its association with and phosphorylation of p300, and its disruption may be a common theme in RUNX1-associated leukemogenesis. PMID:18695000

  9. Mutations in the Ca2+/H+ Transporter CAX1 Increase CBF/DREB1 Expression and the Cold-Acclimation Response in Arabidopsis

    PubMed Central

    Catalá, Rafael; Santos, Elisa; Alonso, José M.; Ecker, Joseph R.; Martínez-Zapater, José M.; Salinas, Julio

    2003-01-01

    Transient increases in cytosolic free calcium concentration ([Ca2+]cyt) are essential for plant responses to a variety of environmental stimuli, including low temperature. Subsequent reestablishment of [Ca2+]cyt to resting levels by Ca2+ pumps and C-REPEAT BINDING FACTOR/DEHYDRATION RESPONSIVE ELEMENT BINDING FACTOR 1 (Ca2+/H+) antiporters is required for the correct transduction of the signal. We have isolated a cDNA from Arabidopsis that corresponds to a new cold-inducible gene, RARE COLD INDUCIBLE4 (RCI4), which was identical to CALCIUM EXCHANGER 1 (CAX1), a gene that encodes a vacuolar Ca2+/H+ antiporter involved in the regulation of intracellular Ca2+ levels. The expression of CAX1 was induced in response to low temperature through an abscisic acid–independent pathway. To determine the function of CAX1 in Arabidopsis stress tolerance, we identified two T-DNA insertion mutants, cax1-3 and cax1-4, that display reduced tonoplast Ca2+/H+ antiport activity. The mutants showed no significant differences with respect to the wild type when analyzed for dehydration, high-salt, chilling, or constitutive freezing tolerance. However, they exhibited increased freezing tolerance after cold acclimation, demonstrating that CAX1 plays an important role in this adaptive response. This phenotype correlates with the enhanced expression of CBF/DREB1 genes and their corresponding targets in response to low temperature. Our results indicate that CAX1 ensures the accurate development of the cold-acclimation response in Arabidopsis by controlling the induction of CBF/DREB1 and downstream genes. PMID:14630965

  10. Electrohydrodynamic flow and chaotic mixing inside drops

    NASA Astrophysics Data System (ADS)

    Xu, Xiumei

    Electrohyodynamics, proposed by G. I. Taylor (1966), is the study of fluid motion under the influence of electric fields. In this work, we investigate theoretically and experimentally the electrohydrodynamic flow field inside a dielectric liquid drop and its application in driving chaotic mixing. Previous works on the electrohydrodynamic flows are mainly restricted to neutrally buoyant drops. Since settling drops are expected to occur more commonly in applications, in the first part of this thesis we extend Taylor's theory to deal with translating drops. Both shape distortion and charge convection, when coupled with an asymmetric velocity profile, will produce a net drag and a shift in the settling speed. Corrections to the settling velocity from both contributions are calculated to the first order. Experiments are performed using a PMM/castor oil system, and are in qualitative agreement with the theory: the deformations and the change in settling velocity are all proportional to E2, as predicted, and the settling speed shows the correct trends with drop size. In the second part of this thesis, we investigate three dimensional chaotic mixing driven by the electrohydrodynamic flows. A spatially uniform electric field is periodically switched through an angle, which is equivalent to switching the symmetry axis of the Taylor circulation back and forth, chaotic mixing is therefore generated inside a drop. Mixing efficiency is studied numerically by tracing trajectories of Lagrangian particles. Our calculations of the mixed volume fraction and Lyapunov exponents give optimal mixing conditions. Mixing experiments for a switching angle of 0.5pi are performed using a silicone oil/castor oil system, and show excellent agreement with the theory. In the third part of this thesis, we discuss effects of finite charge relaxation and charge convection on the flow field in both DC and AC electric fields. A pole-to-equator convection, acting together with a slow charge relaxation

  11. Head-on collision of drops: A numerical investigation

    NASA Technical Reports Server (NTRS)

    Nobari, M. R.; Jan, Y.-J.; Tryggvason, G.

    1993-01-01

    The head-on collision of equal sized drops is studied by full numerical simulations. The Navier-Stokes equations are solved for fluid motion both inside and outside the drops using a front tracking/finite difference technique. The drops are accelerated toward each other by a body force that is turned off before the drops collide. When the drops collide, the fluid between them is pushed outward leaving a thin later bounded by the drop surface. This layer gets progressively thinner as the drops continue to deform and in several of the calculations this double layer is artificially removed once it is thin enough, thus modeling rupture. If no rupture takes place, the drops always rebound, but if the film is ruptured the drops may coalesce permanently or coalesce temporarily and then split again.

  12. Whole-Brain Computed Tomographic Perfusion Imaging in Acute Cerebral Venous Sinus Thrombosis

    PubMed Central

    Mokin, Maxim; Ciambella, Chelsey C.; Masud, Muhammad W.; Levy, Elad I.; Snyder, Kenneth V.; Siddiqui, Adnan H.

    2016-01-01

    Background Acute cerebral venous sinus thrombosis (VST) can be difficult to diagnose because of its diverse clinical presentation. The utility of perfusion imaging for diagnosing VST is not well understood. Summary We retrospectively reviewed cases of acute VST in patients who underwent whole-brain (320-detector-row) computed tomographic (CT) perfusion imaging in combination with craniocervical CT venography. Perfusion maps that were analyzed included cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time, and time to peak. Among the 10 patients with acute VST included in this study, 9 had perfusion abnormalities. All perfusion abnormalities were localized in areas adjacent to the occluded sinus and did not match typical anterior or posterior circulation arterial territories. Bilateral perfusion deficits were seen in 4 cases. In 2 cases, parenchymal hemorrhage was diagnosed on noncontrast CT imaging; in those cases, focal CBV and CBF were reduced. Key Messages Whole-brain CT perfusion imaging with 320-detector-row scanners can further assist in establishing the diagnosis of VST by detecting perfusion abnormalities corresponding to venous and not arterial territories. CT perfusion could assist in the differentiation between focal reversible changes, such as those caused by vasogenic edema, and irreversible changes due to infarction. PMID:27051406

  13. Liquid drops on vertical and inclined surfaces; I. An experimental study of drop geometry.

    PubMed

    ElSherbini, A I; Jacobi, A M

    2004-05-15

    Experiments have been conducted to investigate the geometric parameters necessary to describe the shapes of liquid drops on vertical and inclined plane surfaces. Two liquids and eight surfaces have been used to study contact angles, contact lines, profiles, and volumes of drops of different sizes for a range of surface conditions. The results show the contact-angle variation along the circumference of a drop to be best fit by a third-degree polynomial in the azimuthal angle. This contact-angle function is expressed in terms of the maximum and minimum contact angles of the drop, which are determined for various conditions. The maximum contact angle, thetamax, is approximately equal to the advancing contact angle, thetaA, of the liquid on the surface. As the Bond number, Bo, increases from 0 to a maximum, the minimum contact angle, thetamin, decreases almost linearly from the advancing to the receding angle. A general relation is found between thetamin/thetaA and Bo for different liquid-surface combinations. The drop contour can be described by an ellipse, with the aspect ratio increasing with Bo. These experimental results are valuable in modeling drop shape, as presented in Part II of this work.

  14. Dropping In a Microgravity Environment (DIME) Contest

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Students from Sycamore High School in Cincinnati, Ohio (girls), and the COSI Academy, Columbus, Ohio (boys), participated. This image is from a digital still camera; higher resolution is not available.

  15. DROP: Durable Reconnaissance and Observation Platform

    NASA Technical Reports Server (NTRS)

    Parness, Aaron; McKenzie, Clifford F.

    2012-01-01

    Robots have been a valuable tool for providing a remote presence in areas that are either inaccessible or too dangerous for humans. Having a robot with a high degree of adaptability becomes crucial during such events. The adaptability that comes from high mobility and high durability greatly increases the potential uses of a robot in these situations, and therefore greatly increases its usefulness to humans. DROP is a lightweight robot that addresses these challenges with the capability to survive large impacts, carry a usable payload, and traverse a variety of surfaces, including climbing vertical surfaces like wood, stone, and concrete. The platform is crash-proof, allowing it to be deployed in ways including being dropped from an unmanned aerial vehicle or thrown from a large MSL-class (Mars Science Laboratory) rover.

  16. Control of Drop Motion by Mechanical Vibrations

    NASA Astrophysics Data System (ADS)

    Bestehorn, Michael

    2014-11-01

    Since the first experimental observations of Michael Faraday in 1831 it is known that a vibrating liquid may show an instability of its flat free surface with respect to oscillating regular surface patterns. We study thin liquid films on a horizontal substrate in the long wave approximation. The films are parametrically excited by mechanical horizontal or inclined oscillations. Inertia effects are taken into account and the standard thin film formulation is extended by a second equation for the vertically averaged mass flux. The films can be additionally unstable by Van der Waals forces on a partially wetting substrate, leading to the formation of drops. These drops can be manipulated by the vibrations to move in a desired direction. Linear results based on a damped complex valued Mathieu equation as well as fully nonlinear results using a reduced model will be presented, for more details see.

  17. Surface-controlled drop oscillations in space

    NASA Astrophysics Data System (ADS)

    Holt, R. Glynn

    2001-05-01

    A series of experiments probing the effects of surfactants was performed by Bob Apfel and his research group in the 1990s. Several laboratory experiments were carried out in uni-axial acoustic levitators. Two experiments were carried out in a triple-axis levitator called the Drop Physics Module, which was carried on Space Shuttle Columbia as part of the First and Second United States Microgravity Laboratory missions. Liquid drops containing aqueous solutions of soluble surfactants were acoustically positioned and deformed (and in some cases rotated) in order to excite shape mode oscillations. The results of these experiments allowed the inference of surface rheological properties (Gibb's elasticity, surface viscosity coefficients) as functions of surfactant type and concentration. The highlights of this effort will be presented in a semi-technical fashion. [Work supported by NASA.

  18. Measuring the force of drag on air sheared sessile drops

    NASA Astrophysics Data System (ADS)

    Milne, Andrew J. B.; Fleck, Brian; Amirfazli, Alidad

    2012-11-01

    To blow a drop along or off of a surface (i.e. to shed the drop), the drag force on the drop (based on flow conditions, drop shape, and fluid properties) must overcome the adhesion force between the drop and the surface (based on surface tension, drop shape, and contact angle). While the shedding of sessile drops by shear flow has been studied [Milne, A. J. B. & Amirfazli, A. Langmuir 25, 14155 (2009).], no independent measurements of the drag or adhesion forces have been made. Likewise, analytic predictions are limited to hemispherical drops and low air velocities. We present, therefore, measurements of the drag force on sessile drops at air velocities up to the point of incipient motion. Measurements were made using a modified floating element shear sensor in a laminar low speed wind tunnel to record drag force over the surface with the drop absent, and over the combined system of the surface and drop partially immersed in the boundary layer. Surfaces of different wettabilities were used to study the effects of drop shape and contact angles, with drop volume ranged between approximately 10 and 100 microlitres. The drag force for incipient motion (which by definition equals the maximum of the adhesion force) is compared to simplified models for drop adhesion such as that of Furmidge

  19. Low-Pressure-Drop Shutoff Valve

    NASA Technical Reports Server (NTRS)

    Thornborrow, John

    1994-01-01

    Flapper valve remains open under normal flow conditions but closes upon sudden increases to high rate of flow and remains closed until reset. Valve is fluid/mechanical analog of electrical fuse or circuit breaker. Low-pressure-drop shutoff valve contains flapper machined from cylindrical surface. During normal flow conditions, flapper presents small cross section to flow. (Useful in stopping loss of fluid through leaks in cooling systems.)

  20. Impact of water drops on small targets

    NASA Astrophysics Data System (ADS)

    Rozhkov, A.; Prunet-Foch, B.; Vignes-Adler, M.

    2002-10-01

    The collision of water drops against small targets was studied experimentally by means of a high-speed photography technique. The drop impact velocity was about 3.5 m/s. Drop diameters were in the range of 2.8-4.0 mm. The target was a stainless steel disk of 3.9 mm diameter. The drop spread beyond the target like a central cap surrounded by a thin, slightly conical lamella bounded by a thicker rim. By mounting a small obstacle near the target, surface-tension driven Mach waves in the flowing lamella were generated, which are formally equivalent to the familiar compressibility driven Mach waves in gas dynamics. From the measurement of the Mach angle, the values of some flow parameters could be obtained as functions of time, which provided insight into the flow structure. The liquid flowed from the central cap to the liquid rim through the thin lamella at constant momentum flux. At a certain stage of the process, most of the liquid accumulated in the rim and the internal part of the lamella became metastable. In this situation, a rupture wave propagating through the metastable internal part of the lamella caused the rim to retract while forming outwardly directed secondary jets. The jets disintegrated into secondary droplets due to the Savart-Plateau-Rayleigh instability. Prior to the end of the retraction, an internal circular wave of rupture was formed. It originated at the target and then it propagated to meet the retracting rim. Their meeting resulted in a crown of tiny droplets. A theoretical analysis of the ejection process is proposed.

  1. Tendon transfers for the drop foot.

    PubMed

    Schweitzer, Karl M; Jones, Carroll P

    2014-03-01

    The paralytic drop foot represents a challenging problem for even the most experienced orthopedic surgeon. Careful patient selection, thorough preoperative examination and planning, and application of tendon transfer biomechanical and physiologic principles outlined in this article can lead to successful results, either through a posterior tibialis tendon transfer, Bridle transfer, or variations on these procedures. Achilles lengthening or gastrocnemius recession may also be needed at the time of tendon transfer. PMID:24548510

  2. Modeling Evaporation of Drops of Different Kerosenes

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth

    2007-01-01

    A mathematical model describes the evaporation of drops of a hydrocarbon liquid composed of as many as hundreds of chemical species. The model is intended especially for application to any of several types of kerosenes commonly used as fuels. The concept of continuous thermodynamics, according to which the chemical composition of the evaporating multicomponent liquid is described by use of a probability distribution function (PDF). However, the present model is more generally applicable than is its immediate predecessor.

  3. Pollination Drop in Juniperus communis: Response to Deposited Material

    PubMed Central

    Mugnaini, Serena; Nepi, Massimo; Guarnieri, Massimo; Piotto, Beti; Pacini, Ettore

    2007-01-01

    Background and Aims The pollination drop is a liquid secretion produced by the ovule and exposed outside the micropyle. In many gymnosperms, pollen lands on the surface of the pollination drop, rehydrates and enters the ovule as the drop retracts. The objective of this work was to study the formation of the pollination drop in Juniperus communis, its carbohydrate composition and the response to deposition of conspecific pollen, foreign pollen and other particulate material, in an attempt to clarify the mechanism of pollination drop retraction. Method Branches with female cones close to pollination drop secretion were collected. On the first day of pollination drop exposure, an eyelash mounted on a wooden stick with paraffin was used to collect pollen or silica gel particles, which were then deposited by contact with the drop. Volume changes in pollination drops were measured by using a stereomicroscope with a micrometer eyepiece 3 h after deposition. The volume of non-pollinated control drops was also recorded. On the first day of secretion, drops were also collected for sugar analysis by high-performance liquid chromatography. Key Results The pollination drop persisted for about 12 d if not pollinated, and formed again after removal for up to four consecutive days. After pollination with viable conspecific pollen, the drop retracted quickly and did not form again. Partial withdrawal occurred after deposition of other biological and non-biological material. Fructose was the dominant sugar; glucose was also present but at a much lower percentage. Conclusions Sugar analysis confirmed the general trend of fructose dominance in gymnosperm pollination drops. Complete pollination drop withdrawal appears to be triggered by a biochemical mechanism resulting from interaction between pollen and drop constituents. The results of particle deposition suggest the existence of a non-specific, particle-size-dependent mechanism that induces partial pollination drop withdrawal

  4. Viscosity Measurement using Drop Coalescence in Microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.; Ethridge, Edwin; Maxwell, Daniel

    1999-01-01

    We present in here details of a new method, using drop coalescence, for application in microgravity environment for determining the viscosity of highly viscous undercooled liquids. The method has the advantage of eliminating heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Also, due to the rapidity of the measurement, homogeneous nucleation would be avoided. The technique relies on both a highly accurate solution to the Navier-Stokes equations as well as on data gathered from experiments conducted in near zero gravity environment. The liquid viscosity is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity of two coalescing drops. Results are presented from two validation experiments of the method which were conducted recently on board the NASA KC-135 aircraft. In these tests the viscosity of a highly viscous liquid, such as glycerine at different temperatures, was determined to reasonable accuracy using the liquid coalescence method. The experiments measured the free surface velocity of two glycerine drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The free surface velocity was then compared with the computed values obtained from different viscosity values. The results of these experiments were found to agree reasonably well with the calculated values.

  5. Ultrasonic characterization of single drops of liquids

    SciTech Connect

    Sinha, D.N.

    1998-04-14

    Ultrasonic characterization of single drops of liquids is disclosed. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities. 5 figs.

  6. Weight Drop Models in Traumatic Brain Injury.

    PubMed

    Kalish, Brian T; Whalen, Michael J

    2016-01-01

    Weight drop models in rodents have been used for several decades to advance our understanding of the pathophysiology of traumatic brain injury. Weight drop models have been used to replicate focal cerebral contusion as well as diffuse brain injury characterized by axonal damage. More recently, closed head injury models with free head rotation have been developed to model sports concussions, which feature functional disturbances in the absence of overt brain damage assessed by conventional imaging techniques. Here, we describe the history of development of closed head injury models in the first part of the chapter. In the second part, we describe the development of our own weight drop closed head injury model that features impact plus rapid downward head rotation, no structural brain injury, and long-term cognitive deficits in the case of multiple injuries. This rodent model was developed to reproduce key aspects of sports concussion so that a mechanistic understanding of how long-term cognitive deficits might develop will eventually follow. Such knowledge is hoped to impact athletes and war fighters and others who suffer concussive head injuries by leading to targeted therapies aimed at preventing cognitive and other neurological sequelae in these high-risk groups. PMID:27604720

  7. Leaf drop affects herbivory in oaks.

    PubMed

    Pearse, Ian S; Karban, Richard

    2013-11-01

    Leaf phenology is important to herbivores, but the timing and extent of leaf drop has not played an important role in our understanding of herbivore interactions with deciduous plants. Using phylogenetic general least squares regression, we compared the phenology of leaves of 55 oak species in a common garden with the abundance of leaf miners on those trees. Mine abundance was highest on trees with an intermediate leaf retention index, i.e. trees that lost most, but not all, of their leaves for 2-3 months. The leaves of more evergreen species were more heavily sclerotized, and sclerotized leaves accumulated fewer mines in the summer. Leaves of more deciduous species also accumulated fewer mines in the summer, and this was consistent with the idea that trees reduce overwintering herbivores by shedding leaves. Trees with a later leaf set and slower leaf maturation accumulated fewer herbivores. We propose that both leaf drop and early leaf phenology strongly affect herbivore abundance and select for differences in plant defense. Leaf drop may allow trees to dispose of their herbivores so that the herbivores must recolonize in spring, but trees with the longest leaf retention also have the greatest direct defenses against herbivores.

  8. Drop floating on a granular raft

    NASA Astrophysics Data System (ADS)

    Jambon-Puillet, Etienne; Josserand, Christophe; Protiere, Suzie

    2015-11-01

    When a droplet comes in contact with a bath of the same liquid, it coalesces to minimize the surface energy. This phenomenon reduces emulsion stability and is usually fought with surfactant molecules. Another way to slow down coalescence is to use colloidal solid particles. In this case the particles spontaneously migrate to the interface to form ``Pickering'' emulsions and act as a barrier between droplets. Here we use dense, large particles (~ 500 μm) which form a monolayer at an oil/water interface that we call a granular raft. When a droplet is placed on top of such a raft, for a given set of particle properties (contact angle/size), the raft prevents coalescence indefinitely. However, in contrast to what happens when a droplet is placed on a hydrophobic surface and never wets the surface, here the droplet is strongly anchored to the raft and deforms it. We will use this specific configuration to probe the mechanical response of the granular raft: by controlling the droplet volume we can impose tensile or compressive stresses. Finally we will show that the drop, spherical at first, slowly takes a more complex shape as it's volume increases. This shape is not reversible as the drop volume is decreased. The drop can become oblate or prolate with wrinkling of the raft.

  9. Cusp formation in drops inside Taylor cones

    NASA Astrophysics Data System (ADS)

    Marin, Alvaro G.; Loscertales, Ignacio G.; Barrero, Antonio

    2005-11-01

    Here, we report the formation of cusp in insulating drops inside compound Taylor cones. The action of the electrical shear stress acting on the outer interface, which is transmitted by viscous forces inside the Taylor cone, tends to deform the drop of insulating liquid placed inside. For appropriate values of the capillary number, the insulating drop develops a steady cusp angle which depends on both the capillary number and the conducting to insulating viscosity ratio. A self-similar analysis has been developed to qualitatively describe the flow inside these compounds Taylor cones. Any perturbation of the cusp gives rise to an intermittent emission of tiny droplets; this effect may recall the tip-streaming observed by G.I. Taylor in his four-roll mill device. This emission can be stabilized by an appropriate control of the injected flow rate of the insulating liquid. When the capillary number increases, the cusped interface turns into a spout which flows coated by the conducting liquid forming the electrified coaxial jet which has been successfully employed for the production of nanocapsules, coaxial nanofibers and nanotubes (Science 295, n. 5560, 1695, 2002; JACS 126, 5376, 2004).

  10. Leaf drop affects herbivory in oaks.

    PubMed

    Pearse, Ian S; Karban, Richard

    2013-11-01

    Leaf phenology is important to herbivores, but the timing and extent of leaf drop has not played an important role in our understanding of herbivore interactions with deciduous plants. Using phylogenetic general least squares regression, we compared the phenology of leaves of 55 oak species in a common garden with the abundance of leaf miners on those trees. Mine abundance was highest on trees with an intermediate leaf retention index, i.e. trees that lost most, but not all, of their leaves for 2-3 months. The leaves of more evergreen species were more heavily sclerotized, and sclerotized leaves accumulated fewer mines in the summer. Leaves of more deciduous species also accumulated fewer mines in the summer, and this was consistent with the idea that trees reduce overwintering herbivores by shedding leaves. Trees with a later leaf set and slower leaf maturation accumulated fewer herbivores. We propose that both leaf drop and early leaf phenology strongly affect herbivore abundance and select for differences in plant defense. Leaf drop may allow trees to dispose of their herbivores so that the herbivores must recolonize in spring, but trees with the longest leaf retention also have the greatest direct defenses against herbivores. PMID:23774946

  11. Expression responses of five cold tolerant related genes to two temperature dropping treatments in sea cucumber Apostichopus japonicus

    NASA Astrophysics Data System (ADS)

    Li, Chengze; Chang, Yaqing; Pang, Zhenguo; Ding, Jun; Ji, Nanjing

    2015-03-01

    Environmental conditions, including ambient temperature, play important roles in survival, growth development, and reproduction of the Japanese sea cucumber, Apostichopus japonicus. Low temperatures result in slowed growth and skin ulceration disease. In a previous study, we investigated the effect of low temperature on gene expression profiles in A. japonicus by suppression subtractive hybridization (SSH). Genes encoding Ferritin, Lysozyme, Hsp70, gp96, and AjToll were selected from a subtracted cDNA library of A. japonicus under acute cold stress. The transcriptional expression profiles of these genes were investigated in different tissues (coelomocyte, respiratory tree, intestine, longitudinal muscle) after exposure to acute and mild temperature dropping treatments. The results show that (1) the five cold-tolerance-related genes were found in all four tissues and the highest mRNA levels were observed in coelomocyte and respiratory tree; (2) under the temperature dropping treatments, three types of transcriptional regulation patterns were observed: primary suppression followed by up-regulation at -2°C, suppressed expression throughout the two treatments, and more rarely an initial stimulation followed by suppression; and (3) gene expression suppression was more severe under acute temperature dropping than under mild temperature dropping treatment. The five cold-tolerance-related genes that were distributed mainly in coelomocyte and respiratory tissues were generally down-regulated by low temperature stress but an inverse up-regulation event was found at the extreme temperature (-2°C).

  12. Clinical Importance of the Heel Drop Test and a New Clinical Score for Adult Appendicitis

    PubMed Central

    Ahn, Shin; Lee, Hyeji; Choi, Wookjin; Ahn, Ryeok; Hong, Jung-Suk; Sohn, Chang Hwan; Seo, Dong Woo; Lee, Yoon-Seon; Lim, Kyung Soo; Kim, Won Young

    2016-01-01

    Objective We tried to evaluate the accuracy of the heel drop test in patients with suspected appendicitis and tried to develop a new clinical score, which incorporates the heel drop test and other parameters, for the diagnosis of this condition. Methods We performed a prospective observational study on adult patients with suspected appendicitis at two academic urban emergency departments between January and August 2015. The predictive characteristics of each parameter, along with heel drop test results were calculated. A composite score was generated by logistic regression analysis. The performance of the generated score was compared to that of the Alvarado score. Results Of the 292 enrolled patients, 165 (56.5%) had acute appendicitis. The heel drop test had a higher predictive value than rebound tenderness. Variables and their points included in the new (MESH) score were pain migration (2), elevated white blood cell (WBC) >10,000/μL (3), shift to left (2), and positive heel drop test (3). The MESH score had a higher AUC than the Alvarado score (0.805 vs. 0.701). Scores of 5 and 11 were chosen as cut-off values; a MESH score ≥5 compared to an Alvarado score ≥5, and a MESH score ≥8 compared to an Alvarado score ≥7 showed better performance in diagnosing appendicitis. Conclusion MESH (migration, elevated WBC, shift to left, and heel drop test) is a simple clinical scoring system for assessing patients with suspected appendicitis and is more accurate than the Alvarado score. Further validation studies are needed. PMID:27723842

  13. Surfactant and nonlinear drop dynamics in microgravity

    NASA Astrophysics Data System (ADS)

    Jankovsky, Joseph Charles

    2000-11-01

    Large amplitude drop dynamics in microgravity were conducted during the second United States Microgravity Laboratory mission carried onboard the Space Shuttle Columbia (20 October-5 November 1995). Centimeter- sized drops were statically deformed by acoustic radiation pressure and released to oscillate freely about a spherical equilibrium. Initial aspect ratios of up to 2.0 were achieved. Experiments using pure water and varying aqueous concentrations of Triton-X 100 and bovine serum albumin (BSA) were performed. The axisymmetric drop shape oscillations were fit using the degenerate spherical shape modes. The frequency and decay values of the fundamental quadrupole and fourth order shape mode were analyzed. Several large amplitude nonlinear oscillation dynamics were observed. Shape entrainment of the higher modes by the fundamental quadrupole mode occurred. Amplitude- dependent effects were observed. The nonlinear frequency shift, where the oscillation frequency is found to decrease with larger amplitudes, was largely unaffected by the presence of surfactants. The percentage of time spent in the prolate shape over one oscillation cycle was found to increase with oscillation amplitude. This prolate shape bias was also unaffected by the addition of surfactants. These amplitude-dependent effects indicate that the nonlinearities are a function of the bulk properties and not the surface properties. BSA was found to greatly enhance the surface viscoelastic properties by increasing the total damping of the oscillation, while Triton had only a small influence on damping. The surface concentration of BSA was found to be diffusion-controlled over the time of the experiments, while the Triton diffusion rate was very rapid. Using the experimental frequency and decay values, the suface viscoelastic properties of surface dilatational viscosity ( ks ) and surface shear viscosity ( ms ) were found for varying surfactant concentrations using the transcendental equation of Lu

  14. Evolutionary appearance of genes encoding proteins associated with box H/ACA snoRNAs: Cbf5p in Euglena gracilis, an early diverging eukaryote, and candidate Gar1p and Nop10p homologs in archaebacteria

    PubMed Central

    Watanabe, Yoh-ichi; Gray, Michael W.

    2000-01-01

    A reverse transcription–polymerase chain reaction (RT–PCR) approach was used to clone a cDNA encoding the Euglena gracilis homolog of yeast Cbf5p, a protein component of the box H/ACA class of snoRNPs that mediate pseudouridine formation in eukaryotic rRNA. Cbf5p is a putative pseudouridine synthase, and the Euglena homolog is the first full-length Cbf5p sequence to be reported for an early diverging unicellular eukaryote (protist). Phylogenetic analysis of putative pseudouridine synthase sequences confirms that archaebacterial and eukaryotic (including Euglena) Cbf5p proteins are specifically related and are distinct from the TruB/Pus4p clade that is responsible for formation of pseudouridine at position 55 in eubacterial (TruB) and eukaryotic (Pus4p) tRNAs. Using a bioinformatics approach, we also identified archaebacterial genes encoding candidate homologs of yeast Gar1p and Nop10p, two additional proteins known to be associated with eukaryotic box H/ACA snoRNPs. These observations raise the possibility that pseudouridine formation in archaebacterial rRNA may be dependent on analogs of the eukaryotic box H/ACA snoRNPs, whose evolutionary origin may therefore predate the split between Archaea (archaebacteria) and Eucarya (eukaryotes). Database searches further revealed, in archaebacterial and some eukaryotic genomes, two previously unrecognized groups of genes (here designated ‘PsuX’ and ‘PsuY’) distantly related to the Cbf5p/TruB gene family. PMID:10871366

  15. Drop by drop scattering properties of a radar bin : a numerical experiment

    NASA Astrophysics Data System (ADS)

    Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    This paper presents the development and initial results of a numerical simulation of pseudo-radar observations computed as the sum of the electric field backscattered by each drop. Simulations are carried out for three successive radar bins with a gate length of 30 m and beam width of 1°. The first step is the simulation of a 100 m x 100 m x 100 m volume with all its drops. The 3D raindrop generator relies on the findings on the rainfall field very small scales (mm to few tens of m) spatio-temporal structure, of the HYDROP experiment and a recent analysis of 2D video disdrometer data in a Multifractal framework. More precisely: (i) The Liquid Water Content (LWC) distribution is represented with the help a multiplicative cascade down to 0.5 m, below which it is considered as homogeneous. (ii) Within each 0.5 x 0.5 x 0.5 m3 patch, liquid water is distributed into drops according to a pre-defined Drop Size Distribution (DSD) and located randomly uniformly. (iii) Such configuration is compared with the one consisting of the same drops uniformly distributed over the 50 x 50 x 50 m3 volume. Then the backscattered field by the drops located within a radar bin are computed as the sum a individual contribution. Antenna beam weighing is taken into account Due to the fact that the radar wave length is much smaller than the "patches" size for rainfall, it appears that as theoretically expected we retrieved an exponential distribution for potential measure horizontal reflectivity. A much lower dispersion is noticed for differential reflectivity. We show that a simple ballistic assumption for drop velocities does not enable to reproduce radar observations, and turbulence must be taken into account. Finally the sensitivity of these outputs to the various model parameters is quantified.

  16. Dielectrophoresis of a surfactant-laden viscous drop

    NASA Astrophysics Data System (ADS)

    Mandal, Shubhadeep; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-06-01

    The dielectrophoresis of a surfactant-laden viscous drop in the presence of non-uniform DC electric field is investigated analytically and numerically. Considering the presence of bulk-insoluble surfactants at the drop interface, we first perform asymptotic solution for both low and high surface Péclet numbers, where the surface Péclet number signifies the strength of surface convection of surfactants as compared to the diffusion at the drop interface. Neglecting fluid inertia and interfacial charge convection effects, we obtain explicit expression for dielectrophoretic drop velocity for low and high Péclet numbers by assuming small deviation of drop shape from sphericity and small deviation of surfactant concentration from the equilibrium uniform distribution. We then depict a numerical solution, assuming spherical drop, for arbitrary values of Péclet number. Our analyses demonstrate that the asymptotic solution shows excellent agreement with the numerical solution in the limiting conditions of low and high Péclet numbers. The present analysis shows that the flow-induced redistribution of the surfactants at the drop interface generates Marangoni stress, owing to the influence of the surfactant distribution on the local interfacial tension, at the drop interface and significantly alters the drop velocity at steady state. For a perfectly conducting/dielectric drop suspended in perfectly dielectric medium, Marangoni stress always retards the dielectrophoretic velocity of the drop as compared with a surfactant-free drop. For a leaky dielectric drop suspended in another leaky dielectric medium, in the low Péclet number limit, depending on the electrical conductivity and permittivity of both the liquids, the Marangoni stress may aid or retard the dielectrophoretic velocity of the drop. The Marangoni stress also has the ability to move the drop in the opposite direction as compared with a surfactant-free drop. This non-intuitive reverse motion of the drop is

  17. The Effects of Acutely Administered 3,4-Methylenedioxymethamphetamine on Spontaneous Brain Function in Healthy Volunteers Measured with Arterial Spin Labeling and Blood Oxygen Level–Dependent Resting State Functional Connectivity

    PubMed Central

    Carhart-Harris, Robin L.; Murphy, Kevin; Leech, Robert; Erritzoe, David; Wall, Matthew B.; Ferguson, Bart; Williams, Luke T.J.; Roseman, Leor; Brugger, Stefan; De Meer, Ineke; Tanner, Mark; Tyacke, Robin; Wolff, Kim; Sethi, Ajun; Bloomfield, Michael A.P.; Williams, Tim M.; Bolstridge, Mark; Stewart, Lorna; Morgan, Celia; Newbould, Rexford D.; Feilding, Amanda; Curran, H. Val; Nutt, David J.

    2015-01-01

    Background The compound 3,4-methylenedioxymethamphetamine (MDMA) is a potent monoamine releaser that produces an acute euphoria in most individuals. Methods In a double-blind, placebo-controlled, balanced-order study, MDMA was orally administered to 25 physically and mentally healthy individuals. Arterial spin labeling and seed-based resting state functional connectivity (RSFC) were used to produce spatial maps displaying changes in cerebral blood flow (CBF) and RSFC after MDMA administration. Participants underwent two arterial spin labeling and two blood oxygen level–dependent scans in a 90-minute scan session; MDMA and placebo study days were separated by 1 week. Results Marked increases in positive mood were produced by MDMA. Decreased CBF only was observed after MDMA, and this was localized to the right medial temporal lobe (MTL), thalamus, inferior visual cortex, and the somatosensory cortex. Decreased CBF in the right amygdala and hippocampus correlated with ratings of the intensity of global subjective effects of MDMA. The RSFC results complemented the CBF results, with decreases in RSFC between midline cortical regions, the medial prefrontal cortex, and MTL regions, and increases between the amygdala and hippocampus. There were trend-level correlations between these effects and ratings of intense and positive subjective effects. Conclusions The MTLs appear to be specifically implicated in the mechanism of action of MDMA, but further work is required to elucidate how the drug’s characteristic subjective effects arise from its modulation of spontaneous brain activity. PMID:24495461

  18. Evaluation of Ophthacare eye drops--a herbal formulation in the management of various ophthalmic disorders.

    PubMed

    Biswas, N R; Gupta, S K; Das, G K; Kumar, N; Mongre, P K; Haldar, D; Beri, S

    2001-11-01

    An open prospective multicentre clinical trial was conducted in patients suffering from various ophthalmic disorders namely, conjunctivitis, conjunctival xerosis (dry eye), acute dacryocystitis, degenerative conditions (pterygium or pinguecula) and postoperative cataract patients with a herbal eye drop preparation (Ophthacare) containing basic principles of different herbs which have been conventionally used in the Ayurvedic system of medicine since time immemorial. These include Carum copticum, Terminalia belirica, Emblica officinalis, Curcuma longa, Ocimum sanctum, Cinnamomum camphora, Rosa damascena and meldespumapum. These herbs reportedly possess antiinfective and antiinflammatory properties. The present study was undertaken to elucidate the role of this herbal product in a variety of eye ailments. Side effects, if any, were noted during the study. An improvement was observed with the treatment of the herbal eye drop treatment in most cases. There were no side effects observed during the course of the study and the eye drop was well tolerated by the patients. The herbal eye drop Ophthacare has a useful role in a variety of infective, inflammatory and degenerative ophthalmic disorders. PMID:11746845

  19. Flow visualization and characterization of evaporating liquid drops

    NASA Technical Reports Server (NTRS)

    Chao, David F. (Inventor); Zhang, Nengli (Inventor)

    2004-01-01

    An optical system, consisting of drop-reflection image, reflection-refracted shadowgraphy and top-view photography, is used to measure the spreading and instant dynamic contact angle of a volatile-liquid drop on a non-transparent substrate. The drop-reflection image and the shadowgraphy is shown by projecting the images of a collimated laser beam partially reflected by the drop and partially passing through the drop onto a screen while the top view photograph is separately viewed by use of a camera video recorder and monitor. For a transparent liquid on a reflective solid surface, thermocapillary convection in the drop, induced by evaporation, can be viewed nonintrusively, and the drop real-time profile data are synchronously recorded by video recording systems. Experimental results obtained from this technique clearly reveal that evaporation and thermocapillary convection greatly affect the spreading process and the characteristics of dynamic contact angle of the drop.

  20. Modeling of drop breakup in the bag breakup regime

    NASA Astrophysics Data System (ADS)

    Wang, C.; Chang, S.; Wu, H.; Xu, J.

    2014-04-01

    Several analytic models for predicting the drop deformation and breakup have been developed over the last three decades, but modeling drop breakup in the bag-type regime is less reported. In this Letter, a breakup model has been proposed to predict the drop deformation length and breakup time in the bag-type breakup regime in a more accurate manner. In the present model, the drop deformation which is approximately as the displacement of the centre of mass (c. m.) along the axis located at the centre of the drop, and the movement of c. m. is obtained by solving the pressure balance equation. The effects of the drop deformation on the drop external aerodynamic force are considered in this model. Drop breakup occurs when the deformation length reaches the maximum value and the maximum deformation length is a function of Weber number. The performance and applicability of the proposed breakup model are tested against the published experimental data.

  1. Drop-by-drop chemical reaction and sample introduction for capillary electrophoresis.

    PubMed

    Chen, Fengming; Rang, Ying; Weng, Ying; Lin, Luyao; Zeng, Hulie; Nakajim, Hizuru; Lin, Jin-Ming; Uchiyama, Katsumi

    2015-06-21

    In this paper, we report a novel sample introduction and chemical reaction strategy by drop-by-drop inkjet injection for an electrophoretically mediated microanalysis (EMMA). This method makes it possible to achieve an on-line introduction of reactant solutions by alternately ejecting small plugs, with an overlapping region of the plugs for mixing the reactants by electrophoresis, supporting chemical reactions, followed by electrophoretic separation of the final compounds. As a proof-of-concept of the method, the EMMA of an inkjetted mixture of 4-fluoro-7-nitrobenzofurazan (NBD-F) and amino acids was carried out as a model chemical reaction. The product NBD-amino acids were quantified by detection with laser induced fluorescence. The optimal conditions for the procedure were: inkjet driving voltage: +40-44 V; pulse width: 20-24 μs; drop-by-drop injection of reactant solutions: alternately 2 drops × 25 times for the amino acid solution and the NBD-F solution; zone overlapping voltage and time: 3 kV and 2 s; incubation time after overlapping: 5 min; separation voltage: 18 kV. Under the optimized conditions, a significant enhancement in sensitivity and a sensitive quantitative analysis were realized. The results obtained were comparable with those using the off-line labeling method. This method is rapid, cost-effective, and readily automated for EMMA. PMID:25728632

  2. Drop-by-drop chemical reaction and sample introduction for capillary electrophoresis.

    PubMed

    Chen, Fengming; Rang, Ying; Weng, Ying; Lin, Luyao; Zeng, Hulie; Nakajim, Hizuru; Lin, Jin-Ming; Uchiyama, Katsumi

    2015-06-21

    In this paper, we report a novel sample introduction and chemical reaction strategy by drop-by-drop inkjet injection for an electrophoretically mediated microanalysis (EMMA). This method makes it possible to achieve an on-line introduction of reactant solutions by alternately ejecting small plugs, with an overlapping region of the plugs for mixing the reactants by electrophoresis, supporting chemical reactions, followed by electrophoretic separation of the final compounds. As a proof-of-concept of the method, the EMMA of an inkjetted mixture of 4-fluoro-7-nitrobenzofurazan (NBD-F) and amino acids was carried out as a model chemical reaction. The product NBD-amino acids were quantified by detection with laser induced fluorescence. The optimal conditions for the procedure were: inkjet driving voltage: +40-44 V; pulse width: 20-24 μs; drop-by-drop injection of reactant solutions: alternately 2 drops × 25 times for the amino acid solution and the NBD-F solution; zone overlapping voltage and time: 3 kV and 2 s; incubation time after overlapping: 5 min; separation voltage: 18 kV. Under the optimized conditions, a significant enhancement in sensitivity and a sensitive quantitative analysis were realized. The results obtained were comparable with those using the off-line labeling method. This method is rapid, cost-effective, and readily automated for EMMA.

  3. Safety and Efficacy of Phenylephrine Nasal Drops in Bronchiolitis

    PubMed Central

    Soleimani, Gholamreza; Akbarpour, Marzieh; Mohammadi, Mehdi

    2014-01-01

    Objective: Bronchiolitis is a common lower respiratory tract infection in the first year of life. In this disease upper respiratory tract infection is associated with nasal congestion, respiratory distress and hypoxia. We studied the effect of phenylephrine drops as a decongestant in treatment of light and moderately severe cases of acute bronchiolitis. Methods: This is a double blind randomized trial involving 100 children aged 4 weeks to 12 months. The patients were divided into two groups, the first group received 0.1 ml phenylephrine 0.5% and the second group 0.1 ml sodium chloride (NaCl) 0.9% as placebo in both nostrils. Respiratory rate, heart rate, O2 saturation, dyspnea, retractions and wheezing were assessed before and 30 minutes after medication. Findings: After medication, O2 saturation and respiratory muscles retractions in the phenylephrine group were significantly better than those of the placebo group (P=0.004 and P=0.002, respectively). In the phenylephrine group, O2 saturation, retractions and wheezing were also significantly better before than those after medication (P=0.003 and P<0.0001 respectively). In the placebo group no significant difference before and after intervention was observed. Conclusion: Phenylephrine as a topical decongestant is an inexpensive, easily available and suitable means in the treatment of mild to moderately severe bronchiolitis. PMID:25793067

  4. Pressure Drop in Radiator Air Tubes

    NASA Technical Reports Server (NTRS)

    Parsons, S R

    1921-01-01

    This report describes a method for measuring the drop in static pressure of air flowing through a radiator and shows (1) a reason for the discrepancy noted by various observers between head resistance and drop in pressure; (2) a difference in degree of contraction of the jet in entering a circular cell and a square cell; (3) the ratio of internal frictional resistance to total head resistance for two representative types; (4) the effect of smoothness of surface on pressure gradient; and (5) the effects of supplying heat to the radiator on pressure gradient. The fact that the pressure gradients are found to be approximately proportional to the square of the rate of flow of air appears to indicate turbulent flow, even in the short tubes of the radiator. It was found that the drop in the static pressure in the air stream through a cellular radiator and the pressure gradient in the air tubes are practically proportional to the square of the air flow in a given air density; that the difference between the head resistance per unit area and the fall of static pressure through the air tubes in radiators is apparent rather than real; and that radiators of different types differ widely in the amount of contraction of the jet at entrance. The frictional resistance was found to vary considerably, and in one case to be two-thirds of the head resistance in the type using circular cells and one-half of the head resistance of the radiator type using square cells of approximately the same dimensions.

  5. Impact dynamics of oxidized liquid metal drops

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Brown, Eric; Jaeger, Heinrich M.

    2013-04-01

    With exposure to air, many liquid metals spontaneously generate an oxide layer on their surface. In oscillatory rheological tests, this skin is found to introduce a yield stress that typically dominates the elastic response but can be tuned by exposing the metal to hydrochloric acid solutions of different concentration. We systematically studied the normal impact of eutectic gallium-indium (eGaIn) drops under different oxidation conditions and show how this leads to two different dynamical regimes. At low impact velocity (or low Weber number), eGaIn droplets display strong recoil and rebound from the impacted surface when the oxide layer is removed. In addition, the degree of drop deformation or spreading during impact is controlled by the oxide skin. We show that the scaling law known from ordinary liquids for the maximum spreading radius as a function of impact velocity can still be applied to the case of oxidized eGaIn if an effective Weber number We is employed that uses an effective surface tension factoring in the yield stress. In contrast, no influence on spreading from different oxidations conditions is observed for high impact velocity. This suggests that the initial kinetic energy is mostly damped by bulk viscous dissipation. Results from both regimes can be collapsed in an impact phase diagram controlled by two variables, the maximum spreading factor Pm=R0/Rm, given by the ratio of initial to maximum drop radius, and the impact number K=We/Re4/5, which scales with the effective Weber number We as well as the Reynolds number Re. The data exhibit a transition from capillary to viscous behavior at a critical impact number Kc≈0.1.

  6. Improved Refractometer for Measuring Temperatures of Drops

    NASA Technical Reports Server (NTRS)

    Naqwi, Amir A.

    2004-01-01

    The Dual Rainbow refractometer is an enhanced version of the Rainbow refractometer, which is added to, and extends the capabilities of, a phase Doppler particle analyzer (PDPA). A PDPA utilizes pairs of laser beams to measure individual components of velocity and sizes of drops in a spray. The Rainbow-refractometer addition measures the temperatures of individual drops. The designs of prior versions of the Rainbow refractometer have required substantial modifications of PDPA transmitting optics, plus dedicated lasers as sources of illumination separate from, and in addition to, those needed for PDPA measurements. The enhancement embodied in the Dual Rainbow refractometer eliminates the need for a dedicated laser and confers other advantages as described below. A dedicated laser is no longer needed because the Dual Rainbow refractometer utilizes one of the pairs of laser beams already present in a PDPA. Hence, the design of the Dual Rainbow refractometer simplifies the task of upgrading PDPA hardware to enable measurement of temperature. Furthermore, in a PDPA/Dual Rainbow refractometer system, a single argon-ion laser with three main wavelengths can be used to measure the temperatures, sizes, and all three components of velocity (in contradistinction to only two components of velocity in a prior PDPA/Rainbow refractometer system). In order to enable the Dual Rainbow refractometer to utilize a pair of PDPA laser beams, it was necessary to (1) find a location for the refractometer receiver, such that the combined rainbow patterns of two laser beams amount to a pattern identical to that of a single beam, (2) adjust the polarization of the two beams to obtain the strongest rainbow pattern, and (3) find a location for the PDPA receiver to obtain a linear relationship between the measured phase shift and drop size.

  7. Hospital addresses ED overcrowding, sees treatment times and walkout rates drop.

    PubMed

    2005-11-01

    Mary Washington Hospital in Fredericksburg, VA, addressed the new accreditation standard on overcrowding and saw its treatment times drop by about two hours and its walkout rate drop to 2%, despite increases in volume. A Patient Flow Excellence and Accountability Team focused on getting patients upstairs in under one hour, which was achieved through nurse and supervisor buy-in. Monthly staff meetings were added for all shifts. Computers and equipment for trauma and codes were placed closer to where they were needed. The staffing ratio on the acute side was reduced to 1:4 for nurses and 1:12 for physicians. The ED converted to a five-level triage system, and the hospital is experimenting with a triage nurse focused on lower acuity areas and a "virtual bed system" in which patients are seen by a physician/nurse team at triage and start having labs and X-rays done immediately. PMID:16752445

  8. Drop-in substitute for dichlorodifluoromethane refrigerant

    SciTech Connect

    Goble, G.H.

    1993-06-01

    A method for producing refrigeration in a refrigeration system designed for a dichlorodifluoromethane refrigerant is described, comprising drop-in substituting for said dichlorodifluoromethane a ternary mixture of about 2 to 20 weight percent isobutane, about 21 to 51 weight percent 1-chloro-1,1-difluoroethane, and about 41 to 71 weight percent chlorodifluoromethane, with the weight percentages of said components being weight percentages of the overall mixture; condensing said ternary mixture; and thereafter evaporating said ternary mixture in the vicinity of a body to be cooled.

  9. Naval Waste Package Drop With Emplacement Pallet

    SciTech Connect

    D.G. McLenzie

    2005-08-04

    The objective of this calculation was to determine the structural responses of the Emplacement Pallet and Naval Long Waste Package (WP) to drops from their highest possible lift heights. The scope of this document was limited to reporting the calculation results in terms of maximum stress intensities. The Naval Long WP is classified as Quality Level 1 (Ref 12, page 7, Table 1). The Emplacement Pallet is classified as Quality Level 2 (Ref. 19, page 7, Table 1). Therefore, this calculation is subject to the requirements of the Quality Assurance Requirements and Description (Ref. 11). AP-3.12Q, Calculations, was used to perform the calculation and develop the document (Ref. 3).

  10. [Development of intranasal lactocin (oxytocin) drops technology].

    PubMed

    Klimas, Rimantas; Baranauskas, Algirdas; Gendrolis, Antanas

    2002-01-01

    Pure oxytocin substance was obtained from posterior part of cattle pituitary gland by high pressure liquid chromatography. Biological activity of the substance--450-500 IU/mg. Chromatographically pure Oxytocin substance was used in developing two different compositions of Lactocin intranasal drops (40 IU/ml). Stability evaluation was performed for 2 year period. The technical documentation was prepared on the basis of the research results. Lactocin is active preparation helping lactation and is indicated for lactostasis treatment and its prophylaxis after delivery. PMID:12474675

  11. Solid drop based liquid-phase microextraction.

    PubMed

    Ganjali, Mohammad Reza; Sobhi, Hamid Reza; Farahani, Hadi; Norouzi, Parviz; Dinarvand, Rassoul; Kashtiaray, Amir

    2010-04-16

    Solid drop based liquid-phase microextraction (SDLPME) is a novel sample preparation technique possessing obvious advantages of simple operation with a high pre-concentration factor, low cost and low consumption of organic solvent. SDLPME coupled with gas chromatography (GC), high-performance liquid chromatography (HPLC), and atomic absorption spectrometry (AAS) has been widely applied to the analyses of a different variety of samples. The basic principles, parameters affecting the extraction efficiency, and the latest applications of SDLPME are reviewed in this article. PMID:19962710

  12. Equilibrium of an elastically confined liquid drop

    NASA Astrophysics Data System (ADS)

    Kwon, Hyuk-Min; Kim, Ho-Young; Puëll, Jérôme; Mahadevan, L.

    2008-05-01

    When a liquid drop is confined between an elastic plate and a rigid substrate, it spreads spontaneously due to the effects of interfacial forces, eventually reaching an equilibrium shape determined by the balance between elastic and capillary effects. We provide an analytical theory for the static shape of the sheet and the extent of liquid spreading and show that our experiments are quantitatively consistent with the theory. The theory is relevant for the first step of painting when a brush is brought down on to canvas. More mundanely, it allows us to understand the stiction of microcantilevers to wafer substrates occurring in microelectromechanical fabrication processes.

  13. Predicting Pressure Drop In Porous Materials

    NASA Technical Reports Server (NTRS)

    Lawing, Pierce L.

    1990-01-01

    Theory developed to predict drop in pressure based on drag of individual fibers. Simple correlation method for data also developed. Helps in predicting flow characteristics of many strain-isolation pad (SIP) glow geometries in Shuttle Orbiter tile system. Also helps in predicting venting characteristics of tile assemblies during ascent and leakage of hot gas under tiles during descent. Useful in study of mechanics of flows through fibrous and porous media, and procedures applicable to purged fiberglass insulation, dialysis filters, and other fibrous and porous media.

  14. A ballistic gravimeter with dropping holographic grating

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. L.; Kotova, E. I.; Nikushchenko, E. M.; Smirnova, A. L.; Prokopenko, V. T.

    2014-11-01

    The principle of operation of a ballistic laser gravimeter based on a dropping holographic diffraction grating is described. The free-fall acceleration of the grating is determined from a change in the frequency of beats that arise during the interference of light beams diffracted on the hologram in the zeroth and first orders of diffraction. An experiment demonstrating this principle of measurement is described. The main distinctive features of the proposed gravimeter are simple design, compact size, and the possibility of using this device for analysis of high-frequency fluctuations in the gravitational-field strength.

  15. Thermocapillary Migration and Interactions of Bubbles and Drops

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Lacy, Claud E.; Wozniak, Guenter; Subramanian, R. Shankar

    1996-01-01

    When a drop or bubble is placed in another fluid and subjected to the action of a temperature gradient, the drop will move. Such motion is a direct consequence of the variation of interfacial tension with temperature, and is termed thermocapillary migration. This paper discusses results from experiments conducted in reduced gravity on the thermocapillary motion of bubbles and drops.

  16. The Illustrated Topology of Liquid Drops during Formation

    ERIC Educational Resources Information Center

    Libii, Josue Njock

    2004-01-01

    High-speed photography can show that the shape often used for a newly forming drop is wrong. Knowledge of drop behaviour is important for inkjet printers, and a close look at the formation of drops as given here can enhance critical observation, thinking and analysis.

  17. Dropping out from School. Policy Brief Number 8

    ERIC Educational Resources Information Center

    Hunt, Frances

    2009-01-01

    While initial access to education is increasing in many countries, drop out rates continue to be high. This seriously affects MDG and EFA goals around educational access. This briefing paper looks at the issue of dropping out from school. It is based on the CREATE Pathways to Access Research Monograph, "Dropping out from school: a cross country…

  18. Inverse Leidenfrost Effect: Levitating Drops on Liquid Nitrogen.

    PubMed

    Adda-Bedia, M; Kumar, S; Lechenault, F; Moulinet, S; Schillaci, M; Vella, D

    2016-05-01

    We explore the interaction between a liquid drop (initially at room temperature) and a bath of liquid nitrogen. In this scenario, heat transfer occurs through film-boiling: a nitrogen vapor layer develops that may cause the drop to levitate at the bath surface. We report the phenomenology of this inverse Leidenfrost effect, investigating the effect of the drop size and density by using an aqueous solution of a tungsten salt to vary the drop density. We find that (depending on its size and density) a drop either levitates or instantaneously sinks into the bulk nitrogen. We begin by measuring the duration of the levitation as a function of the radius R and density ρd of the liquid drop. We find that the levitation time increases roughly linearly with drop radius but depends weakly on the drop density. However, for sufficiently large drops, R ≥ Rc(ρd), the drop sinks instantaneously; levitation does not occur. This sinking of a (relatively) hot droplet induces film-boiling, releasing a stream of vapor bubbles for a well-defined length of time. We study the duration of this immersed-drop bubbling finding similar scalings (but with different prefactors) to the levitating drop case. With these observations, we study the physical factors limiting the levitation and immersed-film-boiling times, proposing a simple model that explains the scalings observed for the duration of these phenomena, as well as the boundary of (R,ρd) parameter space that separates them. PMID:27054550

  19. Drop Testing of DOE Spent Nuclear Fuel Canisters

    SciTech Connect

    S. D. Snow; D. K. Morton; T. E. Rahl; R. K. Blandford; T. J. Hill

    2005-07-01

    The National Spent Nuclear Fuel Program (NSNFP) at the Idaho National Engineering and Environmental Laboratory INEEL) prepared four representative Department of Energy DOE) spent nuclear fuel (SNF) canisters for the purpose of drop testing. The first two canisters represented a modified 24- inch diameter standardized DOE SNF canister and the second two canisters represented the Hanford Multi-Canister Overpack MCO). The modified canisters and internals were constructed and assembled at the INEEL. The MCO internal weights were fabricated at the INEEL and assembled into two MCOs at Hanford and later shipped to the INEEL for drop test preparation. Drop testing of these four canisters was completed in August 2004 at Sandia National Laboratories. The modified canisters were dropped from 30 feet onto a flat, essentially unyielding surface, with the canisters oriented at 45 degrees and 70 degrees off-vertical at impact. One representative MCO was dropped from 23 feet onto the same flat surface, oriented vertically at impact. The second representative MCO was dropped onto the flat surface from 2 feet oriented at 60 degrees off-vertical. These drop heights and orientations were chosen to meet or exceed the Yucca Mountain repository drop criteria. This paper discusses the comparison of deformations between the actual dropped canisters and those predicted by pre-drop and limited post-drop finite element evaluations performed using ABAQUS/Explicit. Post-drop containment of all four canisters, demonstrated by way of helium leak testing, is also discussed.

  20. Spent Nuclear Fuel (SNF) Bounding Drop Support Calculations

    SciTech Connect

    CHENAULT, D.M.

    1999-11-16

    This report evaluates different drop heights, concrete and other impact media to which the transport package and/or the MCO is dropped. A prediction method is derived for estimating the resultant impact factor for determining the bounding drop case for the SNF Project.

  1. Variables Affecting Students' Decisions to Drop Out of School

    ERIC Educational Resources Information Center

    Dunn, Caroline; Chambers, Dalee; Rabren, Karen

    2004-01-01

    This study examined factors predictive of dropping out of high school for students with learning disabilities (LD) and mental retardation (MR). The sample was composed of 228 students with LD or MR who dropped out of school and 228 students with LD or MR who had not dropped out. Two sets of pre- dictor variables (student demographics and interview…

  2. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  3. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  4. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  5. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  6. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  7. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  8. 14 CFR 27.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reserve energy absorption drop test. 27.727 Section 27.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted as...

  9. 14 CFR 29.727 - Reserve energy absorption drop test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reserve energy absorption drop test. 29.727 Section 29.727 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION....727 Reserve energy absorption drop test. The reserve energy absorption drop test must be conducted...

  10. Pendant-Drop Surface-Tension Measurement On Molten Metal

    NASA Technical Reports Server (NTRS)

    Man, Kin Fung; Thiessen, David

    1996-01-01

    Method of measuring surface tension of molten metal based on pendant-drop method implemented in quasi-containerless manner and augmented with digital processing of image data. Electrons bombard lower end of sample rod in vacuum, generating hanging drop of molten metal. Surface tension of drop computed from its shape. Technique minimizes effects of contamination.

  11. Delayed Frost Growth on Jumping-Drop Superhydrophobic Surfaces

    SciTech Connect

    Boreyko, Jonathan B; Collier, Pat

    2013-01-01

    Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an inter-drop frost wave. The growth of this inter-drop frost front is shown to be up to three times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of inter-drop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an inter-drop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser was found to be superior to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by minimizing the success of interdrop ice bridge formation.

  12. 14 CFR 23.725 - Limit drop tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... their proper relation, from free drop heights not less than those determined by the following formula: h... must be dropped with an effective weight equal to EC28SE91.014 where— W e=the effective weight to be... the drop mass (inches); W=W M for main gear units (lbs), equal to the static weight on that unit...

  13. 14 CFR 23.725 - Limit drop tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... their proper relation, from free drop heights not less than those determined by the following formula: h... must be dropped with an effective weight equal to EC28SE91.014 where— W e=the effective weight to be... the drop mass (inches); W=W M for main gear units (lbs), equal to the static weight on that unit...

  14. Acute gastroenteritis.

    PubMed

    Graves, Nancy S

    2013-09-01

    Acute gastroenteritis is a common infectious disease syndrome, causing a combination of nausea, vomiting, diarrhea, and abdominal pain. There are more than 350 million cases of acute gastroenteritis in the United States annually and 48 million of these cases are caused by foodborne bacteria. Traveler's diarrhea affects more than half of people traveling from developed countries to developing countries. In adult and pediatric patients, the prevalence of Clostridium difficile is increasing. Contact precautions, public health education, and prudent use of antibiotics are necessary goals in decreasing the prevalence of Clostridium difficle. Preventing dehydration or providing appropriate rehydration is the primary supportive treatment of acute gastroenteritis.

  15. PROGRAM DROP: A computer program for prediction of evaporation from freely falling multicomponent drops

    SciTech Connect

    Gavin, P.M.

    1996-12-01

    PROGRAM DROP consists of a series of FORTRAN routine which together are used to model the evaporation of a freely falling, multicomponent drop composed of an arbitrary number of volatile species and a single nonvolatile, inert component. The physics underlying the model are clearly identified, and the model`s relationship to previous work in the literature is described. Test cases are used to illustrate the viability of the model and to highlight its potential usefulness in the accurate prediction of multicomponent droplet vaporization in a variety of applications.

  16. Electrically induced drop detachment and ejection

    NASA Astrophysics Data System (ADS)

    Cavalli, Andrea; Preston, Daniel J.; Tio, Evelyn; Martin, David W.; Miljkovic, Nenad; Wang, Evelyn N.; Blanchette, Francois; Bush, John W. M.

    2016-02-01

    A deformed droplet may leap from a solid substrate, impelled to detach through the conversion of surface energy into kinetic energy that arises as it relaxes to a sphere. Electrowetting provides a means of preparing a droplet on a substrate for lift-off. When a voltage is applied between a water droplet and a dielectric-coated electrode, the wettability of the substrate increases in a controlled way, leading to the spreading of the droplet. Once the voltage is released, the droplet recoils, due to a sudden excess in surface energy, and droplet detachment may follow. The process of drop detachment and lift-off, prevalent in both biology and micro-engineering, has to date been considered primarily in terms of qualitative scaling arguments for idealized superhydrophobic substrates. We here consider the eletrically-induced ejection of droplets from substrates of finite wettability and analyze the process quantitatively. We compare experiments to numerical simulations and analyze how the energy conversion efficiency is affected by the applied voltage and the intrinsic contact angle of the droplet on the substrate. Our results indicate that the finite wettability of the substrate significantly affects the detachment dynamics, and so provide new rationale for the previously reported large critical radius for drop ejection from micro-textured substrates.

  17. Electrohydrodynamically Driven Chaotic Advection in Drops

    NASA Astrophysics Data System (ADS)

    Ward, Thomas; Homsy, G. M.

    2002-11-01

    When a liquid drop of given dielectric constant, resistivity and viscosity is translating in a liquid of different dielectric constant, resistivity and viscosity under Stokes flow conditions in the presence of an electric field, the resulting internal circulation is a superposition of the Hadamard-Rybcynski circulation and the circulation first described theoretically by G. I. Taylor. For sufficiently strong electric field strengths, the quadrapole structure of the Taylor circulation can cause an internal stagnation disk to occur. Our interest is in the situation where a modulation of the electric field causes the stagnation disk to modulate its position, potentially leading to chaotic flows within the drop. The dimensionless electric field strength is characterized by W = 4V(1+lambda)/U where V is the maximum interfacial velocity of the Taylor circulation, U the translational velocity, and lambda the viscosity ratio. The streamfunction for the flow is: 1) psi = (r4-r2) sin2)(theta + W(t) (r3 - r5) sin2 (theta) cos(theta) 2) W(t) = W1 + W2 cos ((epsilon)t) where epsilon is the dimensionless frequency, and W1, W2 are the amplitudes of the DC and AC components, respectively. We have found it useful to replace these parameters by a secondary set, epsilon, Wmax and delta = (1 / W1 - 1 / W2) - (1 / W1 + 1 / W2). As shown in Figure 1a, delta is the dimensionless distance the stagnation disk moves over one period of modulation. The advection equations corresponding to the flow were integrated by standard techniques, and it was found that the trajectories were chaotic over a wide range of parameters. Experiments were conducted to test the predictions of rapid mixing on convective time scales. Drops of silicon oil were suspended in a small 60 mm x 120 mm x 120 mm test cell filled with castor oil, and subject to time-modulated axial electric fields with a wave form corresponding to eq(2). The drops were typically 5 mm in diameter and settled with typical speeds of O(10-1 mm

  18. Force-displacement differences in the lower extremities of young healthy adults between drop jumps and drop landings.

    PubMed

    Hackney, James M; Clay, Rachel L; James, Meredith

    2016-10-01

    We measured ground reaction force and lower extremity shortening in ten healthy, young adults in order to compare five trials of drop jumps to drop landings. Our dependent variable was the percentage of displacement (shortening) between the markers on the ASIS and second metatarsal heads on each LE, relative to the maximum shortening (100% displacement) for that trial at the point of greatest ground reaction force. We defined this as "percent displacement at maximum force" (%dFmax). The sample mean %dFmax was 0.73%±0.14% for the drop jumps, and 0.47%±0.09% for the drop landings. The mean within-subject difference score was 0.26%±0.20%. Two-tailed paired t test comparing %dFmax between the drop jump and drop landing yielded P=0.002. For all participants in this study, the %dFmax was greater in drop jumps than in drop landings. This indicates that in drop jumps, the point of maximum force and of maximum shortening was nearly simultaneous, compared to drop landings, where the point of maximum shortening followed that of maximum force by a greater proportion. This difference in force to displacement behavior is explained by linear spring behavior in drop jumps, and linear damping behavior in drop landings. PMID:27344129

  19. Force-displacement differences in the lower extremities of young healthy adults between drop jumps and drop landings.

    PubMed

    Hackney, James M; Clay, Rachel L; James, Meredith

    2016-10-01

    We measured ground reaction force and lower extremity shortening in ten healthy, young adults in order to compare five trials of drop jumps to drop landings. Our dependent variable was the percentage of displacement (shortening) between the markers on the ASIS and second metatarsal heads on each LE, relative to the maximum shortening (100% displacement) for that trial at the point of greatest ground reaction force. We defined this as "percent displacement at maximum force" (%dFmax). The sample mean %dFmax was 0.73%±0.14% for the drop jumps, and 0.47%±0.09% for the drop landings. The mean within-subject difference score was 0.26%±0.20%. Two-tailed paired t test comparing %dFmax between the drop jump and drop landing yielded P=0.002. For all participants in this study, the %dFmax was greater in drop jumps than in drop landings. This indicates that in drop jumps, the point of maximum force and of maximum shortening was nearly simultaneous, compared to drop landings, where the point of maximum shortening followed that of maximum force by a greater proportion. This difference in force to displacement behavior is explained by linear spring behavior in drop jumps, and linear damping behavior in drop landings.

  20. Acute Bronchitis

    MedlinePlus

    ... bronchitis? Acute bronchitis is almost always caused by viruses that attack the lining of the bronchial tree ... infection. As your body fights back against these viruses, more swelling occurs and more mucus is produced. ...

  1. Acute Pericarditis

    MedlinePlus

    ... large pericardial effusions). Acute pericarditis usually responds to colchicine or NSAIDs (such as aspirin and ibuprofen ) taken ... reduce pain but relieves it by reducing inflammation. Colchicine also decreases the chance of pericarditis returning later. ...

  2. Surface Patterns of Parametrically-Excited Sessile Drops

    NASA Astrophysics Data System (ADS)

    Chang, Chun-Ti; Bostwick, Joshua; Daniel, Susan; Steen, Paul

    2012-11-01

    A mechanically-excited sessile water drop exhibits surface patterns that vary with driving amplitude and frequency. At small amplitudes, drops exhibit axisymmetric wave patterns. At sufficiently large amplitudes and at particular frequencies, symmetry breaks and there appear subharmonically-resonating sectoral and tesseral mode shapes. We report observations from experiment and compare to results from modeling the parametric excitation of the drops. The modeling uses the spectrum and eigenmodes from a linear stability analysis of the inviscid sessile Rayleigh drop with moving/pinned contact-line. Manipulating drop motion can be important to a variety of applications.

  3. Vertical vibration and shape oscillation of acoustically levitated water drops

    SciTech Connect

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

    2014-09-08

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  4. Vertical vibration and shape oscillation of acoustically levitated water drops

    NASA Astrophysics Data System (ADS)

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

    2014-09-01

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  5. Thermocapillary Migration and Interactions of Bubbles and Drops

    NASA Technical Reports Server (NTRS)

    Subramaniam, R. Shankar; Balasubramaniam, R.; Wozniak, G.; Hadland, P. H.

    1999-01-01

    Experiments were performed aboard the LMS mission of the Space Shuttle in summer 1996 in the BDPU on isolated air bubbles and Fluorinert FC-75 drops as well as on interacting bubbles/drops migrating in a temperature gradient in a Dow-Corning DC-200 series silicone oil of nominal viscosity 10 centistokes. The data, recorded in the form of videotape images as well as cine images in selected runs, have been analyzed. The behavior of the isolated objects is consistent with earlier observations made aboard the IML-2 mission while the range of Reynolds and Marangoni numbers has been extended substantially over that in the IML-2 experiments. Large bubbles were found to be slightly deformed to an oblate shape while no deformation could be detected in the case of similarly large drops. Results on interacting drops and bubbles display interesting and unanticipated features. In some experiments, drops are found to follow a three-dimensional trajectory. In others, trailing drops and bubbles are found to move off the axis of the cell when migrating behind a leading drop or bubble which moves along the axis. In this type of run, if the trailing drop is sufficiently large, it is found to pass the leading drop. Finally, behavior similar to that observed in IML-2, namely that a small leading drop slows the movement of a larger trailing drop moving along the cell axis, was observed as well.

  6. Characterization of biofluids prepared by sessile drop formation.

    PubMed

    Esmonde-White, Karen A; Esmonde-White, Francis W L; Morris, Michael D; Roessler, Blake J

    2014-06-01

    Sessile drop formation, also called drop deposition, has been studied as a potential medical diagnostic, but the effects of complex biofluid rheology on the final deposition pattern are not well understood. We studied two model biofluids, blood plasma and synovial fluid, when deposited onto slightly hydrophilic substrates forming a contact angle of 50-90°. Drops were imaged during the evaporation process and geometric properties of the drop, such as contact angle and drop height, were calculated from the images. The resulting dried biofluid drops were then examined using light microscopy and Raman spectroscopy to assess morphological and chemical composition of the dried drop. The effect of substrate contact angle (surface wetting) and fluid concentration was examined. We found that when biofluids are deposited onto slightly hydrophilic surfaces, with a contact angle of 50-90°, a ring-shaped deposit was formed. Analysis of the drying drop's geometric properties indicates that biofluid dynamics follow the piling model of drop formation, as proposed by Deegan et al. The final deposition pattern varied with substrate surface and concentration, as shown by light microscopy photos of dried drops. The chemical composition of the outer ring was minimally affected by substrate surface, but the spatial heterogeneity of protein distribution within the ring varied with concentration. These results indicate that biofluid drop deposition produces ring-shaped deposits which can be examined by multiple analytical techniques.

  7. An experimental study of dynamics of drop formation

    SciTech Connect

    Zhang, X.; Basaran, O.A.

    1995-06-01

    A liquid being ejected from a nozzle emanates from it as discrete, uniformly sized drops when the flow rate is sufficiently low. In this paper, an experimental study is presented of the dynamics of a viscous liquid drop that is being formed directly at the tip of a vertical tube into ambient air. The evolution in time of the drop shape and volume is monitored with a time resolution of 1/12 to 1 ms. Following the detachment of the previous drop, the profile of the new growing drop at first changes from spherical to pear-shaped. As time advances, the throat of the pear-shaped drop takes on the appearance of a liquid thread that connects the bottom portion of the drop that is about to detach to the rest of the liquid that is pendant from the tube. The focus here is on probing the effects of physical and geometric parameters on the universal features of drop formation, paying special attention to the development, extension, and breakup of the liquid thread and the satellite drops that are formed subsequent to its breakup. The role of surfactants in modifying the dynamics of drop formation is also studied. The effects of finite inertial, capillary, viscous, and gravitational forces are all accounted for to classify drastically different formation dynamics and to elucidate the fate of satellite drops following thread rupture.

  8. Characterization of biofluids prepared by sessile drop formation.

    PubMed

    Esmonde-White, Karen A; Esmonde-White, Francis W L; Morris, Michael D; Roessler, Blake J

    2014-06-01

    Sessile drop formation, also called drop deposition, has been studied as a potential medical diagnostic, but the effects of complex biofluid rheology on the final deposition pattern are not well understood. We studied two model biofluids, blood plasma and synovial fluid, when deposited onto slightly hydrophilic substrates forming a contact angle of 50-90°. Drops were imaged during the evaporation process and geometric properties of the drop, such as contact angle and drop height, were calculated from the images. The resulting dried biofluid drops were then examined using light microscopy and Raman spectroscopy to assess morphological and chemical composition of the dried drop. The effect of substrate contact angle (surface wetting) and fluid concentration was examined. We found that when biofluids are deposited onto slightly hydrophilic surfaces, with a contact angle of 50-90°, a ring-shaped deposit was formed. Analysis of the drying drop's geometric properties indicates that biofluid dynamics follow the piling model of drop formation, as proposed by Deegan et al. The final deposition pattern varied with substrate surface and concentration, as shown by light microscopy photos of dried drops. The chemical composition of the outer ring was minimally affected by substrate surface, but the spatial heterogeneity of protein distribution within the ring varied with concentration. These results indicate that biofluid drop deposition produces ring-shaped deposits which can be examined by multiple analytical techniques. PMID:24757707

  9. Leidenfrost drops and micro-particles: organization and evaporation

    NASA Astrophysics Data System (ADS)

    Maquet, Laurent; Colinet, Pierre; Dorbolo, Stéphane

    2014-11-01

    We investigate the behavior of hydrophilic microparticles dropped into Leidenfrost drops. These particles appears to go through the drop until they reach the bottom surface of the drop where they are dewetted. Due to the evaporation of the drop, the surface of the drop decreases. Thus, the particles that are trapped at the surface of the drop due to the dewetting begin to cover more and more the drop. At a point, they even cover the whole surface of the drop. The superficial density of the particles at the surface is ~0.8 and the fraction of the beads that stay trapped at the surface until the cover is complete is always larger than 0 . 7 . We measured evaporation rates and compared the case of drops with and without particles. These evaporation rates are always decreased by the presence of the particles. This is due to the dewetting. Indeed, the effective surface of evaporation is decreased by the presence of particles at the surface. Thus, knowing how the evaporation is affected by the presence of the particles, we can measure contact angles at the lower surface of these levitating drops.

  10. Directional motion of impacting drops on dual-textured surfaces.

    PubMed

    Vaikuntanathan, V; Sivakumar, D

    2012-09-01

    In this work, we analyze the directional movement of impacting liquid drops on dual-textured solid surfaces comprising two different surface morphologies: a textured surface and a smooth surface. The dynamics of liquid drops impacting onto the junction line between the two parts of the dual-textured surfaces is studied experimentally for varying drop impact velocity. The dual-textured surfaces used here featured a variation in their textures' geometrical parameters as well as their surface chemistry. Two types of liquid drop differing in their surface tension were used. The impact process develops a net horizontal drop velocity towards the higher-wettability surface portion and results in a bulk movement of the impacting drop liquid. The final distance moved by the impacting drop from the junction line decreases with increasing impacting drop Weber number We. A fully theoretical model, employing a balance of forces acting at the drop contact line as well as energy conservation, is formulated to determine the variation, with We, of net horizontal drop velocity and subsequent movement of the impacting drop on the dual-textured surfaces.

  11. Large ultrathin shelled drops produced via non-confined microfluidics.

    PubMed

    Chaurasia, Ankur S; Josephides, Dimitris N; Sajjadi, Shahriar

    2015-02-01

    We present a facile approach for producing large and monodisperse core-shell drops with ultrathin shells using a single-step process. A biphasic compound jet is introduced into a quiescent third (outer) phase that ruptures to form core-shell drops. Ultrathin shelled drops could only be produced within a certain range of surfactant concentrations and flow rates, highlighting the effect of interfacial tension in engulfing the core in a thin shell. An increase in surfactant concentrations initially resulted in drops with thinner shells. However, the drops with thinnest shells were obtained at an optimum surfactant concentration, and a further increase in the surfactant concentrations increased the shell thickness. Highly monodisperse (coefficient of variation smaller than 3 %) core-shell drops with diameter of ∼200 μm-2 mm with shell thickness as small as ∼2 μm were produced. The resulting drops were stable enough to undergo polymerisation and produce ultrathin shelled capsules.

  12. Jumps, somersaults, and symmetry breaking in Leidenfrost drops

    NASA Astrophysics Data System (ADS)

    Chen, Simeng; Bertola, Volfango

    2016-08-01

    When a droplet of water impacts a heated surface, the drop may be observed to bounce. Recently is has been found that small quantities (˜100 ppm) of polymer additives such as polyethylene oxide can significantly increase the maximum bouncing height of drops. This effect has been explained in terms of the reduction of energy dissipation caused by polymer additives during the drop retraction and rebound, resulting in higher mechanical energy available for bouncing. Here we demonstrate, by comparing three types of fluids (Newtonian, shear-thinning, and viscoelastic), that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated when compared with high-viscosity or non-Newtonian drops. We also show that non-Newtonian effects play little role in the energy distribution during drop impact, while the main effect is due to the symmetry break observed during the retraction of low-viscosity drops.

  13. Jumps, somersaults, and symmetry breaking in Leidenfrost drops.

    PubMed

    Chen, Simeng; Bertola, Volfango

    2016-08-01

    When a droplet of water impacts a heated surface, the drop may be observed to bounce. Recently is has been found that small quantities (∼100 ppm) of polymer additives such as polyethylene oxide can significantly increase the maximum bouncing height of drops. This effect has been explained in terms of the reduction of energy dissipation caused by polymer additives during the drop retraction and rebound, resulting in higher mechanical energy available for bouncing. Here we demonstrate, by comparing three types of fluids (Newtonian, shear-thinning, and viscoelastic), that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated when compared with high-viscosity or non-Newtonian drops. We also show that non-Newtonian effects play little role in the energy distribution during drop impact, while the main effect is due to the symmetry break observed during the retraction of low-viscosity drops. PMID:27627234

  14. The Oil Drop Experiment: How Did Millikan Decide What Was an Appropriate Drop?

    ERIC Educational Resources Information Center

    Niaz, Mansoor

    2003-01-01

    The oil drop experiment is considered an important contribution to the understanding of modern physics and chemistry. The objective of this investigation is to study and contrast the views and understanding with respect to the experiment of physicists or philosophers of science with those of authors of physics or chemistry textbooks and…

  15. Metal particle compaction during drop-substrate impact for inkjet printing and drop-casting processes

    NASA Astrophysics Data System (ADS)

    Clancy, I.; Amarandei, G.; Nash, C.; Glowacki, B. A.

    2016-02-01

    Direct coating methods using metal particles from aqueous solutions or solvent-based inks become central in the roll-to-roll fabrication processes as these methods can lead to continuous or pre-defined conductive layers on a large variety of substrates. For good electrical conductivity, the metal particles have to be brought into contact, and traditionally, additional sintering treatments are required. Such treatments can degrade the sensitive substrates as paper or polymer films. In this study, the possibility of obtaining conductive layers at room temperature is investigated for direct coating methods with an emphasis on drop-casting and inkjet printing. Thus, it is shown that electrical conductive layers can be achieved if the metal particles can compact during the drop-substrate impact interaction. It is theoretically shown that the compaction process is directly related to the particle and ink drop size, the initial fractional particle loading of the ink, solvent viscosity, and drop velocity. The theoretical predictions on compaction are experimentally validated, and the particle compaction's influence on changes in the electrical conductivity of the resulting layers is demonstrated.

  16. Pathogenicity and genetic characterization of a duck Tembusu virus associated with egg-dropping in Muscovy ducks.

    PubMed

    Shen, Han-Qin; Lin, Wen-Cheng; Wang, Zhan-Xin; Zhang, Kai; Yan, Zhuan-Qiang; Zhou, Qing-Feng; Qin, Jian-Ping; Xie, Qing-Mei; Bi, Ying-Zuo; Chen, Feng

    2016-09-01

    Duck Tembusu virus (DTMUV) has spread to the major duck-farming region in China, causing acute egg-production drop in Chinese duck population. In this study, we characterized a DTMUV strain (named GD2014) isolated from an egg-production drop duck farm in Guangdong province, South China. The virus was pathogenic to Muscovy duck embryos and caused severe egg production drop for laying Muscovy ducks. The genome sequence of GD2014 shared 97-99% homologies with other waterfowl-origin Tembusu viruses, and shared 89% identities with MM1775 strain isolated from mosquito. Phylogenetic analysis of entire open reading frame (ORF), E gene and NS5 gene indicated that GD2014 belonged to Ntaya group. These results have implications for understanding the orgin, emergence and pathogenicity of DTMUV as well as for the development of vaccines and diagnostics based on epidemiological data. PMID:27354303

  17. Pathogenicity and genetic characterization of a duck Tembusu virus associated with egg-dropping in Muscovy ducks.

    PubMed

    Shen, Han-Qin; Lin, Wen-Cheng; Wang, Zhan-Xin; Zhang, Kai; Yan, Zhuan-Qiang; Zhou, Qing-Feng; Qin, Jian-Ping; Xie, Qing-Mei; Bi, Ying-Zuo; Chen, Feng

    2016-09-01

    Duck Tembusu virus (DTMUV) has spread to the major duck-farming region in China, causing acute egg-production drop in Chinese duck population. In this study, we characterized a DTMUV strain (named GD2014) isolated from an egg-production drop duck farm in Guangdong province, South China. The virus was pathogenic to Muscovy duck embryos and caused severe egg production drop for laying Muscovy ducks. The genome sequence of GD2014 shared 97-99% homologies with other waterfowl-origin Tembusu viruses, and shared 89% identities with MM1775 strain isolated from mosquito. Phylogenetic analysis of entire open reading frame (ORF), E gene and NS5 gene indicated that GD2014 belonged to Ntaya group. These results have implications for understanding the orgin, emergence and pathogenicity of DTMUV as well as for the development of vaccines and diagnostics based on epidemiological data.

  18. Nonlinear Oscillations of Two-Dimensional, Rotating Inviscid Drops

    NASA Astrophysics Data System (ADS)

    Patzek, T. W.; Basaran, O. A.; Benner, R. E.; Scriven, L. E.

    1995-01-01

    We examine the nonlinear response of a drop, rotating as a rigid body at fixed angular velocity, to two-dimensional finite-amplitude disturbances. With these restrictions, the liquid velocity becomes a superposition of the solid-body rotation and the gradient of a velocity potential. To find the drop motion, we solve an integro-differential Bernoulli's equation for the drop shape and Laplace's equation for the velocity potential field within the drop. The integral part of Bernoulli's equation couples all parts of the drop's surface and sets this problem apart from that of the oscillations of nonrotating drops. We use Galerkin's weighted residual method with finite element basis functions which are deployed on a mesh that deforms in proportion to the deformation of the free surface. To alleviate the roundoff error in the initial conditions of the drop motion, we use a Fourier filter which turns off as soon as the highest resolved oscillation mode grows above the machine noise level. The results include sequences of drop shapes, Fourier analysis of oscillation frequencies, and evolution in time of the components of total mechanical energy of the drop. The Fourier power spectral analysis of large-amplitude oscillations of the drop reveals frequency shifts similar to those of the nonrotating free drops. Constant drop volume, total energy, and angular momentum as well as vanishing mass flow across the drop surface are the standards of accuracy against which we test the nonlinear motion of the drop over tens or hundreds of oscillation periods. Finally, we demonstrate that our finite element method has superior stability, accuracy, and computational efficiency over several boundary element algorithms that have previously appeared in the literature.

  19. Planar Jumping-Drop Thermal Diodes

    NASA Astrophysics Data System (ADS)

    Boreyko, Jonathan; Zhao, Yuejun; Chen, Chuan-Hua

    2011-11-01

    Phase-change thermal diodes transport heat asymmetrically with a large rectification coefficient unmatched by their solid-state counterparts, but are limited by either the gravitational orientation or one-dimensional configuration. We report a planar phase-change diode scalable to large areas with an orientation-independent diodicity of up to 100, in which water/vapor is enclosed by parallel superhydrophobic and superhydrophilic plates. The thermal rectification is enabled by spontaneously jumping dropwise condensate which only occurs when the superhydrophobic surface is colder than the superhydrophilic surface. Our jumping-drop thermal diode is expected to be particularly useful for the thermal protection of planar electronic components and the thermal regulation of large-area energy harvesting systems.

  20. Crack formation and prevention in colloidal drops

    NASA Astrophysics Data System (ADS)

    Kim, Jin Young; Cho, Kun; Ryu, Seul-A.; Kim, So Youn; Weon, Byung Mook

    2015-08-01

    Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles.

  1. Load drop evaluation for TWRS FSAR

    SciTech Connect

    Julyk, L.J.; Ralston, G.L.

    1996-09-30

    Operational or remediation activities associated with existing underground high-level waste storage tank structures at the Hanford Site often require the installation/removal of various equipment items. To gain tank access for installation or removal of this equipment, large concrete cover blocks must be removed and reinstalled in existing concrete pits above the tanks. An accidental drop of the equipment or cover blocks while being moved over the tanks that results in the release of contaminants to the air poses a potential risk to onsite workers or to the offsite public. To minimize this potential risk, the use of critical lift hoisting and rigging procedures and restrictions on lift height are being considered during development of the new tank farm Basis for Interim Operation and Final Safety Analysis Report. The analysis contained herein provides information for selecting the appropriate lift height restrictions for these activities.

  2. Horizontal Drop of 21- PWR Waste Package

    SciTech Connect

    A.K. Scheider

    2007-01-31

    The objective of this calculation is to determine the structural response of the waste package (WP) dropped horizontally from a specified height. The WP used for that purpose is the 21-Pressurized Water Reactor (PWR) WP. The scope of this document is limited to reporting the calculation results in-terms of stress intensities. This calculation is associated with the WP design and was performed by the Waste Package Design group in accordance with the ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 16). AP-3.12Q, ''Calculations'' (Ref. 1 1) is used to perform the calculation and develop the document. The sketches attached to this calculation provide the potential dimensions and materials for the 21-PWR WP design.

  3. Drop Impact on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Josserand, C.; Thoroddsen, S. T.

    2016-01-01

    A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications.

  4. Crack formation and prevention in colloidal drops

    PubMed Central

    Kim, Jin Young; Cho, Kun; Ryu, Seul-a; Kim, So Youn; Weon, Byung Mook

    2015-01-01

    Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles. PMID:26279317

  5. Bubble and Drop Nonlinear Dynamics experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Bubble and Drop Nonlinear Dynamics (BDND) experiment was designed to improve understanding of how the shape and behavior of bubbles respond to ultrasound pressure. By understanding this behavior, it may be possible to counteract complications bubbles cause during materials processing on the ground. This 12-second sequence came from video downlinked from STS-94, July 5 1997, MET:3/19:15 (approximate). The BDND guest investigator was Gary Leal of the University of California, Santa Barbara. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced fluid dynamics experiments will be a part of investigations plarned for the International Space Station. (189KB JPEG, 1293 x 1460 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300163.html.

  6. Drop Impact on to Moving Liquid Pools

    NASA Astrophysics Data System (ADS)

    Muñoz-Sánchez, Beatriz Natividad; Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Hutchings, Ian M.

    2014-11-01

    The deposition of droplets on to moving liquid substrates is an omnipresent situation both in nature and industry. A diverse spectrum of phenomena emerges from this simple process. In this work we present a parametric experimental study that discerns the dynamics of the impact in terms of the physical properties of the fluid and the relative velocity between the impacting drop and the moving liquid pool. The behaviour ranges from smooth coalescence (characterized by little mixing) to violent splashing (generation of multiple satellite droplets and interfacial vorticity). In addition, transitional regimes such as bouncing and surfing are also found. We classify the system dynamics and show a parametric diagram for the conditions of each regime. This work was supported by the EPSRC (Grant EP/H018913/1), the Royal Society, Becas Santander Universidades and the International Relationships Office of the University of Extremadura.

  7. The dynamics of free liquid drops

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Trinh, E. H.; Croonquist, A. P.; Elleman, D. D.

    1988-01-01

    The behavior of rotating and oscillating free liquid drops was studied by many investigators theoretically for many years. More recent numerical treatments have yielded predictions which are yet to be verified experimentally. The purpose is to report the results of laboratory work as well as that of the experiments carried out in space during the flight of Spacelab 3, and to compare it with the existing theoretical studies. Ground-based experiments were attempted as a first approximation to the ideal boundary conditions used by the theoretical treatments by neutralizing the overwhelming effects of the Earth's gravitational field with an outside supporting liquid and with the use of levitation technology. The viscous and inertial loading of such a suspending fluid was found to profoundly effect the results, but the information thus gathered has emphasized the uniqueness of the experimental data obtained in the low-gravity environment of space.

  8. Characterization of Biofluids Prepared by Sessile Drop Formation

    PubMed Central

    Esmonde-White, Karen A.; Esmonde-White, Francis W.L.; Morris, Michael D.; Roessler, Blake J.

    2014-01-01

    Sessile drop formation, also called drop deposition, has been studied as a potential medical diagnostic, but the effects of complex biofluid rheology on the final deposition pattern are not well understood. We studied two model biofluids, blood plasma and synovial fluid, when deposited onto slightly hydrophilic substrates forming a contact angle of 50–90°. Drops were imaged during the evaporation process and geometric properties of the drop, such as contact angle and drop height, were calculated from the images. The resulting dried biofluid drops were then examined using light microscopy and Raman spectroscopy to assess morphological and chemical composition of the dried drop. The effect of substrate contact angle (surface wetting) and fluid concentration was examined. We found that when biofluids are deposited onto slightly hydrophilic surfaces, with a contact angle of 50–90°, a ring-shaped deposit was formed. Analysis of the drying drop’s geometric properties indicates that biofluid dynamics follow the piling model of drop formation, as proposed by Deegan et al. The final deposition pattern varied with substrate surface and concentration, as shown by light microscopy photos of dried drops. The chemical composition of the outer ring was minimally affected by substrate surface, but the spatial heterogeneity of protein distribution within the ring varied with concentration. These results indicate that biofluid drop deposition produces ring-shaped deposits which can be examined by multiple analytical techniques. PMID:24757707

  9. Method for reducing pressure drop through filters, and filter exhibiting reduced pressure drop

    DOEpatents

    Sappok, Alexander; Wong, Victor

    2014-11-18

    Methods for generating and applying coatings to filters with porous material in order to reduce large pressure drop increases as material accumulates in a filter, as well as the filter exhibiting reduced and/or more uniform pressure drop. The filter can be a diesel particulate trap for removing particulate matter such as soot from the exhaust of a diesel engine. Porous material such as ash is loaded on the surface of the substrate or filter walls, such as by coating, depositing, distributing or layering the porous material along the channel walls of the filter in an amount effective for minimizing or preventing depth filtration during use of the filter. Efficient filtration at acceptable flow rates is achieved.

  10. Rheological Properties of Viscoelastic Drops on Superamphiphobic Substrates.

    PubMed

    Harrold, Victoria C; Paven, Maxime; Vollmer, Doris; Sharp, James S

    2016-04-26

    The rheological properties of microliter sized drops of polymer solutions were investigated using measurements of their mechanical vibrational response. Drops were suspended on superamphiphobic substrates and vibrated by the application of a short mechanical impulse. Surface vibrations were monitored by refracting laser light through the drops and focusing the refracted light onto the surface of a photodiode. Time dependent variations in the photodiode output were Fourier transformed to obtain the frequency and spectral width of the mechanical resonances of the drops. These quantities were related to the frequency dependent shear storage and loss moduli (G' and G″, respectively) using a simple theoretical model. The resulting rheological properties were found to be in agreement with microrheology measurements of the same solutions. Drop vibration therefore provides a fast and accurate method of quantifying the rheological properties of single drops.

  11. Evaporation, ignition, and combustion of nondilute clusters of drops

    NASA Technical Reports Server (NTRS)

    Bellan, J.; Harstad, K.

    1990-01-01

    A theory of evaporation, ignition, and burning of moderately dense spherical drop clusters has been developed. The theory takes into account burning of premixed air and fuel internal to the cluster at ignition and subsequent burning of fuel emitted from the cluster by a flame sheet surrounding it. The model considers interdrop interaction, momentum exchange between drops and gas, and turbulent exchange processes between the cluster and its surroundings. Calculations are performed for varying initial air-to-fuel-mass ratios, initial cluster radii, ambient gas temperatures and initial drop temperatures. Results are presented for ratios of fuel mass burned to fuel mass lost from the cluster between drop ignition and drop disappearance, fuel burned fractions at ignition and at the moment of drop disappearance, and jump conditions at ignition.

  12. Bursting drops in solid dielectrics caused by high voltages

    NASA Astrophysics Data System (ADS)

    Wang, Qiming; Suo, Zhigang; Zhao, Xuanhe

    2012-10-01

    Fluid drops tend to be spheres—a shape that minimizes surface energy. In thunderstorm clouds, drops can become unstable and emit thin jets when charged beyond certain limits. The instability of electrified drops in gases and liquids has been widely studied and used in applications including ink-jet printing, electrospinning nanofibers, microfluidics and electrospray ionization. Here we report a different scenario: drops in solids become unstable and burst under sufficiently high electric fields. We find the instability of drops in solids morphologically resembles that in liquids, but the critical electric field for the instability follows a different scaling due to elasticity of solids. Our observations and theoretical models not only advance the fundamental understanding of electrified drops, but also suggest a new failure mechanism of high energy density dielectric polymers, which have diverse applications ranging from capacitors for power grids and electric vehicles to muscle-like transducers for soft robots and energy harvesting.

  13. Oscillations of a deformed liquid drop in an acoustic field

    NASA Astrophysics Data System (ADS)

    Shi, Tao; Apfel, Robert E.

    1995-07-01

    The oscillations of an axially symmetric liquid drop in an acoustic standing wave field in air have been studied using the boundary integral method. The interaction between the drop oscillation and sound field has been included in this analysis. Our computations focus on the frequency shift of small-amplitude oscillations of an acoustically deformed drop typical of a drop levitated in air. In the presence or absence of gravity, the trend and the magnitude of the frequency shift have been given in terms of drop size, drop deformation, and the strength of the sound field. Our calculations are compared with experiments performed on the United States Microgravity Laboratory (USML-1) and with ground-based measurements, and are found to be in good agreement within the accuracy of the experimental data.

  14. Bursting drops in solid dielectrics caused by high voltages.

    PubMed

    Wang, Qiming; Suo, Zhigang; Zhao, Xuanhe

    2012-01-01

    Fluid drops tend to be spheres--a shape that minimizes surface energy. In thunderstorm clouds, drops can become unstable and emit thin jets when charged beyond certain limits. The instability of electrified drops in gases and liquids has been widely studied and used in applications including ink-jet printing, electrospinning nanofibers, microfluidics and electrospray ionization. Here we report a different scenario: drops in solids become unstable and burst under sufficiently high electric fields. We find the instability of drops in solids morphologically resembles that in liquids, but the critical electric field for the instability follows a different scaling due to elasticity of solids. Our observations and theoretical models not only advance the fundamental understanding of electrified drops, but also suggest a new failure mechanism of high energy density dielectric polymers, which have diverse applications ranging from capacitors for power grids and electric vehicles to muscle-like transducers for soft robots and energy harvesting. PMID:23093194

  15. Bursting drops in solid dielectrics caused by high voltages.

    PubMed

    Wang, Qiming; Suo, Zhigang; Zhao, Xuanhe

    2012-01-01

    Fluid drops tend to be spheres--a shape that minimizes surface energy. In thunderstorm clouds, drops can become unstable and emit thin jets when charged beyond certain limits. The instability of electrified drops in gases and liquids has been widely studied and used in applications including ink-jet printing, electrospinning nanofibers, microfluidics and electrospray ionization. Here we report a different scenario: drops in solids become unstable and burst under sufficiently high electric fields. We find the instability of drops in solids morphologically resembles that in liquids, but the critical electric field for the instability follows a different scaling due to elasticity of solids. Our observations and theoretical models not only advance the fundamental understanding of electrified drops, but also suggest a new failure mechanism of high energy density dielectric polymers, which have diverse applications ranging from capacitors for power grids and electric vehicles to muscle-like transducers for soft robots and energy harvesting.

  16. Student Drop Tower Competitions: Dropping In a Microgravity Environment (DIME) and What If No Gravity? (WING)

    NASA Technical Reports Server (NTRS)

    Hall, Nancy R.; Stocker, Dennis P.; DeLombard, Richard

    2011-01-01

    This paper describes two student competition programs that allow student teams to conceive a science or engineering experiment for a microgravity environment. Selected teams design and build their experimental hardware, conduct baseline tests, and ship their experiment to NASA where it is operated in the 2.2 Second Drop Tower. The hardware and acquired data is provided to the teams after the tests are conducted so that the teams can prepare their final reports about their findings.

  17. Fluid dynamics and solidification of levitated drops and shells

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.

    1990-01-01

    The fluid dynamic investigaton of simple free liquid drops is described based on ground-based and low-gravity experimental results. The behavior of compound drops and liquid shells as described in recent theoretical and experimental studies is discussed. Experimental investigations using both levitation devices and drop tubes are considered in the case of 1-g laboratory investigations, highlighting the advantages and drawbacks of both techniques.

  18. Drop-out from a psychodynamic group psychotherapy outpatient unit.

    PubMed

    Jensen, Hans Henrik; Mortensen, Erik Lykke; Lotz, Martin

    2014-11-01

    BACKGROUND. Drop-out from psychotherapy is common and represents a considerable problem in clinical practice and research. Aim. To explore pre-treatment predictors of early and late drop-out from psychodynamic group therapy in a public outpatient unit for non-psychotic disorders in Denmark. Methods. Naturalistic design including 329 patients, the majority with mood, neurotic and personality disorders referred to 39-session group therapy. Predictors were socio-demographic and clinical variables, self-reported symptoms (Symptom Check List-90-Revised) and personality style (Millon Clinical Multiaxial Inventory-II). Drop-out was classified into early and late premature termination excluding patients who dropped out for external reasons. Results. Drop-out comprised 20.6% (68 patients) of the sample. Logistic regression revealed social functioning, vocational training, alcohol problems and antisocial behavior to be related to drop-out. However, early drop-outs had prominent agoraphobic symptoms, lower interpersonal sensitivity and compulsive personality features, and late drop-outs cognitive and somatic anxiety symptoms and antisocial personality features. Clinical and psychological variables accounted for the major part of variance in predictions of drop-out, which ranged from 15.6% to 19.5% (Nagelkerke Pseudo R-Square). Conclusion. Social functioning was consistently associated with drop-out, but personality characteristics and anxiety symptoms differentiated between early and late drop-out. Failure to discriminate between stages of premature termination may explain some of the inconsistencies in the drop-out literature. Clinical implications. Before selection of patients to time-limited psychodynamic groups, self-reported symptoms should be thoroughly considered. Patients with agoraphobic symptoms should be offered alternative treatment. Awareness of and motivation to work with interpersonal issues may be essential for compliance with group therapy.

  19. Whole Body Vibration Immediately Decreases Lower Extremity Loading During the Drop Jump.

    PubMed

    Chen, Zong-Rong; Peng, Hsien-Te; Siao, Sheng-Wun; Hou, Yan-Ting; Wang, Li-I

    2016-09-01

    Chen, Z-R, Peng, H-T, Siao, S-W, Hou, Y-T, and Wang, L-I. Whole body vibration immediately decreases lower extremity loading during the drop jump. J Strength Cond Res 30(9): 2476-2481, 2016-The purpose of this study was to evaluate the acute effect of whole body vibration (WBV) on lower extremity loading during the drop jump (DJ). Fifteen male collegiate physical education students randomly completed 3 experimental sessions on 3 separate days with 4 days interval between sessions (performing 3 trials of DJ from 30-, 40-, and 50-cm drop heights before WBV and 4 minutes after WBV). Eight cameras and 2 force platforms were used to record kinematic and kinetic data, respectively. Peak impact force and loading rate significantly decreased after WBV during DJ from 40 and 50 cm. Knee angular displacements significantly increased after WBV during DJ from 30, 40, and 50 cm. Whole body vibration may help immediately reduce lower extremity loading. PMID:26849793

  20. The effects of a unilateral gluteal activation protocol on single leg drop jump performance.

    PubMed

    Healy, Robin; Harrison, Andrew J

    2014-03-01

    Warm-up protocols are commonly used to acutely enhance the performance of dynamic activities. This study examined the acute effect of low-load gluteal exercises on the biomechanics of single-leg drop jumps. Eight men and seven women (18-22 years old) performed 10 single-leg drop jumps on three separate days. The gluteal exercises were performed within the warm-up on day 2. Contact time, flight time, peak vertical ground reaction force (GRF), rate of force development, vertical leg-spring stiffness, and reactive strength index were determined. A repeated measures analysis of variance was used to examine differences on all variables across days. Significant differences were found for contact time, peak GRF, and flight time between days 1 and 2 and for flight time between days 1 and 3 (p < or = 0.05) with no significant difference in any variables between days 2 and 3. This suggested that the improvements in day 2 were due to practice effects rather than the gluteal activation exercises. In addition, a typical error analysis was used to determine individual responses to the gluteal exercises. The results using this analysis showed no discernible response pattern of enhancement or fatigue for any participant. PMID:24968509

  1. Perfusion Angiography in Acute Ischemic Stroke

    PubMed Central

    Liebeskind, David S.

    2016-01-01

    Visualization and quantification of blood flow are essential for the diagnosis and treatment evaluation of cerebrovascular diseases. For rapid imaging of the cerebrovasculature, digital subtraction angiography (DSA) remains the gold standard as it offers high spatial resolution. This paper lays out a methodological framework, named perfusion angiography, for the quantitative analysis and visualization of blood flow parameters from DSA images. The parameters, including cerebral blood flow (CBF) and cerebral blood volume (CBV), mean transit time (MTT), time-to-peak (TTP), and Tmax, are computed using a bolus tracking method based on the deconvolution of the time-density curve on a pixel-by-pixel basis. The method is tested on 66 acute ischemic stroke patients treated with thrombectomy and/or tissue plasminogen activator (tPA) and also evaluated on an estimation task with known ground truth. This novel imaging tool provides unique insights into flow mechanisms that cannot be observed directly in DSA sequences and might be used to evaluate the impact of endovascular interventions more precisely. PMID:27446232

  2. Contribution of two conserved histidines to the dual activity of archaeal RNA guide-dependent and -independent pseudouridine synthase Cbf5.

    PubMed

    Tillault, Anne-Sophie; Fourmann, Jean-Baptiste; Loegler, Christine; Wieden, Hans-Joachim; Kothe, Ute; Charpentier, Bruno

    2015-07-01

    In all organisms, several distinct stand-alone pseudouridine synthase (PUS) family enzymes are expressed to isomerize uridine into pseudouridine (Ψ) by specific recognition of RNAs. In addition, Ψs are generated in Archaea and Eukaryotes by PUS enzymes which are organized as ribonucleoprotein particles (RNP)--the box H/ACA s/snoRNPs. For this modification system, a unique TruB-like catalytic PUS subunit is associated with various RNA guides which specifically target and secure substrate RNAs by base-pairing. The archaeal Cbf5 PUS displays the special feature of exhibiting both RNA guide-dependent and -independent activities. Structures of substrate-bound TruB and H/ACA sRNP revealed the importance of histidines in positioning the target uridine in the active site. To analyze the respective role of H60 and H77, we have generated variants carrying alanine substitutions at these positions. The impact of the mutations was analyzed for unguided modifications U(55) in tRNA and U2603 in 23S rRNA, and for activity of the box H/ACA Pab91 sRNP enzyme. H77 (H43 in TruB), but not H60, appeared to be crucial for the RNA guide-independent activity. In contrast to earlier suggestions, H60 was found to be noncritical for the activity of the H/ACA sRNP, but contributes together with H77 to the full activity of H/ACA sRNPs. The data suggest that a similar catalytic process was conserved in the two divergent pseudouridylation systems.

  3. Contribution of two conserved histidines to the dual activity of archaeal RNA guide-dependent and -independent pseudouridine synthase Cbf5

    PubMed Central

    Tillault, Anne-Sophie; Fourmann, Jean-Baptiste; Loegler, Christine; Wieden, Hans-Joachim; Kothe, Ute

    2015-01-01

    In all organisms, several distinct stand-alone pseudouridine synthase (PUS) family enzymes are expressed to isomerize uridine into pseudouridine (Ψ) by specific recognition of RNAs. In addition, Ψs are generated in Archaea and Eukaryotes by PUS enzymes which are organized as ribonucleoprotein particles (RNP)—the box H/ACA s/snoRNPs. For this modification system, a unique TruB-like catalytic PUS subunit is associated with various RNA guides which specifically target and secure substrate RNAs by base-pairing. The archaeal Cbf5 PUS displays the special feature of exhibiting both RNA guide-dependent and -independent activities. Structures of substrate-bound TruB and H/ACA sRNP revealed the importance of histidines in positioning the target uridine in the active site. To analyze the respective role of H60 and H77, we have generated variants carrying alanine substitutions at these positions. The impact of the mutations was analyzed for unguided modifications U55 in tRNA and U2603 in 23S rRNA, and for activity of the box H/ACA Pab91 sRNP enzyme. H77 (H43 in TruB), but not H60, appeared to be crucial for the RNA guide-independent activity. In contrast to earlier suggestions, H60 was found to be noncritical for the activity of the H/ACA sRNP, but contributes together with H77 to the full activity of H/ACA sRNPs. The data suggest that a similar catalytic process was conserved in the two divergent pseudouridylation systems. PMID:25990001

  4. CBF tomograms with (/sup 99m/Tc-HM-PAO in patients with dementia (Alzheimer type and HIV) and Parkinson's disease--initial results

    SciTech Connect

    Costa, D.C.; Ell, P.J.; Burns, A.; Philpot, M.; Levy, R.

    1988-12-01

    We present preliminary data on the utility of functional brain imaging with (99mTc)-d,l-HM-PAO and single photon emission computed tomography (SPECT) in the study of patients with dementia of the Alzheimer type (DAT), HIV-related dementia syndrome, and the on-off syndrome of Parkinson's disease. In comparison with a group of age-matched controls, the DAT patients revealed distinctive bilateral temporal and posterior parietal deficits, which correlate with detailed psychometric evaluation. Patients with amnesia as the main symptom (group A) showed bilateral mesial temporal lobe perfusion deficits (p less than 0.02). More severely affected patients (group B) with significant apraxia, aphasia, or agnosia exhibited patterns compatible with bilateral reduced perfusion in the posterior parietal cortex, as well as reduced perfusion to both temporal lobes, different from the patients of the control group (p less than 0.05). SPECT studies of HIV patients with no evidence of intracraneal space occupying pathology showed marked perfusion deficits. Patients with Parkinson's disease and the on-off syndrome studied during an on phase (under levodopa therapy) and on another occasion after withdrawal of levodopa (off) demonstrated a significant change in the uptake of (99mTc)-d,l-HM-PAO in the caudate nucleus (lower on off) and thalamus (higher on off). These findings justify the present interest in the functional evaluation of the brain of patients with dementia. (99mTc)-d,l-HM-PAO and regional cerebral blood flow (rCBF)/SPECT appear useful and highlight individual disorders of flow in a variety of neuropsychiatric conditions.

  5. How to optimize the drop plate method for enumerating bacteria.

    PubMed

    Herigstad, B; Hamilton, M; Heersink, J

    2001-03-01

    The drop plate (DP) method can be used to determine the number of viable suspended bacteria in a known beaker volume. The drop plate method has some advantages over the spread plate (SP) method. Less time and effort are required to dispense the drops onto an agar plate than to spread an equivalent total sample volume into the agar. By distributing the sample in drops, colony counting can be done faster and perhaps more accurately. Even though it has been present in the laboratory for many years, the drop plate method has not been standardized. Some technicians use 10-fold dilutions, others use twofold. Some technicians plate a total volume of 0.1 ml, others plate 0.2 ml. The optimal combination of such factors would be useful to know when performing the drop plate method. This investigation was conducted to determine (i) the standard deviation of the bacterial density estimate, (ii) the cost of performing the drop plate procedure, (iii) the optimal drop plate design, and (iv) the advantages of the drop plate method in comparison to the standard spread plate method. The optimal design is the combination of factor settings that achieves the smallest standard deviation for a fixed cost. Computer simulation techniques and regression analysis were used to express the standard deviation as a function of the beaker volume, dilution factor, and volume plated. The standard deviation expression is also applicable to the spread plate method.

  6. Quantitative assessment of ribosome drop-off in E. coli

    PubMed Central

    Sin, Celine; Chiarugi, Davide; Valleriani, Angelo

    2016-01-01

    Premature ribosome drop-off is one of the major errors in translation of mRNA by ribosomes. However, repeated analyses of Ribo-seq data failed to quantify its strength in E. coli. Relying on a novel highly sensitive data analysis method we show that a significant rate of ribosome drop-off is measurable and can be quantified also when cells are cultured under non-stressing conditions. Moreover, we find that the drop-off rate is highly variable, depending on multiple factors. In particular, under environmental stress such as amino acid starvation or ethanol intoxication, the drop-off rate markedly increases. PMID:26935582

  7. Evaporation, ignition and combustion of nondilute clusters of drops

    NASA Technical Reports Server (NTRS)

    Bellan, J.; Harstad, K.

    1988-01-01

    A theory of evaporation, ignition, and burning of moderately dense spherical drop clusters has been developed. The theory takes into account burning of premixed air and fuel internal to the cluster at ignition and subsequent burning of fuel emitted from the cluster by a flame sheet surrounding it. The model considers interdrop interaction, momentum exchange between drops and gas, and turbulent exchange processes between the cluster and its surroundings. Calcualtions are performed for varying initial air to fuel mass ratios, initial cluster radii, ambient gas temperatures, and initial drop temperatures. Results are presented for fuel burn fractions at ignition and at the moment of drop disappearance, as well as jump conditions at ignition.

  8. Studies of the Stability and Dynamics of Levitated Drops

    NASA Technical Reports Server (NTRS)

    Anikumar, A.; Lee, Chun Ping; Wang, T. G.

    1996-01-01

    This is a review of our experimental and theoretical studies relating to equilibrium and stability of liquid drops, typically of low viscosity, levitated in air by a sound field. The major emphasis here is on the physical principles and understanding behind the stability of levitated drops. A comparison with experimental data is also given, along with some fascinating pictures from high-speed photography. One of the aspects we shall deal with is how a drop can suddenly burst in an intense sound field; a phenomenon which can find applications in atomization technology. Also, we are currently investigating the phenomenon of suppression of coalescence between drops levitated in intense acoustic fields.

  9. Electrohydrodynamic deformation and interaction of a pair of emulsion drops

    NASA Technical Reports Server (NTRS)

    Baygents, James C.

    1994-01-01

    The response of a pair of emulsion drops to the imposition of a uniform electric field is examined. The case studied is that of equal-sized drops whose line of centers is parallel to the axis of the applied field. A new boundary integral solution to the governing equations of the leaky dielectric model is developed; the formulation accounts for the electrostatic and hydrodynamic interactions between the drops, as well as their deformations. Numerical calculations show that, after an initial transient during which the drops primarily deform, the pair drift slowly together due to their electrostatic interactions.

  10. Substrate constraint modifies the Rayleigh spectrum of vibrating sessile drops

    NASA Astrophysics Data System (ADS)

    Chang, Chun-Ti; Bostwick, Joshua B.; Steen, Paul H.; Daniel, Susan

    2013-08-01

    In this work, we study the resonance behavior of mechanically oscillated, sessile water drops. By mechanically oscillating sessile drops vertically and within prescribed ranges of frequencies and amplitudes, a rich collection of resonance modes are observed and their dynamics subsequently investigated. We first present our method of identifying each mode uniquely, through association with spherical harmonics and according to their geometric patterns. Next, we compare our measured resonance frequencies of drops to theoretical predictions using both the classical theory of Lord Rayleigh and Lamb for free, oscillating drops, and a prediction by Bostwick and Steen that explicitly considers the effect of the solid substrate on drop dynamics. Finally, we report observations and analysis of drop mode mixing, or the simultaneous coexistence of multiple mode shapes within the resonating sessile drop driven by one sinusoidal signal of a single frequency. The dynamic response of a deformable liquid drop constrained by the substrate it is in contact with is of interest in a number of applications, such as drop atomization and ink jet printing, switchable electronically controlled capillary adhesion, optical microlens devices, as well as digital microfluidic applications where control of droplet motion is induced by means of a harmonically driven substrate.

  11. Substrate constraint modifies the Rayleigh spectrum of vibrating sessile drops.

    PubMed

    Chang, Chun-Ti; Bostwick, Joshua B; Steen, Paul H; Daniel, Susan

    2013-08-01

    In this work, we study the resonance behavior of mechanically oscillated, sessile water drops. By mechanically oscillating sessile drops vertically and within prescribed ranges of frequencies and amplitudes, a rich collection of resonance modes are observed and their dynamics subsequently investigated. We first present our method of identifying each mode uniquely, through association with spherical harmonics and according to their geometric patterns. Next, we compare our measured resonance frequencies of drops to theoretical predictions using both the classical theory of Lord Rayleigh and Lamb for free, oscillating drops, and a prediction by Bostwick and Steen that explicitly considers the effect of the solid substrate on drop dynamics. Finally, we report observations and analysis of drop mode mixing, or the simultaneous coexistence of multiple mode shapes within the resonating sessile drop driven by one sinusoidal signal of a single frequency. The dynamic response of a deformable liquid drop constrained by the substrate it is in contact with is of interest in a number of applications, such as drop atomization and ink jet printing, switchable electronically controlled capillary adhesion, optical microlens devices, as well as digital microfluidic applications where control of droplet motion is induced by means of a harmonically driven substrate. PMID:24032932

  12. PRESERVATIVES FROM THE EYE DROPS AND THE OCULAR SURFACE.

    PubMed

    Coroi, Mihaela Cristina; Bungau, Simona; Tit, Mirela

    2015-01-01

    The use of preservatives in eye drops (eyewashes) has known glory at the beginning, but the side effects that they have on the ocular surface have led to a decrease of their popularity. Lachrymal film dysfunction, ocular hyperemia, dotted keratitis or toxic keratopathy were reported and analyzed in terms of pathophysiological mechanism of the role played by preservatives in ophthalmic drops (eyewashes). This article reviews the most common preservatives and the existing alternatives for the maintenance of the eye sterile drops. Keywords: preservatives, eye drops, ocular surface

  13. Surface structuring of particle laden drops using electric fields

    NASA Astrophysics Data System (ADS)

    Dommersnes, P.; Fossum, J. O.

    2016-07-01

    Emulsion drops readily adsorb particles at their surfaces, which may lead to a fluid or solid layer encapsulating the drop, known as an armored drop. In this review, we discuss how electric fields can be used to manipulate colloidal surface structures, by dielectrophoretic or electro-hydrodynamic mechanisms and we also compare this to related phenomena in lipid bilayer vesicles. The phenomena discussed are important for a wide range of uses of particle laden drops, including emulsion stabilization, Janus or patchy mesocapsule-, scaffold- or other materials-production.

  14. Acute Pancreatitis

    PubMed Central

    Geokas, Michael C.

    1972-01-01

    For many decades two types of acute pancreatitis have been recognized: the edematous or interstitial and the hemorrhagic or necrotic. In most cases acute pancreatitis is associated with alcoholism or biliary tract disease. Elevated serum or urinary α-amylase is the most important finding in diagnosis. The presence of methemalbumin in serum and in peritoneal or pleural fluid supports the diagnosis of the hemorrhagic form of the disease in patients with a history and enzyme studies suggestive of pancreatitis. There is no characteristic clinical picture in acute pancreatitis, and its complications are legion. Pancreatic pseudocyst is probably the most common and pancreatic abscess is the most serious complication. The pathogenetic principle is autodigestion, but the precise sequence of biochemical events is unclear, especially the mode of trypsinogen activation and the role of lysosomal hydrolases. A host of metabolic derangements have been identified in acute pancreatitis, involving lipid, glucose, calcium and magnesium metabolism and changes of the blood clotting mechanism, to name but a few. Medical treatment includes intestinal decompression, analgesics, correction of hypovolemia and other supportive and protective measures. Surgical exploration is advisable in selected cases, when the diagnosis is in doubt, and is considered imperative in the presence of certain complications, especially pancreatic abscess. PMID:4559467

  15. Fertility drop precedes development in Thailand.

    PubMed

    Elliott, R

    1978-01-01

    In Thailand, birthrates among married women have declined by almost 1/2 over a 5-year period. Simultaneously, the proportion of women using contraception has doubled, knowledge of at least the rudiments of contraception has become close to universal, and family size preferences have dropped markedly. Authors John Knodel and Nibbon Debavalya, writing in a recent issue of "International Family Planning Perspectives and Digest," report a concurrent development of one of the world's largest family planning programs. They conclude that existing evidence suggests a relationship between improved fertility regulation and the growth of the family planning programs. The most significant features of the transition between 1968-1975 have included a decline in birthrates among rural women that is twice that of their counterparts and a nearly tripling of the proportion of women who had "ever" used contraception (from 19 to 51%). Also, the impact of the family planning program has been heightened by supportive factors in the Thai culture, the most important of which is the relatively high status of women in that country.

  16. Court decision dropping toxic substance rules stands

    SciTech Connect

    Bryant, C.R.

    1993-06-01

    In a somewhat surprising move, the U.S. Department of Labor has decided not to appeal a court decision essentially dropping regulations established by the Occupational Safety and Health Administration (OSHA) for about 400 hazardous substances. The decision leaves unregulated or subject to reduced standards substances that range from carbon monoxide to perchloroethylene. The Labor Department had until March 22, 1993, to appeal the court decision. On July 8, 1992, the U.S. Court of Appeals for the 11th Circuit overturned OSHA's final Air Contaminants Standard, which was promulgated in 1989. The standard established permissible exposure limits (PELs) for 428 toxic substances. In AFL-CIO vs. OSHA, the Court ruled that OSHA failed to make a separate scientific case for evaluating health risks of each chemical. Because of the decision not to appeal, PELs for more than half of the substances regulated by OSHA now are removed from the books or revert to the voluntary industry standards adopted by OSHA in 1970 and in force prior to the 1989 final rule.

  17. STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS

    SciTech Connect

    Lam, P; Philip Zapp, P; Jonathan Duffey, J; Kerry Dunn, K

    2009-05-01

    Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.

  18. GENDER, DEBT, AND DROPPING OUT OF COLLEGE

    PubMed Central

    DWYER, RACHEL E.; HODSON, RANDY; MCLOUD, LAURA

    2012-01-01

    For many young Americans, access to credit has become critical to completing a college education and embarking on a successful career path. Young people increasingly face the trade-off of taking on debt to complete college or foregoing college and taking their chances in the labor market without a college degree. These trade-offs are gendered by differences in college preparation and support and by the different labor market opportunities women and men face that affect the value of a college degree and future difficulties they may face in repaying college debt. We examine these new realities by studying gender differences in the role of debt in the pivotal event of graduating from college using the 1997 cohort of the national longitudinal Survey of youth. In this article, we find that women and men both experience slowing and even diminishing probabilities of graduating when carrying high levels of debt, but that men drop out at lower levels of debt than do women. We conclude by theorizing that high levels of debt are one of the mechanisms that sort women and men into different positions in the social stratification system. PMID:23626403

  19. The Viruses of Wild Pigeon Droppings

    PubMed Central

    Phan, Tung Gia; Vo, Nguyen Phung; Boros, Ákos; Pankovics, Péter; Reuter, Gábor; Li, Olive T. W.; Wang, Chunling; Deng, Xutao; Poon, Leo L. M.; Delwart, Eric

    2013-01-01

    Birds are frequent sources of emerging human infectious diseases. Viral particles were enriched from the feces of 51 wild urban pigeons (Columba livia) from Hong Kong and Hungary, their nucleic acids randomly amplified and then sequenced. We identified sequences from known and novel species from the viral families Circoviridae, Parvoviridae, Picornaviridae, Reoviridae, Adenovirus, Astroviridae, and Caliciviridae (listed in decreasing number of reads), as well as plant and insect viruses likely originating from consumed food. The near full genome of a new species of a proposed parvovirus genus provisionally called Aviparvovirus contained an unusually long middle ORF showing weak similarity to an ORF of unknown function from a fowl adenovirus. Picornaviruses found in both Asia and Europe that are distantly related to the turkey megrivirus and contained a highly divergent 2A1 region were named mesiviruses. All eleven segments of a novel rotavirus subgroup related to a chicken rotavirus in group G were sequenced and phylogenetically analyzed. This study provides an initial assessment of the enteric virome in the droppings of pigeons, a feral urban species with frequent human contact. PMID:24023772

  20. Drop impact on natural porous stones.

    PubMed

    Lee, J B; Derome, D; Carmeliet, J

    2016-05-01

    Drop impact and spreading on three natural porous stones are experimentally determined using high-speed imaging and compared with spreading over an impermeable steel surface. The dynamic non-wetting behavior during spreading and the hydrophobic contact angle >90° is attributed to the presence of an air layer between the droplet and the porous substrate. As the contact line pins at maximum spreading on the porous stone, the maximum spreading determines the liquid contact area on such substrate. The droplet gets pinned when the air layer is broken at the contact line and capillary forces develop in fines pores at the droplet edge, pinning the droplet. Maximum spreading on porous stones increases with impact velocity but does not scale with Weber number at low impact velocity. It is demonstrated that dynamic wetting plays an important role in the spreading at low velocity and that the dynamic wetting as characterized by the dynamic contact angle θD has to be taken into account for predicting the maximum spreading. Correcting the maximum spreading ratio with the dynamic wetting behavior, all data for porous stones and non-porous substrate collapse onto a single curve.