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Sample records for 2u-globulin hyaline droplet

  1. Differences in alpha 2u-globulins increased in male rat kidneys following treatment with several alpha 2u-globulin accumulating agents: cystein protease(s) play(s) an important role in production of kidney-type-alpha 2u-globulin.

    Science.gov (United States)

    Saito, K; Kaneko, H; Isobe, N; Nakatsuka, I; Yoshitake, A; Yamada, H

    1992-11-30

    Effects of alpha 2u-globulin accumulating agents on alpha 2u-globulins in rat kidneys were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting analysis. Treatment of male animals with decalin (150 mg/kg), 2,2,4-trimethylpentane (50 mg/kg), isophorone (150 mg/kg), d-limonene (150 mg/kg) or 1,4-dichlorobenzene (150 mg/kg) by gavage for 14 consecutive days in each case resulted in a marked intensification of a protein band corresponding to kidney-type-alpha 2u-globulin, with a molecular mass calculated to be approximately 16 kDa. However, intraperitoneal treatment with leupeptin and E-64 (two times 0.07 mmol/kg, for each), well known cystein protease inhibitors, while only slightly increasing this kidney-type-alpha 2u-globulin band, caused the intensification of a approximately 19-kDa molecular mass protein band which was revealed to be a native-type-alpha 2u-globulin by SDS-PAGE and immunoblotting. These results indicated that at least two types of alpha 2u-globulin can be increased in male rat kidney by chemical treatment. Moreover, cystein protease(s) appear(s) to play an important role in the degradation of alpha 2u-globulin and particularly in the conversion of native-type-alpha 2u-globulin to kidney-type-alpha 2u-globulin in rat kidneys.

  2. A Comparative Study Regarding the Association of Alpha-2U Globulin with the Nephrotoxic Mechanism of Certain Petroleum-Based Air Force Fuels

    Science.gov (United States)

    1988-12-01

    our method for the isolation of alpha-2U globulin isotypes using a combination of preparative isoelectric focusing and chromatofocusing techniques...the urinary pH as methods to investigate the hydrocarbon-induced nephrotoxic response. Two significant advances have been made in the first year of...globulin molecule and metabolic alteration of the urinary pH as methods to investigate the hydrocarbon-induced nephrotoxic response. Two significant

  3. Complex histopathologic response in rat kidney to oral β-myrcene: an unusual dose-related nephrosis and low-dose alpha2u-globulin nephropathy.

    Science.gov (United States)

    Cesta, Mark F; Hard, Gordon C; Boyce, John T; Ryan, Michael J; Chan, Po C; Sills, Robert C

    2013-01-01

    Oral gavage studies with β-myrcene in male F344 rats showed a complex renal pathology comprising both alpha2u-globulin (α2u-g) nephropathy, an unusual nephrosis involving the outer stripe of outer medulla (OSOM), and an increased incidence of renal tubule tumors by 2 years. In the 90-day and 2-year studies, respectively, α2u-g nephropathy and linear papillary mineralization were observed in males at the two lower doses but were absent from the high dose. Nephrosis was characterized by dilation of the S3 tubules, nuclear enlargement (including karyomegaly), and luminal pyknotic cells, all in the outermost OSOM. Nephrosis was minimal at the higher doses in the 90-day study, but progressed to a severe grade in males dosed with 1,000 mg/kg for 2 years. Renal tubule tumors developed in treated groups with incidences up to 30% in the 250 and 500 mg/kg male dose groups. Tumors at the lower doses in males may have been associated with α2u-g nephropathy, while those at higher doses in both sexes may have been due to the nephrosis. Because β-myrcene induced a complex spectrum of renal pathology, the α2u-g nephropathy mechanism cannot be the sole mechanism of carcinogenesis in these rats.

  4. Methyl isobutyl ketone exposure-related increases in specific measures of α2u-globulin (α2u) nephropathy in male rats along with in vitro evidence of reversible protein binding.

    Science.gov (United States)

    Borghoff, S J; Poet, T S; Green, S; Davis, J; Hughes, B; Mensing, T; Sarang, S S; Lynch, A M; Hard, G C

    2015-07-03

    Chronic exposure to methyl isobutyl ketone (MIBK) resulted in an increase in the incidence of renal tubule adenomas and occurrence of renal tubule carcinomas in male, but not female Fischer 344 rats. Since a number of chemicals have been shown to cause male rat renal tumors through the α2u nephropathy-mediated mode of action, the objective of this study is to evaluate the ability of MIBK to induce measures of α2u nephropathy including renal cell proliferation in male and female F344 rats following exposure to the same inhalation concentrations used in the National Toxicology Program (NTP) cancer bioassay (0, 450, 900, or 1800ppm). Rats were exposed 6h/day for 1 or 4 weeks and kidneys excised approximately 18h post exposure to evaluate hyaline droplet accumulation (HDA), α2u staining of hyaline droplets, renal cell proliferation, and to quantitate renal α2u concentration. There was an exposure-related increase in all measures of α2u nephropathy in male, but not female rat kidneys. The hyaline droplets present in male rat kidney stained positively for α2u. The changes in HDA and α2u concentration were comparable to d-limonene, an acknowledged inducer of α2u nephropathy. In a separate in vitro study using a two-compartment vial equilibration model to assess the interaction between MIBK and α2u, the dissociation constant (Kd) was estimated to be 1.27×10(-5)M. This Kd is within the range of other chemicals known to bind to α2u and cause nephropathy. Together, the exposure-related increase in measures of α2u nephropathy, sustained increase in renal cell proliferation along with an indication of reversible binding of MIBK to α2u, support the inclusion of MIBK in the category of chemicals exerting renal effects through a protein droplet α2u nephropathy-mediated mode of action (MoA).

  5. Hyaline droplet accumulation in kidney of rats treated with hexachloro-1:3-butadiene: influence of age, dose and time-course.

    Science.gov (United States)

    Cristofori, Patrizia; Defazio, Rossella; Chiusolo, Arianna; Mongillo, Michele; Bartolucci, Giovanni Battista; Chiara, Federica; Trevisan, Andrea

    2013-03-01

    The present research investigates the occurrence of hyaline droplet (HD) accumulation related to age, dose and time after treatment in male Wistar rats given a single i.p. injection of hexachloro-1:3-butadiene (HCBD). In the study on age, rats from 1 to 12 months of age were treated with 100 mg kg(-1) body weight (b.w.) HCBD dose. Rats treated at 2 months of age showed a greater accumulation of HD than the other age groups; HD accumulation was not observed in 1-month-old rats. In the dose-response study, the treatment with 25, 50 and 100 mg kg(-1) b.w. at 2 months of age caused HD accumulation in the proximal convoluted tubule at all doses, with the 100 mg kg(-1) b.w. group slightly more affected. Finally, in the time-course study, rats treated with a 100 mg kg(-1) b.w. dose at 2 months of age and sacrificed at 6, 12, 24, 48, 72 and 96 h post-dosing showed a time-related HD accumulation in terms of incidence and severity, after 6 h, with a peak at 24 and 48 h and decreasing at 72 and 96 h. The present results show that HD accumulation is an early finding, and is unrelated to dose level and particularly evident in rats of 2 month of age. These findings in male rats treated with HCBD emphasize the importance of considering the age of rats at the start of a study. The more sensitive model was used in the detection of nephrotoxic effects of chemicals.

  6. Physiologically based pharmacokinetic model for ethyl tertiary-butyl ether and tertiary-butyl alcohol in rats: Contribution of binding to α2u-globulin in male rats and high-exposure nonlinear kinetics to toxicity and cancer outcomes.

    Science.gov (United States)

    Borghoff, Susan J; Ring, Caroline; Banton, Marcy I; Leavens, Teresa L

    2017-05-01

    In cancer bioassays, inhalation, but not drinking water exposure to ethyl tertiary-butyl ether (ETBE), caused liver tumors in male rats, while tertiary-butyl alcohol (TBA), an ETBE metabolite, caused kidney tumors in male rats following exposure via drinking water. To understand the contribution of ETBE and TBA kinetics under varying exposure scenarios to these tumor responses, a physiologically based pharmacokinetic model was developed based on a previously published model for methyl tertiary-butyl ether, a structurally similar chemical, and verified against the literature and study report data. The model included ETBE and TBA binding to the male rat-specific protein α2u-globulin, which plays a role in the ETBE and TBA kidney response observed in male rats. Metabolism of ETBE and TBA was described as a single, saturable pathway in the liver. The model predicted similar kidney AUC0-∞ for TBA for various exposure scenarios from ETBE and TBA cancer bioassays, supporting a male-rat-specific mode of action for TBA-induced kidney tumors. The model also predicted nonlinear kinetics at ETBE inhalation exposure concentrations above ~2000 ppm, based on blood AUC0-∞ for ETBE and TBA. The shift from linear to nonlinear kinetics at exposure concentrations below the concentration associated with liver tumors in rats (5000 ppm) suggests the mode of action for liver tumors operates under nonlinear kinetics following chronic exposure and is not relevant for assessing human risk. Copyright © 2016 The Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.

  7. Juvenile hyaline fibromatosis.

    Science.gov (United States)

    Larralde, M; Santos-Muñoz, A; Calb, I; Magariños, C

    2001-01-01

    Juvenile hyaline fibromatosis (JHF) is a rare autosomal recessive disease with onset in infancy or early childhood. It is characterized by papulonodular skin lesions, soft tissue masses, gingival hypertrophy, and flexion contractures of the large joints. The light and electron microscopic features are very distinctive. Here we report an 8-month-old boy with characteristic stiffness of the knees and elbows and pink confluent papules on the paranasal folds, and periauricular and perianal regions. He also had hard nodules all over the scalp and around the mouth, and severe gingival hypertrophy. Histologic and ultrastructural features were typical of JHF. Clinical features, pathology, and physiology are discussed.

  8. Hyaline fibromatosis syndrome: cutaneous manifestations*

    Science.gov (United States)

    Marques, Silvio Alencar; Stolf, Hamilton Ometto; Polizel, Juliana Ocanha; Munhoz, Tânia; Brandão, Marcela Calixto; Marques, Mariangela Esther Alencar

    2016-01-01

    Hyaline fibromatosis syndrome is the current name for clinical manifestations of diseases previously known as “infantile systemic hyalinosis” and “juvenile hyaline fibromatosis”. The authors report representative clinical cases of each one of the above subtypes with emphasis on cutaneous manifestations and difficulties for early diagnosis in this syndrome, essentially of multidisciplinary approach. PMID:27192526

  9. Juvenile hyaline fibromatosis

    Directory of Open Access Journals (Sweden)

    Jayashree Krishnamurthy

    2011-01-01

    Full Text Available Juvenile hyaline fibromatosis is a rare, autosomal-recessive disease characterized by papular and nodular skin lesions, gingival hyperplasia, joint contractures and bone involvement in variable degrees. It is a connective tissue disorder with aberrant synthesis of glycosaminoglycans by fibroblasts. We report a 5-year-old female born of first-degree consanguineous marriage who presented with multiple, recurrent, painless, variable-sized nodules. Fine needle aspiration cytology smears and the subsequent histopathological examination from the nodules showed benign spindle cells in a Periodic acid Schiff-positive myxoid background. The disease has a relentlessly progressive course, with most patients surviving only up to the 4 th decade. As of now, there is no specific treatment for this disorder. Genetic counseling is essential to explain to parents about a 25% chance of having a diseased baby in any pregnancy. With the gene being mapped recently, techniques for antenatal diagnosis are likely to be established.

  10. Genetics Home Reference: juvenile hyaline fibromatosis

    Science.gov (United States)

    ... Antaya RJ, Cajaiba MM, Madri J, Lopez MA, Ramirez MC, Martignetti JA, Reyes-Múgica M. Juvenile hyaline ... 103. Citation on PubMed Dowling O, Difeo A, Ramirez MC, Tukel T, Narla G, Bonafe L, Kayserili ...

  11. A case of juvenile hyaline fibromatosis.

    Science.gov (United States)

    Yayli, Savaş; Uncu, Sibel; Alpay, Köksal; Yildiz, Kadriye; Cimşit, Gülseren; Bahadir, Sevgi

    2006-04-01

    Juvenile hyaline fibromatosis (JHF) is a rare, autosomally-recessive disease characterized by papulonodular skin lesions, soft tissue masses, joint contractures, gingival hypertrophy and osteolytic bone lesions. Its onset is in infancy or early childhood. The most commonly affected sites are the nose, chin, ears, scalp, back and knees. The accumulation of an amorphous, hyaline material is typical in the skin and the other organs. Herein, we report a 14-month-old boy who presented with confluent pink papules on the paranasal folds and the chin, and nodular lesions on the periauricular and perianal regions. He had gingival hypertrophy and contractures of the shoulders, knees and elbows. He also had third-degree consanguineous parents. Histopathological studies confirmed the diagnosis of JHF with the presence of increased numbers of fibroblasts embedded in a hyalinized connective tissue stroma.

  12. Castleman′s disease: Hyaline vascular type

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    Srikanth Shastry

    2014-01-01

    Full Text Available Castleman′s disease is a rare disease of lymph node with two identified forms, the hyaline vascular type and plasma cell type. It presents as localized or systemic lymphadenopathy or even as extranodal mass and may give rise to several differential diagnoses. Castleman′s disease represents a morphologically distinct form of lymph node hyperplasia rather than a neoplasm or a hamartoma. It occurs most commonly in adults but it can also affect children. Here we present a case of Castleman′s disease in a 22 year male patient involving right cervical lymphnode.

  13. Juvenile hyaline fibromatosis: a case report.

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    Karaçal, Naci; Gülçelik, Nevzat; Yildiz, Kadriye; Mungan, Sevdegül; Kutlu, Necmettin

    2005-07-01

    Juvenile hyaline fibromatosis ( JHF ) is a rare autosomal recessive disease characterized by papulonodular skin lesions, gingival hyperplasia, joint contractures, and bone lesions. The skin lesions may consist of multiple large tumors, commonly on the scalp and around the neck, and small pearly, pink papules and plaques on the trunk, chin, ears, and around the nostrils. Here, we report a 2-year-old boy with characteristic stiffness of the knees and elbows and pink confluent papules on the paranasal folds, and periauricular and perianal regions. He also had hard nodules all over the scalp and around the mouth, and severe gingival hyperplasia. The lesions were totally excised and clinicopathological diagnosis was JHF.

  14. Hyaline cartilage degenerates after autologous osteochondral transplantation.

    Science.gov (United States)

    Tibesku, C O; Szuwart, T; Kleffner, T O; Schlegel, P M; Jahn, U R; Van Aken, H; Fuchs, S

    2004-11-01

    Autologous osteochondral grafting is a well-established clinical procedure to treat focal cartilage defects in patients, although basic research on this topic remains sparse. The aim of the current study was to evaluate (1) histological changes of transplanted hyaline cartilage of osteochondral grafts and (2) the tissue that connects the transplanted cartilage with the adjacent cartilage in a sheep model. Both knee joints of four sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral femoral condyle. The animals were sacrificed after three months and the received knee joints were evaluated histologically. Histological evaluation showed a complete ingrowth of the osseous part of the osteochondral grafts. A healing or ingrowth at the level of the cartilage could not be observed. Histological evaluation of the transplanted grafts according to Mankin revealed significantly more and more severe signs of degeneration than the adjacent cartilage, such as cloning of chondrocytes and irregularities of the articular surface. We found no connecting tissue between the transplanted and the adjacent cartilage and histological signs of degeneration of the transplanted hyaline cartilage. In the light of these findings, long-term results of autologous osteochondral grafts in human beings have to be followed critically.

  15. Autologous chondrocyte implantation: superior biologic properties of hyaline cartilage repairs.

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    Henderson, Ian; Lavigne, Patrick; Valenzuela, Herminio; Oakes, Barry

    2007-02-01

    Information regarding the quality of autologous chondrocyte implantation repair is needed to determine whether the current autologous chondrocyte implantation surgical technology and the subsequent biologic repair processes are capable of reliably forming durable hyaline or hyaline-like cartilage in vivo. We report and analyze the properties and qualities of autologous chondrocyte implantation repairs. We evaluated 66 autologous chondrocyte implantation repairs in 57 patients, 55 of whom had histology, indentometry, and International Cartilage Repair Society repair scoring at reoperation for mechanical symptoms or pain. International Knee Documentation Committee scores were used to address clinical outcome. Maximum stiffness, normalized stiffness, and International Cartilage Repair Society repair scoring were higher for hyaline articular cartilage repairs compared with fibrocartilage, with no difference in clinical outcome. Reoperations revealed 32 macroscopically abnormal repairs (Group B) and 23 knees with normal-looking repairs in which symptoms leading to arthroscopy were accounted for by other joint disorders (Group A). In Group A, 65% of repairs were either hyaline or hyaline-like cartilage compared with 28% in Group B. Autologous chondrocyte repairs composed of fibrocartilage showed more morphologic abnormalities and became symptomatic earlier than hyaline or hyaline-like cartilage repairs. The hyaline articular cartilage repairs had biomechanical properties comparable to surrounding cartilage and superior to those associated with fibrocartilage repairs.

  16. Pulmonary hyalinizing granuloma presenting with dysphagia: a rare presentation.

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    Khan, Fazal; Hamid, Arsalan; Fatima, Benish; Hashmi, Shiraz; Fatimi, Saulat

    2017-01-01

    A 25-year-old man presented with a 2-month history of dysphagia and past history of pulmonary and intestinal tuberculosis. A barium swallow showed a point of constriction 42 mm above the gastroesophageal junction. Computed tomography revealed large opacities in bilateral lung fields, encroaching more on the esophagus. The lesion progressively compressed the esophagus as it moved inferiorly. A right posterolateral thoracotomy was performed for sub-anatomical resection of the mass. A biopsy revealed homogenous whirling hyalinized collagen fibers, highly suggestive of pulmonary hyalinizing granuloma, with no evidence of malignancy. Pulmonary hyalinizing granuloma should be considered in the differential diagnosis of longstanding dysphagia.

  17. Surgical correction of joint deformities and hyaline cartilage regeneration

    National Research Council Canada - National Science Library

    Vinokurov, Vyacheslav Alexandrovich; Norkin, Igor Alekseevich

    2015-01-01

    Aim. To determine a method of extra-articular osteochondral fragment formation for the improvement of surgical correction results of joint deformities and optimization of regenerative conditions for hyaline cartilage...

  18. Precision of hyaline cartilage thickness measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, K.; Buckwalter, K.; Helvie, M.; Niklason, L.; Martel, W. (Univ. of Michigan Hospitals, Ann Arbor, MI (United States). Dept. of Radiology)

    1992-05-01

    Measurement of cartilage thickness in vivo is an important indicator of the status of a joint as the various degenerative and inflammatory arthritides directly affect the condition of the cartilage. In order to assess the precision of thickness measurements of hyaline articular cartilage, we undertook a pilot study using MR imaging, plain radiography, and ultrasonography (US). We measured the cartilage of the hip and knee joints in 10 persons (4 healthy volunteers and 6 patients). The joints in each patient were examined on two separate occasions using each modality. In the hips a swell as the knee joints, the most precise measuring method was plain film radiography. For radiographs of the knees obtained in the standing position, the coefficient of variation was 6.5%; in the hips this figure was 6.34%. US of the knees and MR imaging of the hips were the second best modalities in the measurement of cartilage thickness. In addition, MR imaging enabled the most complete visualization of the joint cartilage. (orig.).

  19. Swimming Droplets

    Science.gov (United States)

    Maass, Corinna C.; Krüger, Carsten; Herminghaus, Stephan; Bahr, Christian

    2016-03-01

    Swimming droplets are artificial microswimmers based on liquid droplets that show self-propelled motion when immersed in a second liquid. These systems are of tremendous interest as experimental models for the study of collective dynamics far from thermal equilibrium. For biological systems, such as bacterial colonies, plankton, or fish swarms, swimming droplets can provide a vital link between simulations and real life. We review the experimental systems and discuss the mechanisms of self-propulsion. Most systems are based on surfactant-stabilized droplets, the surfactant layer of which is modified in a way that leads to a steady Marangoni stress resulting in an autonomous motion of the droplet. The modification of the surfactant layer is caused either by the advection of a chemical reactant or by a solubilization process. Some types of swimming droplets possess a very simple design and long active periods, rendering them promising model systems for future studies of collective behavior.

  20. Dancing Droplets

    Science.gov (United States)

    Cira, Nate; Prakash, Manu

    2013-11-01

    Inspired by the observation of intricate and beautifully dynamic patterns generated by food coloring on corona treated glass slides, we have investigated the behavior of propylene glycol and water droplets on clean glass surfaces. These droplets exhibit a range of interesting behaviors including long distance attraction or repulsion, and chasing/fleeing upon contact. We present explanations for each of these behaviors, and propose a detailed model for the long distance interactions based on vapor facilitated coupling. Finally we use our understanding to create several novel devices which: passively sort droplets by surface tension, spontaneously align droplets, drive droplets in circles, and cause droplets to bounce on a vertical surface. The simplicity of this system lends it particularly well to application as a toy model for physical systems with force fields and biological systems such as chemotaxis and motility.

  1. Black Droplets

    CERN Document Server

    Santos, Jorge E

    2014-01-01

    Black droplets and black funnels are gravitational duals to states of a large N, strongly coupled CFT on a fixed black hole background. We numerically construct black droplets corresponding to a CFT on a Schwarzchild background with finite asymptotic temperature. We find two branches of such droplet solutions which meet at a turning point. Our results suggest that the equilibrium black droplet solution does not exist, which would imply that the Hartle-Hawking state in this system is dual to the black funnel constructed in \\cite{Santos:2012he}. We also compute the holographic stress energy tensor and match its asymptotic behaviour to perturbation theory.

  2. Dancing Droplets

    CERN Document Server

    Cira, Nate J

    2013-01-01

    Inspired by the observation of intricate and beautifully dynamic patterns generated by food coloring on clean glass slides, we have investigated the behavior of propylene glycol and water droplets on high energy surfaces. In this fluid dynamics video we show a range of interesting behaviors including long distance attraction, and chasing/fleeing upon contact. We present explanations for each of these behaviors including a mechanism for the long distance interactions based on vapor facilitated coupling. Finally we use our understanding to create several novel devices which: spontaneously align droplets, drive droplets in circles, cause droplets to bounce on a vertical surface, and passively sort droplets by surface tension. The simplicity of this system lends it particularly well to application as a toy model for physical systems with force fields and biological systems such as chemotaxis and motility.

  3. Hyaline fibromatosis of Hoffa's fat pad in a patient with a mild type of hyaline fibromatosis syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Raak, Sjoerd M. van [Albert Schweitzer Hospital, Department of Radiology, Dordrecht (Netherlands); Meuffels, Duncan E. [Erasmus MC - University Medical Center, Department of Orthopaedic Surgery, Rotterdam (Netherlands); Leenders, Geert J.L.H. van [Erasmus MC - University Medical Center, Department of Pathology, Rotterdam (Netherlands); Oei, Edwin H.G. [Erasmus MC - University Medical Center, Department of Radiology, Rotterdam (Netherlands)

    2014-04-15

    Hyaline fibromatosis syndrome (HFS) is a rare, homozygous, autosomal recessive disease, characterized by deposition of hyaline material in skin and other organs, resulting in esthetic problems, disability, and potential life-threatening complications. Most patients become clinically apparent in the first few years of life, and the disorder typically progresses with the appearance of new lesions. We describe a rare case of a 20-year-old patient with juvenile-onset mild HFS who presented with a history of progressive anterior knee pain. Detailed magnetic resonance (MR) imaging findings with histopathological correlation are presented of hyaline fibromatosis of Hoffa's fat pad, including differential diagnosis. The diagnosis of HFS is generally made on basis of clinical and histopathological findings. Imaging findings, however, may contribute to the correct diagnosis in patients who present with a less typical clinical course of HFS. (orig.)

  4. Droplets Acoustics

    CERN Document Server

    Dahan, Raphael; Carmon, Tal

    2015-01-01

    Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality factor are optically excited and interrogated at an optical threshold of 68 microWatt. Our vibrations span a spectral band that is 1000 times higher when compared with drops previously-studied capillary vibration.

  5. Hydrogels as a Replacement Material for Damaged Articular Hyaline Cartilage

    Directory of Open Access Journals (Sweden)

    Charlotte M. Beddoes

    2016-06-01

    Full Text Available Hyaline cartilage is a strong durable material that lubricates joint movement. Due to its avascular structure, cartilage has a poor self-healing ability, thus, a challenge in joint recovery. When severely damaged, cartilage may need to be replaced. However, currently we are unable to replicate the hyaline cartilage, and as such, alternative materials with considerably different properties are used. This results in undesirable side effects, including inadequate lubrication, wear debris, wear of the opposing articular cartilage, and weakening of the surrounding tissue. With the number of surgeries for cartilage repair increasing, a need for materials that can better mimic cartilage, and support the surrounding material in its typical function, is becoming evident. Here, we present a brief overview of the structure and properties of the hyaline cartilage and the current methods for cartilage repair. We then highlight some of the alternative materials under development as potential methods of repair; this is followed by an overview of the development of tough hydrogels. In particular, double network (DN hydrogels are a promising replacement material, with continually improving physical properties. These hydrogels are coming closer to replicating the strength and toughness of the hyaline cartilage, while offering excellent lubrication. We conclude by highlighting several different methods of integrating replacement materials with the native joint to ensure stability and optimal behaviour.

  6. Pulmonary hyalinizing granuloma and retroperitoneal fibrosis in an adolescent

    Energy Technology Data Exchange (ETDEWEB)

    Young, Adam S.; Binkovitz, Larry A.; Adler, Brent H. [Columbus Children' s Hospital, Children' s Radiological Institute, Columbus, OH (United States); Nicol, Kathleen K. [Columbus Children' s Hospital, Department of Pathology, Columbus, OH (United States); Rennebohm, Robert M. [Columbus Children' s Hospital, Department of Rheumatology, Columbus, OH (United States)

    2007-01-15

    We describe a 15-year-old boy who developed pulmonary hyalinizing granuloma (PHG) and retroperitoneal fibrosis (RPF). His PHG and RPF were not associated with histoplasmosis or tuberculosis and appeared to represent idiopathic autoimmune phenomena. This is the first reported case of PHG in a pediatric patient and the fourth reported co-occurrence of PHG and RPF. The use of F-18 fluorodeoxyglucose positron emission tomography in the diagnostic and follow-up evaluation of PHG is reported. (orig.)

  7. OUTCOME OF VENTILATION IN HYALINE MEMBRANE DISEASE: THE INDIAN EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Nayana Prabha

    2016-06-01

    Full Text Available OBJECTIVE To study the short-term outcome of both preterm and term babies requiring assisted ventilation for hyaline membrane disease and report the complications contributing to morbidity and mortality of these patients from a regional medical college with limited resources. DESIGN Retrospective file review. SETTING Regional Medical College. PARTICIPANTS All babies ventilated for HMD over a 6-year period from June 2008 to June 2014. OUTCOME MEASURES Outcome of ventilation and factors contributing to mortality. RESULTS Out of 100 babies with hyaline membrane disease who were ventilated, 82% survived. Increasing gestational age and birth weight was associated with survival. The commonest complication was shock (77% and the commonest cause of mortality was septicaemia (77%. Septicaemia, Disseminated Intravascular Coagulation (DIC and pulmonary haemorrhage were significantly more common complications babies who died (p<0.05. Binary logistic regression analysis showed that DIC (Odds ratio 5.2 [Confidence intervals (C.I. 1.1-27.1] and pulmonary haemorrhage (OR 18 [1.72-45.2] to be predictors of mortality. The incidence of intraventricular haemorrhage was 1% and that of pneumothorax was 2%. The initial peak inspiratory pressure administered was significantly lower (p=0.033 and maximum peak end expiratory pressure was significantly higher in those who expired (p=0.027. CONCLUSION Outcome of ventilation for hyaline membrane disease improves with increasing gestational age and birth weight. The commonest cause of mortality and morbidity were septicaemia and shock respectively.

  8. Three new species of Trichoderma with hyaline ascospores from China.

    Science.gov (United States)

    Zhu, Z X; Zhuang, W Y

    2015-01-01

    Collections of Trichoderma having hyaline ascospores from different areas of China were examined. Using combined analyses of morphological data, culture characters and phylogenetic information based on rDNA sequences of partial nuc translation elongation factor 1-α encoding gene (TEF1-α) and the gene encoding the second largest nuc RNA polymerase subunit (RPB2), three new species, Trichoderma applanatum, T. oligosporum and T. sinoluteum, were discovered and are described. Trichoderma applanatum produces continuous flat to pulvinate, white to cream stromata with dense orange or pale brown ostioles, and simple acremonium-like to verticillium-like conidiophores, belongs to the Hypocreanum clade and is closely related to T. decipiens. Trichoderma oligosporum forms reddish brown stromata with a downy surface, hyaline conidia and gliocladium-like conidiophores, and is closely related to but distinct from T. crystalligenum in the Psychrophila clade. Trichoderma sinoluteum, as a member of the Polysporum clade, is characterized by pale yellow stromata, white pustulate conidiomata, pachybasium-like conidiophores, and hyaline conidia. Differences between the new species and their close relatives are discussed.

  9. Pulmonary Hyalinizing Granuloma Associated with Idiopathic Thrombocytopenic Purpura

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    Christopher Coleman

    2014-01-01

    Full Text Available Pulmonary hyalinizing granuloma (PHG is a rare, benign lung disease of unknown etiology. It manifests as discrete, rounded nodules within the lung parenchyma. A 39-year-old woman presented for investigation after pulmonary nodules were found incidentally. Chest computed tomography showed multiple, discrete, non-enhancing pulmonary nodules bilaterally. Positron emission tomography (PET was negative. Biopsy demonstrated a non-specific lymphoplasmacytic infiltrate. Open resection yielded two nodules consistent with hyalinizing granulomas. The differential for multiple pulmonary nodules is broad. PET scan can help rule out metastatic disease, although some cancers are not hypermetabolic on PET. Furthermore, some non-malignant conditions, including hyalinizing granuloma, can show increased activity on PET. PHG should be included in the differential of multiple pulmonary nodules, especially if nodule stability can be demonstrated and/or needle biopsies are non-diagnostic. Associated immune-mediated conditions, such as idiopathic thrombocytopenic purpura (ITP in our patient, may also favor HG. In this case report we find an association between PHG and ITP.

  10. Surgical correction of joint deformities and hyaline cartilage regeneration

    Directory of Open Access Journals (Sweden)

    Вячеслав Александрович Винокуров

    2015-12-01

    Full Text Available Aim. To determine a method of extra-articular osteochondral fragment formation for the improvement of surgical correction results of joint deformities and optimization of regenerative conditions for hyaline cartilage. Materials and Methods. The method of formation of an articular osteochondral fragment without penetration into the joint cavity was devised experimentally. More than 30 patients with joint deformities underwent the surgery. Results. During the experiments, we postulated that there may potentially be a complete recovery of joint defects because of hyaline cartilage regeneration. By destructing the osteochondral fragment and reforming it extra-articularally, joint defects were recovered in all patients. The results were evaluated as excellent and good in majority of the patients. Conclusion. These findings indicate a novel method in which the complete recovery of joint defects due to dysplastic genesis or osteochondral defects as a result of injuries can be obtained. The devised method can be used in future experiments for objectification and regenerative potential of hyaline cartilage (e.g., rate and volume of the reformed joints that regenerate, detection of cartilage elements, and the regeneration process.

  11. Multicentric hyaline-vascular Castleman's disease in the retroperitoneum

    Institute of Scientific and Technical Information of China (English)

    Li-Ying Wang; Tian-An Jiang; Xiao-Dong Teng; Qi-Yu Zhao; Fen Chen

    2009-01-01

    BACKGROUND: Castleman's disease is a rare lymphopro-liferative disease of unknown cause. Most multicentric cases described have been of the plasma-cell variety. This article presents a case of multicentric hyaline-vascular Castleman's disease in the retroperitoneum with the ultrasonographic and computed tomography (CT) imaging manifestations. METHODS: During routine physical examination, a mass was detected in the left abdomen of a 53-year-old man with no signs or symptoms. The patient underwent ultrasound-guided aspiration biopsy and operative excision after laboratory examination, ultrasonography, and CT. RESULTS: Ultrasonography demonstrated a dominant hypoechogenic mass with hypervascularity in the retroperitoneum. CT detected a relatively homogenous enhanced lesion and several satellite nodules. After the mass and several lymph nodes were resected, histopathologic examination demonstrated a lymphocyte-predominant infiltrate surrounding the germinal centres and extensive capillary proliferation, consistent with the hyaline-vascular type of Castleman's disease. The patient received postoperative chemotherapy and remained free of recurrence 3 months later. CONCLUSION: Ultrasonography and contrast-enhanced CT can provide a positive differential diagnosis of hyaline-vascular Castleman's disease which is a kind of giant lymph node hyperplasia with hypervascularity.

  12. Droplet organelles?

    Science.gov (United States)

    Courchaine, Edward M; Lu, Alice; Neugebauer, Karla M

    2016-08-01

    Cells contain numerous, molecularly distinct cellular compartments that are not enclosed by lipid bilayers. These compartments are implicated in a wide range of cellular activities, and they have been variously described as bodies, granules, or organelles. Recent evidence suggests that a liquid-liquid phase separation (LLPS) process may drive their formation, possibly justifying the unifying term "droplet organelle". A veritable deluge of recent publications points to the importance of low-complexity proteins and RNA in determining the physical properties of phase-separated structures. Many of the proteins linked to such structures are implicated in human diseases, such as amyotrophic lateral sclerosis (ALS). We provide an overview of the organizational principles that characterize putative "droplet organelles" in healthy and diseased cells, connecting protein biochemistry with cell physiology.

  13. Juvenile hyaline fibromatosis. Radiological diagnosis. Fibromatosis hialina juvenil. Diagnostico radiologico

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, R.; Sar, V.; Cabrera, J.J.; Diaz, L.; Hernandez, B.; Valeron, P.; Baez, O.; Rodriguez, M.

    1993-10-01

    Juvenile hyaline fibromatosis (JHF) is a rare disorder of unknown etiology, very few cases of which have been reported in the literature. It presents similarities to other fibromatosys, but has its particular radiological features which differentiate it from them. The clinical findings consist of several, slow growing, subcutaneous nodules, flexion contractures of the joints which can lead to disability, gingival hypertrophy and muscular atrophy. The suspected radiological diagnosis is confirmed by electron microscopy study of the nodules, although light microscopy can also reveal suggestive images. Author (9 refs.)

  14. Hyalinizing trabecular tumor and papillary carcinoma of the thyroid

    Institute of Scientific and Technical Information of China (English)

    ZHU Hong; QI Ji-ping; WANG Ying-wei; SONG Yue-jia; ZHANG Zhi-yi

    2010-01-01

    Background Hyalinizing trabecular tumor (HTT) is a rare thyroid neoplasm, which shares some histologic features with thyroid papillary carcinoma (TPC). Clinically, it is frequently misdiagnosed as papillary carcinoma, even for some experienced pathologists. The aim of this study was to investigate whether HTT is variant of TPC or HTT is an independent entity of thyroid neoplasm.Methods The expression of CK19, galectin-3, HBME-1 and MIB-1 was detected by immunohistochemical staining in 12 cases of hyalinizing trabecular tumor and 20 cases of thyroid papillary carcinoma.Results Two of the 12 HTT samples were positive or focally positive for CK19. Four of the 12 samples of HTT presented positive to galectin-3; 3 were stained strongly and the other one was focally positive. None of the 12 samples of HTT was positive for HBME-1. Five in 12 HTT samples were stained in nucleus for MIB-1. Almost all the 20 cases of thyroid papillary carcinoma were intensely stained for CK19, galectin-3 and HBME-1. Fifteen in 20 cases of thyroid papillary carcinoma showed nuclear staining for MIB-1.Conclusions HTT is an independent thyroid neoplasm, not a variant of TPC. This study could help in the differential diagnosis of HTT from TPC. CK19, galectin-3 and HBME-1 are adequate to identify HTT and TPC, but MIB-1 does not play an important role in discrimination between HTT and TPC.

  15. Quasi-static elastography comparison of hyaline cartilage structures

    Energy Technology Data Exchange (ETDEWEB)

    McCredie, A J; Stride, E; Saffari, N [Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom)

    2009-11-01

    Joint cartilage, a load bearing structure in mammals, has only limited ability for regeneration after damage. For tissue engineers to design functional constructs, better understanding of the properties of healthy tissue is required. Joint cartilage is a specialised structure of hyaline cartilage; a poroviscoelastic solid containing fibril matrix reinforcements. Healthy joint cartilage is layered, which is thought to be important for correct tissue function. However, the behaviour of each layer during loading is poorly understood. Ultrasound elastography provides access to depth-dependent information in real-time for a sample during loading. A 15 MHz focussed transducer provided details from scatterers within a small fixed region in each sample. Quasi-static loading was applied to cartilage samples while ultrasonic signals before and during compressions were recorded. Ultrasonic signals were processed to provide time-shift profiles using a sum-squared difference method and cross-correlation. Two structures of hyaline cartilage have been tested ultrasonically and mechanically to determine method suitability for monitoring internal deformation differences under load and the effect of the layers on the global mechanical material behaviour. Results show differences in both the global mechanical properties and the ultrasonically tested strain distributions between the two structures tested. It was concluded that these differences are caused primarily by the fibril orientations.

  16. The junction between hyaline cartilage and engineered cartilage in rabbits.

    Science.gov (United States)

    Komura, Makoto; Komura, Hiroko; Otani, Yushi; Kanamori, Yutaka; Iwanaka, Tadashi; Hoshi, Kazuto; Tsuyoshi, Takato; Tabata, Yasuhiko

    2013-06-01

    Tracheoplasty using costal cartilage grafts to enlarge the tracheal lumen was performed to treat congenital tracheal stenosis. Fibrotic granulomatous tissue was observed at the edge of grafted costal cartilage. We investigated the junction between the native hyaline cartilage and the engineered cartilage plates that were generated by auricular chondrocytes for fabricating the airway. Controlled, prospecive study. In group 1, costal cartilage from New Zealand white rabbits was collected and implanted into a space created in the cervical trachea. In group 2, chondrocytes from auricular cartilages were seeded on absorbable scaffolds. These constructs were implanted in the subcutaneous space. Engineered cartilage plates were then implanted into the trachea after 3 weeks of implantation of the constructs. The grafts in group 1 and 2 were retrieved after 4 weeks. In group 1, histological studies of the junction between the native hyaline cartilage and the implanted costal cartilage demonstrated chondrogenic tissue in four anastomoses sides out of the 10 examined. In group 2, the junction between the native trachea and the engineered cartilage showed neocartilage tissue in nine anastomoses sides out of 10. Engineered cartilage may be beneficial for engineered airways, based on the findings of the junction between the native and engineered grafts. Copyright © 2012 The American Laryngological, Rhinological and Otological Society, Inc.

  17. Mechanical properties of hyaline and repair cartilage studied by nanoindentation.

    Science.gov (United States)

    Franke, O; Durst, K; Maier, V; Göken, M; Birkholz, T; Schneider, H; Hennig, F; Gelse, K

    2007-11-01

    Articular cartilage is a highly organized tissue that is well adapted to the functional demands in joints but difficult to replicate via tissue engineering or regeneration. Its viscoelastic properties allow cartilage to adapt to both slow and rapid mechanical loading. Several cartilage repair strategies that aim to restore tissue and protect it from further degeneration have been introduced. The key to their success is the quality of the newly formed tissue. In this study, periosteal cells loaded on a scaffold were used to repair large partial-thickness cartilage defects in the knee joint of miniature pigs. The repair cartilage was analyzed 26 weeks after surgery and compared both morphologically and mechanically with healthy hyaline cartilage. Contact stiffness, reduced modulus and hardness as key mechanical properties were examined in vitro by nanoindentation in phosphate-buffered saline at room temperature. In addition, the influence of tissue fixation with paraformaldehyde on the biomechanical properties was investigated. Although the repair process resulted in the formation of a stable fibrocartilaginous tissue, its contact stiffness was lower than that of hyaline cartilage by a factor of 10. Fixation with paraformaldehyde significantly increased the stiffness of cartilaginous tissue by one order of magnitude, and therefore, should not be used when studying biomechanical properties of cartilage. Our study suggests a sensitive method for measuring the contact stiffness of articular cartilage and demonstrates the importance of mechanical analysis for proper evaluation of the success of cartilage repair strategies.

  18. Lack of BRAF mutations in hyalinizing trabecular neoplasm

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    Brose Marcia

    2006-01-01

    Full Text Available Abstract The hyalinizing trabecular neoplasm (HTN of the thyroid is an unusual and controversial lesion. Some consider it a peculiar type of papillary thyroid carcinoma (PTC because of its nuclear features and presence of psammoma bodies. Others consider it an adenoma. Molecular studies have found RET/PTC translocations in some examples, supporting HTN as a PTC; however mutations in BRAF (another marker for PTC have not been found. We report two cases of classic HTN and a case of trabecular PTC and show BRAF mutations in the latter and not in HTN. Trabecular growth pattern is insufficient for a diagnosis of HTN and lesions with such a pattern and nuclear features of PTC are cancers. Morphologically classic HTN are not associated with metastatic potential and should be considered adenomas.

  19. Brief report: reconstruction of joint hyaline cartilage by autologous progenitor cells derived from ear elastic cartilage.

    Science.gov (United States)

    Mizuno, Mitsuru; Kobayashi, Shinji; Takebe, Takanori; Kan, Hiroomi; Yabuki, Yuichiro; Matsuzaki, Takahisa; Yoshikawa, Hiroshi Y; Nakabayashi, Seiichiro; Ik, Lee Jeong; Maegawa, Jiro; Taniguchi, Hideki

    2014-03-01

    In healthy joints, hyaline cartilage covering the joint surfaces of bones provides cushioning due to its unique mechanical properties. However, because of its limited regenerative capacity, age- and sports-related injuries to this tissue may lead to degenerative arthropathies, prompting researchers to investigate a variety of cell sources. We recently succeeded in isolating human cartilage progenitor cells from ear elastic cartilage. Human cartilage progenitor cells have high chondrogenic and proliferative potential to form elastic cartilage with long-term tissue maintenance. However, it is unknown whether ear-derived cartilage progenitor cells can be used to reconstruct hyaline cartilage, which has different mechanical and histological properties from elastic cartilage. In our efforts to develop foundational technologies for joint hyaline cartilage repair and reconstruction, we conducted this study to obtain an answer to this question. We created an experimental canine model of knee joint cartilage damage, transplanted ear-derived autologous cartilage progenitor cells. The reconstructed cartilage was rich in proteoglycans and showed unique histological characteristics similar to joint hyaline cartilage. In addition, mechanical properties of the reconstructed tissues were higher than those of ear cartilage and equal to those of joint hyaline cartilage. This study suggested that joint hyaline cartilage was reconstructed from ear-derived cartilage progenitor cells. It also demonstrated that ear-derived cartilage progenitor cells, which can be harvested by a minimally invasive method, would be useful for reconstructing joint hyaline cartilage in patients with degenerative arthropathies.

  20. The biomechanical behaviour of the hyalinized periodontal ligament in dogs during experimental orthodontic tooth movement.

    Science.gov (United States)

    Jónsdóttir, S H; Giesen, E B W; Maltha, J C

    2012-10-01

    During orthodontic tooth movement, the mechanical behaviour of the extracellular matrix of the periodontal ligament (PDL) determines the cellular processes involved in turnover of the PDL and alveolar bone. This mechanical behaviour is the basis for finite element (FE) models and FE analyses. Five young adult male beagle dogs were used to test the null hypothesis that the mechanical behaviour of the PDL is identical in normal and hyalinized PDL. Therefore, tooth transposition was measured after standardized force application by super-elastic nickel titanium (NiTi) coil springs, exerting a constant force of 100 cN for 5 hours in both conditions. A rapid transposition during the first few seconds was found. However, it was significantly less for hyalinized than for non-hyalinized PDL. Subsequently, a short-lived creep movement was found for hyalinized PDL, while creep persisted at the non-hyalinized sides (analysis of variance and Tukey's multiple comparisons post hoc tests). The results showed substantial biomechanical differences between hyalinized and non-hyalinized PDL at different time points (Mann-Whitney). This indicates that FE models in the study of long-term orthodontic tooth movement, which are based solely on the characteristics of normal PDL should be reconsidered.

  1. 1. 5 MRT of the hyaline articular cartilage of the knee joint

    Energy Technology Data Exchange (ETDEWEB)

    Adam, G.; Bohndorf, K.; Krasny, R.; Guenther, R.W.; Prescher, A.

    1988-06-01

    MRI is a new method for imaging the knee joint. There is still some uncertainty regarding the extent and the signal from hyaline articular cartilage. MRI images were therefore compared with anatomical and histological preparations of the knee joint and the difference between MRI and the anatomical sections have been determined. It was shown that demonstration of hyaline cartilage was obscured by an artifact. Further investigations are required to determine the cause of this artifact and to achieve accurate imaging of hyaline cartilage by MRI.

  2. Joint immobilization inhibits spontaneous hyaline cartilage regeneration induced by a novel double-network gel implantation.

    Science.gov (United States)

    Arakaki, Kazunobu; Kitamura, Nobuto; Kurokawa, Takayuki; Onodera, Shin; Kanaya, Fuminori; Gong, Jian-Ping; Yasuda, Kazunori

    2011-02-01

    We have recently discovered that spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect in the rabbit, when we implant a novel double-network (DN) gel plug at the bottom of the defect. To clarify whether joint immobilization inhibits the spontaneous hyaline cartilage regeneration, we conducted this study with 20 rabbits. At 4 or 12 weeks after surgery, the defect in the mobile knees was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen, while no cartilage tissues were observed in the defect in the immobilized knees. Type-2 collagen, Aggrecan, and SOX9 mRNAs were expressed only in the mobile knees at each period. This study demonstrated that joint immobilization significantly inhibits the spontaneous hyaline cartilage regeneration induced by the DN gel implantation. This fact suggested that the mechanical environment is one of the significant factors to induce this phenomenon.

  3. Hyaline membrane disease (HMD: the role of the perinatal pathologist

    Directory of Open Access Journals (Sweden)

    Giorgia Locci

    2014-06-01

    Full Text Available Hyaline membrane disease (HMD, the pathologic correlate of respiratory distress syndrome (RDS of the newborn, is an acute lung disease of premature infant caused by inadequate amounts of surfactant. Decreased surfactant results in insufficient surface tension in the alveolus during expiration, leading to atelectasis, decreased gas exchange, severe hypoxia and acidosis. HMD predominantly occurs in infants younger than 32 weeks of gestation and weighing less than 1,200 g. In the interpretation of perinatal lung pathology, it is necessary to consider the development of the immature lung, particulary in the third trimester. Microscopically HMD is characterized by the occurrence of dilated terminal and respiratory bronchioles and of alveolar ducts lined by acellular eosinophilic hyaline membranes. The membranes are composed of necrotic alveolar lining cells, amniotic fluid constituents and fibrin. Retinopathy of prematurity and bronchopulmonary dysplasia are late complications of RDS that usually occur in infants who weigh less than 1,500 g and were maintained on a mechanical respiration more than 6 days. Here a pratical approach to a microscopic analysis of the lung in newborns died with the clinical setting of RDS is presented. The most important pathological findings for a complete clinical pathological diagnosis are: the evaluation of the architectural lung development; the endothelial cell lesions; the interstitial edema; the occurrence of disseminated intravascular coagulation; the presence of associated inflammatory lesions. The usefulness of some immunohistochemical stains is also underlined, including anti-surfactant, anti-smooth muscle actin and anti-CD31 to better evaluate surfactant production, pulmonary artery maturation and endothelial cell damage, respectively. Finally, the prevalent role of endothelial dysfunction and endothelial barrier loss is underlined, representing a major pathological event in the deposition of HMD

  4. Study of differential properties of fibrochondrocytes and hyaline chondrocytes in growing rabbits.

    Science.gov (United States)

    Huang, L; Li, M; Li, H; Yang, C; Cai, X

    2015-02-01

    We aimed to build a culture model of chondrocytes in vitro, and to study the differential properties between fibrochondrocytes and hyaline chondrocytes. Histological sections were stained with haematoxylin and eosin so that we could analyse the histological structure of the fibrocartilage and hyaline cartilage. Condylar fibrochondrocytes and femoral hyaline chondrocytes were cultured from four, 4-week-old, New Zealand white rabbits. The production of COL2A1, COL1OA1, SOX9 and aggrecan was detected by real time-q polymerase chain reaction (RT-qPCR) and immunoblotting and the differences between them were compared statistically. Histological structures obviously differed between fibrocartilage and hyaline cartilage. COL2A1 and SOX9 were highly expressed within cell passage 2 (P2) of both fibrochondrocytes and hyaline chondrocytes, and reduced significantly after cell passage 4 (P4). The mRNA expressions of COL2A1 (p=0.05), COL10A1 (p=0.04), SOX9 (p=0.03), and aggrecan (p=0.04) were significantly higher in hyaline chondrocytes than in fibrochondrocytes, whereas the expression of COL1A1 (p=0.02) was the opposite. Immunoblotting showed similar results. We have built a simple and effective culture model of chondrocytes in vitro, and the P2 of chondrocytes is recommended for further studies. Condylar fibrocartilage and femoral hyaline cartilage have unique biological properties, and the regulatory mechanisms of endochondral ossification for the condyle should be studied independently in the future. Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  5. Effects of three hydrocarbons on the histologic structure of male rat kidneys. Final report, 1 July 1993-30 June 1994

    Energy Technology Data Exchange (ETDEWEB)

    Eurell, T.E.

    1994-08-31

    Using a lysosome specific, acid phosphatase stain developed by our research team, F344 and NBR male rats were found to respond to decalin, JP-4 and JP-8 exposure. Hydrocarbon-induced renal tubular lysosomal alterations were more closely related to the length of exposure rather than the strain of experimental animal. The NBR rats (extended exposure) had significantly enlarged lysosomes that would often be located in the basal aspect of the renal tubular epithelial cell in a manner similar to the characteristic F344 male rat response, whereas, the F344 rats (short exposure) showed groups of perinuclear lysosomal aggregates in a manner similar to the characteristic NBR male rat response. This effect could not be detected using, HE, LMBBF, and MH stains. This finding is important in regards to the controversy of alpha 2U-globulin's association with hyaline droplet nephropathy because: (1) the NBR rat demonstrates significant lysosomal alterations following extended hydrocarbon exposure in the presence of negligible concentrations of androgen-dependent alpha 2U-globulin and (2) the F344 rat demonstrates minimal lysosomal alteration following short hydrocarbon exposure in the presence of high concentrations of androgen-dependent alpha 2U-globulin. Immunohistochemical studies of renal tubular epithelial cells from NBR and F344 male rats exposed to decalin. JP-4 and JP-8 revealed that the microtubules of the cytoskeleton form a characteristic aggregate pattern in the apical portion of the cell in association with hydrocarbon-induced lysosomal alterations. The nephrotoxic effect of decalin, JP-4 and JP-8 appeared to be equivalent as judged by renal tubular lysosomal and cytoskeletal alterations.

  6. Prevalence and factors associated with scleral hyaline plaque: clinical study of older adults in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Horowitz S

    2015-06-01

    Full Text Available Soraya Horowitz,1 Nadyr Damasceno,1 Eduardo Damasceno21Department of Ophthalmology, Hospital Naval Marcilio Dias, Rio de Janeiro, 2Department of Ophthalmology, Universidade Federal Fluminense, Niterói, BrazilPurpose: To investigate the prevalence of scleral hyaline plaque among older adults in the city of Niterói in southeastern Brazil. A second goal was to assess the correlation between scleral hyaline plaque and several age-related diseases, including eye diseases and systemic diseases.Methods: The study sample comprised 667 participants who were followed for 15 months. The study had a prospective, longitudinal, observational design that established inclusion and exclusion criteria. The following variables were selected for correlation with scleral hyaline plaque: sex, age, age range, iris color, ethnicity, presence of cataract, moderate to high myopia, age-related macular degeneration (AMD, diabetes mellitus, systemic arterial hypertension, degenerative arthritis, and osteoporosis. These correlations were assessed by means of the χ2 test and Student’s t-test. Multivariate analysis was performed to exclude factors that were potentially associated with aging exclusively but that did not have a direct relationship with hyaline plaque. Binary logistic regression was used to calculate odds ratios, significance, and confidence intervals.Results: Scleral hyaline plaques were found in 177 patients (17.54%. There was a statistically significant association between the presence of hyaline plaques and sex (female, age range (≥70 years old, ethnicity (Caucasian, cataract, moderate to high myopia, systemic arterial hypertension, degenerative arthritis, and osteoporosis (P<0.05. On multivariate binary logistic regression analysis, only female sex, age range (≥70 years, moderate to high myopia, and degenerative arthritis exhibited significant correlation.Conclusion: The prevalence of scleral hyaline plaque in the present study was higher than in

  7. The value of MDCT in diagnosis of hyaline-vascular Castleman's disease

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiaoli [Department of Radiology, Beijing Shijitan Hospital affiliated to Capital University of Medical Sciences, Yangfangdian Tieyiyuan, Road No. 10, Haidian District, Beijing, 100038 China (China); Liu, Cheng [CT Department, Shandong Medical Imaging Research Institute (China); Wang, Rengui, E-mail: 490150302@qq.com [Department of Radiology, Beijing Shijitan Hospital affiliated to Capital University of Medical Sciences, Yangfangdian Tieyiyuan, Road No. 10, Haidian District, Beijing, 100038 China (China); Zhu, Xuejun [Dermatology Department, Beijing University First Hospital (China); Gao, Li [Department of Radiology, Beijing University First Hospital (China); Chen, Jiuhong [Healthcare, Siemens Ltd. (China)

    2012-09-15

    Purpose: Castleman's disease (CD) is an uncommon entity characterized by a massive growth of lymphoid tissue. There are two types: the hyaline-vascular (HV) type and the plasma cell (PC) type. The purpose of this study was to evaluate the clinical value of multiple detector computed tomography (MDCT) in the diagnosis and planning of treatment for hyaline-vascular CD. Materials and methods: Fifty-two cases of confirmed hyaline-vascular CD were retrospectively reviewed. Unenhanced and contrast-enhanced MDCT scans had been performed in all patients, followed by surgery and pathological analysis of the lesion. Original MDCT transverse and reconstructed images were used for image interpretation. Features of the lesion and its adjacent structures were identified. Results: The lesion was present in the thorax of 24 patients and the abdomen in 28. Obvious features of hyaline-vascular CD (especially feeding vessels and draining veins) and its adjacent structures were demonstrated on 52 patients. Conclusion: On MDCT imaging, original MDCT transverse and reconstructed images provide an excellent tool for diagnosis of hyaline-vascular CD and have high value in the determination of a treatment plan.

  8. HYALINIZING TRABECULAR ADENOMA FEIGNING PAPILLARY CARCINOMA THYROID: CASE REPORT WITH REVIEW OF LITERATURE

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    Kandukuri Mahesh

    2014-05-01

    Full Text Available Hyalinizing Trabecular Adenoma (HTA of the thyroid is a rare neoplasm that was first described by Carney in 1987. It is a tumor of follicular derivation with peculiar nuclear, architectural, histochemical, and immunohistochemical features. We report a case of Hyalinizing trabecular adenoma in a 36-year-old woman with enlarged thyroid lobe. Ultrasonographic features and fine needle aspiration cytology (FNAC of the enlarged thyroid was performed and the diagnosis given was Papillary carcinoma of the thyroid. The patient underwent total thyroidectomy, with a histopathological diagnosis of hyalinizing trabecular Adenoma (HTA. We present this case in view of its rarity and to discuss the clinical and diagnostic approach, including the role of FNAC, and the pathologic features of HTA with special reference to the possible differential diagnosis and also review of literature. Although rare cases of malignant Hyalinizing trabecular adenoma (HTA have been documented, this tumor should be considered a benign neoplasm or at most, a neoplasm of extremely low malignant potential, however invasion of the capsule should be considered on histopathology. An awareness of hyalinizing trabecular adenomas and their characteristic features is valuable for their recognition and management as well as for the possible prevention of over diagnosis and over treatment for benign disease

  9. Dynamics of droplets

    Energy Technology Data Exchange (ETDEWEB)

    Frohn, A.; Roth, N. [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik der Luft- und Raumfahrt

    2000-07-01

    Intended to privide an up-to-date overview of the field, this book is also likely to become a standard work of reference on the science of droplets. Beginning with the theoretical background important for droplet dynamics, it continues with a presentation of the various methods for generating single droplets and regular droplet systems. Also included is a detailed description of the experimental methods employed in droplet research. A special chapter is devoted to the various types of droplet interactions without phase transition. A separate chapter then treats many examples of the possible phase transition processes. The final part of the book gives a summary of important applications. With its comprehensive content, this book will be of interest to all scientists and lecturers concerned with two-phase flow, spray technology, heterogeneous combustion, and aerosol science. (orig.)

  10. Magnetic resonance imaging of hyaline cartilage regeneration in neocartilage graft implantation.

    Science.gov (United States)

    Tan, C F; Ng, K K; Ng, S H; Cheung, Y C

    2003-12-01

    The purpose of this study was to investigate the regenerative potential of hyaline cartilage in a neocartilage graft implant with the aid of MR cartilage imaging using a rabbit model. Surgical osteochondral defects were created in the femoral condyles of 30 mature New Zealand rabbits. The findings of neocartilage in autologous cartilage grafts packed into osteochondral defects were compared with control group of no implant to the osteochondral defect. The outcome of the implantations was correlated with histologic and MR cartilage imaging findings over a 3-month interval. Neocartilage grafts packed into osteochondral defects showed regeneration of hyaline cartilage at the outer layer of the implant using MR cartilage imaging. Fibrosis of fibrocartilage developed at the outer layer of the autologous cartilage graft together with an inflammatory reaction within the osteochondral defect. This animal study provides evidence of the regenerative ability of hyaline cartilage in neocartilage transplants to repair articular cartilage.

  11. Hyaline cartilage cells outperform mandibular condylar cartilage cells in a TMJ fibrocartilage tissue engineering application.

    Science.gov (United States)

    Wang, L; Lazebnik, M; Detamore, M S

    2009-03-01

    To compare temporomandibular joint (TMJ) condylar cartilage cells in vitro to hyaline cartilage cells cultured in a three-dimensional (3D) environment for tissue engineering of mandibular condylar cartilage. Mandibular condylar cartilage and hyaline cartilage cells were harvested from pigs and cultured for 6 weeks in polyglycolic acid (PGA) scaffolds. Both types of cells were treated with glucosamine sulfate (0.4 mM), insulin-like growth factor-I (IGF-I) (100 ng/ml) and their combination. At weeks 0 and 6, cell number, glycosaminoglycan (GAG) and collagen content were determined, types I and II collagen were visualized by immunohistochemistry and GAGs were visualized by histology. Hyaline cartilage cells produced from half an order to a full order of magnitude more GAGs and collagen than mandibular condylar cartilage cells in 3D culture. IGF-I was a highly effective signal for biosynthesis with hyaline cartilage cells, while glucosamine sulfate decreased cell proliferation and biosynthesis with both types of cells. In vitro culture of TMJ condylar cartilage cells produced a fibrous tissue with predominantly type I collagen, while hyaline cartilage cells formed a fibrocartilage-like tissue with types I and II collagen. The combination of IGF and glucosamine had a synergistic effect on maintaining the phenotype of TMJ condylar cells to generate both types I and II collagen. Given the superior biosynthetic activity by hyaline cartilage cells and the practical surgical limitations of harvesting cells from the TMJ of a patient requiring TMJ reconstruction, cartilage cells from elsewhere in the body may be a potentially better alternative to cells harvested from the TMJ for TMJ tissue engineering. This finding may also apply to other fibrocartilages such as the intervertebral disc and knee meniscus in applications where a mature cartilage cell source is desired.

  12. Oral pulse or hyaline ring granuloma: A case report and a brief review

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    Swetha Acharya

    2015-01-01

    Full Text Available Pulse or hyaline ring granulomas are rare but are well-defined oral and extraoral lesions due to implantation of the cellulose moiety of plant foods in contrast starch components. A unique form as reactive gingival growth showing histologic features of oral pulse or hyaline ring granuloma (OPHRG which had resulted from implantation of food particles of plant or vegetable origin into the periodontium has been illustrated. Such a presentation is attributable to compromised periodontal health and poor oral hygiene favoring the implantation of food particles has been described here along with a literature update on OPHRG.

  13. Hyalinizing trabecular tumor of the thyroid gland: characteristic features on ultrasonography.

    Science.gov (United States)

    Kobayashi, Kaoru; Hirokawa, Mitsuyoshi; Jikuzono, Tomoo; Fukata, Shuji; Amino, Nobuyuki; Miyauchi, Akira; Nakamura, Yasushi

    2007-03-01

    We report a case of hyalinizing trabecular tumor of the thyroid gland and describe the characteristic ultrasonographic features of this tumor. This was a rare tumor of follicular cell origin with a trabecular pattern of growth and marked intratrabecular hyalinization. The tumor had an irregular shape, a delicately jagged border, and hypoechoic and heterogeneous internal echoes on B-mode ultrasonography. Very rich intratumoral blood flow, the so-called "tumor inferno" was evident on power Doppler ultrasonography. In the clinical management of thyroid nodules, clinicians should be aware of this peculiar type of thyroid tumor and its characteristic ultrasonographic findings.

  14. Quantitative assessment of hyaline cartilage elasticity during optical clearing using optical coherence elastography

    Science.gov (United States)

    Liu, Chih-Hao; Singh, Manmohan; Li, Jiasong; Han, Zhaolong; Wu, Chen; Wang, Shang; Idugboe, Rita; Raghunathan, Raksha; Zakharov, Valery P.; Sobol, Emil N.; Tuchin, Valery V.; Twa, Michael; Larin, Kirill V.

    2015-03-01

    We report the first study on using optical coherence elastography (OCE) to quantitatively monitor the elasticity change of the hyaline cartilage during the optical clearing administrated by glucose solution. The measurement of the elasticity is verified using uniaxial compression test, demonstrating the feasibility of using OCE to quantify the Young's modulus of the cartilage tissue. As the results, we found that the stiffness of the hyaline cartilage increases during the optical clearing of the tissue. This study might be potentially useful for the early detection of osteoarthritis disease.

  15. Juvenile hyaline fibromatosis and infantile systemic hyalinosis: Divergent expressions of the same genetic defect?

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    Dhingra Mandeep

    2008-01-01

    Full Text Available We describe here a three year-old girl with classic clinical and histological features of juvenile hyaline fibromatosis. We found a history of similar skin findings in her eldest sister, in whom the disorder took a rapidly progressive and fatal course in the second year of life, suggesting either a very severe form of juvenile hyaline fibromatosis, or the possibility of infantile systemic hyalinosis. The similarities and differences between these two described types of hyalinoses have been reviewed in reference to the present report.

  16. Similar hyaline-like cartilage repair of osteochondral defects in rabbits using isotropic and anisotropic collagen scaffolds

    NARCIS (Netherlands)

    Mulder, E.L.W. de; Hannink, G.J.; Kuppevelt, T.H. van; Daamen, W.F.; Buma, P.

    2014-01-01

    Lesions in knee joint articular cartilage (AC) have limited repair capacity. Many clinically available treatments induce a fibrous-like cartilage repair instead of hyaline cartilage. To induce hyaline cartilage repair, we hypothesized that type I collagen scaffolds with fibers aligned perpendicular

  17. Magnetic resonance tomography (MRT) of the knee joint: Meniscus, cruciate ligaments and hyaline cartilage. Magnetresonanztomographie (MRT) des Kniegelenks: Meniskus, Kreuzbaender und hyaliner Gelenkknorpel

    Energy Technology Data Exchange (ETDEWEB)

    Hodler, J. (Radiologie, Universitaetsspital, Zurich (Switzerland) Orthopaedische Universitaetsklinik Balgrist, Zurich (Switzerland). Radiologische Abt.); Buess, E. (Orthopaedische Universitaetsklinik Balgrist, Zurich (Switzerland)); Rodriguez, M. (Orthopaedische Universitaetsklinik Balgrist, Zurich (Switzerland)); Imhoff, A. (Orthopaedische Universitaetsklinik Balgrist, Zurich (Switzerland))

    1993-08-01

    The use of MRT for diagnosing injury to the meniscus, the cruciate ligaments and hyaline cartilage was evaluated retrospectively in 82 knee joints without any knowledge of operative findings. In 49 cases the results were verified by arthroscopy and in 33 cases by arthrotomy. Sensitivity, specificity and diagnostic accuracy of MRT for meniscus lesions was 73.9%, 96.9%, and 94.6%. Corresponding values for lesions of the anterior cruciate ligament were 88.9%, 96.6%, and 94.7%, and for lesions of the hyaline cartilage 62.6%, 96.1%, and 87.9%, respectively. In addition to its high specificity, MRT proved accurate in excluding lesions of the meniscus (97.1%) of the anterior cruciate ligament (96.6%) and of hyaline cartilage (88.8%). A negative finding on MRT therefore makes the presence of a lesion of the meniscus, cruciate ligaments of cartilage unlikely. In such cases one is justified in delaying the use of arthroscopy or arthrotomy. (orig.)

  18. Levitated droplet dye laser

    DEFF Research Database (Denmark)

    Azzouz, H.; Alkafadiji, L.; Balslev, Søren

    2006-01-01

    a high quality optical resonator. Our 750 nL lasing droplets consist of Rhodamine 6G dissolved in ethylene glycol, at a concentration of 0.02 M. The droplets are optically pumped at 532 nm light from a pulsed, frequency doubled Nd:YAG laser, and the dye laser emission is analyzed by a fixed grating...

  19. Droplet collisions in turbulence

    NARCIS (Netherlands)

    Oldenziel, G.

    2014-01-01

    Liquid droplets occur in many natural phenomena and play an important role in a large number of industrial applications. One of the distinct properties of droplets as opposed to solid particles is their ability to merge, or coalesce upon collision. Coalescence of liquid drops is of importance in for

  20. Droplet collisions in turbulence

    NARCIS (Netherlands)

    Oldenziel, G.

    2014-01-01

    Liquid droplets occur in many natural phenomena and play an important role in a large number of industrial applications. One of the distinct properties of droplets as opposed to solid particles is their ability to merge, or coalesce upon collision. Coalescence of liquid drops is of importance in for

  1. Self-propelled droplets

    Science.gov (United States)

    Seemann, Ralf; Fleury, Jean-Baptiste; Maass, Corinna C.

    2016-11-01

    Self-propelled droplets are a special kind of self-propelled matter that are easily fabricated by standard microfluidic tools and locomote for a certain time without external sources of energy. The typical driving mechanism is a Marangoni flow due to gradients in the interfacial energy on the droplet interface. In this article we review the hydrodynamic prerequisites for self-sustained locomotion and present two examples to realize those conditions for emulsion droplets, i.e. droplets stabilized by a surfactant layer in a surrounding immiscible liquid. One possibility to achieve self-propelled motion relies on chemical reactions affecting the surface active properties of the surfactant molecules. The other relies on micellar solubilization of the droplet phase into the surrounding liquid phase. Remarkable cruising ranges can be achieved in both cases and the relative insensitivity to their own `exhausts' allows to additionally study collective phenomena.

  2. Computed tomography findings in patients with pulmonary hyalinizing granulomas: a case report; Granulomas hialinizantes pulmonares: aspectos na tomografia computadorizada - relato de caso

    Energy Technology Data Exchange (ETDEWEB)

    Marchiori, Edson [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Radiologia]. E-mail: edmarchiori@zipmail.com.br; Valiante, Paulo Marcos [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Medicina. Dept. de Patologia; Correia, Ana Helena Pereira; Carneiro, Leonardo Hoehl; Caldas, Carolina Rodrigues [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil). Servico de Anatomia Patologica; Souza Junior, Arthur Soares [Faculdade de Medicina de Sao Jose do Rio Preto (FAMERP), SP (Brazil). Dept. de Radiologia

    2003-12-01

    Hyalinizing granulomas are benign fibrotic lesions that generally present multiple nodules seen on radiological examinations, which are frequently cavitary and/or calcified lesions. We report a case of a 28 year-old-woman with hyalinizing granulomas probably secondary to a previous tuberculosis infection. Hyalinizing granulomas should be included in the differential diagnosis of patients with multiple pulmonary nodules. (author)

  3. Quantification of collagen distributions in rat hyaline and fibro cartilages based on second harmonic generation imaging

    Science.gov (United States)

    Zhu, Xiaoqin; Liao, Chenxi; Wang, Zhenyu; Zhuo, Shuangmu; Liu, Wenge; Chen, Jianxin

    2016-10-01

    Hyaline cartilage is a semitransparent tissue composed of proteoglycan and thicker type II collagen fibers, while fibro cartilage large bundles of type I collagen besides other territorial matrix and chondrocytes. It is reported that the meniscus (fibro cartilage) has a greater capacity to regenerate and close a wound compared to articular cartilage (hyaline cartilage). And fibro cartilage often replaces the type II collagen-rich hyaline following trauma, leading to scar tissue that is composed of rigid type I collagen. The visualization and quantification of the collagen fibrillar meshwork is important for understanding the role of fibril reorganization during the healing process and how different types of cartilage contribute to wound closure. In this study, second harmonic generation (SHG) microscope was applied to image the articular and meniscus cartilage, and textural analysis were developed to quantify the collagen distribution. High-resolution images were achieved based on the SHG signal from collagen within fresh specimens, and detailed observations of tissue morphology and microstructural distribution were obtained without shrinkage or distortion. Textural analysis of SHG images was performed to confirm that collagen in fibrocartilage showed significantly coarser compared to collagen in hyaline cartilage (p imaging degenerative tissues or assessing wound repair following cartilage injury.

  4. Juvenile hyaline fibromatosis and infantile systemic hyalinosis: a unifying term and a proposed grading system.

    Science.gov (United States)

    Nofal, Ahmad; Sanad, Mohammad; Assaf, Magda; Nofal, Eman; Nassar, Amani; Almokadem, Sahar; Attwa, Enayat; Elmosalamy, Khaled

    2009-10-01

    It has been suggested that juvenile hyaline fibromatosis and infantile systemic hyalinosis represent different severities of the same disease. We sought to redefine these disorders clearly to establish a common inclusive terminology. The study included two children with early onset of similar pink papulonodular skin lesions and marked gingival hyperplasia. The first case was characterized by flexion contractures of the large joints, fractures, persistent diarrhea, recurrent chest infections, and retarded physical growth. The second patient had large swellings on the scalp and knees without systemic involvement. Radiologic examination revealed fractures and osteolytic bone lesions in the first case, and soft tissue masses in the second case. Laboratory tests showed anemia in both cases, and hypogammaglobulinemia, hypoalbuminemia, and electrolyte imbalance in the first case. Histopathological and ultrastructural evaluation demonstrated hyalinized fibrous tissue in the dermis in both cases. Genetic studies were unavailable. Juvenile hyaline fibromatosis and infantile systemic hyalinosis share many common features that strongly support consideration of these conditions as different expressions of the same disorder. We propose a common term, "hyaline fibromatosis syndrome," which can be divided into mild, moderate, and severe subtypes.

  5. Generation of hyaline cartilaginous tissue from mouse adult dermal fibroblast culture by defined factors

    Science.gov (United States)

    Hiramatsu, Kunihiko; Sasagawa, Satoru; Outani, Hidetatsu; Nakagawa, Kanako; Yoshikawa, Hideki; Tsumaki, Noriyuki

    2011-01-01

    Repair of cartilage injury with hyaline cartilage continues to be a challenging clinical problem. Because of the limited number of chondrocytes in vivo, coupled with in vitro de-differentiation of chondrocytes into fibrochondrocytes, which secrete type I collagen and have an altered matrix architecture and mechanical function, there is a need for a novel cell source that produces hyaline cartilage. The generation of induced pluripotent stem (iPS) cells has provided a tool for reprogramming dermal fibroblasts to an undifferentiated state by ectopic expression of reprogramming factors. Here, we show that retroviral expression of two reprogramming factors (c-Myc and Klf4) and one chondrogenic factor (SOX9) induces polygonal chondrogenic cells directly from adult dermal fibroblast cultures. Induced cells expressed marker genes for chondrocytes but not fibroblasts, i.e., the promoters of type I collagen genes were extensively methylated. Although some induced cell lines formed tumors when subcutaneously injected into nude mice, other induced cell lines generated stable homogenous hyaline cartilage–like tissue. Further, the doxycycline-inducible induction system demonstrated that induced cells are able to respond to chondrogenic medium by expressing endogenous Sox9 and maintain chondrogenic potential after substantial reduction of transgene expression. Thus, this approach could lead to the preparation of hyaline cartilage directly from skin, without generating iPS cells. PMID:21293062

  6. Uninduced adipose-derived stem cells repair the defect of full-thickness hyaline cartilage.

    Science.gov (United States)

    Zhang, Hai-Ning; Li, Lei; Leng, Ping; Wang, Ying-Zhen; Lv, Cheng-Yu

    2009-04-01

    To testify the effect of the stem cells derived from the widely distributed fat tissue on repairing full-thickness hyaline cartilage defects. Adipose-derived stem cells (ADSCs) were derived from adipose tissue and cultured in vitro. Twenty-seven New Zealand white rabbits were divided into three groups randomly. The cultured ADSCs mixed with calcium alginate gel were used to fill the full-thickness hyaline cartilage defects created at the patellafemoral joint, and the defects repaired with gel or without treatment served as control groups. After 4, 8 and 12 weeks, the reconstructed tissue was evaluated macroscopically and microscopically. Histological analysis and qualitative scoring were also performed to detect the outcome. Full thickness hyaline cartilage defects were repaired completely with ADSCs-derived tissue. The result was better in ADSCs group than the control ones. The microstructure of reconstructed tissue with ADSCs was similar to that of hyaline cartilage and contained more cells and regular matrix fibers, being better than other groups. Plenty of collagen fibers around cells could be seen under transmission electron microscopy. Statistical analysis revealed a significant difference in comparison with other groups at each time point (t equal to 4.360, P less than 0.01). These results indicate that stem cells derived from mature adipose without induction possess the ability to repair cartilage defects.

  7. Pulmonary Changes in Preterm Neonates with Hyaline Membrane Disease (a Clinicomorphological Study

    Directory of Open Access Journals (Sweden)

    A. M. Golubev

    2009-01-01

    Full Text Available Objective: to reveal lung morphological changes in preterm neonatal infants with hyaline membrane disease (HMD in the use of exogenous surfactants and artificial ventilation. Materials and methods. Case histories and autopsy protocols were analyzed in 90 preterm neonates who had died from severe respiratory failure. All the neonates were divided into 4 groups: 1 20 (22.2% infants who had received the exogenous surfactant Curosurf in the combined therapy of HMD; 2 19 (21.1% babies with HMD who had taken Surfactant BL; 3 25 (27.8% surfactant-untreated infants who had died from HMD; 4 26 (28.9% very preterm neonates with extremely low birth weight who had died within the first hour of life. The lungs were histologically and morphometrically examined. Results. The study demonstrated the specific course of HMD when exogenous surfactants and artificial ventilation were used. The contributors to the development of the disease are intranatal amniotic fluid aspiration and intranatal fetal hypoxia. Conclusion. Artificial ventilation and the use of exogenous surfactants do not block the generation of hyaline membranes. The latter differ in formation time, form, and location. The differences in a cell response to hyaline membranes were found in the neonatal infants receiving exogenous surfactants. The characteristic morphological signs of the disease for all the neonates enrolled in the study are alveolar and bronchial epithelial damages and microcirculatory disorders. Key words: preterm neonatal infants, hyaline membrane disease, exogenous surfactants, artificial ventilation, histology, morphometry.

  8. Waveguides for walking droplets

    CERN Document Server

    Filoux, Boris; Schlagheck, Peter; Vandewalle, Nicolas

    2015-01-01

    When gently placing a droplet onto a vertically vibrated bath, a drop can bounce permanently. Upon increasing the forcing acceleration, the droplet is propelled by the wave it generates and becomes a walker with a well defined speed. We investigate the confinement of a walker in different rectangular cavities, used as waveguides for the Faraday waves emitted by successive droplet bounces. By studying the walker velocities, we discover that 1d confinement is optimal for narrow channels. We also propose an analogy with waveguide models based on the observation of the Faraday instability within the channels.

  9. Electrostatic charging of jumping droplets

    Science.gov (United States)

    Miljkovic, Nenad; Preston, Daniel J.; Enright, Ryan; Wang, Evelyn N.

    2013-09-01

    With the broad interest in and development of superhydrophobic surfaces for self-cleaning, condensation heat transfer enhancement and anti-icing applications, more detailed insights on droplet interactions on these surfaces have emerged. Specifically, when two droplets coalesce, they can spontaneously jump away from a superhydrophobic surface due to the release of excess surface energy. Here we show that jumping droplets gain a net positive charge that causes them to repel each other mid-flight. We used electric fields to quantify the charge on the droplets and identified the mechanism for the charge accumulation, which is associated with the formation of the electric double layer at the droplet-surface interface. The observation of droplet charge accumulation provides insight into jumping droplet physics as well as processes involving charged liquid droplets. Furthermore, this work is a starting point for more advanced approaches for enhancing jumping droplet surface performance by using external electric fields to control droplet jumping.

  10. Bioprinting: Functional droplet networks

    Science.gov (United States)

    Durmus, Naside Gozde; Tasoglu, Savas; Demirci, Utkan

    2013-06-01

    Tissue-mimicking printed networks of droplets separated by lipid bilayers that can be functionalized with membrane proteins are able to spontaneously fold and transmit electrical currents along predefined paths.

  11. Butschli Dynamic Droplet System

    DEFF Research Database (Denmark)

    Armstrong, R.; Hanczyc, M.

    2013-01-01

    of a technology with living properties. Otto Butschli first described the system in 1898, when he used alkaline water droplets in olive oil to initiate a saponification reaction. This simple recipe produced structures that moved and exhibited characteristics that resembled, at least superficially, the amoeba. We......Dynamical oil-water systems such as droplets display lifelike properties and may lend themselves to chemical programming to perform useful work, specifically with respect to the built environment. We present Butschli water-in-oil droplets as a model for further investigation into the development...... to the oil phase), qualify this system as an example of living technology. The analysis of the Butschli droplets suggests that a set of conditions may precede the emergence of lifelike characteristics and exemplifies the richness of this rudimentary chemical system, not only for artificial life...

  12. Resonant and rolling droplet

    CERN Document Server

    Dorbolo, S; Vandewalle, N; Gilet, T

    2008-01-01

    When an oil droplet is placed on a quiescent oil bath, it eventually collapses into the bath due to gravity. The resulting coalescence may be eliminated when the bath is vertically vibrated. The droplet bounces periodically on the bath, and the air layer between the droplet and the bath is replenished at each bounce. This sustained bouncing motion is achieved when the forcing acceleration is higher than a threshold value. When the droplet has a sufficiently low viscosity, it significantly deforms : spherical harmonic \\boldmath{$Y_{\\ell}^m$} modes are excited, resulting in resonant effects on the threshold acceleration curve. Indeed, a lower acceleration is needed when $\\ell$ modes with $m=0$ are excited. Modes $m \

  13. Functions of the Coacervate Droplets

    Science.gov (United States)

    Okihana, Hiroyuki; Ponnamperuma, Cyril

    1982-12-01

    Functions of coacervate droplets as protocells are studied by using synthetic polymers. The coacervate droplets were made from PVA-A and PVA-S. When glycine or diglycine were in the surrounding medium, the coacervate droplets concentrated them. The concentration of glycine in the coacervate droplets was higher than that of diglycine. When this mixture was irradiated by UV light, the coacervate droplets protected them from the photochemical decomposition.

  14. Droplet impacts upon liquid surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ching, B.; Golay, M.W.; Johnson, T.J.

    1984-11-02

    The absorption and rebounding of single droplets and streams of droplets (of diameter less than 1200 micrometers) impacting upon the surface of a deep liquid were examined experimentally. Conservation of mechanical energy and momentum were used to explain rebounding droplet interactions, and impaction criteria have been established regarding the absorption of droplet streams. Surface tension is the dominant mechanism governing the observed behavior. Single droplets were never observed to rebound.

  15. Is the T1ρ MRI profile of hyaline cartilage in the normal hip uniform?

    Science.gov (United States)

    Rakhra, Kawan S; Cárdenas-Blanco, Arturo; Melkus, Gerd; Schweitzer, Mark E; Cameron, Ian G; Beaulé, Paul E

    2015-04-01

    T1ρ MRI is an imaging technique sensitive to proteoglycan (PG) content of hyaline cartilage. However, normative T1ρ values have not been established for the weightbearing cartilage of the hip, and it is not known whether it is uniform or whether there is topographic variation. Knowledge of the T1ρ profile of hyaline cartilage in the normal hip is important for establishing a baseline against which comparisons can be made to experimental and clinical arthritic subjects. In this diagnostic study, we determined (1) the T1ρ MRI values of hyaline cartilage of the normal hip; and (2) whether the T1ρ MRI profile of the normal hip hyaline cartilage is uniform. Fourteen asymptomatic volunteers (11 men, three women; mean age, 35 years) prospectively underwent 1.5-T T1ρ MRI of a single hip. The weightbearing hyaline cartilage bilayer of the acetabulum and femoral head was evaluated on sagittal images and segmented into four zones: (1) anterior; (2) anterosuperior; (3) posterosuperior; and (4) and posterior. For the full region of interest and within each zone and each sagittal slice, we calculated the mean T1ρ relaxation value, a parameter that indirectly quantifies PG content, where T1ρ is inversely related to PG concentration. There was variation in the T1ρ relaxation values depending on zone (anterior to posterior) and slice (medial to lateral). When combining the most anterior quadrants (Zones 1 and 2), the T1ρ relaxation values were lower than those in the combined posterior quadrants (Zones 3 and 4) (30.4 msec versus 32.2 msec, respectively; p = 0.002), reflecting higher PG concentration. There was a difference between the T1ρ relaxation values of the sagittal slices (p = 0.038), most pronounced anteriorly in Zone 1 (26.6 msec, p = 0.001). With a selective combination of zones and slices, there were lower mean T1ρ values in the anterolateral-most region compared with the remainder of the weightbearing portion of the hip (28.6 msec versus 32.2 msec

  16. OCS in He droplets

    Energy Technology Data Exchange (ETDEWEB)

    Grebenev, V.

    2000-06-01

    Phenomenon of superfluidity of para-hydrogen (pH{sub 2}){sub 1-17} and helium {sup 4}He{sub 1-7000} systems doped with an OCS chromophore molecule was investigated in this work. The study of such systems became possible after the development of the depletion spectroscopy technique in helium droplets. The droplets can be easily created and doped with up to 100 particles such as OCS, para-hydrogen or ortho-hydrogen molecules and {sup 4}He atoms. The measured infrared depletion spectra give the information about the temperature of the droplets and their aggregate state. The depletion spectrum of OCS in pure {sup 4}He droplets was comprehensively studied. The rovibrational OCS spectrum shows well resolved narrow lines. The spectrum is shifted to the red relative to the corresponding gas phase spectrum and the rotational constant of OCS in {sup 4}He droplet is three times smaller than that for free molecule. Different models of OCS rotation in the helium environment were discussed. It was shown that the shapes of the rovibrational lines are defined mainly by inhomogeneous broadening due to the droplet size distribution. The sub-rotational structure of the OCS rovibrational lines was revealed in microwave-infrared double resonance experiments. This structure arises due to the interaction of the OCS with the He environment. However, the information obtained in the experiments was not enough to understand the nature of this interaction. (orig.)

  17. Droplet based microfluidics.

    Science.gov (United States)

    Seemann, Ralf; Brinkmann, Martin; Pfohl, Thomas; Herminghaus, Stephan

    2012-01-01

    Droplet based microfluidics is a rapidly growing interdisciplinary field of research combining soft matter physics, biochemistry and microsystems engineering. Its applications range from fast analytical systems or the synthesis of advanced materials to protein crystallization and biological assays for living cells. Precise control of droplet volumes and reliable manipulation of individual droplets such as coalescence, mixing of their contents, and sorting in combination with fast analysis tools allow us to perform chemical reactions inside the droplets under defined conditions. In this paper, we will review available drop generation and manipulation techniques. The main focus of this review is not to be comprehensive and explain all techniques in great detail but to identify and shed light on similarities and underlying physical principles. Since geometry and wetting properties of the microfluidic channels are crucial factors for droplet generation, we also briefly describe typical device fabrication methods in droplet based microfluidics. Examples of applications and reaction schemes which rely on the discussed manipulation techniques are also presented, such as the fabrication of special materials and biophysical experiments.

  18. Droplet based microfluidics

    Science.gov (United States)

    Seemann, Ralf; Brinkmann, Martin; Pfohl, Thomas; Herminghaus, Stephan

    2012-01-01

    Droplet based microfluidics is a rapidly growing interdisciplinary field of research combining soft matter physics, biochemistry and microsystems engineering. Its applications range from fast analytical systems or the synthesis of advanced materials to protein crystallization and biological assays for living cells. Precise control of droplet volumes and reliable manipulation of individual droplets such as coalescence, mixing of their contents, and sorting in combination with fast analysis tools allow us to perform chemical reactions inside the droplets under defined conditions. In this paper, we will review available drop generation and manipulation techniques. The main focus of this review is not to be comprehensive and explain all techniques in great detail but to identify and shed light on similarities and underlying physical principles. Since geometry and wetting properties of the microfluidic channels are crucial factors for droplet generation, we also briefly describe typical device fabrication methods in droplet based microfluidics. Examples of applications and reaction schemes which rely on the discussed manipulation techniques are also presented, such as the fabrication of special materials and biophysical experiments.

  19. Dynamics of a Water Droplet over a Sessile Oil Droplet: Compound Droplets Satisfying a Neumann Condition.

    Science.gov (United States)

    Iqbal, R; Dhiman, S; Sen, A K; Shen, Amy Q

    2017-06-13

    We report the dynamics of compound droplets with a denser liquid (water) droplet over a less dense sessile droplet (mineral oil) that satisfies the Neumann condition. For a fixed size of an oil droplet, depending on the size of the water droplet, either it attains the axisymmetric position or tends to migrate toward the edge of the oil droplet. For a water droplet-to-oil droplet at volume ratio Vw/Vo ≥ 0.05, stable axisymmetric configuration is achieved; for Vw/Vo droplet is observed. The stability and migration of water droplets of size above and below critical size, respectively, are explained using the force balance at the three-phase contact line and film tension. The larger and smaller droplets that initially attain the axisymmetric position or some radial position, respectively, evaporate continuously and thus migrate toward the edge of the oil droplet. The radial location and migration of the water droplets of different initial sizes with respect to time are studied. Experiments with water droplets on a flat oil-air interface did not show migration, which signified the role of the curved oil-air interface for droplet migration. Finally, coalescence of water droplets of size above the critical size at the axisymmetric position is demonstrated. Our compound droplet studies could be beneficial for applications involving droplet transport where contamination due to direct contact and pinning of droplets on solid surfaces is of concern. Migration and coalescence of water droplets on curved oil-air interfaces could open new frontiers in chemical and biological applications including multiphase processing and biological interaction of cells and atmospheric chemistry.

  20. Postnatal expression in hyaline cartilage of constitutively active human collagenase-3 (MMP-13) induces osteoarthritis in mice

    National Research Council Canada - National Science Library

    Neuhold, L A; Killar, L; Zhao, W; Sung, M L; Warner, L; Kulik, J; Turner, J; Wu, W; Billinghurst, C; Meijers, T; Poole, A R; Babij, P; DeGennaro, L J

    2001-01-01

    ...). We have used tetracycline-regulated transcription in conjunction with a cartilage-specific promoter to target a constitutively active human MMP-13 to the hyaline cartilages and joints of transgenic mice...

  1. Calcifying fibrous pseudotumor in association with hyaline vascular type Castleman′s disease

    Directory of Open Access Journals (Sweden)

    Azam Muhammad

    2009-10-01

    Full Text Available Calcifying fibrous pseudotumor is a recently described rare entity. It is considered as sclerosing end stage of inflammatory myofibroblastic tumor. An association with hyaline vascular type Castleman′s disease has also been described. We report a case of a 13-year-old boy who presented with pain in epigastrium. Computed tomography scan of abdomen revealed a circumscribed mass arising from the gastric wall along the greater curvature. Histology revealed a tumor composed of spindle cells present within the dense hyalinized collagenous tissue. Lymphoplasmacytic infiltrate was seen along with lymphoid follicles, dystrophic and ossifying calcification. Tumor cells were focally positive for alpha smooth muscle actin and negative for anaplastic lymphoma kinase protein.

  2. Hyaline cartilage formation and tumorigenesis of implanted tissues derived from human induced pluripotent stem cells.

    Science.gov (United States)

    Saito, Taku; Yano, Fumiko; Mori, Daisuke; Kawata, Manabu; Hoshi, Kazuto; Takato, Tsuyoshi; Masaki, Hideki; Otsu, Makoto; Eto, Koji; Nakauchi, Hiromitsu; Chung, Ung-il; Tanaka, Sakae

    2015-01-01

    Induced pluripotent stem cells (iPSCs) are a promising cell source for cartilage regenerative medicine. Meanwhile, the risk of tumorigenesis should be considered in the clinical application of human iPSCs (hiPSCs). Here, we report in vitro chondrogenic differentiation of hiPSCs and maturation of the differentiated hiPSCs through transplantation into mouse knee joints. Three hiPSC clones showed efficient chondrogenic differentiation using an established protocol for human embryonic stem cells. The differentiated hiPSCs formed hyaline cartilage tissues at 8 weeks after transplantation into the articular cartilage of NOD/SCID mouse knee joints. Although tumors were not observed during the 8 weeks after transplantation, an immature teratoma had developed in one mouse at 16 weeks. In conclusion, hiPSCs are a potent cell source for regeneration of hyaline articular cartilage. However, the risk of tumorigenesis should be managed for clinical application in the future.

  3. Visualization of the macroscopic structure of hyaline cartilage with MR imaging.

    Science.gov (United States)

    Goodwin, D W

    2001-12-01

    The extracellular matrix of any tissue, including hyaline cartilage, has a structure that allows it to meet the physical demands placed upon that tissue. Accordingly, the structure of hyaline cartilage is not uniform. There is considerable variation from one joint to the next and even within a particular joint surface, probably reflecting a joint-specific architecture. This structure has a strong influence on T(2) relaxation. The relationship between T2 and matrix curvature relative to the main magnetic field (B(0)) provides tissue contrast. Images obtained with adequate resolution can exploit this contrast and demonstrate the structure of cartilage. Magnetic resonance imaging is thus capable of providing a detailed description of the structure of joint surfaces, information that is difficult to obtain even with histologic techniques.

  4. MIXED HYALINE VASCULAR AND PLASMA CELL TYPE CASTLEMAN’S DISEASE: REPORT OF A CASE

    Directory of Open Access Journals (Sweden)

    F. Asgarani

    2006-05-01

    Full Text Available Castleman’s disease (angiofollicular lymphoid hyperplasia includes a heterogeneous group of lymphoproliferative disorders. The cause of this disease remains uncertain. There are two types of localized Castleman’s disease: the more common hyaline vascular and the plasma cell types. Mixed variant is an uncommon localized lesion in general population. The lesions can occur in any part of the body that contains lymphoid tissue, although seventy percent are found in the anterior mediastinum. We report a thirty years old boy with Castleman’s disease who presented with fever, anorexia, weight loss,sweating, anemia and abdominal mass. The histologic examination of the biopsy specimens revealed a mixed hyaline vascular and plasma cell type of Castleman’s disease.

  5. Can one generate stable hyaline cartilage from adult mesenchymal stem cells? A developmental approach.

    Science.gov (United States)

    Hellingman, Catharine A; Koevoet, Wendy; van Osch, Gerjo J V M

    2012-11-01

    Chondrogenically differentiating bone marrow-derived mesenchymal stem cells (BMSCs) display signs of chondrocyte hypertrophy, such as production of collagen type X, MMP13 and alkaline phosphatase (ALPL). For cartilage reconstructions this is undesirable, as terminally differentiated cartilage produced by BMSCs mineralizes when implanted in vivo. Terminal differentiation is not restricted to BMSCs but is also encountered in chondrogenic differentiation of adipose-derived mesenchymal stem cells (MSCs) as well as embryonic stem cells, which by definition should be able to generate all types of tissues, including stable cartilage. Therefore, we propose that the currently used culture conditions may drive the cells towards terminal differentiation. In this manuscript we aim to review the literature, supplemented by our own data to answer the question, is it possible to generate stable hyaline cartilage from adult MSCs? We demonstrate that recently published methods for inhibiting terminal differentiation (through PTHrP, MMP13 or blocking phosphorylation of Smad1/5/8) result in cartilage formation with reduction of hypertrophic markers, although this does not reach the low level of stable chondrocytes. A set of hypertrophy markers should be included in future studies to characterize the phenotype more precisely. Finally, we used what is currently known in developmental biology about the differential development of hyaline and terminally differentiated cartilage to provide thought and insights to change current culture models for creating hyaline cartilage. Inhibiting terminal differentiation may not result in stable hyaline cartilage if the right balance of signals has not been created from the start of culture onwards. Copyright © 2011 John Wiley & Sons, Ltd.

  6. Microfluidic devices for droplet injection

    Science.gov (United States)

    Aubrecht, Donald; Akartuna, Ilke; Weitz, David

    2012-02-01

    As picoliter-scale reaction vessels, microfluidic water-in-oil emulsions have found application for high-throughput, large-sample number analyses. Often, the biological or chemical system under investigation needs to be encapsulated into droplets to prevent cross contamination prior to the introduction of reaction reagents. Previous techniques of picoinjection or droplet synchronization and merging enable the addition of reagents to individual droplets, but present limitations on what can be added to each droplet. We present microfluidic devices that couple the strengths of picoinjection and droplet merging, allowing us to selectively add precise volume to our droplet reactions.

  7. Castleman Disease of Hyaline Vascular Type in the Infrathyroidal Region: A Masquerader of Parathyroid Adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Kwon; Kwon, Sun Young [Dongsan Medical Center, Keimyung University School of Medicine, Daegu (Korea, Republic of)

    2013-03-15

    Castleman disease of the infrathyroidal region is extremely rare. We report both CT and sonographic findings of a case of infrathyroidal paratracheal Castleman disease of hyaline vascular type, which masquerades parathyroid adenoma, in a 48-year-old woman. We further provide its histological findings at sonographically guided core-needle biopsy (US-CNB) and excisional biopsy. The lesion was ovoid with homogeneous intense enhancement on contrast-enhanced CT (CECT), and was homogeneous, markedly hypoechoic, and hypervascular on ultrasonography (US). Histological findings of the specimen obtained by US-CNB suggested lymphoproliferative lesion, and thus was inconclusive; those obtained by excisional biopsy were characteristics of Castleman disease of hyaline vascular type. Hyaline vascular type Castleman's disease should be included in the differential diagnosis of a mass of the infrathyroidal region with homogeneous intense enhancement on CECT, as well as with marked hypoechogenicity and hypervascularity on US. US-CNB may be of limited value in the histological diagnosis of this entity.

  8. Elastic cartilage reconstruction by transplantation of cultured hyaline cartilage-derived chondrocytes.

    Science.gov (United States)

    Mizuno, M; Takebe, T; Kobayashi, S; Kimura, S; Masutani, M; Lee, S; Jo, Y H; Lee, J I; Taniguchi, H

    2014-05-01

    Current surgical intervention of craniofacial defects caused by injuries or abnormalities uses reconstructive materials, such as autologous cartilage grafts. Transplantation of autologous tissues, however, places a significant invasiveness on patients, and many efforts have been made for establishing an alternative graft. Recently, we and others have shown the potential use of reconstructed elastic cartilage from ear-derived chondrocytes or progenitors with the unique elastic properties. Here, we examined the differentiation potential of canine joint cartilage-derived chondrocytes into elastic cartilage for expanding the cell sources, such as hyaline cartilage. Articular chondrocytes are isolated from canine joint, cultivated, and compared regarding characteristic differences with auricular chondrocytes, including proliferation rates, gene expression, extracellular matrix production, and cartilage reconstruction capability after transplantation. Canine articular chondrocytes proliferated less robustly than auricular chondrocytes, but there was no significant difference in the amount of sulfated glycosaminoglycan produced from redifferentiated chondrocytes. Furthermore, in vitro expanded and redifferentiated articular chondrocytes have been shown to reconstruct elastic cartilage on transplantation that has histologic characteristics distinct from hyaline cartilage. Taken together, cultured hyaline cartilage-derived chondrocytes are a possible cell source for elastic cartilage reconstruction. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  9. Hyalinizing trabecular tumor of the thyroid gland: A puzzling entity on fine needle aspiration cytology

    Directory of Open Access Journals (Sweden)

    Jitendra Nasit

    2014-01-01

    Full Text Available Hyalinizing trabecular tumor (HTT is a rare unique but controversial thyroid neoplasm, characterized by prominent trabecular growth pattern and stromal hyalinization. Whether HTT is a benign tumor or a variant of papillary thyroid carcinoma (PTC is still unclear. Cytology findings of HTT have been described in few reports. Cytological features of HTT frequently overlap with those of PTC and medullary thyroid carcinoma, which can lead to frequent misdiagnosis. In order to avoid overtreatment like total thyroidectomy, pathologist should be aware of cytological features of HTT. We present a case of 35-year-old female with a right-side thyroid swelling for three years. Fine needle aspiration cytology was performed. According to The Bethesda System for Reporting Thyroid Cytopathology, cytological diagnosis of benign thyroid neoplasm was made. Histopathology of the right thyroidectomy specimen showed HTT. Accurate preoperative diagnosis of HTT requires a very meticulous and cautious approach in the evaluation of cytological features. Trabecular pattern of cells, vague curved nuclear palisading, radiating arrangement of cells around hyaline material, spindled to elongated cells, filamentous cytoplasmic processes with ill-defined cell border and yellow bodies are important diagnostic features of HTT. Nuclear features alone are insufficient for the diagnosis of HTT. Any suspicious cytology of thyroid lesion should follow hemithyroidectomy and histopathological evaluation.

  10. Uninduced adipose-derived stem cells repair the defect of full-thickness hyaline cartilage

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-ning; LI Lei; LENG Ping; WANG Ying-zhen; Lü Cheng-yu

    2009-01-01

    Objective: To testify the effect of the stem cells derived from the widely distributed fat tissue on repairing full-thickness hyaline cartilage defects.Methods: Adipose-derived stem cells (ADSCs) were derived from adipose tissue and cultured in vitro.Twentyseven New Zealand white rabbits were divided into three groups randomly.The cultured ADSCs mixed with calcium alginate gel were used to fill the full-thickness hyaline cartilage defects created at the patellafemoral joint,and the defects repaired with gel or without treatment served as control groups.After 4,8 and 12 weeks,the reconstructed tissue was evaluated macroscopically and microscopically.Histological analysis and qualitative scoring were also performed to detect the outcome.Results: Full thickness hyaline cartilage defects were repaired completely with ADSCs-derived dssue.The result was better in ADSCs group than the control ones.The microstructure of reconstructed tissue with ADSCs was similar to that of hvaline cartilage and contained more cells and regular matrix fibers,being better than other groups.Plenty of collagen fibers around cells could be seen under transmission electron microscopy.Statistical analysis revealed a significant difference in comparison with other groups at each time point(t=4.360,P<0.01).Conclusion: Thcse results indicate that stem cells derived from mature adipose without induction possess the ability to repair cartilage defects

  11. Explosion of Leidenfrost Droplets

    Science.gov (United States)

    Moreau, Florian; Colinet, Pierre; Dorbolo, Stephane

    2012-11-01

    When a drop is released on a plate heated above a given temperature, a thin layer of vapour can isolate the droplet so that it levitates over the plate. This effect was first reported by Leidenfrost in 1756. However, this fascinating subject remains an active field of research in both fundamental and applied researches. In this work, we focus on what happens when surfactant is added to the drop. The aim is to study the influence of a decrease of the surface tension. Surprisingly, as the droplet evaporates, suddenly it explodes. The evolution of the droplet and the resulting explosion are followed using a high speed camera. We show that when a critical concentration of surfactant is reached inside the drop, a shell of surfactant is formed leading to the explosion. The authors would like to thank FNRS for financial support. This work is financially supported by ODILE project (Contract No. FRFC 2.4623.11).

  12. Chip-based droplet sorting

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald; Lee, Abraham; Hatch, Andrew

    2014-07-01

    A non-contact system for sorting monodisperse water-in-oil emulsion droplets in a microfluidic device based on the droplet's contents and their interaction with an applied electromagnetic field or by identification and sorting.

  13. Chip-based droplet sorting

    Science.gov (United States)

    Beer, Neil Reginald; Lee, Abraham; Hatch, Andrew

    2014-07-01

    A non-contact system for sorting monodisperse water-in-oil emulsion droplets in a microfluidic device based on the droplet's contents and their interaction with an applied electromagnetic field or by identification and sorting.

  14. Enhancing Throughput of Combinatorial Droplet Devices via Droplet Bifurcation, Parallelized Droplet Fusion, and Parallelized Detection

    Directory of Open Access Journals (Sweden)

    Kuangwen Hsieh

    2015-10-01

    Full Text Available Combinatorial droplet microfluidic devices with programmable microfluidic valves have recently emerged as a viable approach for performing multiplexed experiments in microfluidic droplets. However, the serial operation in these devices restricts their throughput. To address this limitation, we present a parallelized combinatorial droplet device that enhances device throughput via droplet bifurcation, parallelized droplet fusion, and parallelized droplet detection. In this device, sample droplets split evenly at bifurcating Y-junctions before multiple independent reagent droplets are injected directly into the split sample droplets for robust droplet fusion. Finally, the fused sample and reagent droplets can be imaged in parallel via microscopy. The combination of these approaches enabled us to improve the throughput over traditional, serially-operated combinatorial droplet devices by 16-fold—with ready potential for further enhancement. Given its current performance and prospect for future improvements, we believe the parallelized combinatorial droplet device has the potential to meet the demand as a flexible and cost-effective tool that can perform high throughput screening applications.

  15. Hydrodynamics of a quark droplet

    DEFF Research Database (Denmark)

    Bjerrum-Bohr, Johan J.; Mishustin, Igor N.; Døssing, Thomas

    2012-01-01

    We present a simple model of a multi-quark droplet evolution based on the hydrodynamical description. This model includes collective expansion of the droplet, effects of the vacuum pressure and surface tension. The hadron emission from the droplet is described following Weisskopf's statistical...

  16. Impact of blood droplets

    NARCIS (Netherlands)

    N. Laan

    2015-01-01

    Within Bloodstain Pattern Analysis, forensic experts commonly use the stringing method, based on a straight line approximation of the blood droplets trajectories to determine where the source of a bloodstain pattern was. However, by ignoring gravity, large errors may arise when inferring the 3D-loca

  17. Sessile nanofluid droplet drying.

    Science.gov (United States)

    Zhong, Xin; Crivoi, Alexandru; Duan, Fei

    2015-03-01

    Nanofluid droplet evaporation has gained much audience nowadays due to its wide applications in painting, coating, surface patterning, particle deposition, etc. This paper reviews the drying progress and deposition formation from the evaporative sessile droplets with the suspended insoluble solutes, especially nanoparticles. The main content covers the evaporation fundamental, the particle self-assembly, and deposition patterns in sessile nanofluid droplet. Both experimental and theoretical studies are presented. The effects of the type, concentration and size of nanoparticles on the spreading and evaporative dynamics are elucidated at first, serving the basis for the understanding of particle motion and deposition process which are introduced afterward. Stressing on particle assembly and production of desirable residue patterns, we express abundant experimental interventions, various types of deposits, and the effects on nanoparticle deposition. The review ends with the introduction of theoretical investigations, including the Navier-Stokes equations in terms of solutions, the Diffusion Limited Aggregation approach, the Kinetic Monte Carlo method, and the Dynamical Density Functional Theory. Nanoparticles have shown great influences in spreading, evaporation rate, evaporation regime, fluid flow and pattern formation of sessile droplets. Under different experimental conditions, various deposition patterns can be formed. The existing theoretical approaches are able to predict fluid dynamics, particle motion and deposition patterns in the particular cases. On the basis of further understanding of the effects of fluid dynamics and particle motion, the desirable patterns can be obtained with appropriate experimental regulations.

  18. Buckling instability of squeezed droplets

    CERN Document Server

    Elfring, Gwynn J

    2015-01-01

    Motivated by recent experiments, we consider theoretically the compression of droplets pinned at the bottom on a surface of finite area. We show that if the droplet is sufficiently compressed at the top by a surface, it will always develop a shape instability at a critical compression. When the top surface is flat, the shape instability occurs precisely when the apparent contact angle of the droplet at the pinned surface is pi, regardless of the contact angle of the upper surface, reminiscent of past work on liquid bridges and sessile droplets as first observed by Plateau. After the critical compression, the droplet transitions from a symmetric to an asymmetric shape. The force required to deform the droplet peaks at the critical point then progressively decreases indicative of catastrophic buckling. We characterize the transition in droplet shape using illustrative examples in two dimensions followed by perturbative analysis as well as numerical simulation in three dimensions. When the upper surface is not f...

  19. Developments in dynamic MR elastography for in vitro biomechanical assessment of hyaline cartilage under high-frequency cyclical shear.

    Science.gov (United States)

    Lopez, Orlando; Amrami, Kimberly K; Manduca, Armando; Rossman, Phillip J; Ehman, Richard L

    2007-02-01

    The design, construction, and evaluation of a customized dynamic magnetic resonance elastography (MRE) technique for biomechanical assessment of hyaline cartilage in vitro are described. For quantification of the dynamic shear properties of hyaline cartilage by dynamic MRE, mechanical excitation and motion sensitization were performed at frequencies in the kilohertz range. A custom electromechanical actuator and a z-axis gradient coil were used to generate and image shear waves throughout cartilage at 1000-10,000 Hz. A radiofrequency (RF) coil was also constructed for high-resolution imaging. The technique was validated at 4000 and 6000 Hz by quantifying differences in shear stiffness between soft ( approximately 200 kPa) and stiff ( approximately 300 kPa) layers of 5-mm-thick bilayered phantoms. The technique was then used to quantify the dynamic shear properties of bovine and shark hyaline cartilage samples at frequencies up to 9000 Hz. The results demonstrate that one can obtain high-resolution shear stiffness measurements of hyaline cartilage and small, stiff, multilayered phantoms at high frequencies by generating robust mechanical excitations and using large magnetic field gradients. Dynamic MRE can potentially be used to directly quantify the dynamic shear properties of hyaline and articular cartilage, as well as other cartilaginous materials and engineered constructs. (c) 2007 Wiley-Liss, Inc.

  20. Hyaline membrane disease or respiratory distress syndrome? A new approach for an old disease

    Directory of Open Access Journals (Sweden)

    Lidia Grappone

    2014-06-01

    Full Text Available The term “hyaline membrane disease” refers to the histological aspect of the most frequent pulmonary pathology in preterm newborn patients. The lung of the preterm baby is morphologically and functionally immature. Surfactant deficiency in the immature lungs causes alveolar instability and collapse, capillary edema and the formation of hyaline membrane. Thus, the hyaline membranes are epiphenomena and are not the cause of respiratory failure in infants with immature lungs. This definition is presently used to indicate surfactant deficit alone and should not be used for other causes of respiratory distress. Clinicians prefer to talk of “respiratory distress syndrome” (RDS. Improvement in neonatal treatment has changed the natural course of the illness, its clinical and radiological features and has enabled extremely low birth weight newborns (ELBW to survive. Alveoli paucity and pulmonary interstitial thickness in ELBW impair gas exchange and may necessitate prolonged ventilation treatment, increasing the risk of ventilator-induced lung injury (VILI and bronchopulmonary dysplasia (BPD. RDS, therefore, is a complex illness where pulmonary immaturity and surfactant deficit play a role together with other pathological conditions that determine the course of the illness and both short and long-term results. Proceedings of the International Course on Perinatal Pathology (part of the 10th International Workshop on Neonatology · October 22nd-25th, 2014 · Cagliari (Italy · October 25th, 2014 · The role of the clinical pathological dialogue in problem solving Guest Editors: Gavino Faa, Vassilios Fanos, Peter Van Eyken

  1. A comparison of different bioinks for 3D bioprinting of fibrocartilage and hyaline cartilage.

    Science.gov (United States)

    Daly, Andrew C; Critchley, Susan E; Rencsok, Emily M; Kelly, Daniel J

    2016-10-07

    Cartilage is a dense connective tissue with limited self-repair capabilities. Mesenchymal stem cell (MSC) laden hydrogels are commonly used for fibrocartilage and articular cartilage tissue engineering, however they typically lack the mechanical integrity for implantation into high load bearing environments. This has led to increased interested in 3D bioprinting of cell laden hydrogel bioinks reinforced with stiffer polymer fibres. The objective of this study was to compare a range of commonly used hydrogel bioinks (agarose, alginate, GelMA and BioINK™) for their printing properties and capacity to support the development of either hyaline cartilage or fibrocartilage in vitro. Each hydrogel was seeded with MSCs, cultured for 28 days in the presence of TGF-β3 and then analysed for markers indicative of differentiation towards either a fibrocartilaginous or hyaline cartilage-like phenotype. Alginate and agarose hydrogels best supported the development of hyaline-like cartilage, as evident by the development of a tissue staining predominantly for type II collagen. In contrast, GelMA and BioINK(™) (a PEGMA based hydrogel) supported the development of a more fibrocartilage-like tissue, as evident by the development of a tissue containing both type I and type II collagen. GelMA demonstrated superior printability, generating structures with greater fidelity, followed by the alginate and agarose bioinks. High levels of MSC viability were observed in all bioinks post-printing (∼80%). Finally we demonstrate that it is possible to engineer mechanically reinforced hydrogels with high cell viability by co-depositing a hydrogel bioink with polycaprolactone filaments, generating composites with bulk compressive moduli comparable to articular cartilage. This study demonstrates the importance of the choice of bioink when bioprinting different cartilaginous tissues for musculoskeletal applications.

  2. Droplets and sprays

    CERN Document Server

    Sazhin, Sergei

    2014-01-01

    Providing a clear and systematic description of droplets and spray dynamic models, this book maximises reader insight into the underlying physics of the processes involved, outlines the development of new physical and mathematical models, and broadens understanding of interactions between the complex physical processes which take place in sprays. Complementing approaches based on the direct application of computational fluid dynamics (CFD), Droplets and Sprays treats both theoretical and practical aspects of internal combustion engine process such as the direct injection of liquid fuel, subcritical heating and evaporation. Includes case studies that illustrate the approaches relevance to automotive applications,  it is also anticipated that the described models can find use in other areas such as in medicine and environmental science.

  3. Hovering UFO Droplets

    CERN Document Server

    Anand, Sushant; Dhiman, Rajeev; Smith, J David; Varanasi, Kripa K

    2012-01-01

    This fluid dynamics video is an entry for the Gallery of Fluid Motion of the 65th Annual Meeting of the APS-DFD. This video shows behavior of condensing droplets on a lubricant impregnated surface and a comparison with a superhydrophobic surface. On impregnated surfaces, drops appear like UFOs hovering over a surface. The videos were recorded in an Environmental SEM and a specially built condensation rig.

  4. Simulation of Interpersonal Transport of Expiratory Droplets and Droplet Nuclei between Two Standing Manikins

    DEFF Research Database (Denmark)

    Liu, Li; Y, Li,

    2012-01-01

    Interpersonal transport of expiratory droplets and droplet nuclei constitutes a prerequisite for the transmission of pathogens as well as the transmission of respiratory diseases. Numerical simulations considering droplet evaporation and droplet nucleus sizes were carried out, using two detailed...

  5. Rapidly pulsed helium droplet source

    Energy Technology Data Exchange (ETDEWEB)

    Pentlehner, Dominik; Riechers, Ricarda; Dick, Bernhard; Slenczka, Alkwin [Institute for Physical and Theoretical Chemistry, University of Regensburg, 93053 Regensburg (Germany); Even, Uzi; Lavie, Nachum; Brown, Raviv; Luria, Kfir [Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv (Israel)

    2009-04-15

    A pulsed valve connected to a closed-cycle cryostat was optimized for producing helium droplets. The pulsed droplet beam appeared with a bimodal size distribution. The leading part of the pulse consists of droplets suitable for doping with molecules. The average size of this part can be varied between 10{sup 4} and 10{sup 6} helium atoms, and the width of the distribution is smaller as compared to a continuous-flow droplet source. The system has been tested in a single pulse mode and at repetition rates of up to 500 Hz with almost constant intensity. The droplet density was found to be increased by more than an order of magnitude as compared to a continuous-flow droplet source.

  6. Droplet microfluidics based microseparation systems.

    Science.gov (United States)

    Xiao, Zhiliang; Niu, Menglei; Zhang, Bo

    2012-06-01

    Lab on a chip (LOC) technology is a promising miniaturization approach. The feature that it significantly reduced sample consumption makes great sense in analytical and bioanalytical chemistry. Since the start of LOC technology, much attention has been focused on continuous flow microfluidic systems. At the turn of the century, droplet microfluidics, which was also termed segmented flow microfluidics, was introduced. Droplet microfluidics employs two immiscible phases to form discrete droplets, which are ideal vessels with confined volume, restricted dispersion, limited cross-contamination, and high surface area. Due to these unique features, droplet microfluidics proves to be a versatile tool in microscale sample handling. This article reviews the utility of droplet microfluidics in microanalytical systems with an emphasize on separation science, including sample encapsulation at ultra-small volume, compartmentalization of separation bands, isolation of droplet contents, and related detection techniques.

  7. Evaporation of inclined water droplets

    Science.gov (United States)

    Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

    2017-02-01

    When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets.

  8. Evaporation of inclined water droplets

    Science.gov (United States)

    Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

    2017-01-01

    When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets. PMID:28205642

  9. Generation of Scaffoldless Hyaline Cartilaginous Tissue from Human iPSCs

    Directory of Open Access Journals (Sweden)

    Akihiro Yamashita

    2015-03-01

    Full Text Available Defects in articular cartilage ultimately result in loss of joint function. Repairing cartilage defects requires cell sources. We developed an approach to generate scaffoldless hyaline cartilage from human induced pluripotent stem cells (hiPSCs. We initially generated an hiPSC line that specifically expressed GFP in cartilage when teratoma was formed. We optimized the culture conditions and found BMP2, transforming growth factor β1 (TGF-β1, and GDF5 critical for GFP expression and thus chondrogenic differentiation of the hiPSCs. The subsequent use of scaffoldless suspension culture contributed to purification, producing homogenous cartilaginous particles. Subcutaneous transplantation of the hiPSC-derived particles generated hyaline cartilage that expressed type II collagen, but not type I collagen, in immunodeficiency mice. Transplantation of the particles into joint surface defects in immunodeficiency rats and immunosuppressed mini-pigs indicated that neocartilage survived and had potential for integration into native cartilage. The immunodeficiency mice and rats suffered from neither tumors nor ectopic tissue formation. The hiPSC-derived cartilaginous particles constitute a viable cell source for regenerating cartilage defects.

  10. Two new hyaline-ascospored species of Trichoderma and their phylogenetic positions.

    Science.gov (United States)

    Qin, W T; Zhuang, W Y

    2016-01-01

    Collections of hypocrealean fungi found on decaying wood in subtropical regions of China were examined. Two new species, Trichoderma confluens and T. hubeiense, were discovered and are described. Trichoderma confluens is characterized by its widely effuse to rarely pulvinate, yellow stromata with densely disposed yellowish brown ostioles, simple acremonium- to verticillium-like conidiophores, hyaline conidia and multiform chlamydospores. Trichoderma hubeiense has pulvinate, grayish yellow stromata with brownish ostioles, trichoderma- to verticillium-like conidiophores and hyaline conidia. The phylogenetic positions of the two fungi were investigated based on sequence analyses of RNA polymerase II subunit b and translation elongation factor 1-α genes. The results indicate that T. confluens belongs to the Hypocreanum clade and is associated with but clearly separated from T. applanatum and T. decipiens. Trichoderma hubeiense belongs to the Polysporum clade and related to T. bavaricum but obviously differs from other members of the clade in sequence data. Morphological distinctions between the new species and their close relatives are noted and discussed.

  11. Granular cell tumor of the cecum with extensive hyalinization and calcification: A case report

    Institute of Scientific and Technical Information of China (English)

    Ran Hong; Sung-Chul Lim

    2009-01-01

    A granular cell tumor (GCT) is a benign neoplasm of unclear histogenesis that is generally believed to be of nerve sheath origin. GCT is not common and most often affects the tongue, skin and soft tissue, although it may occur anywhere in the body. We experienced a case of GCT that arose in the cecum of a 55-yearold man. The GCT was removed by laparoscopic resection. In addition to the tumor, endoscopic examination revealed the presence of a 5-mm-polyp in the descending colon and multiple tiny polyps in the sigmoid colon and rectum. Histological examination with a hard consistency; in cut sections, mixed cells with yellowish and whitish portions were seen. The tumor was located between the mucosa and subserosa,and was composed of plump histiocyte-like tumor cells with abundant granular eosinophilic cytoplasm, which were immunoreactive for S-100 protein, vimentin,neuron-specific enolase, inhibin-a and calretinin.The tumor showed extensive hyalinization and focal dystrophic calcification. Immunohistochemical profiles did not confirm any particular cell type for the histogenetic origin of the GCT, including a nerve sheath origin. Extensive hyalinization and calcification showing involution of tumor cells suggest benign clinical behavior of GCT.

  12. Radiologic and histologic features of hyaline membrane diseases of the newbone

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Seung Yon; Choi, Kyung Hee; Suh, Jeong Soo; Rhee, Chung Sik; Kim, Hee Seup [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    1984-12-15

    This study represents the radiologic, histologic features and clinical analysis of hyaline membrane diseases in 47 newbone infants who were delivered in Ewha Womans Univ. Hospital and expired caused by respiratory distress and confirmed by autopsy, during Jan. 1981 to June. 1984. The results were as follows: 1. Classification of radiographic stage (by Wolfson's criteria); Stage III (34.1%) was the most frequent. 2. Male to female ratio was 2.4 : 1. 3. Method of delivery; Cesarean section (44.7%) was the highest frequency, compared with percent of cesarean section to total delivery (29.0%) 4. Distribution of birth weight; 1.0-2.0 kg (48.9%) was the most frequent. 5. Distribution of gestational period; 32-36 weeks (29.8%) was the most frequent. 6. Complication; pulmonary hemorrhage (31.9%) was the most frequent, in order, subarachnoid hemorrhage and pneumothorax were followed. 7. Final diagnosis of hyaline membrane diseases was based on histo-pathologic diagnosis.

  13. Pulmonary hyalinizing granuloma%肺玻璃样变肉芽肿病

    Institute of Scientific and Technical Information of China (English)

    Zhao-lin XU; Drew BETHUNE; Daria MANOS; Annette FOYLE; Harry HENTELEFF; Michael JOHNS-TON; Yannick CARTIER

    2009-01-01

    Objective:To present clinical and pathologic features of pulmonary hyalnizing granuloma through analyzing three cases found in our institution and reviewing cases reported in the English language literature. Methods and Results: Three eases of pulmonary hyalnizing granuloma identified at our institu-tion during the past ten years were reviewed. In the first case, the patient presented with concurrent pulmonary hyalinizing granuloma and histoplasmosis. In the second case, the patient presented with a 5.5 cm lung mass and a separate smaller lesion radiologically resembling bronchogenic carcinoma. There was very prominent polyclonal lymphocytic proliferation at the periphery especially of the smaller lesion likely representing an early stage of the disease process. In the third case, the patient presented with multiple subpleural plaque-like lesions in addition to nodular lesions of the lung. All cases also demonstrated various degrees of lymphocytic infiltration within the lesions. The English literature has been reviewed through searching the PubMed. Conclusion: Since patients with pulmonary hyalinizing granuloma demonstrated a spectrum of clinical presentations, radiologic changes and histologic features with a variety of associated clinical disorders, pulmonary hyalnizing granuloma is more in keeping with a clinicopathologic entity rather than a specific pathologic disease.

  14. Hyaline cartilage involvement in patients with gout and calcium pyrophosphate deposition disease. An ultrasound study.

    Science.gov (United States)

    Filippucci, E; Riveros, M Gutierrez; Georgescu, D; Salaffi, F; Grassi, W

    2009-02-01

    The main aim of the present study was to determine the sensitivity, specificity and accuracy of ultrasonography (US) in detecting monosodium urate and calcium pyrophosphate dihydrate crystals deposits at knee cartilage level using clinical definite diagnosis as standard reference. A total of 32 patients with a diagnosis of gout and 48 patients with pyrophosphate arthropathy were included in the study. Fifty-two patients with rheumatoid arthritis (RA), psoriatic arthritis or osteoarthritis (OA) were recruited as disease controls. All diagnoses were made using an international clinical criterion. US examinations were performed by an experienced sonographer, blind to clinical and laboratory data. Hyaline cartilage was assessed to detect two US findings recently indicated as indicative of crystal deposits: hyperechoic enhancement of the superficial margin of the hyaline cartilage and hyperechoic spots within the cartilage layer not generating a posterior acoustic shadow. Hyperechoic enhancement of the chondrosynovial margin was found in at least one knee of 14 out of 32 (43.7%) patients with gout and in a single knee of only one patient affected by pyrophosphate arthropathy (specificity=99%). Intra-cartilaginous hyperechoic spots were detected in at least one knee of 33 out of 48 (68.7%) patients with pyrophosphate arthropathy and in two disease controls one with OA and the second with RA (specificity=97.6%). The results of the present study indicate that US may play a relevant role in distinguishing cartilage involvement in patients with crystal-related arthropathy. The selected US findings were found to be highly specific.

  15. Changes of rabbit meniscus influenced by hyaline cartilage injury of osteoarthritis.

    Science.gov (United States)

    Zhao, Jiajun; Huang, Suizhu; Zheng, Jia; Zhong, Chunan; Tang, Chao; Zheng, Lei; Zhang, Zhen; Xu, Jianzhong

    2014-01-01

    Osteoarthritis (OA) is a common disease in the elderly population. Most of the previous OA-related researches focused on articular cartilage degeneration, osteophyte formation and synovitis etc. However, the role of the meniscus in these pathological changes has not been given enough attention. The goal of our study was to find the pathological changes of the meniscus in OA knee and determine their relationship. 20 months old female Chinese rabbits received either knee damaging operations with articular cartilage scratch method or sham operation randomly on one of their knees. They were sacrificed after 1-6 weeks post-operation. Medial Displacement Index (MDI) for meniscus dislocation, hematoxylin and eosin (HE) for routine histological evaluation, Toluidine blue (TB) stains for evaluating proteoglycans were carried out. Immunohistochemical (IHC) staining was performed with a two-step detection kit. Histological analysis showed chondrocyte clusters around cartilage lesions and moderate loss of proteoglycans in the operation model, as well as MDI increase and all characteristics of OA. High expression of MMP-3 and TIMP-1 also were found in both hyaline cartilage and meniscus. Biomechanical and biochemistry environment around the meniscus is altered when OA occur. If meniscus showed degeneration, subluxation and dysfunction, OA would be more severe. Prompt repair or reconstruction of hyaline cartilage in weight bearing area when it injured could prevent meniscus degeneration and subluxation, then prevent the development of OA.

  16. Talocalcaneal Joint Middle Facet Coalition Resection With Interposition of a Juvenile Hyaline Cartilage Graft.

    Science.gov (United States)

    Tower, Dyane E; Wood, Ryan W; Vaardahl, Michael D

    2015-01-01

    Talocalcaneal joint middle facet coalition is the most common tarsal coalition, occurring in ≤2% of the population. Fewer than 50% of involved feet obtain lasting relief of symptoms after nonoperative treatment, and surgical intervention is commonly used to relieve symptoms, increase the range of motion, improve function, reconstruct concomitant pes planovalgus, and prevent future arthrosis from occurring at the surrounding joints. Several approaches to surgical intervention are available for patients with middle facet coalitions, ranging from resection to hindfoot arthrodesis. We present a series of 4 cases, in 3 adolescent patients, of talocalcaneal joint middle facet coalition resection with interposition of a particulate juvenile hyaline cartilaginous allograft (DeNovo(®) NT Natural Tissue Graft, Zimmer, Inc., Warsaw, IN). With a mean follow-up period of 42.8 ± 2.9 (range 41 to 47) months, the 3 adolescent patients in the present series were doing well with improved subtalar joint motion and decreased pain, and 1 foot showed no bony regrowth on a follow-up computed tomography scan. The use of a particulate juvenile hyaline cartilaginous allograft as interposition material after talocalcaneal middle facet coalition resection combined with adjunct procedures to address concomitant pes planovalgus resulted in good short-term outcomes in 4 feet in 3 adolescent patients. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  17. Sprifermin (rhFGF18) enables proliferation of chondrocytes producing a hyaline cartilage matrix.

    Science.gov (United States)

    Gigout, A; Guehring, H; Froemel, D; Meurer, A; Ladel, C; Reker, D; Bay-Jensen, A C; Karsdal, M A; Lindemann, S

    2017-08-18

    Fibroblast growth factor (FGF) 18 has been shown to increase cartilage volume when injected intra-articularly in animal models of osteoarthritis (OA) and in patients with knee OA (during clinical development of the recombinant human FGF18, sprifermin). However, the exact nature of this effect is still unknown. In this study, we aimed to investigate the effects of sprifermin at the cellular level. A combination of different chondrocyte culture systems was used and the effects of sprifermin on proliferation, the phenotype and matrix production were evaluated. The involvement of MAPKs in sprifermin signalling was also studied. In monolayer, we observed that sprifermin promoted a round cell morphology and stimulated both cellular proliferation and Sox9 expression while strongly decreasing type I collagen expression. In 3D culture, sprifermin increased the number of matrix-producing chondrocytes, improved the type II:I collagen ratio and enabled human OA chondrocytes to produce a hyaline extracellular matrix (ECM). Furthermore, we found that sprifermin displayed a 'hit and run' mode of action, with intermittent exposure required for the compound to fully exert its anabolic effect. Finally, sprifermin appeared to signal through activation of ERK. Our results indicate that intermittent exposure to sprifermin leads to expansion of hyaline cartilage-producing chondrocytes. These in vitro findings are consistent with the increased cartilage volume observed in the knees of OA patients after intra-articular injection with sprifermin in clinical studies. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Generation of scaffoldless hyaline cartilaginous tissue from human iPSCs.

    Science.gov (United States)

    Yamashita, Akihiro; Morioka, Miho; Yahara, Yasuhito; Okada, Minoru; Kobayashi, Tomohito; Kuriyama, Shinichi; Matsuda, Shuichi; Tsumaki, Noriyuki

    2015-03-10

    Defects in articular cartilage ultimately result in loss of joint function. Repairing cartilage defects requires cell sources. We developed an approach to generate scaffoldless hyaline cartilage from human induced pluripotent stem cells (hiPSCs). We initially generated an hiPSC line that specifically expressed GFP in cartilage when teratoma was formed. We optimized the culture conditions and found BMP2, transforming growth factor β1 (TGF-β1), and GDF5 critical for GFP expression and thus chondrogenic differentiation of the hiPSCs. The subsequent use of scaffoldless suspension culture contributed to purification, producing homogenous cartilaginous particles. Subcutaneous transplantation of the hiPSC-derived particles generated hyaline cartilage that expressed type II collagen, but not type I collagen, in immunodeficiency mice. Transplantation of the particles into joint surface defects in immunodeficiency rats and immunosuppressed mini-pigs indicated that neocartilage survived and had potential for integration into native cartilage. The immunodeficiency mice and rats suffered from neither tumors nor ectopic tissue formation. The hiPSC-derived cartilaginous particles constitute a viable cell source for regenerating cartilage defects. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Droplets Evaporation on Heated Wall

    Directory of Open Access Journals (Sweden)

    Misyura S. Y.

    2015-01-01

    Full Text Available Various modes of evaporation in a wide range of droplet sizes and wall temperatures have been investigated in the present work. For any initial drop size there are three typical boiling regime: 1 the nucleate boiling; 2 the transitional regime; 3 the film boiling. The width of the transition region of boiling crisis increases with increasing the initial volume V0. Evaporation of large droplets at high superheat depends on the initial droplet shape.

  20. Small droplets on superhydrophobic substrates.

    Science.gov (United States)

    Gross, Markus; Varnik, Fathollah; Raabe, Dierk; Steinbach, Ingo

    2010-05-01

    We investigate the wetting behavior of liquid droplets on rough hydrophobic substrates for the case of droplets that are of comparable size to the surface asperities. Using a simple three-dimensional analytical free-energy model, we have shown in a recent letter [M. Gross, F. Varnik, and D. Raabe, EPL 88, 26002 (2009)] that, in addition to the well-known Cassie-Baxter and Wenzel states, there exists a further metastable wetting state where the droplet is immersed into the texture to a finite depth, yet not touching the bottom of the substrate. Due to this new state, a quasistatically evaporating droplet can be saved from going over to the Wenzel state and instead remains close to the top of the surface. In the present paper, we give an in-depth account of the droplet behavior based on the results of extensive computer simulations and an improved theoretical model. In particular, we show that releasing the assumption that the droplet is pinned at the outer edges of the pillars improves the analytical results for larger droplets. Interestingly, all qualitative aspects, such as the existence of an intermediate minimum and the "reentrant transition," remain unchanged. We also give a detailed description of the evaporation process for droplets of varying sizes. Our results point out the role of droplet size for superhydrophobicity and give hints for achieving the desired wetting properties of technically produced materials.

  1. Significance of droplet-droplet interactions in droplet streams: Atmospheric to supercritical conditions

    Science.gov (United States)

    Connon, Corinne Shirley

    In an effort to optimize liquid fuel combustion a considerable amount of research has been directed towards the atomization of large liquid masses into small droplets to increase the surface area available for vaporization. The current work uses a single linear array of moving droplets of uniform size and spacing to investigate the behavior of interacting droplets. A series of experiments, over a range of ambient conditions, demonstrate how a lead droplet alters the environment experienced by its trailing neighbor. This behavior is of particular interest for droplet groups under high pressure and temperature, where experimental data has been limited. Gas phase velocity and vapor concentration measurements show that as the space between adjacent droplets decreases entrainment of fluid towards the axis of motion is reduced. Trapped gases create a gaseous cylinder, composed of ambient gas and fuel vapor, which surrounds and moves with the droplet stream. As ambient pressure increase, the oscillatory behavior of the lead droplet wake begins to interfere with its trailing neighbor. Loss of stream stability and enhanced droplet stripping in part result from these oscillating wakes. However, acceleration of droplet stripping is mainly produced by liquid and gas density similarity, which increases the centrifugal stress and the growth rate of capillary waves. Further, injection of subcritical droplets into an ambient environment at temperatures and pressures above the liquid droplet critical point shows behavior not greatly different from the results obtained at high ambient pressures. The similarity results from thermal heatup times exceeding the breakup times generated from the severe aerodynamics encountered at high ambient density and high liquid-gas relative velocities.

  2. Coalescence-induced droplet actuation

    Science.gov (United States)

    Sellier, Mathieu; Verdier, Claude; Nock, Volker

    2011-11-01

    This work investigates a little explored driving mechanism to actuate droplets: the surface tension gradient which arises during the coalescence of two droplets of liquid having different compositions and therefore surface tensions. The resulting surface tension gradient gives rise to a Marangoni flow which, if sufficiently large, can displace the droplet. In order to understand, the flow dynamics arising during the coalescence of droplets of different fluids, a model has been developed in the lubrication framework. The numerical results confirm the existence of a self-propulsion window which depends on two dimensionless groups representing competing effects during the coalescence: the surface tension contrast between the droplets which promotes actuation and species diffusion which tends to make the mixture uniform thereby anihilating Marangoni flow and droplet motion. In parallel, experiments have been conducted to confirm this self-propulsion behaviour. The experiment consists in depositing a droplet of distilled water on a ``hydrophilic highway.'' This stripe was obtained by plasma-treating a piece of PDMS shielded in some parts by glass coverslips. This surface functionalization was found to be the most convenient way to control the coalescence. When a droplet of ethanol is deposited near the ``water slug,'' coalescence occurs and a rapid motion of the resulting mixture is observed. The support of the Dumont d'Urville NZ-France Science & Technology program is gratefully acknowledged.

  3. Osseous oral hyaline ring granuloma mimicking a mandible tumor in a child with congenital agenesis of the corpus callosum

    Science.gov (United States)

    Neves-Silva, Rodrigo; Ferreira-Gomes, Camilla-Borges; Palmier, Natalia; Brum-Corrêa, Marcelo; Paes-Almeida, Oslei; Ajudarte-Lopes, Marcio; Agustin-Vargas, Pablo

    2017-01-01

    Background Hyaline ring granuloma (HRG) of the oral cavity is an uncommon disorder considered to be a foreign-body reaction resulting from implantation of food vegetable particles. Microscopically, it is characterized by the presence of structures of hyaline rings in an inflamed fibrous tissue background, which contains multinucleated giant cells. Material and Methods We present the case of a 4-year-old boy diagnosed with a mandible osseous HRG, which showed clinical and tomographic aspects suggestive of an aggressive bone tumor. Results The patient underwent surgical exploration and histopathologic analysis showed fragments composed predominantly of widespread dense connective tissue with an acute and chronic inflammatory infiltrate containing multinucleated giant cells and scattered areas of eosinophilic material associated with hyaline rings, strongly suggestive of vegetable particles. The eosinophilic material was positive for periodic acid-Schiff (PAS) and resistant to diastase digestion. These features led to diagnosis of osseous HRG. Scanning electron microscopy (SEM) analysis was performed for illustrative purposes and the multiple structures resembling vegetable particles were characterized in more detail. Conclusions Although rare, this case highlights the importance of the clinician’s awareness regarding the existence of an osseous counterpart of HRG. Key words:Agenesis of the corpus callosum, child, hyaline ring granuloma, intraosseous, mandible, pulse granuloma. PMID:28210458

  4. Regeneration of hyaline-like cartilage in situ with SOX9 stimulation of bone marrow-derived mesenchymal stem cells.

    Science.gov (United States)

    Zhang, Xiaowei; Wu, Shili; Naccarato, Ty; Prakash-Damani, Manan; Chou, Yuan; Chu, Cong-Qiu; Zhu, Yong

    2017-01-01

    Microfracture, a common procedure for treatment of cartilage injury, induces fibrocartilage repair by recruiting bone marrow derived mesenchymal stem cells (MSC) to the site of cartilage injury. However, fibrocartilage is inferior biomechanically to hyaline cartilage. SRY-type high-mobility group box-9 (SOX9) is a master regulator of chondrogenesis by promoting proliferation and differentiation of MSC into chondrocytes. In this study we aimed to test the therapeutic potential of cell penetrating recombinant SOX9 protein in regeneration of hyaline cartilage in situ at the site of cartilage injury. We generated a recombinant SOX9 protein which was fused with super positively charged green fluorescence protein (GFP) (scSOX9) to facilitate cell penetration. scSOX9 was able to induce chondrogenesis of bone marrow derived MSC in vitro. In a rabbit cartilage injury model, scSOX9 in combination with microfracture significantly improved quality of repaired cartilage as shown by macroscopic appearance. Histological analysis revealed that the reparative tissue induced by microfracture with scSOX9 had features of hyaline cartilage; and collagen type II to type I ratio was similar to that in normal cartilage. This short term in vivo study demonstrated that when administered at the site of microfracture, scSOX9 was able to induce reparative tissue with features of hyaline cartilage.

  5. Fibrous cartilage of human menisci is less shock-absorbing and energy-dissipating than hyaline cartilage.

    Science.gov (United States)

    Gaugler, Mario; Wirz, Dieter; Ronken, Sarah; Hafner, Mirjam; Göpfert, Beat; Friederich, Niklaus F; Elke, Reinhard

    2015-04-01

    To test meniscal mechanical properties such as the dynamic modulus of elasticity E* and the loss angle δ at two loading frequencies ω at different locations of the menisci and compare it to E* and δ of hyaline cartilage in indentation mode with spherical indenters. On nine pairs of human menisci, the dynamic E*-modulus and loss angle δ (as a measure of the energy dissipation) were determined. The measurements were performed at two different strain rates (slow sinusoidal and fast single impact) to show the strain rate dependence of the material. The measurements were compared to previous similar measurements with the same equipment on human hyaline cartilage. The resultant E* at fast indentation (median 1.16 MPa) was significantly higher, and the loss angle was significantly lower (median 10.2°) compared to slow-loading mode's E* and δ (median 0.18 MPa and 16.9°, respectively). Further, significant differences for different locations are shown. On the medial meniscus, the anterior horn shows the highest resultant dynamic modulus. In dynamic measurements with a spherical indenter, the menisci are much softer and less energy-dissipating than hyaline cartilage. Further, the menisci are stiffer and less energy-dissipating in the middle, intermediate part compared to the meniscal base. In compression, the energy dissipation of meniscus cartilage plays a minor role compared to hyaline cartilage. At high impacts, energy dissipation is less than on low impacts, similar to cartilage.

  6. Distinction between the extracellular matrix of the nucleus pulposus and hyaline cartilage: a requisite for tissue engineering of intervertebral disc

    Directory of Open Access Journals (Sweden)

    Mwale F.

    2004-12-01

    Full Text Available Tissue engineering of intervertebral discs (IVD using mesenchymal stem cells (MSCs induced to differentiate into a disc-cell phenotype has been considered as an alternative treatment for disc degeneration. However, since there is no unique marker characteristic of discs and since hyaline cartilage and immature nucleus pulposus (NP possess similar macromolecules in their extracellular matrix, it is currently difficult to recognize MSC conversion to a disc cell. This study was performed to compare the proteoglycan to collagen ratio (measured as GAG to hydroxyproline ratio in the NP of normal disc to that of the hyaline cartilage of the endplate within the same group of individuals and test the hypothesis that this ratio can be used for in vivo studies to distinguish between a normal NP and hyaline cartilage phenotype. Whole human lumbar spine specimens from fresh cadavers, ranging in age from 12 weeks to 79 years, were used to harvest the IVDs and adjacent endplates. The GAG to hydroxyproline ratio within the NP of young adults is approximately 27:1, whereas the ratio within the hyaline cartilage endplate of the same aged individuals is about 2:1. The production of an extracellular matrix with a high proteoglycan to collagen ratio can be used in vivo to distinguish NP cells from chondrocytes, and could help in identifying a NP-like phenotype in vivo as opposed to a chondrocyte when MSCs are induced to differentiate for tissue engineering of a disc.

  7. Similar hyaline-like cartilage repair of osteochondral defects in rabbits using isotropic and anisotropic collagen scaffolds.

    Science.gov (United States)

    de Mulder, Eric L W; Hannink, Gerjon; van Kuppevelt, Toin H; Daamen, Willeke F; Buma, Pieter

    2014-02-01

    Lesions in knee joint articular cartilage (AC) have limited repair capacity. Many clinically available treatments induce a fibrous-like cartilage repair instead of hyaline cartilage. To induce hyaline cartilage repair, we hypothesized that type I collagen scaffolds with fibers aligned perpendicular to the AC surface would result in qualitatively better tissue repair due to a guided cellular influx from the subchondral bone. By specific freezing protocols, type I collagen scaffolds with isotropic and anisotropic fiber architectures were produced. Rabbits were operated on bilaterally and two full thickness defects were created in each knee joint. The defects were filled with (1) an isotropic scaffold, (2) an anisotropic scaffold with pores parallel to the cartilage surface, and (3) an anisotropic scaffold with pores perpendicular to the cartilage surface. Empty defects served as controls. After 4 (n=13) and 12 (n=13) weeks, regeneration was scored qualitatively and quantitatively using histological analysis and a modified O'Driscoll score. After 4 weeks, all defects were completely filled with partially differentiated hyaline cartilage tissue. No differences in O'Driscoll scores were measured between empty defects and scaffold types. After 12 weeks, all treatments led to hyaline cartilage repair visualized by increased glycosaminoglycan staining. Total scores were significantly increased for parallel anisotropic and empty defects over time (phyaline-like cartilage repair. Fiber architecture had no effect on cartilage repair.

  8. DROPLET COLLISION AND COALESCENCE MODEL

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; CAI Ti-min; HE Guo-qiang; HU Chun-bo

    2006-01-01

    A new droplet collision and coalescence model was presented, a quick-sort method for locating collision partners was also devised and based on theoretical and experimental results, further advancement was made to the droplet collision outcome.The advantages of the two implementations of smoothed particle hydrodynamics (SPH)method were used to limit the collision of droplets to a given number of nearest droplets and define the probability of coalescence, numerical simulations were carried out for model validation. Results show that the model presented is mesh-independent and less time consuming, it can not only maintains the system momentum conservation perfectly, but not susceptible to initial droplet size distribution as well.

  9. Hyaline Tintinnina (Protozoa-Ciliophora-Oligotrichida from northeast Brazilian coastal reefs

    Directory of Open Access Journals (Sweden)

    Roberto Sassi

    1989-01-01

    Full Text Available Seven species of hyaline Tintinnina were obtained from plankton samples collected near the coastal reefs of Ponta do Seixas (Lat. 7º09'16"S, Long. 34º4735"W, Northeastern Brazil, from April 1981 to May 1982 and from April 1983 to May 1984: Amphorellopsis acuta (Schmidt, 1901, Dadayiella ganymedes (Entz Sr., 1884, Epiplocyloides reticulata (Ostenfeld & Schmidt, 1901, Eutintinnus tubulosus (Ostenfeld, 1899, Favella ehrenbergi (Claparède & Lachmann, 1858, Metacylis mereschkowskyi Kofoid & Campbell, 1929 and M. perspicax (Hada, 1938. The most frequent and abundant species were M. mereschkowskyi and F. ehrenbergi. Except/.ganymedes, E. reticulata and F. ehrenbergi all species are new records from Brazil. Metacylis perspicax is also the seventh world register. For all species we provide description, drawings, measurements, seasonal occurrence, world distribution and some systematic comments.

  10. Changes of cerebral hemodynamics following the administration of surfactant in the hyaline membrane disease of prematurity

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jeong Hyun; Kim, Kyung Hee [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    2000-09-15

    To evaluate the changes of cerebral blood flow velocity according to the time, before and after surfactant administration in hyaline membrane disease using Doppler ultrasonography. The patients were 15 premature babies who were clinically and radiologically diagnosed HMD. The ratio of male : female was 11:4, the mean gestational age was 30.1 {+-} 2.5 wks, mean body weight was 1.4 {+-} 0.6 kg,mean Apgar score at 5 min was 6.28, and type of delivery was C-section : vaginal delivery 9.6. Before and after, 10 mm, 30 min, 1 hr, 6 hr, 12 hr, 1 day, 3 day, 5 day and 7 day after surfactant administration, peak systolic and end-diastolic cerebral blood flow velocity (PSFV, EDFV) and resistive index (RI) were estimated by Doppler ultrasonography measuring MCA flow velocity using temporal window. The averages of all data according to the time were obtained and analyzed statistical significance. For the evaluation of the clinical status systemic BP, FiO2, pH, and respiratory rate were also checked according to the same time. The clinical status of FiO2, metabolic acidosis, and tachypnea was significantly improved after surfactant administration. There was no significant change of cerebral blood flow velocity (PSFV, EDFV) after the surfactant administration. The change of RI was nor statistically significant. The changes of the systemic BP had no significant changes. In spite of clinical improvement, there were no significant increases of cerebral blood flow velocity and changes of RI after surfactant administration in hyaline membrane disease.

  11. [Biomechanical properties (compressive strength and compressive pressure at break) of hyaline cartilage under axial load].

    Science.gov (United States)

    Spahn, G; Wittig, R

    2003-01-01

    Explanations concerning the physical properties of hyaline cartilage are different. It was the intention of this study to determine the material parameters of hyaline cartilage under axial load (elasticity, plasticity, elasticity and module pressure stress to break). Specimens from the medial femoral condyle (chondro-cortical ships) from adult female domestic pigs (n=28) were used for the experiments. The specimens were completely embedded in plaster to minimize shearing. Axial load was carried out by an universal mechanical testing machine (Zwick Z2.5/TS1S, Ulm, Germany) to determine elastic and plastic deformation and pressure stress to break. Axial load up to 5 MPa produces an almost elastic deformation, an increasing axial load results in a plastic deformation. In the range of 3 to 5 MPa the principle of Hooke is valid. The elasticity module amounted to 39.2 +/- 11.9 N/mm(2), determined under 3.8 MPa axial load. An axial load of 25.8 +/- 5.2 MPa (sigma max ) causes a break of cartilage. A strong correlation between break resistance and thickness of the chondral slice (r=0.71; p .05) was observed. The low module of chondral elasticity characterizes this tissue as "soft". Moderate axial load causes an ideal elastic, higher axial load a plastic deformation. The medium pressure to break to amounted 25.8 MPa. The medium pressure to break of 25.8 MPa is comparable with the forces produced by an unrestrained limited downfall from a height of 4.3 m. It must be concluded that isolated chondral fractures are rare consequences of a trauma as long as accompanying ligamentous or osseous damages are not found.

  12. Hyaline Articular Matrix Formed by Dynamic Self-Regenerating Cartilage and Hydrogels.

    Science.gov (United States)

    Meppelink, Amanda M; Zhao, Xing; Griffin, Darvin J; Erali, Richard; Gill, Thomas J; Bonassar, Lawrence J; Redmond, Robert W; Randolph, Mark A

    2016-07-01

    Injuries to the articular cartilage surface are challenging to repair because cartilage possesses a limited capacity for self-repair. The outcomes of current clinical procedures aimed to address these injuries are inconsistent and unsatisfactory. We have developed a novel method for generating hyaline articular cartilage to improve the outcome of joint surface repair. A suspension of 10(7) swine chondrocytes was cultured under reciprocating motion for 14 days. The resulting dynamic self-regenerating cartilage (dSRC) was placed in a cartilage ring and capped with fibrin and collagen gel. A control group consisted of chondrocytes encapsulated in fibrin gel. Constructs were implanted subcutaneously in nude mice and harvested after 6 weeks. Gross, histological, immunohistochemical, biochemical, and biomechanical analyses were performed. In swine patellar groove, dSRC was implanted into osteochondral defects capped with collagen gel and compared to defects filled with osteochondral plugs, collagen gel, or left empty after 6 weeks. In mice, the fibrin- and collagen-capped dSRC constructs showed enhanced contiguous cartilage matrix formation over the control of cells encapsulated in fibrin gel. Biochemically, the fibrin and collagen gel dSRC groups were statistically improved in glycosaminoglycan and hydroxyproline content compared to the control. There was no statistical difference in the biomechanical data between the dSRC groups and the control. The swine model also showed contiguous cartilage matrix in the dSRC group but not in the collagen gel and empty defects. These data demonstrate the survivability and successful matrix formation of dSRC under the mechanical forces experienced by normal hyaline cartilage in the knee joint. The results from this study demonstrate that dSRC capped with hydrogels successfully engineers contiguous articular cartilage matrix in both nonload-bearing and load-bearing environments.

  13. Ultrasonography shows disappearance of monosodium urate crystal deposition on hyaline cartilage after sustained normouricemia is achieved.

    Science.gov (United States)

    Thiele, Ralf G; Schlesinger, Naomi

    2010-02-01

    This study aimed at determining whether lowering serum urate (SU) to less than 6 mg/dl in patients with gout affects ultrasonographic findings. Seven joints in five patients with monosodium urate (MSU) crystal proven gout and hyperuricemia were examined over time with serial ultrasonography. Four of the five patients were treated with urate lowering drugs (ULDs) (allopurinol, n = 3; probenecid, n = 1). One patient was treated with colchicine alone. Attention was given to changes in a hyperechoic, irregular coating of the hyaline cartilage in the examined joints (double contour sign or "urate icing"). This coating was considered to represent precipitate of MSU crystals. Index joints included metacarpophalangeal (MCP) joints (n = 2), knee joints (n = 3), and first metatarsophalangeal (MTP) joints (n = 2). The interval between baseline and follow-up images ranged from 7 to 18 months. Serial SU levels were obtained during the follow-up period. During the follow-up period, three patients treated with ULD (allopurinol, n = 2; probenecid, n = 1) achieved a SU level of or =7 mg/dl. In one patient treated with allopurinol, SU levels improved from 13 to 7 mg/dl during the follow-up period. Decrease, but not resolution of the hyperechoic coating was seen in this patient. In the patient treated with colchicine alone, SU levels remained >8 mg/dl, and no sonographic change was observed. In our patients, sonographic signs of deposition of MSU crystals on the surface of hyaline cartilage disappeared completely if sustained normouricemia was achieved. This is the first report showing that characteristic sonographic changes are influenced by ULDs once SU levels remain < or =6 mg/dl for 7 months or more. Sonographic changes of gout correlate with SU levels and may be a non-invasive means to track changes in the uric acid pool. Larger prospective studies are needed to further assess these potentially important findings.

  14. Lossless droplet transfer of droplet-based microfluidic analysis

    Science.gov (United States)

    Kelly, Ryan T [West Richland, WA; Tang, Keqi [Richland, WA; Page, Jason S [Kennewick, WA; Smith, Richard D [Richland, WA

    2011-11-22

    A transfer structure for droplet-based microfluidic analysis is characterized by a first conduit containing a first stream having at least one immiscible droplet of aqueous material and a second conduit containing a second stream comprising an aqueous fluid. The interface between the first conduit and the second conduit can define a plurality of apertures, wherein the apertures are sized to prevent exchange of the first and second streams between conduits while allowing lossless transfer of droplets from the first conduit to the second conduit through contact between the first and second streams.

  15. Leidenfrost levitation: beyond droplets.

    Science.gov (United States)

    Hashmi, Ali; Xu, Yuhao; Coder, Benjamin; Osborne, Paul A; Spafford, Jonathon; Michael, Grant E; Yu, Gan; Xu, Jie

    2012-01-01

    Friction is a major inhibitor in almost every mechanical system. Enlightened by the Leidenfrost effect - a droplet can be levitated by its own vapor layer on a sufficiently hot surface - we demonstrate for the first time that a small cart can also be levitated by Leidenfrost vapor. The levitated cart can carry certain amount of load and move frictionlessly over the hot surface. The maximum load that the cart can carry is experimentally tested over a range of surface temperatures. We show that the levitated cart can be propelled not only by gravitational force over a slanted flat surface, but also self-propelled over a ratchet shaped horizontal surface. In the end, we experimentally tested water consumption rate for sustaining the levitated cart, and compared the results to theoretical calculations. If perfected, this frictionless Leidenfrost cart could be used in numerous engineering applications where relative motion exists between surfaces.

  16. Droplets, Bubbles and Ultrasound Interactions.

    Science.gov (United States)

    Shpak, Oleksandr; Verweij, Martin; de Jong, Nico; Versluis, Michel

    2016-01-01

    The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to circulate within blood vessels. Perfluorocarbon liquid droplets can be a potential new generation of microbubble agents as ultrasound can trigger their conversion into gas bubbles. Prior to activation, they are at least five times smaller in diameter than the resulting bubbles. Together with the violent nature of the phase-transition, the droplets can be used for local drug delivery, embolotherapy, HIFU enhancement and tumor imaging. Here we explain the basics of bubble dynamics, described by the Rayleigh-Plesset equation, bubble resonance frequency, damping and quality factor. We show the elegant calculation of the above characteristics for the case of small amplitude oscillations by linearizing the equations. The effect and importance of a bubble coating and effective surface tension are also discussed. We give the main characteristics of the power spectrum of bubble oscillations. Preceding bubble dynamics, ultrasound propagation is introduced. We explain the speed of sound, nonlinearity and attenuation terms. We examine bubble ultrasound scattering and how it depends on the wave-shape of the incident wave. Finally, we introduce droplet interaction with ultrasound. We elucidate the ultrasound-focusing concept within a droplets sphere, droplet shaking due to media compressibility and droplet phase-conversion dynamics.

  17. Simulation of Interpersonal Transport of Expiratory Droplets and Droplet Nuclei between Two Standing Manikins

    DEFF Research Database (Denmark)

    Liu, Li; Y, Li,

    2012-01-01

    Interpersonal transport of expiratory droplets and droplet nuclei constitutes a prerequisite for the transmission of pathogens as well as the transmission of respiratory diseases. Numerical simulations considering droplet evaporation and droplet nucleus sizes were carried out, using two detailed...... the existence of direct spray route of the interpersonal transport of expiratory droplets....

  18. Droplet depinning in a wake

    Science.gov (United States)

    Hooshanginejad, Alireza; Lee, Sungyon

    2017-03-01

    Pinning and depinning of a windswept droplet on a surface is familiar yet deceptively complex for it depends on the interaction of the contact line with the microscopic features of the solid substrate. This physical picture is further compounded when wind of the Reynolds number greater than 100 blows over pinned drops, leading to the boundary layer separation and wake generation. In this Rapid Communication, we incorporate the well-developed ideas of the classical boundary layer to study partially wetting droplets in a wake created by a leader object. Depending on its distance from the leader, the droplet is observed to exhibit drafting, upstream motion, and splitting, due to the wake-induced hydrodynamic coupling that is analogous to drafting of moving bodies. We successfully rationalize the onset of the upstream motion regime using a reduced model that computes the droplet shape governed by the pressure field inside the wake.

  19. Magnetic droplets and dynamical skyrmions

    Science.gov (United States)

    Akerman, Johan

    2015-03-01

    Nanocontact spin-torque oscillators (NC-STOs) provide an excellent environment for studying nano-magnetic phenomena such as localized and propagating auto-oscillatory spin wave (SW) modes. The recent experimental observation of magnetic droplet solitons in NC-STOs with perpendicular magnetic anisotropy (PMA) free layers, and the numerical and experimental demonstrations of spin transfer torque (STT) nucleated skyrmions in similar magnetic thin films add two interesting and useful nanoscale magnetic objects. Due to the competition between exchange, anisotropy, and, in the case of skyrmions, the Dzyaloshinskii-Moriya interaction (DMI), the droplet and the skyrmion are extremely compact, on the order of 10-100 nm. One of the main differences between a magnetic dissipative droplet soliton and a skyrmion is that the former is a dynamical object with all its spins precessing around an effective field and stabilized by STT, exchange, and PMA, while the latter has static spins and an internal structure stabilized by DMI, exchange, and PMA. The dissipative droplet is furthermore a non-topological soliton, while the skyrmion is topologically protected. In this work I will report on our most recent droplet experiments, including droplet collapse at very high fields, droplets excited in nano-wire based NC-STOs, and studies of the field-current droplet nucleation boundary. I will also demonstrate numerically and analytically that STT driven precession can stabilize so-called dynamical skyrmions even in the absence of DMI, and I will describe their very promising properties in detail. From a more fundamental perspective, precession is hence a third independent possibility to stabilize a skyrmion, without the need for the conventional stabilization from either dipolar energy or DMI.

  20. The energetics of bouncing droplets

    Science.gov (United States)

    Turton, Sam; Molacek, Jan; Bush, John

    2016-11-01

    We present the results of a theoretical investigation of the energetics of droplets bouncing on the surface of a vertically vibrating bath. We first assess the relative magnitudes of the kinetic, surface and gravitational potential energies of both the droplet and its wave field. We then seek to rationalize the transitions between the various bouncing and walking states that arise as the vibrational forcing is increased. Our results are compared with prior theoretical and experimental work.

  1. Influence of Structure and Composition on Dynamic Viscoelastic Property of Cartilaginous Tissue: Criteria for Classification between Hyaline Cartilage and Fibrocartilage Based on Mechanical Function

    Science.gov (United States)

    Miyata, Shogo; Tateishi, Tetsuya; Furukawa, Katsuko; Ushida, Takashi

    Recently, many types of methodologies have been developed to regenerate articular cartilage. It is important to assess whether the reconstructed cartilaginous tissue has the appropriate mechanical functions to qualify as hyaline (articular) cartilage. In some cases, the reconstructed tissue may become fibrocartilage and not hyaline cartilage. In this study, we determined the dynamic viscoelastic properties of these two types of cartilage by using compression and shear tests, respectively. Hyaline cartilage specimens were harvested from the articular surface of bovine knee joints and fibrocartilage specimens were harvested from the meniscus tissue of the same. The results of this study revealed that the compressive energy dissipation of hyaline cartilage showed a strong dependence on testing frequency at low frequencies, while that of fibrocartilage did not. Therefore, the compressive energy dissipation that is indicated by the loss tangent could become the criterion for the in vitro assessment of the mechanical function of regenerated cartilage.

  2. Spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect created in the femoral condyle using a novel double-network hydrogel

    National Research Council Canada - National Science Library

    Yokota, Masashi; Yasuda, Kazunori; Kitamura, Nobuto; Arakaki, Kazunobu; Onodera, Shin; Kurokawa, Takayuki; Gong, Jian-Ping

    2011-01-01

    .... The purpose is to clarify whether the spontaneous hyaline cartilage regeneration can be induced in a large osteochondral defect created in the femoral condyle by means of implanting a novel double-network (DN...

  3. Microstructural and compositional features of the fibrous and hyaline cartilage on the medial tibial plateau imply a unique role for the hopping locomotion of kangaroo

    National Research Council Canada - National Science Library

    He, Bo; Wu, Jian Ping; Xu, Jiake; Day, Robert E; Kirk, Thomas Brett

    2013-01-01

    .... However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined...

  4. Adipose stem cells can secrete angiogenic factors that inhibit hyaline cartilage regeneration.

    Science.gov (United States)

    Lee, Christopher Sd; Burnsed, Olivia A; Raghuram, Vineeth; Kalisvaart, Jonathan; Boyan, Barbara D; Schwartz, Zvi

    2012-08-24

    Adipose stem cells (ASCs) secrete many trophic factors that can stimulate tissue repair, including angiogenic factors, but little is known about how ASCs and their secreted factors influence cartilage regeneration. Therefore, the aim of this study was to determine the effects ASC-secreted factors have in repairing chondral defects. ASCs isolated from male Sprague Dawley rats were cultured in monolayer or alginate microbeads supplemented with growth (GM) or chondrogenic medium (CM). Subsequent co-culture, conditioned media, and in vivo cartilage defect studies were performed. ASC monolayers and microbeads cultured in CM had decreased FGF-2 gene expression and VEGF-A secretion compared to ASCs cultured in GM. Chondrocytes co-cultured with GM-cultured ASCs for 7 days had decreased mRNAs for col2, comp, and runx2. Chondrocytes treated for 12 or 24 hours with conditioned medium from GM-cultured ASCs had reduced sox9, acan, and col2 mRNAs; reduced proliferation and proteoglycan synthesis; and increased apoptosis. ASC-conditioned medium also increased endothelial cell tube lengthening whereas conditioned medium from CM-cultured ASCs had no effect. Treating ASCs with CM reduced or abolished these deleterious effects while adding a neutralizing antibody for VEGF-A eliminated ASC-conditioned medium induced chondrocyte apoptosis and restored proteoglycan synthesis. FGF-2 also mitigated the deleterious effects VEGF-A had on chondrocyte apoptosis and phenotype. When GM-grown ASC pellets were implanted in 1 mm non-critical hyaline cartilage defects in vivo, cartilage regeneration was inhibited as evaluated by radiographic and equilibrium partitioning of an ionic contrast agent via microCT imaging. Histology revealed that defects with GM-cultured ASCs had no tissue ingrowth from the edges of the defect whereas empty defects and defects with CM-grown ASCs had similar amounts of neocartilage formation. ASCs must be treated to reduce the secretion of VEGF-A and other factors that

  5. Hyaline cartilage regeneration by combined therapy of microfracture and long-term bone morphogenetic protein-2 delivery.

    Science.gov (United States)

    Yang, Hee Seok; La, Wan-Geun; Bhang, Suk Ho; Kim, Hak-Jun; Im, Gun-Il; Lee, Haeshin; Park, Jung-Ho; Kim, Byung-Soo

    2011-07-01

    Microfracture of cartilage induces migration of bone-marrow-derived mesenchymal stem cells. However, this treatment often results in fibrocartilage regeneration. Growth factors such as bone morphogenetic protein (BMP)-2 induce the differentiation of bone-marrow-derived mesenchymal stem cells into chondrocytes, which can be used for hyaline cartilage regeneration. Here, we tested the hypothesis that long-term delivery of BMP-2 to cartilage defects subjected to microfracture results in regeneration of high-quality hyaline-like cartilage, as opposed to short-term delivery of BMP-2 or no BMP-2 delivery. Heparin-conjugated fibrin (HCF) and normal fibrin were used as carriers for the long- and short-term delivery of BMP-2, respectively. Rabbit articular cartilage defects were treated with microfracture combined with one of the following: no treatment, fibrin, short-term delivery of BMP-2, HCF, or long-term delivery of BMP-2. Eight weeks after treatment, histological analysis revealed that the long-term delivery of BMP-2 group (microfracture + HCF + BMP-2) showed the most staining with alcian blue. A biochemical assay, real-time polymerase chain reaction assay and Western blot analysis all revealed that the long-term delivery of BMP-2 group had the highest glucosaminoglycan content as well as the highest expression level of collagen type II. Taken together, the long-term delivery of BMP-2 to cartilage defects subjected to microfracture resulted in regeneration of hyaline-like cartilage, as opposed to short-term delivery or no BMP-2 delivery. Therefore, this method could be more convenient for hyaline cartilage regeneration than autologous chondrocyte implantation due to its less invasive nature and lack of cell implantation.

  6. A cell-free scaffold-based cartilage repair provides improved function hyaline-like repair at one year.

    Science.gov (United States)

    Siclari, Alberto; Mascaro, Gennaro; Gentili, Chiara; Cancedda, Ranieri; Boux, Eugenio

    2012-03-01

    Bone marrow stimulation techniques in cartilage repair such as drilling are limited by the formation of fibrous to hyaline-like repair tissue. It has been suggested such techniques can be enhanced by covering the defect with scaffolds. We present an innovative approach using a polyglycolic acid (PGA)-hyaluronan scaffold with platelet-rich-plasma (PRP) in drilling. We asked whether (1) PRP immersed in a cell-free PGA-hyaluronan scaffold improves patient-reported 1-year outcomes for the Knee injury and Osteoarthritis Score (KOOS), and (2) implantation of the scaffold in combination with bone marrow stimulation leads to the formation of hyaline-like cartilage repair tissue. We reviewed 52 patients who had arthroscopic implantation of the PGA-hyaluronan scaffold immersed with PRP in articular cartilage defects of the knee pretreated with Pridie drilling. Patients were assessed by KOOS. At 9 months followup, histologic staining was performed in specimens obtained from five patients to assess the repair tissue quality. The KOOS subscores improved for pain (55 to 91), symptoms (57 to 88), activities of daily living (69 to 86), sports and recreation (36 to 70), and quality of life (38 to 73). The histologic evaluation showed a homogeneous hyaline-like cartilage repair tissue. The cell-free PGA-hyaluronan scaffold combined with PRP leads to cartilage repair and improved patient-reported outcomes (KOOS) during 12 months of followup. Histologic sections showed morphologic features of hyaline-like repair tissue. Long-term followup is needed to determine if the cartilage repair tissue is durable. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

  7. Deleted in Malignant Brain Tumors 1 (DMBT1 is present in hyaline membranes and modulates surface tension of surfactant

    Directory of Open Access Journals (Sweden)

    Griese Matthias

    2007-10-01

    Full Text Available Abstract Background Deleted in Malignant Brain Tumors 1 (DMBT1 is a secreted scavenger receptor cysteine-rich protein that binds various bacteria and is thought to participate in innate pulmonary host defense. We hypothesized that pulmonary DMBT1 could contribute to respiratory distress syndrome in neonates by modulating surfactant function. Methods DMBT1 expression was studied by immunohistochemistry and mRNA in situ hybridization in post-mortem lungs of preterm and full-term neonates with pulmonary hyaline membranes. The effect of human recombinant DMBT1 on the function of bovine and porcine surfactant was measured by a capillary surfactometer. DMBT1-levels in tracheal aspirates of ventilated preterm and term infants were determined by ELISA. Results Pulmonary DMBT1 was localized in hyaline membranes during respiratory distress syndrome. In vitro addition of human recombinant DMBT1 to the surfactants increased surface tension in a dose-dependent manner. The DMBT1-mediated effect was reverted by the addition of calcium depending on the surfactant preparation. Conclusion Our data showed pulmonary DMBT1 expression in hyaline membranes during respiratory distress syndrome and demonstrated that DMBT1 increases lung surface tension in vitro. This raises the possibility that DMBT1 could antagonize surfactant supplementation in respiratory distress syndrome and could represent a candidate target molecule for therapeutic intervention in neonatal lung disease.

  8. Rotating three-dimensional dynamic culture of adult human bone marrow-derived cells for tissue engineering of hyaline cartilage.

    Science.gov (United States)

    Sakai, Shinsuke; Mishima, Hajime; Ishii, Tomoo; Akaogi, Hiroshi; Yoshioka, Tomokazu; Ohyabu, Yoshimi; Chang, Fei; Ochiai, Naoyuki; Uemura, Toshimasa

    2009-04-01

    The method of constructing cartilage tissue from bone marrow-derived cells in vitro is considered a valuable technique for hyaline cartilage regenerative medicine. Using a rotating wall vessel (RWV) bioreactor developed in a NASA space experiment, we attempted to efficiently construct hyaline cartilage tissue from human bone marrow-derived cells without using a scaffold. Bone marrow aspirates were obtained from the iliac crest of nine patients during orthopedic operation. After their proliferation in monolayer culture, the adherent cells were cultured in the RWV bioreactor with chondrogenic medium for 2 weeks. Cells from the same source were cultured in pellet culture as controls. Histological and immunohistological evaluations (collagen type I and II) and quantification of glycosaminoglycan were performed on formed tissues and compared. The engineered constructs obtained using the RWV bioreactor showed strong features of hyaline cartilage in terms of their morphology as determined by histological and immunohistological evaluations. The glycosaminoglycan contents per microg DNA of the tissues were 10.01 +/- 3.49 microg/microg DNA in the case of the RWV bioreactor and 6.27 +/- 3.41 microg/microg DNA in the case of the pellet culture, and their difference was significant. The RWV bioreactor could provide an excellent environment for three-dimensional cartilage tissue architecture that can promote the chondrogenic differentiation of adult human bone marrow-derived cells.

  9. Regeneration of hyaline cartilage by cell-mediated gene therapy using transforming growth factor beta 1-producing fibroblasts.

    Science.gov (United States)

    Lee, K H; Song, S U; Hwang, T S; Yi, Y; Oh, I S; Lee, J Y; Choi, K B; Choi, M S; Kim, S J

    2001-09-20

    Transforming growth factor beta (TGF-beta) has been considered as a candidate for gene therapy of orthopedic diseases. The possible application of cell-mediated TGF-beta gene therapy as a new treatment regimen for degenerative arthritis was investigated. In this study, fibroblasts expressing active TGF-beta 1 were injected into the knee joints of rabbits with artificially made cartilage defects to evaluate the feasibility of this therapy for orthopedic diseases. Two to 3 weeks after the injection there was evidence of cartilage regeneration, and at 4 to 6 weeks the cartilage defect was completely filled with newly grown hyaline cartilage. Histological analyses of the regenerated cartilage suggested that it was well integrated with the adjacent normal cartilage at the sides of the defect and that the newly formed tissue was indeed hyaline cartilage. Our findings suggest that cell-mediated TGF-beta 1 gene therapy may be a novel treatment for orthopedic diseases in which hyaline cartilage damage has occurred.

  10. Effects of growth factors and glucosamine on porcine mandibular condylar cartilage cells and hyaline cartilage cells for tissue engineering applications.

    Science.gov (United States)

    Wang, Limin; Detamore, Michael S

    2009-01-01

    Temporomandibular joint (TMJ) condylar cartilage is a distinct cartilage that has both fibrocartilaginous and hyaline-like character, with a thin proliferative zone that separates the fibrocartilaginous fibrous zone at the surface from the hyaline-like mature and hypertrophic zones below. In this study, we compared the effects of insulin-like growth factor-I (IGF-I), basic fibroblast growth factor (bFGF), transforming growth factor beta1 (TGF-beta1), and glucosamine sulphate on porcine TMJ condylar cartilage and ankle cartilage cells in monolayer culture. In general, TMJ condylar cartilage cells proliferated faster than ankle cartilage cells, while ankle cells produced significantly greater amounts of glycosaminoglycans (GAGs) and collagen than TMJ condylar cartilage cells. IGF-I and bFGF were potent stimulators of TMJ cell proliferation, while no signals statistically outperformed controls for ankle cell proliferation. IGF-I was the most effective signal for GAG production with ankle cells, and the most potent upregulator of collagen synthesis for both cell types. Glucosamine sulphate promoted cell proliferation and biosynthesis at specific concentrations and outperformed growth factors in certain instances. In conclusion, hyaline cartilage cells had lower cell numbers and superior biosynthesis compared to TMJ condylar cartilage cells, and we have found IGF-I at 100 ng/mL and glucosamine sulphate at 100 microg/mL to be the most effective signals for these cells under the prescribed conditions.

  11. Uniform-droplet spray forming

    Energy Technology Data Exchange (ETDEWEB)

    Blue, C.A.; Sikka, V.K. [Oak Ridge National Lab., TN (United States); Chun, Jung-Hoon [Massachusetts Institute of Technology, Cambridge, MA (United States); Ando, T. [Tufts Univ., Medford, MA (United States)

    1997-04-01

    The uniform-droplet process is a new method of liquid-metal atomization that results in single droplets that can be used to produce mono-size powders or sprayed-on to substrates to produce near-net shapes with tailored microstructure. The mono-sized powder-production capability of the uniform-droplet process also has the potential of permitting engineered powder blends to produce components of controlled porosity. Metal and alloy powders are commercially produced by at least three different methods: gas atomization, water atomization, and rotating disk. All three methods produce powders of a broad range in size with a very small yield of fine powders with single-sized droplets that can be used to produce mono-size powders or sprayed-on substrates to produce near-net shapes with tailored microstructures. The economical analysis has shown the process to have the potential of reducing capital cost by 50% and operating cost by 37.5% when applied to powder making. For the spray-forming process, a 25% savings is expected in both the capital and operating costs. The project is jointly carried out at Massachusetts Institute of Technology (MIT), Tuffs University, and Oak Ridge National Laboratory (ORNL). Preliminary interactions with both finished parts and powder producers have shown a strong interest in the uniform-droplet process. Systematic studies are being conducted to optimize the process parameters, understand the solidification of droplets and spray deposits, and develop a uniform-droplet-system (UDS) apparatus appropriate for processing engineering alloys.

  12. Castleman′s disease - hyaline vascular type - clinical, cytological and histological features with review of literature

    Directory of Open Access Journals (Sweden)

    Ghosh Arnab

    2010-04-01

    Full Text Available Background and Aims: Castleman′s disease (CD is a rare disease of lymph node with two identified forms - the hyaline vascular (HV type or angiofollicular type and plasma cell (PC type. It usually presents as localized or systemic lymphadenopathy or even as extra nodal mass and may give rise to several differential diagnoses. Fine needle aspiration cytology (FNAC, as the initial investigation, may be misleading. Excision biopsy usually gives the diagnosis. This study analyzes the clinical, cytological and histological features of CD of HV type Materials and Methods: All the cases of CD reported between 2001 and March 2008 have been reviewed. Cytology and histopathology slides of all cases were reviewed by two reporting pathologists independently and the clinical records were analyzed. Result: We had five cases of CD all of which presented as cervical lymphadenopathy of 1 to 5 cms in young patients. Patients were mostly asymptomatic with all relevant investigations within normal limits. The cytology findings mostly showed a predominance of small lymphocytes with capillary fragments. On excision biopsy, all cases were diagnosed as CD of HV type. Conclusion: CD should be kept as a differential of lymphadenopathy, especially in asymptomatic and young patients.

  13. Roentgenographic findings in hyaline membrane disease treated with exogenous surfactant: comparison with control group

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun Kyoung; Lim, Chae Ha; Lim, Woo Young; Kim, Young Sook; Byen, Ju Nam; Oh, Jae Hee; Kim, Young Chul [Chosun Univ. College of Medicine, Kwangju (Korea, Republic of)

    1997-01-01

    To compare, with the use of chest radiographic findings, improvement and complications in newborns treated with exogenous surfactant for hyaline membrane disease (HMD), and an untreated control group. Thirty-six patients with HMD were randomly assigned to a control group (n=18) or surfactant treated group (n=18). As part of an initial evaluation of their pulmonary status, we then performed a retrospective statistical analysis of chest radiographic findings obtained in exogenous surfactant treated and untreated infants within the first 90 minutes of life. Subsequent examinations were performed at less than 24 hours of age. Chest radiograph before treatment showed no significant differences between the two groups, but significant improvement was noted in the surfactant treated group, in contrast to the control group. The most common chest radiographic finding after surfactant administration was uniform (n=15) or disproportionate (n=2) improvement of pulmonary aeration. Patent ductus arteriosus developed in three treated neonates and in four cases in the control group. Air leak occurred in three cases in the treated group and in five cases in the control group. In one treated patient pulmonary hemorrhage developed and intracranial hemorrhage occurred in three treated neonates and in four cases in the control group. Bronchopulmonary dysplasia was developed in 6 cases of treated group and 3 cases of control group. A chest radiograph is considered to be helpful in the evaluation of improvement and complications of HMD in infants treated with surfactant.

  14. Absence of hyaline cartilage in the tongue of 'Caspian miniature horse'.

    Science.gov (United States)

    Rezaian, M

    2006-08-01

    Histology of the tongue, including apex, root and body, in four adult Caspian miniature horses was examined. Serial sections with 6 mum thickness were stained with haematoxylin-eosin and Masson trichrome and studied under light microscope. The tongue was covered by stratified squamous epithelium. It was thick and keratinized bearing numerous lingual papillae on the dorsum, mostly filiform with a very fine keratinized thread projecting above the surface and bending backward. The fungiform papillae were sparsely scattered among the filiform papillae and covered with keratinized squamous epithelium. Few taste buds were detected on it. The two very large vallate papillae were detected on the dorsum, just rostral to the root, which were covered with stratified squamous epithelium with relatively high amounts of taste buds in the epithelium of the surrounding grooves. The foliate papillae were present near the palatoglossal arch and had a few taste buds. The epithelium covering the ventral surface of the tongue was thin and keratinized. The lingual muscle core consisted of transverse, longitudinal and perpendicular bundles of skeletal muscle fibres. Clusters of minor salivary glands were present between the muscle fibres and lamia propria. Most of the lingual glands were mucous and most of the gustatory ones were serous type. The mid-dorsal special structure of the tongue (dorsal lingual cartilage) contained sparse skeletal muscle fibres and was rich in white adipose tissue. Hyaline cartilage, routinely observed in this structure in the horses, was not detected in Caspian miniature horse.

  15. [Quantitative analysis of chondrocyte distribution patterns in hyaline cartilage tissue--a comparison of different models].

    Science.gov (United States)

    Ranke, T P; Ranke, I; Schwandtke, A; Rother, P

    1989-01-01

    The purpose of our investigations were aging changes in hyaline cartilage of the trachea and of the larynx. 42 samples of carina tracheae and 29 samples of arytenoid cartilage were used in both organs from the newborn age up to the age of 91 a. We have examined patterns of cell distribution with the help of the computer programme "Dichte" ("density") using the following methods of stochastic geometry: product density, L function, and others. Product density allows for a reliable destination between a regular pattern of cells (hard-core distribution), a random pattern (soft-core distribution), and a typical clustering of chondrocytes. 2 examples of arytenoid cartilage have been selected to demonstrate the possibilities of interpretation of product density supported by the L function. Soft-core and in few cases hard-core distribution have been found both with the carina tracheae and the cartilago arytaenoidea in the 1st decade of life. Beginning with the 2nd decade of life, the typical clustering of chondrocytes have been confirmed with both organs.

  16. Droplet Motion on a Shape Gradient Surface.

    Science.gov (United States)

    Zheng, Yanfen; Cheng, Jiang; Zhou, Cailong; Xing, Haiting; Wen, Xiufang; Pi, Pihui; Xu, Shouping

    2017-05-02

    We demonstrate a facile method to induce water droplet motion on an wedge-shaped superhydrophobic copper surface combining with a poly(dimethylsiloxane) (PDMS) oil layer on it. The unbalanced interfacial tension from the shape gradient offers the actuating force. The superhydrophobicity critically eliminates the droplet contact line pinning and the slippery PDMS oil layer lubricates the droplet motion, which makes the droplet move easily. The maximum velocity and furthest position of droplet motion were recorded and found to be influenced by the gradient angle. The mechanism of droplet motion on the shape gradient surface is systematically discussed, and the theoretical model analysis is well matched with the experimental results.

  17. Walking droplets in linear channels

    Science.gov (United States)

    Filoux, Boris; Hubert, Maxime; Schlagheck, Peter; Vandewalle, Nicolas

    2017-01-01

    When a droplet is placed onto a vertically vibrated bath, it can bounce without coalescing. Upon an increase of the forcing acceleration, the droplet is propelled by the wave it generates and becomes a walker with a well-defined speed. We investigate the confinement of a walker in different rectangular cavities, used as waveguides for the Faraday waves emitted by successive droplet bounces. By studying the walker velocities, we discover that one-dimensional confinement is optimal for narrow channels of width of D ≃1.5 λF . Thereby, the walker follows a quasilinear path. We also propose an analogy with waveguide models based on the observation of the Faraday instability within the channels.

  18. Snell's law and walking droplets

    Science.gov (United States)

    Bush, John; Pucci, Giuseppe; Aubin, Benjamin; Brun, Pierre-Thomas; Faria, Luiz

    2016-11-01

    Droplets walking on the surface of a vibrating bath have been shown to exhibit a number of quantum-like features. We here present the results of a combined experimental and theoretical investigation of such droplets crossing a linear step corresponding to a reduction in bath depth. When the step is sufficiently large, the walker reflects off the step; otherwise, it is refracted as it crosses the step. Particular attention is given to an examination of the regime in which the droplet obeys a form of Snell's Law, a behavior captured in accompanying simulations. Attempts to provide theoretical rationale for the dependence of the effective refractive index on the system parameters are described. Supported by NSF through CMMI-1333242.

  19. Soft substrates suppress droplet splashing

    CERN Document Server

    Howland, Christopher J; Style, Robert W; Castrejón-Pita, A A

    2015-01-01

    Droplets splash when they impact dry, flat substrates above a critical velocity that depends on parameters such as droplet size, viscosity and air pressure. We show that substrate stiffness also impacts the splashing threshold by imaging ethanol drops impacting silicone gels of different stiffnesses. Splashing is significantly suppressed: droplets on the softest substrates need over 70% more kinetic energy to splash than they do on rigid substrates. We show that splash suppression is likely to be due to energy losses caused by deformations of soft substrates during the first few microseconds of impact. We find that solids with Youngs modulus $\\lesssim O(10^5)$Pa suppress splashing, in agreement with simple scaling arguments. Thus materials like soft gels and elastomers can be used as simple coatings for effective splash prevention.

  20. Film boiling of mercury droplets

    Science.gov (United States)

    Baumeister, K. J.; Schoessow, G. J.; Chmielewski, C. E.

    1975-01-01

    Vaporization times of mercury droplets in Leidenfrost film boiling on a flat horizontal plate are measured in an air atmosphere. Extreme care was used to prevent large amplitude droplet vibrations and surface wetting; therefore, these data can be compared to film boiling theory. For these data, diffusion from the upper surface of the drop is a dominant mode of mass transfer from the drop. A closed-form analytical film boiling theory is developed to account for the diffusive evaporation. Reasonable agreement between data and theory is seen.

  1. Evaporation of elongated droplets on chemically stripe-patterned surfaces

    NARCIS (Netherlands)

    Jansen, H.P.; Zandvliet, H.J.W.; Kooij, E.S.

    2015-01-01

    We investigate the evaporation of elongated droplets on chemically striped patterned surfaces. Variation of elongation is achieved by depositing droplets on surfaces with varying ratios of hydrophobic and hydrophilic stripe widths. Elongated droplets evaporate faster than more spherical droplets. Bo

  2. Renal histopathology in toxicity and carcinogenicity studies with tert-butyl alcohol administered in drinking water to F344 rats: a pathology working group review and re-evaluation.

    Science.gov (United States)

    Hard, Gordon C; Bruner, Richard H; Cohen, Samuel M; Pletcher, John M; Regan, Karen S

    2011-04-01

    An independent Pathology Working Group (PWG) re-evaluated the kidney changes in National Toxicology Program (NTP) toxicology/carcinogenicity studies of tert-butyl alcohol (TBA) in F344/N rats to determine possible mode(s) of action underlying renal tubule tumors in male rats at 2-years. In the 13-week study, the PWG confirmed that the normal pattern of round hyaline droplets in proximal convoluted tubules was replaced by angular droplet accumulation, and identified precursors of granular casts in the outer medulla, changes typical of alpha(2u)-globulin (α(2u)-g) nephropathy. In the 2-year study, the PWG confirmed the NTP observation of increased renal tubule tumors in treated male groups. Linear papillary mineralization, another hallmark of the α(2u)-g pathway was present only in treated male rats. Chronic progressive nephropathy (CPN) was exacerbated in high-dose males and females, with a relationship between advanced grades of CPN and renal tumor occurrence. Hyperplasia of the papilla lining was a component of CPN in both sexes, but there was no pelvic urothelial hyperplasia. High-dose females showed no TBA-related nephrotoxicity. The PWG concluded that both α(2u)-g nephropathy and exacerbated CPN modes of action were operative in TBA renal tumorigenicity in male rats, neither of which has relevance for human cancer risk.

  3. Droplet migration characteristics in confined oscillatory microflows

    CERN Document Server

    Chaudhury, Kaustav; Chakraborty, Suman

    2015-01-01

    We analyze the migration characteristics of a droplet in an oscillatory flow field in a parallel plate micro-confinement. Using phase filed formalism, we capture the dynamical evolution of the droplet over a wide range of the frequency of the imposed oscillation in the flow field, drop size relative to the channel gap, and the capillary number. The latter two factors imply the contribution of droplet deformability, commonly considered in the study of droplet migration under steady shear flow conditions. We show that the imposed oscillation brings in additional time complexity in the droplet movement, realized through temporally varying drop-shape, flow direction and the inertial response of the droplet. As a consequence, we observe a spatially complicated pathway of the droplet along the transverse direction, in sharp contrast to the smooth migration under a similar yet steady shear flow condition. Intuitively, the longitudinal component of the droplet movement is in tandem with the flow continuity and evolve...

  4. Materials science: Droplets leap into action

    Science.gov (United States)

    Vollmer, Doris; Butt, Hans-Jürgen

    2015-11-01

    What could cause a water droplet to start bouncing on a surface? It seems that a combination of evaporation and a highly water-repellent surface induces droplet bouncing when ambient pressure is reduced. See Letter p.82

  5. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) of cadaveric shoulders: comparison of contrast dynamics in hyaline and fibrous cartilage after intraarticular gadolinium injection.

    Science.gov (United States)

    Wiener, E; Hodler, J; Pfirrmann, C W A

    2009-01-01

    Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a novel method to investigate cartilaginous and fibrocartilaginous structures. To investigate the contrast dynamics in hyaline and fibrous cartilage of the glenohumeral joint after intraarticular injection of gadopentetate dimeglumine. Transverse T(1) maps were acquired on a 1.5T scanner before and after intraarticular injection of 2.0 mmol/l gadopentetate dimeglumine in five cadaveric shoulders using a dual flip angle three-dimensional gradient echo (3D-GRE) sequence. The acquisition time for the T(1) maps was 5 min 5 s for the whole shoulder. Measurements were repeated every 15 min over 2.5 hours. Regions of interest (ROIs) covering the glenoid cartilage and the labrum were drawn to assess the temporal evolution of the relaxation parameters. T(1) of unenhanced hyaline cartilage of the glenoid was 568+/-34 ms. T(1) of unenhanced fibrous cartilage of the labrum was 552+/-38 ms. Significant differences (P=0.002 and 0.03) in the relaxation parameters were already measurable after 15 min. After 2 to 2.5 hours, hyaline and fibrous cartilage still demonstrated decreasing relaxation parameters, with a larger range of the T(1)(Gd) values in fibrous cartilage. T(1) and triangle Delta R(1) values of hyaline and fibrous cartilage after 2.5 hours were 351+/-16 ms and 1.1+/-0.09 s(-1), and 332+/-31 ms and 1.2+/-0.1 s(-1), respectively. A significant decrease in T(1)(Gd) was found 15 min after intraarticular contrast injection. Contrast accumulation was faster in hyaline than in fibrous cartilage. After 2.5 hours, contrast accumulation showed a higher rate of decrease in hyaline cartilage, but neither hyaline nor fibrous cartilage had reached equilibrium.

  6. Delayed Gadolinium-Enhanced MRI of Cartilage (dGEMRIC) of Cadaveric Shoulders: Comparison of Contrast Dynamics in Hyaline and Fibrous Cartilage after Intraarticular Gadolinium Injection

    Energy Technology Data Exchange (ETDEWEB)

    Wiener, E. (Dept. of Radiology, Charite Universitaetsmedizin Berlin (Germany)); Hodler, J.; Pfirrmann, C.W.A. (Dept. of Radiology, Orthopedic Univ. Hospital Balgrist, Zuerich (Switzerland))

    2009-01-15

    Background: Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a novel method to investigate cartilaginous and fibrocartilaginous structures. Purpose: To investigate the contrast dynamics in hyaline and fibrous cartilage of the glenohumeral joint after intraarticular injection of gadopentetate dimeglumine. Material and Methods: Transverse T1 maps were acquired on a 1.5T scanner before and after intraarticular injection of 2.0 mmol/l gadopentetate dimeglumine in five cadaveric shoulders using a dual flip angle three-dimensional gradient echo (3D-GRE) sequence. The acquisition time for the T1 maps was 5 min 5 s for the whole shoulder. Measurements were repeated every 15 min over 2.5 hours. Regions of interest (ROIs) covering the glenoid cartilage and the labrum were drawn to assess the temporal evolution of the relaxation parameters. Results: T1 of unenhanced hyaline cartilage of the glenoid was 568+-34 ms. T1 of unenhanced fibrous cartilage of the labrum was 552+-38 ms. Significant differences (P=0.002 and 0.03) in the relaxation parameters were already measurable after 15 min. After 2 to 2.5 hours, hyaline and fibrous cartilage still demonstrated decreasing relaxation parameters, with a larger range of the T1(Gd) values in fibrous cartilage. T1 and ?R1 values of hyaline and fibrous cartilage after 2.5 hours were 351+-16 ms and 1.1+-0.09/s, and 332+-31 ms and 1.2+-0.1/s, respectively. Conclusion: A significant decrease in T1(Gd) was found 15 min after intraarticular contrast injection. Contrast accumulation was faster in hyaline than in fibrous cartilage. After 2.5 hours, contrast accumulation showed a higher rate of decrease in hyaline cartilage, but neither hyaline nor fibrous cartilage had reached equilibrium

  7. Microstructural and compositional features of the fibrous and hyaline cartilage on the medial tibial plateau imply a unique role for the hopping locomotion of kangaroo.

    Directory of Open Access Journals (Sweden)

    Bo He

    Full Text Available Hopping provides efficient and energy saving locomotion for kangaroos, but it results in great forces in the knee joints. A previous study has suggested that a unique fibrous cartilage in the central region of the tibial cartilage could serve to decrease the peak stresses generated within kangaroo tibiofemoral joints. However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined. The present study showed that the fibrous cartilage was thicker and had a lower chondrocyte density than the hyaline cartilage. Despite having a higher PG content in the middle and deep zones, the fibrous cartilage had an inferior compressive strength compared to the peripheral hyaline cartilage. The fibrous cartilage had a complex three dimensional collagen meshwork with collagen bundles parallel to the surface in the superficial zone, and with collagen bundles both parallel and perpendicular to the surface in the middle and deep zones. The collagen in the hyaline cartilage displayed a typical Benninghoff structure, with collagen fibres parallel to the surface in the superficial zone and collagen fibres perpendicular to the surface in the deep zone. Elastin fibres were found throughout the entire tissue depth of the fibrous cartilage and displayed a similar alignment to the adjacent collagen bundles. In comparison, the elastin fibres in the hyaline cartilage were confined within the superficial zone. This study examined for the first time the fibrillary structure, PG content and compressive properties of the central fibrous cartilage pad and peripheral hyaline cartilage within the kangaroo medial tibial plateau. It provided insights into the microstructure and composition of the fibrous and peripheral hyaline cartilage in relation to the unique mechanical properties of the tissues to provide for the normal activities of kangaroos.

  8. Microstructural and compositional features of the fibrous and hyaline cartilage on the medial tibial plateau imply a unique role for the hopping locomotion of kangaroo.

    Science.gov (United States)

    He, Bo; Wu, Jian Ping; Xu, Jiake; Day, Robert E; Kirk, Thomas Brett

    2013-01-01

    Hopping provides efficient and energy saving locomotion for kangaroos, but it results in great forces in the knee joints. A previous study has suggested that a unique fibrous cartilage in the central region of the tibial cartilage could serve to decrease the peak stresses generated within kangaroo tibiofemoral joints. However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined. The present study showed that the fibrous cartilage was thicker and had a lower chondrocyte density than the hyaline cartilage. Despite having a higher PG content in the middle and deep zones, the fibrous cartilage had an inferior compressive strength compared to the peripheral hyaline cartilage. The fibrous cartilage had a complex three dimensional collagen meshwork with collagen bundles parallel to the surface in the superficial zone, and with collagen bundles both parallel and perpendicular to the surface in the middle and deep zones. The collagen in the hyaline cartilage displayed a typical Benninghoff structure, with collagen fibres parallel to the surface in the superficial zone and collagen fibres perpendicular to the surface in the deep zone. Elastin fibres were found throughout the entire tissue depth of the fibrous cartilage and displayed a similar alignment to the adjacent collagen bundles. In comparison, the elastin fibres in the hyaline cartilage were confined within the superficial zone. This study examined for the first time the fibrillary structure, PG content and compressive properties of the central fibrous cartilage pad and peripheral hyaline cartilage within the kangaroo medial tibial plateau. It provided insights into the microstructure and composition of the fibrous and peripheral hyaline cartilage in relation to the unique mechanical properties of the tissues to provide for the normal activities of kangaroos.

  9. Engineering of hyaline cartilage with a calcified zone using bone marrow stromal cells.

    Science.gov (United States)

    Lee, W D; Hurtig, M B; Pilliar, R M; Stanford, W L; Kandel, R A

    2015-08-01

    In healthy joints, a zone of calcified cartilage (ZCC) provides the mechanical integration between articular cartilage and subchondral bone. Recapitulation of this architectural feature should serve to resist the constant shear force from the movement of the joint and prevent the delamination of tissue-engineered cartilage. Previous approaches to create the ZCC at the cartilage-substrate interface have relied on strategic use of exogenous scaffolds and adhesives, which are susceptible to failure by degradation and wear. In contrast, we report a successful scaffold-free engineering of ZCC to integrate tissue-engineered cartilage and a porous biodegradable bone substitute, using sheep bone marrow stromal cells (BMSCs) as the cell source for both cartilaginous zones. BMSCs were predifferentiated to chondrocytes, harvested and then grown on a porous calcium polyphosphate substrate in the presence of triiodothyronine (T3). T3 was withdrawn, and additional predifferentiated chondrocytes were placed on top of the construct and grown for 21 days. This protocol yielded two distinct zones: hyaline cartilage that accumulated proteoglycans and collagen type II, and calcified cartilage adjacent to the substrate that additionally accumulated mineral and collagen type X. Constructs with the calcified interface had comparable compressive strength to native sheep osteochondral tissue and higher interfacial shear strength compared to control without a calcified zone. This protocol improves on the existing scaffold-free approaches to cartilage tissue engineering by incorporating a calcified zone. Since this protocol employs no xenogeneic material, it will be appropriate for use in preclinical large-animal studies. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  10. Hyaline cartilage thickness in radiographically normal cadaveric hips: comparison of spiral CT arthrographic and macroscopic measurements.

    Science.gov (United States)

    Wyler, Annabelle; Bousson, Valérie; Bergot, Catherine; Polivka, Marc; Leveque, Eric; Vicaut, Eric; Laredo, Jean-Denis

    2007-02-01

    To assess spiral multidetector computed tomographic (CT) arthrography for the depiction of cartilage thickness in hips without cartilage loss, with evaluation of anatomic slices as the reference standard. Permission to perform imaging studies in cadaveric specimens of individuals who had willed their bodies to science was obtained from the institutional review board. Two independent observers measured the femoral and acetabular hyaline cartilage thickness of 12 radiographically normal cadaveric hips (from six women and five men; age range at death, 52-98 years; mean, 76.5 years) on spiral multidetector CT arthrographic reformations and on coronal anatomic slices. Regions of cartilage loss at gross or histologic examination were excluded. CT arthrographic and anatomic measurements in the coronal plane were compared by using Bland-Altman representation and a paired t test. Differences between mean cartilage thicknesses at the points of measurement were tested by means of analysis of variance. Interobserver and intraobserver reproducibilities were determined. At CT arthrography, mean cartilage thickness ranged from 0.32 to 2.53 mm on the femoral head and from 0.95 to 3.13 mm on the acetabulum. Observers underestimated cartilage thickness in the coronal plane by 0.30 mm +/- 0.52 (mean +/- standard error) at CT arthrography (P cartilage thicknesses at the different measurement points was significant for coronal spiral multidetector CT arthrography and anatomic measurement of the femoral head and acetabulum and for sagittal and transverse CT arthrography of the femoral head (P cartilage thickness from the periphery to the center of the joint ("gradients") were found by means of spiral multidetector CT arthrography and anatomic measurement. Spiral multidetector CT arthrography depicts cartilage thickness gradients in radiographically normal cadaveric hips. (c) RSNA, 2007.

  11. Mechanical vibrations of pendant liquid droplets

    OpenAIRE

    Temperton, Robert H.; Smith, Michael I.; Sharp, James S.

    2015-01-01

    A simple optical deflection technique was used to monitor the vibrations of microlitre pendant droplets of deuterium oxide, formamide, and 1,1,2,2-tetrabromoethane. Droplets of different volumes of each liquid were suspended from the end of a microlitre pipette and vibrated using a small puff of nitrogen gas. A laser was passed through the droplets and the scattered light was collected using a photodiode. Vibration of the droplets resulted in the motion of the scattered beam and time-dependen...

  12. Dynamics of Droplet Motion under Electrowetting Actuation

    OpenAIRE

    Annapragada, S. Ravi; Dash, Susmita; Garimella, Suresh V.; Murthy, Jayathi Y.

    2011-01-01

    The static shape of droplets under electrowetting actuation is well understood. The steady-state shape of the droplet is obtained on the basis of the balance of surface tension and electrowetting forces, and the change in the apparent contact angle is well characterized by the Young-Lippmann equation However, the transient droplet shape behavior when a voltage is suddenly applied across a droplet has received less attention. Additional dynamic frictional forces are at play during this transie...

  13. Droplet centrifugation, droplet DNA extraction, and rapid droplet thermocycling for simpler and faster PCR assay using wire-guided manipulations

    Directory of Open Access Journals (Sweden)

    You David J

    2012-09-01

    Full Text Available Abstract A computer numerical control (CNC apparatus was used to perform droplet centrifugation, droplet DNA extraction, and rapid droplet thermocycling on a single superhydrophobic surface and a multi-chambered PCB heater. Droplets were manipulated using “wire-guided” method (a pipette tip was used in this study. This methodology can be easily adapted to existing commercial robotic pipetting system, while demonstrated added capabilities such as vibrational mixing, high-speed centrifuging of droplets, simple DNA extraction utilizing the hydrophobicity difference between the tip and the superhydrophobic surface, and rapid thermocycling with a moving droplet, all with wire-guided droplet manipulations on a superhydrophobic surface and a multi-chambered PCB heater (i.e., not on a 96-well plate. Serial dilutions were demonstrated for diluting sample matrix. Centrifuging was demonstrated by rotating a 10 μL droplet at 2300 round per minute, concentrating E. coli by more than 3-fold within 3 min. DNA extraction was demonstrated from E. coli sample utilizing the disposable pipette tip to cleverly attract the extracted DNA from the droplet residing on a superhydrophobic surface, which took less than 10 min. Following extraction, the 1500 bp sequence of Peptidase D from E. coli was amplified using rapid droplet thermocycling, which took 10 min for 30 cycles. The total assay time was 23 min, including droplet centrifugation, droplet DNA extraction and rapid droplet thermocycling. Evaporation from of 10 μL droplets was not significant during these procedures, since the longest time exposure to air and the vibrations was less than 5 min (during DNA extraction. The results of these sequentially executed processes were analyzed using gel electrophoresis. Thus, this work demonstrates the adaptability of the system to replace many common laboratory tasks on a single platform (through re-programmability, in rapid succession (using droplets

  14. Floating Droplet Array: An Ultrahigh-Throughput Device for Droplet Trapping, Real-time Analysisand Recovery

    Directory of Open Access Journals (Sweden)

    Louai Labanieh

    2015-09-01

    Full Text Available We describe the design, fabrication and use of a dual-layered microfluidic device for ultrahigh-throughput droplet trapping, analysis, and recovery using droplet buoyancy. To demonstrate the utility of this device for digital quantification of analytes, we quantify the number of droplets, which contain a β-galactosidase-conjugated bead among more than 100,000 immobilized droplets. In addition, we demonstrate that this device can be used for droplet clustering and real-time analysis by clustering several droplets together into microwells and monitoring diffusion of fluorescein, a product of the enzymatic reaction of β-galactosidase and its fluorogenic substrate FDG, between droplets.

  15. Sophisticated compound droplets on fiber networks

    Science.gov (United States)

    Weyer, Floriane; Lismont, Marjorie; Dreesen, Laurent; Vandewalle, Nicolas

    2015-11-01

    Droplets on fibers are part of our everyday lives. Indeed, many phenomena involve drops and fibers such as the formation of dew droplets on a spiderweb, the trapping of water droplets on cactus spines or the dyeing of cotton or wool fibers. Therefore, this topic has been widely studied in the recent years and it appears that droplets on fibers can be the starting point for an open digital microfluidics. We study the behavior of soapy water droplets on a fiber array. When a droplet slides along a vertical fiber and encounters a horizontal fiber, it can either stick there or continue its way. In the latter case, the droplet releases a tiny residue. We study the volume of these residues depending on the geometry of the node. By using this technique, a large number of small droplets can be trapped at the nodes of a fiber array. These residues can be encapsulated and collected by an oil droplet in order to create a multicompound droplet. Moreover, by using optical fibers, we can provoke and detect the fluorescence of the inner droplets. Fibers provide therefore an original way to study compound droplets and multiple reactions. F. Weyer is financially supported by an FNRS grant. This work is also supported by the FRFC 2.4504.12.

  16. Droplet size influences division of mammalian cell factories in droplet microfluidic cultivation

    DEFF Research Database (Denmark)

    Periyannan Rajeswari, Prem Kumar; Joensson, Haakan N.; Svahn, Helene Andersson

    2017-01-01

    The potential of using droplet microfluidics for screening mammalian cell factories has been limited by the difficulty in achieving continuous cell division during cultivation in droplets. Here, we report the influence of droplet size on mammalian cell division and viability during cultivation...... in droplets. Chinese Hamster Ovary (CHO) cells, the most widely used mammalian host cells for biopharmaceuticals production were encapsulated and cultivated in 33, 180 and 320 pL droplets for 3 days. Periodic monitoring of the droplets during incubation showed that the cell divisions in 33 pL droplets stopped...... after 24 h, whereas continuous cell division was observed in 180 and 320 pL droplets for 72 h. The viability of the cells cultivated in the 33 pL droplets also dropped to about 50% in 72 h. In contrast, the viability of the cells in the larger droplets was above 90% even after 72 h of cultivation...

  17. Droplet based cavities and lasers

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Kristensen, Anders; Mortensen, Asger

    2009-01-01

    The self-organized and molecularly smooth surface on liquid microdroplets makes them attractive as optical cavities with very high quality factors. This chapter describes the basic theory of optical modes in spherical droplets. The mechanical properties including vibrational excitation are also d...

  18. Droplets, Bubbles and Ultrasound Interactions

    NARCIS (Netherlands)

    Shpak, O.; Verweij, M.; Jong, de N.; Versluis, M.; Escoffre, J.M.; Bouakaz, A.

    2016-01-01

    The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to

  19. Salt stains from evaporating droplets

    NARCIS (Netherlands)

    Shahidzadeh, N.; Schut, M.F.L.; Desarnaud, J.; Prat, M.; Bonn, D.

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls, but also very important in many applications such as purification of pharmaceuticals, deicing of

  20. Salt stains from evaporating droplets

    NARCIS (Netherlands)

    Shahidzadeh, N.; Schut, M.F.L.; Desarnaud, J.; Prat, M.; Bonn, D.

    2015-01-01

    The study of the behavior of sessile droplets on solid substrates is not only associated with common everyday phenomena, such as the coffee stain effect, limescale deposits on our bathroom walls, but also very important in many applications such as purification of pharmaceuticals, deicing of airplan

  1. Shock wave-droplet interaction

    Science.gov (United States)

    Habibi Khoshmehr, Hamed; Krechetnikov, Rouslan

    2016-11-01

    Disintegration of a liquid droplet under the action of a shock wave is experimentally investigated. The shock wave-pulse is electromagnetically generated by discharging a high voltage capacitor into a flat spiral coil, above which an isolated circular metal membrane is placed in a close proximity. The Lorentz force arising due to the eddy current induced in the membrane abruptly accelerates it away from the spiral coil thus generating a shock wave. The liquid droplet placed at the center of the membrane, where the maximum deflection occurs, is disintegrated in the process of interaction with the shock wave. The effects of droplet viscosity and surface tension on the droplet destruction are studied with high-speed photography. Water-glycerol solution at different concentrations is used for investigating the effect of viscosity and various concentrations of water-sugar and water-ethanol solution are used for studying the effect of surface tension. Here we report on how the metamorphoses, which a liquid drop undergoes in the process of interaction with a shock wave, are affected by varied viscosity and surface tension.

  2. Chitosan-glycerol phosphate/blood implants elicit hyaline cartilage repair integrated with porous subchondral bone in microdrilled rabbit defects.

    Science.gov (United States)

    Hoemann, C D; Sun, J; McKee, M D; Chevrier, A; Rossomacha, E; Rivard, G-E; Hurtig, M; Buschmann, M D

    2007-01-01

    We have previously shown that microfractured ovine defects are repaired with more hyaline cartilage when the defect is treated with in situ-solidified implants of chitosan-glycerol phosphate (chitosan-GP) mixed with autologous whole blood. The objectives of this study were (1) to characterize chitosan-GP/blood clots in vitro, and (2) to develop a rabbit marrow stimulation model in order to determine the effects of the chitosan-GP/blood implant and of debridement on the formation of incipient cartilage repair tissue. Blood clots were characterized by histology and in vitro clot retraction tests. Bilateral 3.5 x 4 mm trochlear defects debrided into the calcified layer were pierced with four microdrill holes and filled with a chitosan-GP/blood implant or allowed to bleed freely as a control. At 1 day post-surgery, initial defects were characterized by histomorphometry (n=3). After 8 weeks of repair, osteochondral repair tissues between or through the drill holes were evaluated by histology, histomorphometry, collagen type II expression, and stereology (n=16). Chitosan-GP solutions structurally stabilized the blood clots by inhibiting clot retraction. Treatment of drilled defects with chitosan-GP/blood clots led to the formation of a more integrated and hyaline repair tissue above a more porous and vascularized subchondral bone plate compared to drilling alone. Correlation analysis of repair tissue between the drill holes revealed that the absence of calcified cartilage and the presence of a porous subchondral bone plate were predictors of greater repair tissue integration with subchondral bone (Phyaline and integrated repair tissue associated with a porous subchondral bone replete with blood vessels. Concomitant regeneration of a vascularized bone plate during cartilage repair could provide progenitors, anabolic factors and nutrients that aid in the formation of hyaline cartilage.

  3. 新生儿肺透明膜病的护理%Nursing care for neonates with hyaline membrane disease

    Institute of Scientific and Technical Information of China (English)

    黎婷; 彭间英; 罗冰贤

    2013-01-01

    目的 总结讨论新生儿肺透明膜病的护理体会,加强护理意识与方法.方法 对我院收治的82例新生儿肺透明膜病患儿进行系统的回顾性分析,对其护理方法进行总结.结果 经过采取综合护理后大部分患儿康复出院,少数患儿发生并发症,其中4例因肺出血合并弥漫性血管内凝血(DIC)死亡.结论 在积极治疗新生儿肺透明膜病的过程中,采取行之有效的综合护理可显著降低其病死率,提高生存率.%Objective To summarize the nursing experience on neonates with hyaline membrane disease,and to strengthen nursing consciousness and measures.Methods The data on 82 neonates with hyaline membrane disease who had been treated in our hospital were retrospectively analyzed.The nursing methods were summarized.Results After receiving comprehensive nursing care,most of the infants were discharged with rehabilitation.Complications occurred in a few of patients,4 of whom were dead due to pulmonary hemorrhage complicated by disseminated intravascular coagulation (DIC).Conclusions Effective nursing care can significantly reduce the mortality rate and improve the survival rate in the treatment of neonates with hyaline membrane disease.

  4. Droplet size distribution in homogeneous isotropic turbulence

    Science.gov (United States)

    Perlekar, Prasad; Biferale, Luca; Sbragaglia, Mauro; Srivastava, Sudhir; Toschi, Federico

    2012-06-01

    We study the physics of droplet breakup in a statistically stationary homogeneous and isotropic turbulent flow by means of high resolution numerical investigations based on the multicomponent lattice Boltzmann method. We verified the validity of the criterion proposed by Hinze [AIChE J. 1, 289 (1955)] for droplet breakup and we measured the full probability distribution function of droplets radii at different Reynolds numbers and for different volume fractions. By means of a Lagrangian tracking we could follow individual droplets along their trajectories, define a local Weber number based on the velocity gradients, and study its cross-correlation with droplet deformation.

  5. Cartilage T2 assessment: differentiation of normal hyaline cartilage and reparative tissue after arthroscopic cartilage repair in equine subjects.

    Science.gov (United States)

    White, Lawrence M; Sussman, Marshall S; Hurtig, Mark; Probyn, Linda; Tomlinson, George; Kandel, Rita

    2006-11-01

    To prospectively assess T2 mapping characteristics of normal articular cartilage and of cartilage at sites of arthroscopic repair, including comparison with histologic results and collagen organization assessed at polarized light microscopy (PLM). Study protocol was compliant with the Canadian Council on Animal Care Guidelines and approved by the institutional animal care committee. Arthroscopic osteochondral autograft transplantation (OAT) and microfracture arthroplasty (MFx) were performed in knees of 10 equine subjects (seven female, three male; age range, 3-5 years). A site of arthroscopically normal cartilage was documented in each joint as a control site. Joints were harvested at 12 (n = 5) and 24 (n = 5) weeks postoperatively and were imaged at 1.5-T magnetic resonance (MR) with a 10-echo sagittal fast spin-echo acquisition. T2 maps of each site (21 OAT harvest, 10 MFx, 12 OAT plug, and 10 control sites) were calculated with linear least-squares curve fitting. Cartilage T2 maps were qualitatively graded as "organized" (normal transition of low-to-high T2 signal from deep to superficial cartilage zones) or "disorganized." Quantitative mean T2 values were calculated for deep, middle, and superficial cartilage at each location. Results were compared with histologic and PLM assessments by using kappa analysis. T2 maps were qualitatively graded as organized at 20 of 53 sites and as disorganized at 33 sites. Perfect agreement was seen between organized T2 and histologic findings of hyaline cartilage and between disorganized T2 and histologic findings of fibrous reparative tissue (kappa = 1.0). Strong agreement was seen between organized T2 and normal PLM findings and between disorganized T2 and abnormal PLM findings (kappa = .92). Quantitative assessment of the deep, middle, and superficial cartilage, respectively, showed mean T2 values of 53.3, 58.6, and 54.9 msec at reparative fibrous tissue sites and 40.7, 53.6, and 61.6 msec at hyaline cartilage sites. A

  6. Dynamics of droplet motion under electrowetting actuation.

    Science.gov (United States)

    Annapragada, S Ravi; Dash, Susmita; Garimella, Suresh V; Murthy, Jayathi Y

    2011-07-05

    The static shape of droplets under electrowetting actuation is well understood. The steady-state shape of the droplet is obtained on the basis of the balance of surface tension and electrowetting forces, and the change in the apparent contact angle is well characterized by the Young-Lippmann equation. However, the transient droplet shape behavior when a voltage is suddenly applied across a droplet has received less attention. Additional dynamic frictional forces are at play during this transient process. We present a model to predict this transient behavior of the droplet shape under electrowetting actuation. The droplet shape is modeled using the volume of fluid method. The electrowetting and dynamic frictional forces are included as an effective dynamic contact angle through a force balance at the contact line. The model is used to predict the transient behavior of water droplets on smooth hydrophobic surfaces under electrowetting actuation. The predictions of the transient behavior of droplet shape and contact radius are in excellent agreement with our experimental measurements. The internal fluid motion is explained, and the droplet motion is shown to initiate from the contact line. An approximate mathematical model is also developed to understand the physics of the droplet motion and to describe the overall droplet motion and the contact line velocities.

  7. Thermophoresis of water droplets inside carbon nanotubes

    Science.gov (United States)

    Zambrano, Harvey; Walther, Jh; Oyarzua, Elton; Rojano, Andres

    2016-11-01

    Carbon Nanotubes (CNTs) offer unique possibilities as fluid conduits with applications ranging from lab on a chip devices to encapsulation media for drug delivery. CNTs feature high mechanical strength, chemical and thermal stability and biocompatibility therefore they are promising candidates for nanodevice fabrication. Thermal gradients have been proposed as mechanism to drive particles, fullerenes and droplets inside CNTs. Here, by conducting Molecular Dynamics (MD) simulations, we study thermophoresis of water droplets inside CNTs. We systematically change the size of the droplets, the axial thermal gradient and CNT chirality. We find that the droplet motion in the armchair CNTs exhibits two clearly delimited stages, a regime wherein the droplet is accelerated and subsequently, a regime wherein the droplet moves with constant velocity. Inside the zig zag CNTs, the droplet accelerates during a very short time and then it moves with constant velocity. We compute the net force during the droplet acceleration and find a correlation between the droplet acceleration and the magnitude of the thermal gradient without any dependence on the droplet size. Moreover, we conduct velocity constrained MD simulations to determine the friction and thermophoretic forces acting on the droplet. We acknowledge partial funding from FONDECYT through the Project No. 11130559 and from VRID Universidad de Concepcion.

  8. Droplet lasers: a review of current progress

    Science.gov (United States)

    McGloin, D.

    2017-05-01

    It is perhaps surprising that something as fragile as a microscopic droplet could possibly form a laser. In this article we will review some of the underpinning physics as to how this might be possible, and then examine the state of the art in the field. The technology to create and manipulate droplets will be examined, as will the different classes of droplet lasers. We discuss the rapidly developing fields of droplet biolasers, liquid crystal laser droplets and explore how droplet lasers could give rise to new bio and chemical sensing and analysis. The challenges that droplet lasers face in becoming robust devices, either as sensors or as photonic components in the lab on chip devices, is assessed.

  9. Enhanced Droplet Control by Transition Boiling

    Science.gov (United States)

    Grounds, Alex; Still, Richard; Takashina, Kei

    2012-10-01

    A droplet of water on a heated surface can levitate over a film of gas produced by its own evaporation in the Leidenfrost effect. When the surface is prepared with ratchet-like saw-teeth topography, these droplets can self-propel and can even climb uphill. However, the extent to which the droplets can be controlled is limited by the physics of the Leidenfrost effect. Here, we show that transition boiling can be induced even at very high surface temperatures and provide additional control over the droplets. Ratchets with acute protrusions enable droplets to climb steeper inclines while ratchets with sub-structures enable their direction of motion to be controlled by varying the temperature of the surface. The droplets' departure from the Leidenfrost regime is assessed by analysing the sound produced by their boiling. We anticipate these techniques will enable the development of more sophisticated methods for controlling small droplets and heat transfer.

  10. Uptake of water droplets by nonwetting capillaries

    CERN Document Server

    Willmott, Geoff R; Hendy, Shaun C

    2010-01-01

    We present direct experimental evidence that water droplets can spontaneously penetrate non-wetting capillaries, driven by the action of Laplace pressure due to high droplet curvature. Using high-speed optical imaging, microcapillaries of radius 50 to 150 micron, and water microdroplets of average radius between 100 and 1900 micron, we demonstrate that there is a critical droplet radius below which water droplets can be taken up by hydrophobised glass and polytetrafluoroethylene (PTFE) capillaries. The rate of capillary uptake is shown to depend strongly on droplet size, with smaller droplets being absorbed more quickly. Droplet size is also shown to influence meniscus motion in a pre-filled non-wetting capillary, and quantitative measurements of this effect result in a derived water-PTFE static contact angle between 96 degrees and 114 degrees. Our measurements confirm recent theoretical predictions and simulations for metal nanodroplets penetrating carbon nanotubes (CNTs). The results are relevant to a wide ...

  11. Dancing droplets: Contact angle, drag, and confinement

    Science.gov (United States)

    Benusiglio, Adrien; Cira, Nate; Prakash, Manu

    2015-11-01

    When deposited on a clean glass slide, a mixture of water and propylene glycol forms a droplet of given contact angle, when both pure liquids spread. (Cira, Benusiglio, Prakash: Nature, 2015). The droplet is stabilized by a gradient of surface tension due to evaporation that induces a Marangoni flow from the border to the apex of the droplets. The apparent contact angle of the droplets depends on both their composition and the external humidity as captured by simple models. These droplets present remarkable properties such as lack of a large pinning force. We discuss the drag on these droplets as a function of various parameters. We show theoretical and experimental results of how various confinement geometries change the vapor gradient and the dynamics of droplet attraction.

  12. Leidenfrost droplets in an electric field

    Science.gov (United States)

    Wildeman, Sander; Sun, Chao; Lohse, Detlef

    2014-11-01

    In a recent video broadcast dubbed the ``Knitting Needle Experiment,'' astronaut Don Petit aboard the ISS demonstrated how weightless water droplets can be made to orbit a statically charged Teflon rod. We study the earthly analogue of mobile droplets in an electric field, whereby the mobility is ensured by a thin vapor film sustained between the droplet and a hot plate (the Leidenfrost effect). We find that in a strong vertical electric field the droplet starts to bounce progressively higher, defying gravitational attraction. From its trajectory we can deduce the temporal evolution of the charge on the droplet. The measurements show that the charge starts high and then decreases in a step-like manner as the droplet evaporates. The discharge trend is predicted well by treating the droplet as a dielectric sphere in electrical contact with the hot plate, but the mechanism by which definite lumps of charge are transferred through the vapor film is still an open question.

  13. Dancing droplets: Autonomous surface tension-driven droplet motion

    OpenAIRE

    Cira, Nate J.; Benusiglio, Adrien; Prakash, Manu

    2014-01-01

    International audience; When droplets of water and food coloring at different concentrations are deposited on a clean glass slide they enter a complex dance. We reproduce this phenomenon by using a two-component mixture of propylene glycol and water deposited on corona treated (Electro-TechnicBD-20AC) glass slides and record the phenomena using a Cannon 5D Mark II camera with a 50mm macro lens

  14. Chitosan-glycerol phosphate/blood implants improve hyaline cartilage repair in ovine microfracture defects.

    Science.gov (United States)

    Hoemann, Caroline D; Hurtig, Mark; Rossomacha, Evgeny; Sun, Jun; Chevrier, Anik; Shive, Matthew S; Buschmann, Michael D

    2005-12-01

    one hour postoperatively, chitosan-glycerol phosphate/blood clots showed increased adhesion to the walls of the defects as compared with the blood clots in the untreated microfracture defects. After histological processing, all blood clots in the control microfracture defects had been lost, whereas chitosanglycerol phosphate/blood clot adhered to and was partly retained on the surfaces of the defect. At six months, defects that had been treated with chitosan-glycerol phosphate/blood were filled with significantly more hyaline repair tissue (p cartilage repair compared with microfracture alone by increasing the amount of tissue and improving its biochemical composition and cellular organization.

  15. Reconstruction of Hyaline Cartilage Deep Layer Properties in 3-Dimensional Cultures of Human Articular Chondrocytes.

    Science.gov (United States)

    Nanduri, Vibudha; Tattikota, Surendra Mohan; T, Avinash Raj; Sriramagiri, Vijaya Rama Rao; Kantipudi, Suma; Pande, Gopal

    2014-06-01

    Articular cartilage (AC) injuries and malformations are commonly noticed because of trauma or age-related degeneration. Many methods have been adopted for replacing or repairing the damaged tissue. Currently available AC repair methods, in several cases, fail to yield good-quality long-lasting results, perhaps because the reconstructed tissue lacks the cellular and matrix properties seen in hyaline cartilage (HC). To reconstruct HC tissue from 2-dimensional (2D) and 3-dimensional (3D) cultures of AC-derived human chondrocytes that would specifically exhibit the cellular and biochemical properties of the deep layer of HC. Descriptive laboratory study. Two-dimensional cultures of human AC-derived chondrocytes were established in classical medium (CM) and newly defined medium (NDM) and maintained for a period of 6 weeks. These cells were suspended in 2 mm-thick collagen I gels, placed in 24-well culture inserts, and further cultured up to 30 days. Properties of chondrocytes, grown in 2D cultures and the reconstructed 3D cartilage tissue, were studied by optical and scanning electron microscopic techniques, immunohistochemistry, and cartilage-specific gene expression profiling by reverse transcription polymerase chain reaction and were compared with those of the deep layer of native human AC. Two-dimensional chondrocyte cultures grown in NDM, in comparison with those grown in CM, showed more chondrocyte-specific gene activity and matrix properties. The NDM-grown chondrocytes in 3D cultures also showed better reproduction of deep layer properties of HC, as confirmed by microscopic and gene expression analysis. The method used in this study can yield cartilage tissue up to approximately 1.6 cm in diameter and 2 mm in thickness that satisfies the very low cell density and matrix composition properties present in the deep layer of normal HC. This study presents a novel and reproducible method for long-term culture of AC-derived chondrocytes and reconstruction of cartilage

  16. Granuloma hialinizante de pulmão recidivante Recurrent pulmonary hyalinizing granuloma

    Directory of Open Access Journals (Sweden)

    Guilherme D'Andréa Saba Arruda

    2010-10-01

    Full Text Available Relatamos o caso de um paciente de 61 anos, masculino, internado com objetivo de exérese de massa pulmonar para estudo anatomopatológico. O paciente apresentara anteriormente um quadro de febre, tosse seca e dor torácica, associado à presença de massas pulmonares detectadas por radiografia de tórax, tendo sido submetido em duas ocasiões (1976 e 1981 a toracotomia para a investigação diagnóstica, sem diagnóstico anatomopatológico conclusivo. A TC de tórax revelou volumosas massas com áreas de calcificação em ambos os campos pulmonares. O material do estudo anatomopatológico foi compatível com granuloma hialinizante de pulmão. No pós-operatório, o paciente apresentou vários episódios de broncoespasmo que foram revertidos com medicação sintomática. Foi mantido com prednisona na dose de 40 mg/dia com boa evolução clínica até o envio deste relato.We report the case of a 61-year-old male patient who underwent surgical excision of a lung mass for anatomopathological study. The patient had previously presented with fever, dry cough, and chest pain, together with lung masses detected by chest X-ray, and had undergone thoracotomy for diagnostic investigation on two occasions (1976 and 1981, although a conclusive diagnosis had not been made. A CT scan of the chest revealed large masses with areas of calcification in both lung fields. The anatomopathological study was consistent with pulmonary hyalinizing granuloma. In the postoperative period, the patient experienced several episodes of bronchospasm, which was reversible with the use of symptomatic medication. At this writing, the patient was receiving maintenance therapy with prednisone (40 mg/day and had shown clinical improvement.

  17. Integrated microfluidic system capable of size-specific droplet generation with size-dependent droplet separation.

    Science.gov (United States)

    Lee, Sangmin; Hong, Seok Jun; Yoo, Hyung Jung; Ahn, Jae Hyun; Cho, Dong-il Dan

    2013-06-01

    Droplet-based microfluidics is receiving much attention in biomedical research area due to its advantage in uniform size droplet generation. Our previous results have reported that droplet size plays an important role in drug delivery actuated by flagellated bacteria. Recently, many research groups have been reported the size-dependent separation of emulsion droplets by a microfluidic system. In this paper, an integrated microfluidic system is proposed to produce and sort specificsized droplets sequentially. Operation of the system relies on two microfluidic transport processes: initial generation of droplets by hydrodynamic focusing and subsequent separation of droplets by a T-junction channel. The microfluidic system is fabricated by the SU-8 rapid prototyping method and poly-di-methyl-siloxane (PDMS) replica molding. A biodegradable polymer, poly-capro-lactone (PCL), is used for the droplet material. Using the proposed integrated microfluidic system, specific-sized droplets which can be delivered by flagellated bacteria are successfully generated and obtained.

  18. Shape-Shifting Droplet Networks

    Science.gov (United States)

    Zhang, T.; Wan, Duanduan; Schwarz, J. M.; Bowick, M. J.

    2016-03-01

    We consider a three-dimensional network of aqueous droplets joined by single lipid bilayers to form a cohesive, tissuelike material. The droplets in these networks can be programed to have distinct osmolarities so that osmotic gradients generate internal stresses via local fluid flows to cause the network to change shape. We discover, using molecular dynamics simulations, a reversible folding-unfolding process by adding an osmotic interaction with the surrounding environment which necessarily evolves dynamically as the shape of the network changes. This discovery is the next important step towards osmotic robotics in this system. We also explore analytically and numerically how the networks become faceted via buckling and how quasi-one-dimensional networks become three dimensional.

  19. Walking droplets in confined geometries

    Science.gov (United States)

    Filoux, Boris; Mathieu, Olivier; Vandewalle, Nicolas

    2014-11-01

    When gently placing a droplet onto a vertically vibrated bath, coalescence may be avoided: the drop bounces permanently. Upon increasing forcing acceleration, a drop interacts with the wave it generates, and becomes a ``walker'' with a well defined velocity. In this work, we investigate the confinement of a walker in a mono-dimensional geometry. The system consists of linear submarine channels used as waveguides for a walker. By studying the dynamics of walkers in those channels, we discover some 1D-2D transition. We also propose a model based on an analogy with ``Quantum Wires.'' Finally, we consider the situation of a walker in a circular submarine channel, and examine the behavior of several walking droplets in this system. We show the quantization of the drop distances, and correlate it to their bouncing modes.

  20. Annulus Fibrosus Can Strip Hyaline Cartilage End Plate from Subchondral Bone: A Study of the Intervertebral Disk in Tension.

    Science.gov (United States)

    Balkovec, Christian; Adams, Michael A; Dolan, Patricia; McGill, Stuart M

    2015-10-01

    Study Design Biomechanical study on cadaveric spines. Objective Spinal bending causes the annulus to pull vertically (axially) on the end plate, but failure mechanisms in response to this type of loading are poorly understood. Therefore, the objective of this study was to identify the weak point of the intervertebral disk in tension. Methods Cadaveric motion segments (aged 79 to 88 years) were dissected to create midsagittal blocks of tissue, with ∼10 mm of bone superior and inferior to the disk. From these blocks, 14 bone-disk-bone slices (average 4.8 mm thick) were cut in the frontal plane. Each slice was gripped by its bony ends and stretched to failure at 1 mm/s. Mode of failure was recorded using a digital camera. Results Of the 14 slices, 10 failed by the hyaline cartilage being peeled off the subchondral bone, with the failure starting opposite the lateral annulus and proceeding medially. Two slices failed by rupturing of the trabecular bone, and a further two failed in the annulus. Conclusions The hyaline cartilage-bone junction is the disk's weak link in tension. These findings provide a plausible mechanism for the appearance of bone and cartilage fragments in herniated material. Stripping cartilage from the bony end plate would result in the herniated mass containing relatively stiff cartilage that does not easily resorb.

  1. Effect of exercise on thicknesses of mature hyaline cartilage, calcified cartilage, and subchondral bone of equine tarsi.

    Science.gov (United States)

    Tranquille, Carolyne A; Blunden, Antony S; Dyson, Sue J; Parkin, Tim D H; Goodship, Allen E; Murray, Rachel C

    2009-12-01

    OBJECTIVE-To investigate effects of exercise on hyaline cartilage (HC), calcified cartilage (CC), and subchondral bone (SCB) thickness patterns of equine tarsi. SAMPLE POPULATION-30 tarsi from cadavers of horses with known exercise history. PROCEDURES-Tarsi were assigned to 3 groups according to known exercise history as follows: pasture exercise only (PE tarsi), low-intensity general-purpose riding exercise (LE tarsi), and high-intensity elite competition riding exercise (EE tarsi). Osteochondral tissue from distal tarsal joints underwent histologic preparation. Hyaline cartilage, CC, and SCB thickness were measured at standard sites at medial, midline, and lateral locations across joints with a histomorphometric technique. RESULTS-HC, CC, and SCB thickness were significantly greater at all sites in EE tarsi, compared with PE tarsi; this was also true when LE tarsi were compared with PE tarsi. At specific sites, HC, CC, and SCB were significantly thicker in EE tarsi, compared with LE tarsi. Along the articular surface of the proximal aspect of the third metatarsal bone, SCB was thickest in EE tarsi and thinnest in LE tarsi; increases were greatest at sites previously reported to undergo peak strains and osteochondral damage. CONCLUSIONS AND CLINICAL RELEVANCE-Increased exercise was associated with increased HC, CC, and SCB thickness in mature horses. At sites that undergo high compressive strains, with a reported predisposition to osteoarthritic change, there was increased CC and SCB thickness. These results may provide insight into the interaction between adaptive response to exercise and pathological change.

  2. Regeneration of hyaline cartilage promoted by xenogeneic mesenchymal stromal cells embedded within elastin-like recombinamer-based bioactive hydrogels.

    Science.gov (United States)

    Pescador, David; Ibáñez-Fonseca, Arturo; Sánchez-Guijo, Fermín; Briñón, Jesús G; Arias, Francisco Javier; Muntión, Sandra; Hernández, Cristina; Girotti, Alessandra; Alonso, Matilde; Del Cañizo, María Consuelo; Rodríguez-Cabello, José Carlos; Blanco, Juan Francisco

    2017-08-01

    Over the last decades, novel therapeutic tools for osteochondral regeneration have arisen from the combination of mesenchymal stromal cells (MSCs) and highly specialized smart biomaterials, such as hydrogel-forming elastin-like recombinamers (ELRs), which could serve as cell-carriers. Herein, we evaluate the delivery of xenogeneic human MSCs (hMSCs) within an injectable ELR-based hydrogel carrier for osteochondral regeneration in rabbits. First, a critical-size osteochondral defect was created in the femora of the animals and subsequently filled with the ELR-based hydrogel alone or with embedded hMSCs. Regeneration outcomes were evaluated after three months by gross assessment, magnetic resonance imaging and computed tomography, showing complete filling of the defect and the de novo formation of hyaline-like cartilage and subchondral bone in the hMSC-treated knees. Furthermore, histological sectioning and staining of every sample confirmed regeneration of the full cartilage thickness and early subchondral bone repair, which was more similar to the native cartilage in the case of the cell-loaded ELR-based hydrogel. Overall histological differences between the two groups were assessed semi-quantitatively using the Wakitani scale and found to be statistically significant (p hyaline cartilage in osteochondral lesions.

  3. Effect of low-dose irradiation on structural and mechanical properties of hyaline cartilage-like fibrocartilage.

    Science.gov (United States)

    Öncan, Tevfik; Demirağ, Burak; Ermutlu, Cenk; Yalçinkaya, Ulviye; Özkan, Lütfü

    2013-01-01

    The aim of this study was to analyze the effect of low-dose irradiation on fibrous cartilage and to obtain a hyaline cartilage-like fibrocartilage (HCLF) with similar structural and mechanical properties to hyaline cartilage. An osteochondral defect was created in 40 knees of 20 rabbits. At the 7th postoperative day, a single knee of each rabbit was irradiated with a total dose of 5.0 Gy in 1.0 Gy fractions for 5 days (radiotherapy group), while the other knee was not irradiated (control group). Rabbits were then divided into four groups of 5 rabbits each. The first three groups were sacrificed at the 4th, 8th and the 12th postoperative weeks and cartilage defects were macroscopically and microscopically evaluated. The remaining group of 5 rabbits was sacrificed at the 12th week and biomechanical compression tests were performed on the cartilage defects. There was no significant biomechanical difference between the radiotherapy and the control group (p=0.686). There was no significant macroscopic and microscopic difference between groups (p=0.300). Chondrocyte clustering was observed in the irradiated group. Low-dose irradiation does not affect the mechanical properties of HCLF in vivo. However, structural changes such as chondrocyte clustering were observed.

  4. A preclinical evaluation of an autologous living hyaline-like cartilaginous graft for articular cartilage repair: a pilot study.

    Science.gov (United States)

    Peck, Yvonne; He, Pengfei; Chilla, Geetha Soujanya V N; Poh, Chueh Loo; Wang, Dong-An

    2015-11-09

    In this pilot study, an autologous synthetic scaffold-free construct with hyaline quality, termed living hyaline cartilaginous graft (LhCG), was applied for treating cartilage lesions. Implantation of autologous LhCG was done at load-bearing regions of the knees in skeletally mature mini-pigs for 6 months. Over the course of this study, significant radiographical improvement in LhCG treated sites was observed via magnetic resonance imaging. Furthermore, macroscopic repair was effected by LhCG at endpoint. Microscopic inspection revealed that LhCG engraftment restored cartilage thickness, promoted integration with surrounding native cartilage, produced abundant cartilage-specific matrix molecules, and re-established an intact superficial tangential zone. Importantly, the repair efficacy of LhCG was quantitatively shown to be comparable to native, unaffected cartilage in terms of biochemical composition and biomechanical properties. There were no complications related to the donor site of cartilage biopsy. Collectively, these results imply that LhCG engraftment may be a viable approach for articular cartilage repair.

  5. Platelet-rich plasma loaded in situ-formed hydrogel enhances hyaline cartilage regeneration by CB1 upregulation.

    Science.gov (United States)

    Lee, Hye-Rim; Park, Kyung Min; Joung, Yoon Ki; Park, Ki Dong; Do, Sun Hee

    2012-11-01

    The efficacy of three-dimensional (3D) culture on the proliferation and maturation of chondrocytes seeded into a hydrogel scaffold was assessed. Three types of hydrogel were prepared for the 3D culture of primary isolated chondrocytes. Chondrocyte proliferation was assessed using a live/dead viability/cytotoxicity assay and semiquantitative RT-PCR after 3D culture in hydrogel. Cylindrical defects in the center of rat xyphoids were used for the implantation of platelet-rich plasma (PRP)/hydrogel composites. Rats were killed at day 7 postoperatively and evaluated histochemically and immunohistologically. Xyphoid chondrocytes proliferated well with time in hydrogels. In the PRP-containing hydrogels, xyphoid defects displayed early formation of chondroid matrix with massive peripheral infiltration of spindle cells. These results were consistent with Safranin-O staining for proteoglycans and immunohistochemistry for type II collagen. Gene expression analyses in vitro revealed aggrecan, type II collagen, and ChM-1 and CB1 upregulation by PRP/hydrogel. PRP/hydrogel provided a suitable environment for hyaline cartilaginous regeneration, leading to anti-inflammation by significant increase of CB1 and inhibiting vascular ingrowth via considerable upregulation of ChM-1. The results provide a valuable reference for the clinical application of hydrogel scaffolds for hyaline cartilage regeneration, as well as the use of autologous PRP to improve cellular proliferation and maturation of xyphoid repair. Copyright © 2012 Wiley Periodicals, Inc.

  6. Which cartilage is regenerated, hyaline cartilage or fibrocartilage? Non-invasive ultrasonic evaluation of tissue-engineered cartilage.

    Science.gov (United States)

    Hattori, K; Takakura, Y; Ohgushi, H; Habata, T; Uematsu, K; Takenaka, M; Ikeuchi, K

    2004-09-01

    To investigate ultrasonic evaluation methods for detecting whether the repair tissue is hyaline cartilage or fibrocartilage in new cartilage regeneration therapy. We examined four experimental rabbit models: a spontaneous repair model (group S), a large cartilage defect model (group L), a periosteal graft model (group P) and a tissue-engineered cartilage regeneration model (group T). From the resulting ultrasonic evaluation, we used %MM (the maximum magnitude of the measurement area divided by that of the intact cartilage) as a quantitative index of cartilage regeneration. The results of the ultrasonic evaluation were compared with the histological findings and histological score. The %MM values were 61.1 +/- 16.5% in group S, 29.8 +/- 15.1% in group L, 36.3 +/- 18.3% in group P and 76.5 +/- 18.7% in group T. The results showed a strong similarity to the histological scoring. The ultrasonic examination showed that all the hyaline-like cartilage in groups S and T had a high %MM (more than 60%). Therefore, we could define the borderline between the two types of regenerated cartilage by the %MM.

  7. Biochemical characterisation of navicular hyaline cartilage, navicular fibrocartilage and the deep digital flexor tendon in horses with navicular disease.

    Science.gov (United States)

    Viitanen, M; Bird, J; Smith, R; Tulamo, R-M; May, S A

    2003-10-01

    The study hypothesis was that navicular disease is a process analogous to degenerative joint disease, which leads to changes in navicular fibrocartilage and in deep digital flexor tendon (DDFT) matrix composition and that the process extends to the adjacent distal interphalangeal joint. The objectives were to compare the biochemical composition of the navicular articular and palmar cartilages from 18 horses with navicular disease with 49 horses with no history of front limb lameness, and to compare navicular fibrocartilage with medial meniscus of the stifle and collateral cartilage of the hoof. Cartilage oligomeric matrix protein (COMP), deoxyribonucleic acid (DNA), total glycosaminoglycan (GAG), metalloproteinases MMP-2 and MMP-9 and water content in tissues were measured. Hyaline cartilage had the highest content of COMP and COMP content in hyaline cartilage and tendon was higher in lame horses than in sound horses (phyaline cartilage was higher in lame horses than in sound horses. The MMP-2 amounts were significantly higher in tendons compared to other tissue types. Overall, 79% of the lame horses with lesions had MMP-9 in their tendons and the amount was higher than in sound horses (phyaline and fibrocartilage as well as the DDFT with potential implications for the pathogenesis and management of the condition.

  8. Vortices catapult droplets in atomization

    Science.gov (United States)

    Jerome, J. John Soundar; Marty, Sylvain; Matas, Jean-Philippe; Zaleski, Stéphane; Hoepffner, Jérôme

    2013-11-01

    A droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave, and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vortex; this reattached flow pushes the liquid film down; by now, a new recirculation vortex is being created in the wake of the wave—just where the liquid film is now located; the liquid film is blown up from below by the newly formed recirculation vortex in a manner similar to a bag-breakup event; the resulting droplets are catapulted by the recirculation vortex.

  9. Vortices catapult droplets in atomization

    Energy Technology Data Exchange (ETDEWEB)

    Jerome, J. John Soundar, E-mail: soundar@dalembert.upmc.fr; Zaleski, Stéphane; Hoepffner, Jérôme [Institut Jean Le Rond d' Alembert, UPMC Univ. Paris 06 and CNRS-UMR 7190, F-75005 Paris (France); Marty, Sylvain; Matas, Jean-Philippe [Laboratoire des Écoulements Géophysiques et Industriels (LEGI), Univ. Grenoble Alpes and CNRS - UMR 5519, F-38000 Grenoble (France)

    2013-11-15

    A droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave, and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vortex; this reattached flow pushes the liquid film down; by now, a new recirculation vortex is being created in the wake of the wave—just where the liquid film is now located; the liquid film is blown up from below by the newly formed recirculation vortex in a manner similar to a bag-breakup event; the resulting droplets are catapulted by the recirculation vortex.

  10. Grating droplets with a mesh

    Science.gov (United States)

    Soto, Dan; Le Helloco, Antoine; Clanet, Cristophe; Quere, David; Varanasi, Kripa

    2016-11-01

    A drop thrown against a mesh can pass through its holes if impacting with enough inertia. As a result, although part of the droplet may remain on one side of the sieve, the rest will end up grated through the other side. This inexpensive method to break up millimetric droplets into micrometric ones may be of particular interest in a wide variety of applications: enhancing evaporation of droplets launched from the top of an evaporative cooling tower or preventing drift of pesticides sprayed above crops by increasing their initial size and atomizing them at the very last moment with a mesh. In order to understand how much liquid will be grated we propose in this presentation to start first by studying a simpler situation: a drop impacting a plate pierced with a single off centered hole. The study of the role of natural parameters such as the radius drop and speed or the hole position, size and thickness allows us to discuss then the more general situation of a plate pierced with multiple holes: the mesh.

  11. Dynamics of Electrically Modulated Colloidal Droplet Transport.

    Science.gov (United States)

    Dey, Ranabir; Ghosh, Udita Uday; Chakraborty, Suman; DasGupta, Sunando

    2015-10-20

    Electrically actuated transport dynamics of colloidal droplets, on a hydrophobic dielectric film covering an array of electrodes, is studied here. Specifically, the effects of the size and electrical properties (zeta-potential) of the colloidal particles on such transport characteristics are investigated. For the colloidal droplets, the application of an electrical voltage leads to additional attenuation of the local dielectric-droplet interfacial tension. This is due to the electrically triggered enhanced colloidal particle adsorption at the dielectric-droplet interface, in the immediate vicinity of the droplet three-phase contact line (TPCL). The extent of such interfacial particle adsorption, and hence, the extent of the consequential reduction in the interfacial tension, is dictated by the combined effects of the three-phase contact line spreading, particle size, the interfacial electrostatic interaction between the colloidal particles (if charged) and the charged dielectric surface above the activated electrode, and the interparticle electrostatic repulsion. The electrical driving force of varying magnitude, stemming from this altered solid-liquid interfacial tension gradient in the presence of the colloidal particles, culminates in different droplet transport velocity and droplet transfer frequency for different colloidal droplets. We substantiate the inferences from our experimental results by a quasi-steady state force balance model for colloidal droplet transport. We believe that the present work will provide an accurate framework for determining the optimal design and operational parameters for digital microfluidic chips handling colloidal droplets, as encountered in a plethora of applications.

  12. Compound droplet manipulations on fiber arrays

    Science.gov (United States)

    Weyer, Floriane; Lismont, Marjorie; Dreesen, Laurent; Vandewalle, Nicolas

    2014-11-01

    Recent works demonstrated that fibers are the basis of an open digital microfluidics. Indeed, various processes such as droplet motion, fragmentation, trapping, releasing, mixing and encapsulation can be constructed on fiber arrays. However, addressing a large number of tiny droplets resulting from the mixing of several liquid components is still a challenge. Here we show that it is possible to manipulate tiny droplets reaching a high level of complexity. Wetting droplets are known to glide along vertical fibers. When a droplet reaches an horizontal fiber, it sticks at the crossing if capillary overcomes gravity. Otherwise, the droplet continues its way, crosses the node and leaves a tiny residue. Therefore, a vertical fiber decorated with a series of horizontal fibers will retain residual droplets at the successive nodes. An oil droplet, sliding on the vertical fiber, is able to collect the residues. Thus a multicompound droplet is created. The volume of the residual droplets has been studied and seems to be related to the diameters of both vertical and horizontal fibers. Moreover, the conditions under which the residues are released have been investigated in order to understand the formation of such a fluidic object. F. Weyer is financially supported by an FNRS grant. This work is also supported by the FRFC 2.4504.12.

  13. Bouncing of polymeric droplets on liquid interfaces

    Science.gov (United States)

    Gier, S.; Dorbolo, S.; Terwagne, D.; Vandewalle, N.; Wagner, C.

    2012-12-01

    The effect of polymers on the bouncing behavior of droplets in a highly viscous, vertically shaken silicone oil bath was investigated in this study. Droplets of a sample liquid were carefully placed on a vibrating bath that was maintained well below the threshold of Faraday waves. The bouncing threshold of the plate acceleration depended on the acceleration frequency. For pure water droplets and droplets of aqueous polymer solutions, a minimum acceleration amplitude was observed in the acceleration threshold curves as a function of frequency. The bouncing acceleration amplitude for a droplet of a dilute aqueous polymer solution was higher than the acceleration amplitude for a pure water droplet. Measurements of the center of mass trajectory and the droplet deformations showed that the controlling parameter in the bouncing process was the oscillating elongational rate of the droplet. This parameter can be directly related to the elongational viscosity of the polymeric samples. The large elongational viscosity of the polymer solution droplets suppressed large droplet deformations, resulting in less chaotic bouncing.

  14. Impinging Water Droplets on Inclined Glass Surfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Armijo, Kenneth Miguel; Lance, Blake; Ho, Clifford K.

    2017-09-01

    Multiphase computational models and tests of falling water droplets on inclined glass surfaces were developed to investigate the physics of impingement and potential of these droplets to self-clean glass surfaces for photovoltaic modules and heliostats. A multiphase volume-of-fluid model was developed in ANSYS Fluent to simulate the impinging droplets. The simulations considered different droplet sizes (1 mm and 3 mm), tilt angles (0deg, 10deg, and 45deg), droplet velocities (1 m/s and 3 m/s), and wetting characteristics (wetting=47deg contact angle and non-wetting = 93deg contact angle). Results showed that the spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) decreased with increasing inclination angle due to the reduced normal force on the surface. The hydrophilic surface yielded greater spread factors than the hydrophobic surface in all cases. With regard to impact forces, the greater surface tilt angles yielded lower normal forces, but higher shear forces. Experiments showed that the experimentally observed spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) was significantly larger than the simulated spread factor. Observed spread factors were on the order of 5 - 6 for droplet velocities of %7E3 m/s, whereas the simulated spread factors were on the order of 2. Droplets were observed to be mobile following impact only for the cases with 45deg tilt angle, which matched the simulations. An interesting phenomenon that was observed was that shortly after being released from the nozzle, the water droplet oscillated (like a trampoline) due to the "snapback" caused by the surface tension of the water droplet being released from the nozzle. This oscillation impacted the velocity immediately after the release. Future work should evaluate the impact of parameters such as tilt angle and surface wettability on the impact of particle/soiling uptake and removal to investigate ways that

  15. Positive effects of cell-free porous PLGA implants and early loading exercise on hyaline cartilage regeneration in rabbits.

    Science.gov (United States)

    Chang, Nai-Jen; Lin, Chih-Chan; Shie, Ming-You; Yeh, Ming-Long; Li, Chien-Feng; Liang, Peir-In; Lee, Kuan-Wei; Shen, Pei-Hsun; Chu, Chih-Jou

    2015-12-01

    The regeneration of hyaline cartilage remains clinically challenging. Here, we evaluated the therapeutic effects of using cell-free porous poly(lactic-co-glycolic acid) (PLGA) graft implants (PGIs) along with early loading exercise to repair a full-thickness osteochondral defect. Rabbits were randomly allocated to a treadmill exercise (TRE) group or a sedentary (SED) group and were prepared as either a PGI model or an empty defect (ED) model. TRE was performed as a short-term loading exercise; SED was physical inactivity in a free cage. The knees were evaluated at 6 and 12 weeks after surgery. At the end of testing, none of the knees developed synovitis, formed osteophytes, or became infected. Macroscopically, the PGI-TRE group regenerated a smooth articular surface, with transparent new hyaline-like tissue soundly integrated with the neighboring cartilage, but the other groups remained distinct at the margins with fibrous or opaque tissues. In a micro-CT analysis, the synthesized bone volume/tissue volume (BV/TV) was significantly higher in the PGI-TRE group, which also had integrating architecture in the regeneration site. The thickness of the trabecular (subchondral) bone was improved in all groups from 6 to 12 weeks. Histologically, remarkable differences in the cartilage regeneration were visible. At week 6, compared with SED groups, the TRE groups manifested modest inflammatory cells with pro-inflammatory cytokines (i.e., TNF-α and IL-6), improved collagen alignment and higher glycosaminoglycan (GAG) content, particularly in the PGI-TRE group. At week 12, the PGI-TRE group had the best regeneration outcomes, showing the formation of hyaline-like cartilage, the development of columnar rounded chondrocytes that expressed enriched levels of collagen type II and GAG, and functionalized trabecular bone with osteocytes. In summary, the combination of implanting cell-free PLGA and performing an early loading exercise can significantly promote the full

  16. Vibration-induced droplet atomization

    Science.gov (United States)

    Vukasinovic, Bojan

    The atomization of liquid drops is investigated experimentally using laser vibrometry, high-speed imaging, and particle tracking techniques. The spray is generated by a novel vibration-induced droplet atomization (VIDA) process in which a sessile drop is atomized by an underlying vibrating thin metal diaphragm, resulting in rapid ejection of small secondary droplets from the free surface of the primary drop. Under some conditions, the primary drop can be atomized extremely rapidly by a bursting-like mechanism (e.g., a 0.1 ml water drop can be atomized in 0.4 seconds). The present research has focused on four major areas: global characteristics of VIDA process, instability modes and free surface dynamics of the forced drop, mechanisms of the interface breakup, and parametric characterization of the ensuing spray. Prior to atomization, the drop free surface undergoes three transitions: from axisymmetric standing waves to azimuthal waves, to a newly-observed lattice mode, and to a disordered pre-ejection state. The droplet ejection results from localized collapse of surface troughs and initiation and ultimate breakup of momentary liquid spikes. Breakup begins with capillary pinch-off from spike tips and can be followed by additional pinching of liquid droplets. For a relatively low-viscosity liquid, e.g., water, a capillary-wave instability of the spike is observed in some cases, while for a very viscous liquid, e.g., a glycerin/water solution, the first breakup occurs near the stem of the spike, with or without subsequent breakup of the detached, elongated thread. Different mechanisms dominating the primary breakup of the spike are operative in the low- and high-viscosity ejection regimes. When ejection of the secondary droplets is triggered, the evolution and rate of atomization depend on the coupled dynamics of the primary drop and the vibrating diaphragm. Due to these dynamics, the process can be either self-intensifying or self-decaying. The resulting VIDA spray

  17. Droplet size influences division of mammalian cell factories in droplet microfluidic cultivation.

    Science.gov (United States)

    Periyannan Rajeswari, Prem Kumar; Joensson, Haakan N; Andersson-Svahn, Helene

    2017-01-01

    The potential of using droplet microfluidics for screening mammalian cell factories has been limited by the difficulty in achieving continuous cell division during cultivation in droplets. Here, we report the influence of droplet size on mammalian cell division and viability during cultivation in droplets. Chinese Hamster Ovary (CHO) cells, the most widely used mammalian host cells for biopharmaceuticals production were encapsulated and cultivated in 33, 180 and 320 pL droplets for 3 days. Periodic monitoring of the droplets during incubation showed that the cell divisions in 33 pL droplets stopped after 24 h, whereas continuous cell division was observed in 180 and 320 pL droplets for 72 h. The viability of the cells cultivated in the 33 pL droplets also dropped to about 50% in 72 h. In contrast, the viability of the cells in the larger droplets was above 90% even after 72 h of cultivation, making them a more suitable droplet size for 72-h cultivation. This study shows a direct correlation of microfluidic droplet size to the division and viability of mammalian cells. This highlights the importance of selecting suitable droplet size for mammalian cell factory screening assays. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. [Micro-droplet characterization and its application for amino acid detection in droplet microfluidic system].

    Science.gov (United States)

    Yuan, Huiling; Dong, Libing; Tu, Ran; Du, Wenbin; Ji, Shiru; Wang, Qinhong

    2014-01-01

    Recently, the droplet microfluidic system attracts interests due to its high throughput and low cost to detect and screen. The picoliter micro-droplets from droplet microfluidics are uniform with respect to the size and shape, and could be used as monodispensed micro-reactors for encapsulation and detection of single cell or its metabolites. Therefore, it is indispensable to characterize micro-droplet and its application from droplet microfluidic system. We first constructed the custom-designed droplet microfluidic system for generating micro-droplets, and then used the micro-droplets to encapsulate important amino acids such as glutamic acid, phenylalanine, tryptophan or tyrosine to test the droplets' properties, including the stability, diffusivity and bio-compatibility for investigating its application for amino acid detection and sorting. The custom-designed droplet microfluidic system could generate the uniformed micro-droplets with a controllable size between 20 to 50 microm. The micro-droplets could be stable for more than 20 h without cross-contamination or fusion each other. The throughput of detection and sorting of the system is about 600 micro-droplets per minute. This study provides a high-throughput platform for the analysis and screening of amino acid-producing microorganisms.

  19. Impact of Viscous Droplets on Superamphiphobic Surfaces

    Science.gov (United States)

    Zhao, Binyu; Chen, Longquan; Deng, Xu

    2016-11-01

    Superamphiphobic coating is promising for various applications in industry, e.g. self-cleaning windows, where the impingement of droplets on surfaces is commonly encountered. In this work, we experimentally investigated the impact of droplets with similar surface tension (63-72 mN/m) but much different viscosity (1-150 mPa s) on superamphiphobic surfaces. We found that droplets can rebound from the superamphiphobic surfaces when the impact velocity is larger than a critical value, which linearly increases with the liquid viscosity. Droplet with higher viscosity spreads, retracts slower, and eventually rebounds lower and fewer times than that of low viscous droplet. These findings have important implications for surface engineers to use superamphiphobic coatings. Furthermore, we measured the maximum spreading factors for droplet impact on superamphiphobic surfaces and proposed a simple model based on energy conversation to describe its relationship to the Weber number and Reynolds number.

  20. Electroporation of cells in microfluidic droplets.

    Science.gov (United States)

    Zhan, Yihong; Wang, Jun; Bao, Ning; Lu, Chang

    2009-03-01

    Droplet-based microfluidics has raised a lot of interest recently due to its wide applications to screening biological/chemical assays with high throughput. Despite the advances on droplet-based assays involving cells, gene delivery methods that are compatible with the droplet platform have been lacking. In this report, we demonstrate a simple microfluidic device that encapsulates cells into aqueous droplets and then electroporates the encapsulated cells. The electroporation occurs when the cell-containing droplets (in oil) flow through a pair of microelectrodes with a constant voltage established in between. We investigate the parameters and characteristics of the electroporation. We demonstrate delivering enhanced green fluorescent protein (EGFP) plasmid into Chinese hamster ovary (CHO) cells. We envision the application of this technique to high-throughput functional genomics studies based on droplet microfluidics.

  1. Supercritical droplet combustion and related transport phenomena

    Science.gov (United States)

    Yang, Vigor; Hsieh, K. C.; Shuen, J. S.

    1993-01-01

    An overview of recent advances in theoretical analyses of supercritical droplet vaporization and combustion is conducted. Both hydrocarbon and cryogenic liquid droplets over a wide range of thermodynamic states are considered. Various important high-pressure effects on droplet behavior, such as thermodynamic non-ideality, transport anomaly, and property variation, are reviewed. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the criticl pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

  2. Curvature Gradient Driving Droplets in Fast Motion

    CERN Document Server

    Lv, Cunjing; Yin, Yajun; Tseng, Fan-gang; Zheng, Quanshui

    2011-01-01

    Earlier works found out spontaneous directional motion of liquid droplets on hydrophilic conical surfaces, however, not hydrophobic case. Here we show that droplets on any surface may take place spontaneous directional motion without considering contact angle property. The driving force is found to be proportional to the curvature gradient of the surface. Fast motion can be lead at surfaces with small curvature radii. The above discovery can help to create more effective transportation technology of droplets, and better understand some observed natural phenomena.

  3. Self-propelled chemotactic ionic liquid droplets

    OpenAIRE

    Francis, Wayne; Fay, Cormac; Florea, Larisa; Diamond, Dermot

    2015-01-01

    Herein we report the chemotactic behaviour of self-propelled droplets composed solely of the ionic liquid trihexyl(tetradecyl)phosphonium chloride ([P6,6,6,14][Cl]). These droplets spontaneously move along an aqueous-air boundary in the direction of chloride gradients to specific destinations due to asymmetric release of [P6,6,6,14]+ cationic surfactant from the droplet into the aqueous phase.

  4. Thermophoresis of water droplets inside carbon nanotubes

    DEFF Research Database (Denmark)

    Zambrano, Harvey; Walther, Jens Honore; Oyarzua, Elton

    2016-01-01

    Carbon Nanotubes(CNTs) offer unique possibilities as fluid conduits with applications ranging from lab on a chip devices to encapsulation media for drug delivery. CNTs feature high mechanical strength, chemical and thermalstability and biocompatibility therefore they are promising candidates...... for nanodevice fabrication. Thermal gradients have been proposed as mechanism to drive particles, fullerenes and droplets inside CNTs. Here, by conducting Molecular Dynamics (MD) simulations, we study thermophoresis of water droplets inside CNTs. We systematically change the size of the droplets, the axial...

  5. Droplets as reaction compartments for protein nanotechnology.

    Science.gov (United States)

    Devenish, Sean R A; Kaltenbach, Miriam; Fischlechner, Martin; Hollfelder, Florian

    2013-01-01

    Extreme miniaturization of biological and chemical reactions in pico- to nanoliter microdroplets is emerging as an experimental paradigm that enables more experiments to be carried out with much lower sample consumption, paving the way for high-throughput experiments. This review provides the protein scientist with an experimental framework for (a) formation of polydisperse droplets by emulsification or, alternatively, of monodisperse droplets using microfluidic devices; (b) construction of experimental rigs and microfluidic chips for this purpose; and (c) handling and analysis of droplets.

  6. Evaporation of nanofluid droplet on heated surface

    Directory of Open Access Journals (Sweden)

    Yeung Chan Kim

    2015-04-01

    Full Text Available In this study, an experiment on the evaporation of nanofluid sessile droplet on a heated surface was conducted. A nanofluid of 0.5% volumetric concentration mixed with 80-nm-sized CuO powder and pure water were used for experiment. Droplet was applied to the heated surface, and images of the evaporation process were obtained. The recorded images were analyzed to find the volume, diameter, and contact angle of the droplet. In addition, the evaporative heat transfer coefficient was calculated from experimental result. The results of this study are summarized as follows: the base diameter of the droplet was maintained stably during the evaporation. The measured temperature of the droplet was increased rapidly for a very short time, then maintained constantly. The nanofluid droplet was evaporated faster than the pure water droplet under the experimental conditions of the same initial volume and temperature, and the average evaporative heat transfer coefficient of the nanofluid droplet was higher than that of pure water. We can consider the effects of the initial contact angle and thermal conductivity of nanofluid as the reason for this experimental result. However, the effect of surface roughness on the evaporative heat transfer of nanofluid droplet appeared unclear.

  7. Quantitative DNA Analysis Using Droplet Digital PCR.

    Science.gov (United States)

    Vossen, Rolf H A M; White, Stefan J

    2017-01-01

    Droplet digital PCR (ddPCR) is based on the isolated amplification of thousands of individual DNA molecules simultaneously, with each molecule compartmentalized in a droplet. The presence of amplified product in each droplet is indicated by a fluorescent signal, and the proportion of positive droplets allows the precise quantification of a given sequence. In this chapter we briefly outline the basis of ddPCR, and describe two different applications using the Bio-Rad QX200 system: genotyping copy number variation and quantification of Illumina sequencing libraries.

  8. Dissonant Black Droplets and Black Funnels

    CERN Document Server

    Fischetti, Sebastian; Way, Benson

    2016-01-01

    A holographic field theory on a fixed black hole background has a gravitational dual represented by a black funnel or a black droplet. These states are "detuned" when the temperature of the field theory near the horizon does not match the temperature of the background black hole. In particular, the gravitational dual to the Boulware state must be a detuned solution. We construct detuned droplets and funnels dual to a Schwarzschild background and show that the Boulware phase is represented by a droplet. We also construct hairy black droplets associated to a low-temperature scalar condensation instability and show that they are thermodynamically preferred to their hairless counterparts.

  9. Compound droplet manipulations on fiber arrays

    CERN Document Server

    Weyer, Floriane; Dreesen, Laurent; Vandewalle, Nicolas

    2015-01-01

    Recent works demonstrated that fiber arrays may constitue the basis of an open digital microfluidics. Various processes, such as droplet motion, fragmentation, trapping, release, mixing and encapsulation, may be achieved on fiber arrays. However, handling a large number of tiny droplets resulting from the mixing of several liquid components is still a challenge for developing microreactors, smart sensors or microemulsifying drugs. Here, we show that the manipulation of tiny droplets onto fiber networks allows for creating compound droplets with a high complexity level. Moreover, this cost-effective and flexible method may also be implemented with optical fibers in order to develop fluorescence-based biosensor.

  10. Interaction between electrically charged droplets in microgravity

    Science.gov (United States)

    Brandenbourger, Martin; Caps, Herve; Hardouin, Jerome; Vitry, Youen; Boigelot, Bernard; Dorbolo, Stephane; Grasp Team; Beams Collaboration

    2015-11-01

    The past ten years, electrically charged droplets have been studied tremendously for their applications in industry (electrospray, electrowetting,...). However, charged droplets are also present in nature. Indeed, it has been shown that the droplets falling from thunderclouds possess an excess of electric charges. Moreover, some research groups try to use the electrical interaction between drops in order to control the coalescence between cloud droplets and control rain generation. The common way to study this kind of system is to make hypothesis on the interaction between two charged drops. Then, these hypothesis are extended to a system of thousands of charged droplets. Thanks to microgravity conditions, we were able to study the interaction between two electrically charged droplets. In practice, the charged droplets were propelled one in front of the other at low speed (less than 1 m/s). The droplets trajectory is studied for various charges and volumes. The repulsion between two charged drops is correctly fitted by a simple Coulomb repulsion law. In the case of attractive interactions, we discuss the collisions observed as a function of the droplets speed, volume and electric charges. Thanks to FNRS for financial support.

  11. Liquid Droplets on a Highly Deformable Membrane

    Science.gov (United States)

    Schulman, Rafael; Dalnoki-Veress, Kari

    2015-11-01

    We present measurements of the deformation produced by micro-droplets atop thin elastomeric and glassy free-standing films. Due to the Laplace pressure, the droplets deform the elastic membrane thereby forming a bulge. Thus, there are two angles that define the droplet/membrane geometry: the angle the liquid surface makes with the film and the angle the deformed bulge makes with the film. The contact line geometry is well captured by a Neumann construction which includes contributions from interfacial and mechanical tensions. Finally, we show that a droplet atop a film with biaxial tension assumes an equilibrium shape which is elongated along the axis of high tension.

  12. Droplet evaporation with complexity of evaporation modes

    Science.gov (United States)

    Hwang, In Gyu; Kim, Jin Young; Weon, Byung Mook

    2017-01-01

    Evaporation of a sessile droplet often exhibits a mixed evaporation mode, where the contact radius and the contact angle simultaneously vary with time. For sessile water droplets containing polymers with different initial polymer concentrations, we experimentally study their evaporation dynamics by measuring mass and volume changes. We show how diffusion-limited evaporation governs droplet evaporation, regardless of the complexity of evaporation behavior, and how the evaporation rate depends on the polymer concentration. Finally, we suggest a unified expression for a diffusion-limited evaporation rate for a sessile droplet with complexity in evaporation dynamics.

  13. A Theory of Shape-Shifting Droplets

    Science.gov (United States)

    Haas, Pierre; Goldstein, Raymond; Smoukov, Stoyan; Denkov, Nikolai

    2016-11-01

    Recent observations of cooled oil emulsion droplets uncovered a remarkable array of shape transformations: the initially spherical droplets flatten into polygonal shapes, first hexagons, then triangles or quadrilaterals that ultimately grow thin protrusions from their corners. These transformations are driven by a partial phase transition of the bulk liquid phase. In this talk, we explore theoretically the simplest geometric competition between this phase transition and surface tension in planar polygons. We recover the experimental sequence of shapes and predict shape statistics in qualitative agreement with experiments. Extending the model to capture some of the three-dimensional structure of the droplets, we analyse the topological transition of droplet puncture observed in experiments.

  14. Tumor fusocelular hialinizante con rosetas gigantes: Reporte de un caso Hyalinizing spindle cell tumor with giant rosettes: Case report

    Directory of Open Access Journals (Sweden)

    Ernesto García Ayala

    2010-12-01

    Full Text Available Introducción: El tumor fusocelular hialinizante con rosetas gigantes es una neoplasia constituida por dos componentes histológicos, uno celular con elementos fusiformes, y el segundo representado por islas bien delimitadas casi acelulares, llenas de material hialino, rodeadas de células redondas u ovales, las cuales muestran un perfil inmunohistoquímico inusual, e histogénesis incierta. Objetivo: Instruir a los patólogos y clínicos sobre este tumor, su forma de presentación y diagnósticos diferenciales. Metodología y resultados: Se presenta el caso de una mujer de 42 años con masa ubicada en región inguinal, de crecimiento progresivo (1 año, que se reseca quirúrgicamente anatomía patológica informó un tumor fusocelular hialinizante con rosetas gigantes, según hallazgos morfológicos e inmuno histoquímicos, en correlación con su localización y cuadro clínico. Conclusión: Se hace necesario ampliar el conocimiento sobre esta entidad y de esta forma obtener una adecuada evaluación de sus criterios pronósticos histológicos, comportamiento clínico y tratamiento. Salud UIS 2010; 42: 282-286Introduction: The hyalinizing spindle cell tumor with giant rosettes is a neoplasia characterized by both histologic components, one of which is cellular, with spindle-shaped elements and the second represented by well defined almost acellular islands filled with hyaline material surrounded by round to oval cells, which shows an unusual immunohistochemical profile and uncertain histogenesis. Objective: Educate pathologists and clinicians about this tumor, its presentation and differential diagnosis. Methods and results: A case of a 42 year old woman with a mass located in the inguinal region, with progressive growth (1 year, surgically resected and histopathology reported as Hyalinizing spindle cell tumor with giant rosettes according to morphological, immunohistochemical findings correlates with its location and clinical. Conclusion: It is

  15. The development of hyaline-cell cartilage in the head of the black molly, Poecilia sphenops. Evidence for secondary cartilage in a teleost.

    Science.gov (United States)

    Benjamin, M

    1989-01-01

    The development of hyaline-cell cartilage attached to membrane (dentary, maxilla, nasal, lacrimal and cleithrum) and cartilage (basioccipital) bones has been studied in the viviparous black molly, Poecilia sphenops. Intramembranous ossification commences before the first appearance of hyaline cells. As hyaline-cell cartilage is densely cellular and as that attached to the dentary, maxilla and cleithrum develops from the periosteum of these membrane bones, it must be regarded as secondary cartilage according to current concepts. It is also argued that the hyaline-cell cartilage attached to the perichondral bone of the basioccipital (a cartilage bone), could also be viewed as secondary. The status of the cartilage on the nasal and lacrimal bones is less clear, for it develops, at least in part, from mucochondroid (mucous connective) tissue. This is the first definitive report of secondary cartilage in any lower vertebrate. The tissue is therefore not restricted to birds and mammals as hitherto believed, and a multipotential periosteum must have arisen early in vertebrate evolution. Images Fig. 1 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 PMID:2481666

  16. Droplet dynamics on patterned substrates

    Indian Academy of Sciences (India)

    A Dupuis; J M Yeomans

    2005-06-01

    We present a lattice Boltzmann algorithm which can be used to explore the spreading of droplets on chemically and topologically patterned substrates. As an example we use the method to show that the final configuration of a drop on a substrate comprising hydrophobic and hydrophilic stripes can depend sensitively on the dynamical pathway by which the state is reached. We also consider a substrate covered with micron-scale posts and investigate how this can lead to superhydrophobic behaviour. Finally we model how a Namibian desert beetle collects water from the wind.

  17. Reappraisal of mesenchymal chondrosarcoma: novel morphologic observations of the hyaline cartilage and endochondral ossification and beta-catenin, Sox9, and osteocalcin immunostaining of 22 cases.

    Science.gov (United States)

    Fanburg-Smith, Julie C; Auerbach, Aaron; Marwaha, Jayson S; Wang, Zengfeng; Rushing, Elisabeth J

    2010-05-01

    Mesenchymal chondrosarcoma, a rare malignant round cell and hyaline cartilage tumor, is most commonly intraosseous but can occur in extraskeletal sites. We intensively observed the morphology and applied Sox9 (master regulator of chondrogenesis), beta-catenin (involved in bone formation, thought to inhibit chondrogenesis in a Sox9-dependent manner), and osteocalcin (a marker for osteoblastic phenotype) to 22 central nervous system and musculoskeletal mesenchymal chondrosarcoma. Cases of mesenchymal chondrosarcoma were retrieved and reviewed from our files. Immunohistochemistry and follow-up were obtained on mesenchymal chondrosarcoma and tumor controls. Twenty-two mesenchymal chondrosarcomas included 5 central nervous system (all female; mean age, 30.2; mean size, 7.8 cm; in frontal lobe [n = 4] and spinal cord [n = 1]) and 17 musculoskeletal (female-male ratio, 11:6; mean age, 31.1; mean size, 6.2 cm; 3 each of humerus and vertebrae; 2 each of pelvis, rib, tibia, neck soft tissue; one each of femur, unspecified bone, and elbow soft tissue). The hyaline cartilage in most tumors revealed a consistent linear progression of chondrocyte morphology, from resting to proliferating to hypertrophic chondrocytes. Sixty-seven percent of cases demonstrated cell death and acquired osteoblastic phenotype, cells positive for osteocalcin at the site of endochondral ossification. Small round cells of mesenchymal chondrosarcoma were negative for osteocalcin. SOX9 was positive in both components of 21 of 22 cases of mesenchymal chondrosarcoma. beta-Catenin highlighted rare nuclei at the interface between round cells and hyaline cartilage in 35% cases. Control skull and central nervous system cases were compared, including chondrosarcomas and small cell osteosarcoma, the latter positive for osteocalcin in small cells. Mesenchymal chondrosarcoma demonstrates centrally located hyaline cartilage with a linear progression of chondrocytes from resting to proliferative to hypertrophic

  18. The epididymis, cytoplasmic droplets and male fertility

    Institute of Scientific and Technical Information of China (English)

    Trevor G Cooper

    2011-01-01

    The potential of spermatozoa to become motile during post-testicular maturation,and the relationship between the cytoplasmic droplet and fertilizing capacity are reviewed.Post-testicular maturation of spermatozoa involves the autonomous induction of motility,which can occur in vivo in testes with occluded excurrent ducts and in vitro in testicular explants,and artefactual changes in morphology that appear to occur in the testis in vitro.Both modifications may reflect time-dependent oxidation of disulphide bonds of head and tail proteins.Regulatory volume decrease(RVD),which counters sperm swelling at ejaculation,is discussed in relation to loss of cytoplasmic droplets and consequences for fertility.It is postulated that:(i)fertile males possess spermatozoa with sufficient osmolytes to drive RVD at ejaculation,permitting the droplet to round up and pinch off without membrane rupture; and(ⅱ)infertile males possess spermatozoa with insufficient osmolytes so that RVD is inadequate,the droplet swells and the resulting flagellar angulation prevents droplet loss.Droplet retention at ejaculation is a harbinger of infertility caused by failure of the spermatozoon to negotiate the uterotubal junction or mucous and reach the egg.In this hypothesis,the epididymis regulates fertility indirectly by the extent of osmolyte provision to spermatozoa,which influences RVD and therefore droplet loss.Man is an exception,because ejaculated human spermatozoa retain their droplets.This may reflect their short midpiece,approximating head length,permitting a swollen droplet to extend along the entire midpiece; this not only obviates droplet migration and flagellar angulation but also hampers droplet loss.

  19. Lineage plasticity and cell biology of fibrocartilage and hyaline cartilage: Its significance in cartilage repair and replacement

    Energy Technology Data Exchange (ETDEWEB)

    Freemont, Anthony J. [Regenerative Medicine Research Group, University of Manchester, England (United Kingdom)]. E-mail: Tony.freemont@man.ac.uk; Hoyland, Judith [Regenerative Medicine Research Group, University of Manchester, England (United Kingdom)

    2006-01-15

    Cartilage repair is a major goal of modern tissue engineering. To produce novel engineered implants requires a knowledge of the basic biology of the tissues that are to be replaced or reproduced. Hyaline articular cartilage and meniscal fibrocartilage are two tissues that have excited attention because of the frequency with which they are damaged. A basic strategy is to re-engineer these tissues ex vivo by stimulating stem cells to differentiate into the cells of the mature tissue capable of producing an intact functional matrix. In this brief review, the sources of cells for tissue engineering cartilage and the culture conditions that have promoted differentiation are discussed within the context of natural cartilage repair. In particular, the role of cell density, cytokines, load, matrices and oxygen tension are discussed.

  20. Hyalinizing cholecystitis with features of immunoglobulin G4-related disease-coincidence or an unrecognized association? A case report.

    Science.gov (United States)

    Gupta, Rajib K; Patton, Kurt T

    2015-04-01

    Hyalinizing cholecystitis (HC) is a recently described rare subtype of chronic cholecystitis characterized by dense, paucicellular collagenous transmural fibrosis, which usually replaces the mucosa and muscularis propria. Immunoglobulin (Ig)G4-associated cholecystitis is also a newly described cholecystitis variant characterized by transmural or extramural lymphoplasmacytic inflammation, lymphoid follicles, storiform fibrosis, phlebitis, and increased tissue IgG4-positive plasma cells. We describe a case of cholecystitis in an elderly white man who harbored features of both HC and IgG4-associated cholecystitis. In retrospect, the patient also had a significantly elevated serum IgG4 level. To the best of our knowledge, an association between HC and IgG4-related disease has not been previously described in the literature. Although not entirely conclusive, our observations raise the possibility that some cases of HC represent the end stage of IgG4-related disease.

  1. Use of Interim Scaffolding and Neotissue Development to Produce a Scaffold-Free Living Hyaline Cartilage Graft.

    Science.gov (United States)

    Lau, Ting Ting; Leong, Wenyan; Peck, Yvonne; Su, Kai; Wang, Dong-An

    2015-01-01

    The fabrication of three-dimensional (3D) constructs relies heavily on the use of biomaterial-based scaffolds. These are required as mechanical supports as well as to translate two-dimensional cultures to 3D cultures for clinical applications. Regardless of the choice of scaffold, timely degradation of scaffolds is difficult to achieve and undegraded scaffold material can lead to interference in further tissue development or morphogenesis. In cartilage tissue engineering, hydrogel is the highly preferred scaffold material as it shares many similar characteristics with native cartilaginous matrix. Hence, we employed gelatin microspheres as porogens to create a microcavitary alginate hydrogel as an interim scaffold to facilitate initial chondrocyte 3D culture and to establish a final scaffold-free living hyaline cartilaginous graft (LhCG) for cartilage tissue engineering.

  2. Vortices catapult droplets in atomization

    CERN Document Server

    Jerome, J John Soundar; Matas, Jean-Philippe; Zaleski, Stéphane; Hoepffner, Jérôme

    2016-01-01

    A droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave, and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vor...

  3. The effect of high-energy extracorporeal shock waves on hyaline cartilage of adult rats in vivo.

    Science.gov (United States)

    Mayer-Wagner, Susanne; Ernst, Judith; Maier, Markus; Chiquet, Matthias; Joos, Helga; Müller, Peter E; Jansson, Volkmar; Sievers, Birte; Hausdorf, Jörg

    2010-08-01

    The aim of this study was to determine if extracorporeal shock wave therapy (ESWT) in vivo affects the structural integrity of articular cartilage. A single bout of ESWT (1500 shock waves of 0.5 mJ/mm(2)) was applied to femoral heads of 18 adult Sprague-Dawley rats. Two sham-treated animals served as controls. Cartilage of each femoral head was harvested at 1, 4, or 10 weeks after ESWT (n = 6 per treatment group) and scored on safranin-O-stained sections. Expression of tenascin-C and chitinase 3-like protein 1 (Chi3L1) was analyzed by immunohistochemistry. Quantitative real-time polymerase chain reaction (PCR) was used to examine collagen (II)alpha(1) (COL2A1) expression and chondrocyte morphology was investigated by transmission electron microscopy no changes in Mankin scores were observed after ESWT. Positive immunostaining for tenascin-C and Chi3L1 was found up to 10 weeks after ESWT in experimental but not in control cartilage. COL2A1 mRNA was increased in samples 1 and 4 weeks after ESWT. Alterations found on the ultrastructural level showed expansion of the rough-surfaced endoplasmatic reticulum, detachment of the cell membrane and necrotic chondrocytes. Extracorporeal shock waves caused alterations of hyaline cartilage on a molecular and ultrastructural level that were distinctly different from control. Similar changes were described before in the very early phase of osteoarthritis (OA). High-energy ESWT might therefore cause degenerative changes in hyaline cartilage as they are found in initial OA. Copyright 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  4. Production of hyaline-like cartilage by bone marrow mesenchymal stem cells in a self-assembly model.

    Science.gov (United States)

    Elder, Steven H; Cooley, Avery J; Borazjani, Ali; Sowell, Brittany L; To, Harrison; Tran, Scott C

    2009-10-01

    A scaffoldless or self-assembly approach to cartilage tissue engineering has been used to produce hyaline cartilage from bone marrow-derived mesenchymal stem cells (bMSCs), but the mechanical properties of such engineered cartilage and the effects the transforming growth factor (TGF) isoform have not been fully explored. This study employs a cell culture insert model to produce tissue-engineered cartilage using bMSCs. Neonatal pig bMSCs were isolated by plastic adherence and expanded in monolayer before being seeded into porous transwell inserts and cultured for 4 or 8 weeks in defined chondrogenic media containing either TGF-beta1 or TGF-beta3. Following biomechanical evaluation in confined compression, colorimetric dimethyl methylene blue and Sircol dye-binding assays were used to analyze glycosaminoglycan (GAG) and collagen contents, respectively. Histological sections were stained with toluidine blue for proteoglycans and with picrosirius red to reveal collagen orientation, and immunostained for detection of collagen types I and II. Neocartilage increased in thickness, collagen, and GAG content between 4 and 8 weeks. Proteoglycan concentration increased with depth from the top surface. The tissue contained much more collagen type II than type I, and there was a consistent pattern of collagen alignment. TGF-beta1-treated and TGF-beta3-treated constructs were similar at 4 weeks, but 8-week TGF-beta1 constructs had a higher aggregate modulus and GAG content compared to TGF-beta3. These results demonstrate that bMSCs can generate functional hyaline-like cartilage through a self-assembling process.

  5. Release of transgenic progranulin from a living hyaline cartilage graft model: An in vitro evaluation on anti-inflammation.

    Science.gov (United States)

    Lau, Ting Ting; Zhang, Feng; Tang, Wei; Wang, Dong-An

    2016-12-01

    Osteoarthritis (OA) is a prevalent condition that compromises and even jeopardizes the life quality of millions of people. Common symptoms in OA includes joint stiffness and soreness, and they are often associated with inflammations to various extend. Due to the avascular and aneural nature of articular hyaline cartilage, it has limited self-repair capabilities; especially under inflammatory conditions, damages inflicted on cartilage are often irreversible. Hence, treatment approaches focus on anti-inflammation or articular cartilage replacement. In this study, an engineered, dual-functional living hyaline cartilage graft (LhCG), capable of releasing transgenic anti-inflammatory cytokine-progranulin (PGRN) is developed and envisioned to simultaneously fulfil both requirements. The therapeutic functionality of PGRN releasing LhCG is evaluated by co-culturing the constructs with tumor necrosis factor-alpha (TNFα) secreting THP-1 cells to simulate the inflammatory condition in arthritis. Non-transgenic LhCG constructs and non-coculture sample groups were set up as controls. Gene expression and ECM composition changes across samples were assessed to understand the effects of PGRN as well as inflammatory environment on the cartilage graft. Collectively, the results in this study suggest that in situ release of transgenic recombinant PGRN protects LhCG from induced inflammation in vitro; contrastively, in the absence of PGRN, cartilage grafts are at risk of being degraded and mineralized under exposure to TNFα signaling. This shows that cartilage graft itself can be at risk of degradation or calcification when implanted in arthritic microenvironment. Hence, the inflammatory microenvironment has to be considered in cartilage replacement therapy to increase chances of successful joint mobility restoration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2968-2977, 2016. © 2016 Wiley Periodicals, Inc.

  6. Forces Acting on Sessile Droplet on Inclined Surfaces

    OpenAIRE

    Annapragada, S. Ravi; Murthy, Jayathi Y.; Garimella, Suresh V.

    2009-01-01

    Although many analytical, experimental and numerical studies have focused on droplet motion, the mechanics of the droplet while still in its static state, and just before motion starts, are not well understood. A study of static droplets would shed light on the threshold voltage (or critical inclination) for initiating electrically (or gravitationally) induced droplet motion. Before the droplet starts to move, the droplet shape changes such that the forces acting at the triple contact line ba...

  7. Droplet turbulence interactions under subcritical and supercritical conditions

    Science.gov (United States)

    Coy, E. B.; Greenfield, S. C.; Ondas, M. S.; Song, Y.-H.; Spegar, T. D.; Santavicca, D. A.

    1993-01-01

    The goal of this research is to experimentally characterize the behavior of droplets in vaporizing liquid sprays under conditions typical of those encountered in high pressure combustion systems such as liquid fueled rocket engines. Of particular interest are measurements of droplet drag, droplet heating, droplet vaporization, droplet distortion, and secondary droplet breakup, under both subcritical and supercritical conditions. The paper presents a brief description of the specific accomplishments which have been made over the past year.

  8. Driving Droplets by Curvi-Propulsion

    CERN Document Server

    Lv, Cunjing; Chuang, Yin-Chuan; Tseng, Fan-Gang; Yin, Yajun; Grey, Francois; Zheng, Quanshui

    2012-01-01

    How to make small liquid droplets move spontaneously and directionally on solid surfaces is a challenge in lab-on-chip technologies, DNA analysis, and heat exchangers. The best-known mechanism, a wettability gradient, does not move droplets rapidly enough for most purposes and cannot move droplets smaller than a critical size defined by the contact angle hysteresis. Here we report on a mechanism using curvature gradients, which we show is particularly effective at accelerating small droplets, and works for both hydrophilic and hydrophobic surfaces. Experiments for water droplets on glass cones in the sub-millimeter range show a maximum speed of 0.28 m/s, two orders of magnitude higher than obtained by wettability gradient. From simple considerations of droplet surface area change, we show that the force exerted on a droplet on a conical surface scales as the curvature gradient. This force therefore diverges for small droplets near the tip of a cone. We illustrate this using molecular dynamics simulations, and...

  9. Dynamic Morphologies of Microscale Droplet Interface Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Mruetusatorn, Prachya [ORNL; Boreyko, Jonathan B [ORNL; Sarles, Stephen A [ORNL; Venkatesan, Guru [The University of Tennessee; Hayes, Douglas G [ORNL; Collier, Pat [ORNL

    2014-01-01

    Droplet interface bilayers (DIBs) are a powerful platform for studying the dynamics of synthetic cellular membranes; however, very little has been done to exploit the unique dynamical features of DIBs. Here, we generate microscale droplet interface bilayers ( DIBs) by bringing together femtoliter-volume water droplets in a microfluidic oil channel, and characterize morphological changes of the DIBs as the droplets shrink due to evaporation. By varying the initial conditions of the system, we identify three distinct classes of dynamic morphology. (1) Buckling and Fission: When forming DIBs using the lipid-out method (lipids in oil phase), lipids in the shrinking monolayers continually pair together and slide into the bilayer to conserve their mass. As the bilayer continues to grow, it becomes confined, buckles, and eventually fissions one or more vesicles. (2) Uniform Shrinking: When using the lipid-in method (lipids in water phase) to form DIBs, lipids uniformly transfer from the monolayers and bilayer into vesicles contained inside the water droplets. (3) Stretching and Unzipping: Finally, when the droplets are pinned to the wall(s) of the microfluidic channel, the droplets become stretched during evaporation, culminating in the unzipping of the bilayer and droplet separation. These findings offer a better understanding of the dynamics of coupled lipid interfaces.

  10. Exotic states of bouncing and walking droplets

    DEFF Research Database (Denmark)

    Wind-Willassen, Øistein; Moláček, Jan; Harris, Daniel M.;

    2013-01-01

    We present the results of an integrated experimental and theoretical investigation of droplets bouncing on a vibrating fluid bath. A comprehensive series of experiments provides the most detailed characterisation to date of the system's dependence on fluid properties, droplet size, and vibrationa...

  11. Binary droplet collision at high Weber number.

    Science.gov (United States)

    Pan, Kuo-Long; Chou, Ping-Chung; Tseng, Yu-Jen

    2009-09-01

    By using the techniques developed for generating high-speed droplets, we have systematically investigated binary droplet collision when the Weber number (We) was increased from the range usually tested in previous studies on the order of 10 to a much larger value of about 5100 for water (a droplet at 23 m/s with a diameter of 0.7 mm). Various liquids were also used to explore the effects of viscosity and surface tension. Specifically, beyond the well-known regimes at moderate We's, which exhibited coalescence, separation, and separation followed by satellite droplets, we found different behaviors showing a fingering lamella, separation after fingering, breakup of outer fingers, and prompt splattering into multiple secondary droplets as We was increased. The critical Weber numbers that mark the boundaries between these impact regimes are identified. The specific impact behaviors, such as fingering and prompt splattering or splashing, share essential similarity with those also observed in droplet-surface impacts, whereas substantial variations in the transition boundaries may result from the disparity of the boundary conditions at impacts. To compare the outcomes of both types of collisions, a simple model based on energy conservation was carried out to predict the maximum diameter of an expanding liquid disk for a binary droplet collision. The results oppose the dominance of viscous drag, as proposed by previous studies, as the main deceleration force to effect a Rayleigh-Taylor instability and ensuing periphery fingers, which may further lead to the formations of satellite droplets.

  12. Droplets bouncing over a vibrating fluid layer

    CERN Document Server

    Cabrera-Garcia, Pablo

    2012-01-01

    This is an entry for the Gallery of Fluid Motion of the 65st Annual Meeting of the APS-DFD (fluid dynamics video). This video shows the motion of levitated liquid droplets. The levitation is produced by the vertical vibration of a liquid container. We made visualizations of the motion of many droplets to study the formation of clusters and their stability.

  13. Analysis of coalescence behavior for compressed droplets

    Science.gov (United States)

    Choi, Sung Woong; Lee, Dong Eon; Lee, Woo Il; Kim, Han Sang

    2017-03-01

    Coalescence of droplets is a significant phenomenon, and it has been adapted to many applications such as raindrop formation, emulsion polymerization, ink-jet printing, coating, and multiphase flows. In this study, the morphological characteristics of two compressed adjacent droplets between two parallel plates were investigated to study the phenomenon of coalescence of droplets. By controlling the distance of the dispensed droplets, various results for coalescence of droplets were evaluated, especially, from the view of the minor axis, major axis, and meniscus liquid bridge of the coalesced droplet. Experimental results show that the length of the meniscus liquid bridge rapidly increases and then the rate of increase slows with time. The increase rate of the major and minor axes is largely influenced by the meniscus liquid bridge, which is mainly due to the curvature between the droplets. The numerical modeling of the coalescence of the two compressed droplets between two parallel plates was presented and simulation was conducted to realize the coalescence behavior. Comparison with numerical simulation showed that there was a good agreement with the experimental results.

  14. Photochemistry inside superfluid helium nano droplets

    Energy Technology Data Exchange (ETDEWEB)

    Slenczka, Alkwin; Vdovin, Alexander; Dick, Bernhard [Inst. fuer Physikalische und Theoretische Chemie, Univ. Regensburg (Germany)

    2007-07-01

    Superfluid helium nano droplets serve as the most gentle cyrogenic matrix for creating isolated and cold molecules. High resolution electronic spectroscopy is sensitive for the investigation of the very weak perturbation of the helium droplet on the embedded molecule. Fluorescence excitation spectra, dispersed emission spectra and pump--probe-spectra show details of the salvation of molecules in helium droplets which were attributed to relaxation processes of the first solvation layer around the dopant. Photochemistry such as ESIPT, tautomerization by proton transfer and charge transfer are highly sensitive on intermolecular perturbations. We have studies such processes in superfluid helium droplets. The comparison with the respective gas phase experiments and quantum chemical calculations reveals further details on the photochemistry as well as on the perturbation by the superfluid helium droplet.

  15. Acoustophoresis in Variously Shaped Liquid Droplets

    CERN Document Server

    Yu, Gan; Xu, Jie; 10.1039/c1sm05871a

    2012-01-01

    The ability to precisely trap, transport and manipulate micrometer-sized objects, including biological cells, DNA-coated microspheres and microorganisms, is very important in life science studies and biomedical applications. In this study, acoustic radiation force in an ultrasonic standing wave field is used for micro-objects manipulation, a technique termed as acoustophoresis. Free surfaces of liquid droplets are used as sound reflectors to confine sound waves inside the droplets. Two techniques were developed for precise control of droplet shapes: edge pinning and hydrophilic/hydrophobic interface pinning. For all tested droplet shapes, including circular, annular and rectangular, our experiments show that polymer micro particles can be manipulated by ultrasound and form into a variety of patterns, for example, concentric rings and radial lines in an annular droplet. The complexity of the pattern increases with increasing frequency, and the observations are in line with simulation results. The acoustic mani...

  16. Preparation and nucleation of spherical metallic droplet

    Directory of Open Access Journals (Sweden)

    Bing-ge Zhao

    2015-03-01

    Full Text Available The preparation and solidification of metallic droplets attract more and more attention for their significance in both engineering and scientific fields. In this paper, the preparation and characterization of Sn-based alloy droplets using different methods such as atomization and consumable electrode direct current arc (CDCA technique are reviewed. The morphology and structure of these droplets were determined by optical microscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The solidification behavior of single droplet was systematically studied by means of scanning calorimetry (DSC, and the nucleation kinetics was also calculated. In particular, the development of fast scanning calorimetry (FSC made it possible to investigate the evolution of undercooling under ultrafast but controllable heating and cooling conditions. The combination of CDCA technique and FSC measurements opens up a new door for quantitative studies on droplet solidification, which is accessible to demonstrate some theories by experiments.

  17. New models for droplet heating and evaporation

    KAUST Repository

    Sazhin, Sergei S.

    2013-02-01

    A brief summary of new models for droplet heating and evaporation, developed mainly at the Sir Harry Ricardo Laboratory of the University of Brighton during 2011-2012, is presented. These are hydrodynamic models for mono-component droplet heating and evaporation, taking into account the effects of the moving boundary due to evaporation, hydrodynamic models of multi-component droplet heating and evaporation, taking and not taking into account the effects of the moving boundary, new kinetic models of mono-component droplet heating and evaporation, and a model for mono-component droplet evaporation, based on molecular dynamics simulation. The results, predicted by the new models are compared with experimental data and the prehctions of the previously developed models where possible. © 2013 Asian Network for Scientific Information.

  18. Statistical steady state in turbulent droplet condensation

    CERN Document Server

    Siewert, Christoph; Krstulovic, Giorgio

    2016-01-01

    Motivated by the early stages of clouds and other systems in which droplets grow and shrink in a turbulence-driven supersaturation field, we investigate the problem of turbulent condensation using direct numerical simulations. The turbulent fluctuations of the supersaturation field offer different conditions for the growth of droplets which evolve in time due to turbulent transport and mixing. Based on that, we propose a Lagrangian stochastic model for condensation and evaporation of small droplets in turbulent flows. It consists of a set of stochastic integro-differential equations for the joint evolution of the squared radius and the supersaturation along the droplet trajectories. The model has two parameters fixed by the total amount of water and the thermodynamic properties, as well as the Lagrangian integral timescale of the turbulent supersaturation. The model reproduces very well the droplet size distributions obtained from direct numerical simulations and their time evolution. A noticeable result is t...

  19. The Lipid-Droplet Proteome Reveals that Droplets Are a Protein-Storage Depot

    Energy Technology Data Exchange (ETDEWEB)

    Cermelli, Silvia; Guo, Yi; Gross, Steven P.; Welte, Michael

    2006-09-19

    Lipid droplets are ubiquitous organelles that are among the basic building blocks of eukaryotic cells. Despite central roles for cholesterol homeostasis and lipid metabolism, their function and protein composition are poorly understood. Results: We purified lipid droplets from Drosophila embryos and analyzed the associated proteins by capillary LC-MS-MS. Important functional groups include enzymes involved in lipid metabolism, signaling molecules, and proteins related to membrane trafficking. Unexpectedly, histones H2A, H2Av, and H2B were present. Using biochemistry, genetics, real-time imaging, and cell biology, we confirm that roughly 50% of certain embryonic histones are physically attached to lipid droplets, a localization conserved in other fly species. Histone association with droplets starts during oogenesis and is prominent in early embryos, but it is undetectable in later stages or in cultured cells. Histones on droplets are not irreversibly trapped; quantitation of droplet histone levels and transplantation experiments suggest that histones are transferred from droplets to nuclei as development proceeds. When this maternal store of histones is unavailable because lipid droplets are mislocalized, zygotic histone production starts prematurely. Conclusions: Because we uncover a striking proteomic similarity of Drosophila droplets to mammalian lipid droplets, Drosophila likely provides a good model for understanding droplet function in general. Our analysis also reveals a new function for these organelles; the massive nature of histone association with droplets and its developmental time-course suggest that droplets sequester maternally provided proteins until they are needed. We propose that lipid droplets can serve as transient storage depots for proteins that lack appropriate binding partners in the cell. Such sequestration may provide a general cellular strategy for handling excess proteins.

  20. Growth and Division of Active Droplets: A Model for Protocells

    CERN Document Server

    Zwicker, David; Weber, Christoph A; Hyman, Anthony A; Jülicher, Frank

    2016-01-01

    It has been proposed that during the early steps in the origin of life, small droplets could have formed via the segregation of molecules from complex mixtures by phase separation. These droplets could have provided chemical reaction centers. However, whether these droplets could divide and propagate is unclear. Here we examine the behavior of droplets in systems that are maintained away from thermodynamic equilibrium by an external supply of energy. In these systems, droplets grow by the addition of droplet material generated by chemical reactions. Surprisingly, we find that chemically driven droplet growth can lead to shape instabilities that trigger the division of droplets into two smaller daughters. Therefore, chemically active droplets can exhibit cycles of growth and division that resemble the proliferation of living cells. Dividing active droplets could serve as a model for prebiotic protocells, where chemical reactions in the droplet play the role of a prebiotic metabolism.

  1. Fluoropolymer surface coatings to control droplets in microfluidic devices.

    Science.gov (United States)

    Riche, Carson T; Zhang, Chuchu; Gupta, Malancha; Malmstadt, Noah

    2014-06-07

    We have demonstrated the application of low surface energy fluoropolymer coatings onto poly(dimethylsiloxane) (PDMS) microfluidic devices for droplet formation and extraction-induced merger of droplets. Initiated chemical vapor deposition (iCVD) was used to pattern fluoropolymer coatings within microchannels based on geometrical constraints. In a two-phase flow system, the range of accessible flow rates for droplet formation was greatly enhanced in the coated devices. The ability to controllably apply the coating only at the inlet facilitated a method for merging droplets. An organic spacer droplet was extracted from between a pair of aqueous droplets. The size of the organic droplet and the flow rate controlled the time to merge the aqueous droplets; the process of merging was independent of the droplet sizes. Extraction-induced droplet merging is a robust method for manipulating droplets that could be applied in translating multi-step reactions to microfluidic platforms.

  2. Numerical simulations of pendant droplets

    Science.gov (United States)

    Pena, Carlos; Kahouadji, Lyes; Matar, Omar; Chergui, Jalel; Juric, Damir; Shin, Seungwon

    2015-11-01

    We simulate the evolution of a three-dimensional pendant droplet through pinch-off using a new parallel two-phase flow solver called BLUE. The parallelization of the code is based on the technique of algebraic domain decomposition where the velocity field is solved by a parallel GMRes method for the viscous terms and the pressure by a parallel multigrid/GMRes method. Communication is handled by MPI message passing procedures. The method for the treatment of the fluid interfaces uses a hybrid Front Tracking/Level Set technique which defines the interface both by a discontinuous density field as well as by a local triangular Lagrangian mesh. This structure allows the interface to undergo large deformations including the rupture and coalescence of fluid interfaces. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  3. Electrospray Droplet Impact/SIMS

    Science.gov (United States)

    Hiraoka, Kenzo

    A new type of cluster SIMS, named as electrospray droplet impact (EDI), has been developed in our laboratory. It was found that peptides deposited on the stainless steel substrate were ionized/desorbed without the accumulation of radiation products. The organic samples with film thickness thinner than 10 monolayers are desorbed/ionized with little damage underneath the surface. In general, rather strong negative ions as well as positive ions are generated. The mechanism for the ionization/desorption in EDI is much less complicated than those for MALDI and SIMS due to the fact that only very thin sample layers take part in the shock-wave excited selvedge and higher-order side reactions are largely suppressed.

  4. Self-propelled droplet behavior during condensation on superhydrophobic surfaces

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin; Zhu, Bei; Zhang, Xuan

    2016-05-01

    Self-propelled droplet motion has applications in various engineering fields such as self-cleaning surfaces, heat transfer enhancement, and anti-icing methods. A superhydrophobic surface was fabricated using two simultaneous chemical reactions with droplet condensation experiments performed on the horizontal superhydrophobic surface to characterize the droplet behavior. The droplet behavior is classified into three types based on their motion features and leftover marks as immobile droplet coalescence, self-propelled droplet jumping, and self-propelled droplet sweeping. This study focuses on the droplet sweeping that occurs due to the ultra-small rolling angle of the superhydrophobic surface, where the resulting droplet sweeps along the surface, merging with all the droplets it meets and leaving a long, narrow, clear track with a large droplet at the end of the track. An easy method is developed to predict the droplet sweeping direction based on the relative positions of the droplets just before coalescence. The droplet sweeping always absorbs dozens of droplets and is not limited by the surface structures; thus, this sweeping has many useful applications. In addition, the relationships between the droplet behavior and the number of participating droplets are also analyzed statistically.

  5. Development of high effectiveness droplet heat exchangers

    Science.gov (United States)

    Thayer, W. J., III; Sekins, K. M.; Bruckner, A. P.

    1985-04-01

    An experimental and analytical investigation has been carried out to assess the feasibility of developing high effectiveness, high temperature droplet heat exchangers and to identify practical applications for this type of direct contact heat exchanger. The droplet heat exchanger (DHX) concept studies uses a counterflowing gas and droplet configuration, uniformly sized droplets or particles, and a uniform dispersion of droplets in gas to achieve high heat exchanger effectiveness. Direct contact between the heat transfer media eliminates the solid heat transfer surfaces that are used in conventional heat exchangers and is expected to make very high temperature heat transfer practical. Low temperature simulation tests and analysis have been used to demonstrate that uniformly sized droplets can be generated over a wide range of fluid properties and operating conditions appropriate for high temperature droplet heat exchanger applications. One- and two-dimensional, two-phase flow and heat transfer computer models have been developed and used to characterize both individual component configurations and overall DHX heat transfer rates and effectiveness. The computer model and test data began to diverge as the operating pressure was increased, indicating a need for more general transport rate correlations and a better understanding of the two-phase flows that govern DHX operation.

  6. Mechanical vibration of viscoelastic liquid droplets

    Science.gov (United States)

    Sharp, James; Harrold, Victoria

    2014-03-01

    The resonant vibrations of viscoelastic sessile droplets supported on different substrates were monitored using a simple laser light scattering technique. In these experiments, laser light was reflected from the surfaces of droplets of high Mw poly acrylamide-co-acrylic acid (PAA) dissolved in water. The scattered light was allowed to fall on the surface of a photodiode detector and a mechanical impulse was applied to the drops using a vibration motor mounted beneath the substrates. The mechanical impulse caused the droplets to vibrate and the scattered light moved across the surface of the photodiode. The resulting time dependent photodiode signal was then Fourier transformed to obtain the mechanical vibrational spectra of the droplets. The frequencies and widths of the resonant peaks were extracted for droplets containing different concentrations of PAA and with a range of sizes. This was repeated for PAA loaded water drops on surfaces which displayed different values of the three phase contact angle. The results were compared to a simple model of droplet vibration which considers the formation of standing wave states on the surface of a viscoelastic droplet. We gratefully acknowledge the support of the Leverhulme trust under grant number RPG-2012-702.

  7. Electrowetting Actuation of Polydisperse Nanofluid Droplets

    Directory of Open Access Journals (Sweden)

    Crismar Patacsil

    2017-01-01

    Full Text Available We present results of electrowetting experiments employing droplets formed from aqueous suspensions of Au nanoparticles. A planar electrowetting system, consisting of a Pt wire electrode and a bottom Cu electrode with an insulating silicone layer, is used to observe changes in droplet contact angle when an external electric field is applied. The equilibrium contact angle at 0 V decreases with increasing nanoparticle concentration, dropping from 100.4° for pure deionized water to 94.7° for a 0.5 μM nanofluid. Increasing the nanoparticle content also lowers the required voltage for effective actuation. With actuation at 15 V, contact angle decreases by 9% and 35% for droplets formed from pure water and a 0.5 μM nanoparticle suspension, respectively. Contact angle saturation is observed with nanofluid droplets, with the threshold voltage decreasing as nanoparticle concentration rises. Maximum droplet actuation before contact angle saturation is achieved at only 10 V for a concentration of 0.5 μM. A proposed mechanism for the enhanced electrowetting response of a nanofluid droplet involves a reduction in surface tension of the droplet as nanoparticles accumulate at the liquid-vapor interface.

  8. Three dimensional force balance of asymmetric droplets

    Science.gov (United States)

    Kim, Yeseul; Lim, Su Jin; Cho, Kun; Weon, Byung Mook

    2016-11-01

    An equilibrium contact angle of a droplet is determined by a horizontal force balance among vapor, liquid, and solid, which is known as Young's law. Conventional wetting law is valid only for axis-symmetric droplets, whereas real droplets are often asymmetric. Here we show that three-dimensional geometry must be considered for a force balance for asymmetric droplets. By visualizing asymmetric droplets placed on a free-standing membrane in air with X-ray microscopy, we are able to identify that force balances in one side and in other side control pinning behaviors during evaporation of droplets. We find that X-ray microscopy is powerful for realizing the three-dimensional force balance, which would be essential in interpretation and manipulation of wetting, spreading, and drying dynamics for asymmetric droplets. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1B01007133).

  9. Self-arraying of charged levitating droplets.

    Science.gov (United States)

    Kauffmann, Paul; Nussbaumer, Jérémie; Masse, Alain; Jeandey, Christian; Grateau, Henri; Pham, Pascale; Reyne, Gilbert; Haguet, Vincent

    2011-06-01

    Diamagnetic levitation of water droplets in air is a promising phenomenon to achieve contactless manipulation of chemical or biochemical samples. This noncontact handling technique prevents contaminations of samples as well as provides measurements of interaction forces between levitating reactors. Under a nonuniform magnetic field, diamagnetic bodies such as water droplets experience a repulsive force which may lead to diamagnetic levitation of a single or few micro-objects. The levitation of several repulsively charged picoliter droplets was successfully performed in a ~1 mm(2) adjustable flat magnetic well provided by a centimeter-sized cylindrical permanent magnet structure. Each droplet position results from the balance between the centripetal diamagnetic force and the repulsive Coulombian forces. Levitating water droplets self-organize into satellite patterns or thin clouds, according to their charge and size. Small triangular lattices of identical droplets reproduce magneto-Wigner crystals. Repulsive forces and inner charges can be measured in the piconewton and the femtocoulomb ranges, respectively. Evolution of interaction forces is accurately followed up over time during droplet evaporation.

  10. Burning Behavior of Liquid Fuel Droplets

    Directory of Open Access Journals (Sweden)

    Shah Shahood Alam

    2015-06-01

    Full Text Available Ignition of flammable liquids by hot surfaces is well known to automotive and aviation industries. However, only a limited data regarding hot surface ignition (HSI of pure and commercial fuels is available in literature. Further, relatively few studies have determined the ignition delay and to our knowledge the combustion lifetime. In the present work, we have generated results from an efficient, reproducible, yet simple experimental setup involving a liquid fuel droplet, a horizontal heated stainless steel plate and quiescent environment. Tests were conducted for diesel, biodiesel and its blends as well as vegetable oils, applied/used as single droplets under variety of conditions to the heated surface. The droplet size range was approximately between 1500 micron to 2000 micron. The objective of this experiment was to determine the minimum temperatures for HSI and also the temperatures where 100% probability of ignition was expected. Further, from this experiment, we were also able to obtain the ignition delay and droplet lifetime. As an extension to this study, a separate droplet combustion model was developed to closely study the general burning behavior of these droplets by generating temperature and species concentration profiles. The droplet mass burning rate was also determined. The results obtained in the present work were in a general agreement with the experimental and modeling observations of other studies.

  11. High Velocity Droplet Rebound On Liquid Pools

    Science.gov (United States)

    Doak, William; Laiacona, Danielle; Chiarot, Paul; German, Guy

    2015-11-01

    Rebound of high velocity, periodic droplet streams off viscous liquid pools is studied experimentally. Droplets, approximately 60 micrometers in diameter, impact the oil surface at velocities up to 13 m/s and at angles between 2-25 degrees. The oil surface does not degrade or lose its ability to provide rebound even after millions of droplet impacts. The oil was varied to examine the effect that surface tension and viscosity had on droplet rebound. Stable rebound is achievable on oils varying in dynamic viscosity in the range 13-970 Pa.s and surface tensions in the range 19-28 mN/m. When rebound occurs, a consistent 29% loss of droplet kinetic energy is observed. This is a surprising relationship due to the fact that it holds true for all cases of stable rebound regardless of the oil used. We further observe an upper inertial limit where droplets no longer provide stable rebound and instead become fully entrained in the oil pool. This limit is governed by the Rayleigh-Plateau instability and can be characterized and predicted using a modified version of the Weber number. The droplet rebound presented in this study is unique due to the size, velocity, and frequency of the droplets used. Another unique feature is that the rebound manifests itself as an effectively static phenomenon. No motion of the interface - oscillations, waves, or otherwise - was observed during rebound. The quasi-static nature of rebound enabled distinctions to be made regarding energy dissipation and the transition from droplet rebound to entrainment.

  12. Photoacoustic spectral characterization of perfluorocarbon droplets

    Science.gov (United States)

    Strohm, Eric; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael

    2012-02-01

    Perfluorocarbon droplets containing optical absorbing nanoparticles have been developed for use as theranostic agents (for both imaging and therapy) and as dual-mode contrast agents. Droplets can be used as photoacoustic contrast agents, vaporized via optical irradiation, then the resulting bubbles can be used as ultrasound imaging and therapeutic agents. The photoacoustic signals from micron-sized droplets containing silica coated gold nanospheres were measured using ultra-high frequencies (100-1000 MHz). The spectra of droplets embedded in a gelatin phantom were compared to a theoretical model which calculates the pressure wave from a spherical homogenous liquid undergoing thermoelastic expansion resulting from laser absorption. The location of the spectral features of the theoretical model and experimental spectra were in agreement after accounting for increases in the droplet sound speed with frequency. The agreement between experiment and model indicate that droplets (which have negligible optical absorption in the visible and infrared spectra by themselves) emitted pressure waves related to the droplet composition and size, and was independent of the physical characteristics of the optical absorbing nanoparticles. The diameter of individual droplets was calculated using three independent methods: the time domain photoacoustic signal, the time domain pulse echo ultrasound signal, and a fit to the photoacoustic model, then compared to the diameter as measured by optical microscopy. It was found the photoacoustic and ultrasound methods calculated diameters an average of 2.6% of each other, and 8.8% lower than that measured using optical microscopy. The discrepancy between the calculated diameters and the optical measurements may be due to the difficulty in resolving the droplet edges after being embedded in the translucent gelatin medium.

  13. From Single Droplet to Column Design

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The technique state to design counter-current extraction columns is based on the performance of pilot plant experiments. The modelling is then either with the equilibrium or dispersion model, whereas in the latter the dispersion coefficient accounts for all hydrodynamic non-idealities. A new approach uses single droplet experiments to obtain the basic laws and functions governing droplet breakage, coalescence,relative velocity, and axial dispersion when using droplet populance balance models (DPBM). The hydrodynamics simulation results show that the mean Sauter diameter, hold-up, and concentration profiles could be well predicted, which promotes the use of DPBM models for further applications in industrial scale.

  14. Nonisothermal desorption of droplets of complex compositions

    Directory of Open Access Journals (Sweden)

    Nakoryakov Vladimir E.

    2012-01-01

    Full Text Available This paper presents the process of nonstationary evaporation of aqueous solutions of LiBr-H2O, CaCl2-H2O, NaCl-H2O droplets on a horizontal heating surface. The following typical stages of heat and mass transfer depending on wall temperature have been considered: evaporation below boiling temperature and nucleate boiling. The significant decrease in desorption intensity with a rise of initial mass concentration of salt has been observed. Formation of a surface crystallization front at evaporation of a droplet has been detected. We have developed the experimental method for direct measurements of the mass of evaporating droplet.

  15. Foam droplet separation for nanoparticle synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Tyree, Corey A.; Allen, Jonathan O. [Arizona State University, Department of Chemical Engineering (United States)], E-mail: joallen@asu.edu

    2008-03-15

    A novel approach to nanoparticle synthesis was developed whereby foam bubble bursting produced aerosol droplets, an approach patterned after the marine foam aerosol cycle. The droplets were dried to remove solvent, leaving nanometer-sized particles composed of precursor material. Nanoparticles composed of sodium chloride (mean diameter, D-bar{sub p} {approx} 100 nm), phosphotungstic acid (D-bar{sub p} {approx} 55 nm), and bovine insulin (D{sub p} {approx} 5-30 nm) were synthesized. Foam droplet separation can be carried out at ambient temperature and pressure. The 'soft' nature of the process makes it compatible with a wide range of materials.

  16. Thermocapillary migration of bubbles and droplets

    Science.gov (United States)

    Subramanian, R. S.

    1983-01-01

    A discussion is presented concerning the motion of droplets in a surrounding fluid induced by a temperature gradient. Such 'thermocapillary migration' may be characterized as the tangential stress at the interface that is induced by the temperature gradient's variation of interfacial tension, causing motion in the neighboring fluid both inside and outside the droplet. As a result, the droplet moves in the direction of the pole with the lower interfacial tension. An analysis is conducted in the creeping flow limit, for the case of small Marangoni number values. The method of matched asymptotic expansions is used for the solution of the field equations.

  17. Liquid Droplets on a Highly Deformable Membrane

    Science.gov (United States)

    Schulman, Rafael D.; Dalnoki-Veress, Kari

    2015-11-01

    We examine the deformation produced by microdroplets atop thin elastomeric and glassy free-standing films. Because of the Laplace pressure, the droplets deform the elastic membrane thereby forming a bulge. Thus, two angles define the droplet or membrane geometry: the angles the deformed bulge and the liquid surface make with the film. These angles are measured as a function of the film tension, and are in excellent agreement with a force balance at the contact line. Finally, we find that if the membrane has an anisotropic tension, the droplets are no longer spherical but become elongated along the direction of high tension.

  18. Vibrations of a diamagnetically levitated water droplet

    CERN Document Server

    Hill, R J A

    2010-01-01

    We measure the frequencies of small-amplitude shape oscillations of a magnetically-levitated water droplet. The drop levitates in a magnetogravitational potential trap. The restoring forces of the trap, acting on the droplet's surface in addition to the surface tension, increase the frequency of the oscillations. We derive the eigenfrequencies of the normal mode vibrations of a spherical droplet in the trap and compare it with our experimental measurements. We also consider the effect of the shape of the potential trap on the eigenfrequencies.

  19. Electronically droplet energy harvesting using piezoelectric cantilevers

    KAUST Repository

    Al Ahmad, Mahmoud Al

    2012-01-01

    A report is presented on free falling droplet energy harvesting using piezoelectric cantilevers. The harvester incorporates a multimorph clamped-free cantilever which is composed of five layers of lead zirconate titanate piezoelectric thick films. During the impact, the droplet kinetic energy is transferred into the form of mechanical stress forcing the piezoelectric structure to vibrate. Experimental results show energy of 0.3 μJ per droplet. The scenario of moderate falling drop intensity, i.e. 230 drops per second, yields a total energy of 400 μJ. © 2012 The Institution of Engineering and Technology.

  20. Orbiting droplets on a vibrated bath

    Science.gov (United States)

    Sampara, Naresh; Burger, Loic; Gilet, Tristan; Microfluidics, university of liege Team

    2015-11-01

    A millimeter-sized oil droplet can bounce on a vertically vibrated liquid bath for unlimited time. It may couple to the surface wave it emits; leading to horizontal self-propulsion called walking. When several walkers coexist close to one another, they either repel or attract each other, in response to the superposition of the waves they generate. Attraction leads to various bound states, including droplets that orbit around each other. We have experimentally investigated the variety of quantized orbital motions exhibited by two, three and more identical walkers, as a function of forcing acceleration. Each motion is quantified in terms of droplet and wave energy.

  1. Analysis of droplet jumping phenomenon with lattice Boltzmann simulation of droplet coalescence

    Science.gov (United States)

    Peng, Benli; Wang, Sifang; Lan, Zhong; Xu, Wei; Wen, Rongfu; Ma, Xuehu

    2013-04-01

    Droplet jumping from condensing surfaces induced by droplet coalescence during dropwise condensation of mixed steam on a superhydrophobic surface can significantly enhance condensation heat transfer of mixed steam with non-condensable gas. This phenomenon was visually observed and theoretically analyzed in the present paper. The dynamic evolution of droplet and the velocity distribution inside the droplet during coalescence were simulated using multiphase lattice Boltzmann method. The energy distribution released by droplet coalescence was calculated statistically, and the jumping height induced by droplet coalescence on a superhydrophobic surface was predicted based on the energy conservation method. The theoretical predictions obtained by the modified model proposed in this paper agree well with the experimental observations.

  2. The effects of turbulence on droplet drag and secondary droplet breakup

    Science.gov (United States)

    Song, Y.-H.; Coy, E.; Greenfield, S.; Ondas, M.; Prevish, T.; Spegar, T.; Santavicca, D.

    1994-01-01

    The objective of this research is to obtain an improved understanding of the behavior of droplets in vaporizing sprays, particularly under conditions typical of those in high pressure rocket sprays. Experiments are conducted in a variety of high pressure, high temperature, optically-accessible flow systems, including one which is capable of operation at pressures up to 70 atm, temperatures up to 600 K, gas velocities up to 30 m/sec and turbulence intensities up to 40 percent. Single droplets, 50 to 500 micron in diameter, are produced by an aerodynamic droplet generator and transversely injected into the flow. Measurements are made of the droplet position, size, velocity and temperature and of the droplet's vapor wake from which droplet drag, dispersion, heating, vaporization and breakup are characterized.

  3. Self-propelled oil droplets consuming "fuel" surfactant

    DEFF Research Database (Denmark)

    Toyota, Taro; Maru, Naoto; Hanczyc, Martin M

    2009-01-01

    A micrometer-sized oil droplet of 4-octylaniline containing 5 mol % of an amphiphilic catalyst exhibited a self-propelled motion, producing tiny oil droplets, in an aqueous dispersion of an amphiphilic precursor of 4-octylaniline. The tiny droplets on the surface of the self-propelled droplet wer...

  4. MRI of the hyaline knee joint cartilage. Animal experimental and clinical studies; MRT des hyalinen Kniegelenkknorpels. Tierexperimentelle und klinische Untersuchungen

    Energy Technology Data Exchange (ETDEWEB)

    Adam, G. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik; Prescher, A. [Technische Hochschule Aachen (Germany). Inst. fuer Anatomie; Nolte-Ernsting, C. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik; Buehne, M. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik; Scherer, K. [Technische Hochschule Aachen (Germany). Inst. fuer Versuchstierkunde; Kuepper, W. [Technische Hochschule Aachen (Germany). Inst. fuer Versuchstierkunde; Guenther, R.W. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik

    1994-02-01

    The value of MR imaging for the detection of hyaline cartilage lesions using 2-D spin-echo and 3-D gradient-echo imaging was evaluated in an animal experiment in 10 dogs and in a clinical study in 30 patients. MR imaging findings were compared with histopathological and arthroscopy findings, respectively. Using MRI neither grade I nor grade II hyaline cartilage lesions were detectable. In the animal experiments 77% of grade III lesions and all the grade IV lesions were seen. However, in the clinical study only about the half of grade III and IV lesions were detected. 3-D gradient-echo MR imaging was superior to 2-D spin-echo imaging (p<0.001), while 3-D FLASH and 3-D FISP did not differ significantly in the detection rate (p<0.34). 3-D gradient-echo MR imaging seems to be the best method for the delineation of high grade cartilage lesions. However, early stages of cartilage degeneration are invisible even with this imaging modality. (orig.) [Deutsch] Die Wertigkeit der MRT in der Erfassung von Knorpellaesionen mit 2-D-Spin-Echo- und 3-D-Grafienten-Echo-Sequenzen wurde in einer tierexperimentellen Untersuchung an 10 Hunden sowie in einer klinischen Studie an 30 Patienten ueberprueft. Die kernspintomographischen Ergebnisse wurden mit dem pathologisch-anatomischen Befund bzw. der Arthroskopie verglichen. MR-tomographisch konnten weder Grad-I- noch Grad-II-Knorpellaesionen erfasst werden. Die Erkennbarkeitsrate der Grad-III- und -IV-Laesionen lag fuer die tierexperimentellen Untersuchungen bei 77 bzw. 100%, waehrend klinisch nur etwa 50% dieser Veraenderungen erkannt werden konnten. Dabei waren die 3-D-Gradienten-Echo-Sequenzen den 2-D-Spin-Echo-Sequenzen signifikant ueberlegen (p<0,001), waehrend sich die 3-D-Gradienten-Echo-Sequenzen FISP und FLASH nicht voneinander unterschieden (p<0,34). Derzeit muessen die 3-D-Gradienten-Echo-Sequenzen als die beste Methode zur Erfassung hoehergradiger Knorpellaesionen angesehen werden. Fruehe Stadien der Knorpelschaedigung sind

  5. Quasistatic packings of droplets in flat microfluidic channels

    Science.gov (United States)

    Kadivar, Erfan

    2016-02-01

    As observed in recent experiments, monodisperse droplets self-assemble spontaneously in different ordered packings. In this work, we present a numerical study of the droplet packings in the flat rectangular microfluidic channels. Employing the boundary element method, we numerically solve the Stokes equation in two-dimension and investigate the appearance of droplet packing and transition between one and two-row packings of monodisperse emulsion droplets. By calculating packing force applied on the droplet interface, we investigate the effect of flow rate, droplet size, and surface tension on the packing configurations of droplets and transition between different topological packings.

  6. Investigations into the visualisation of osseous and hyaline cartilaginous surface structures of the femural head using X-ray computed tomography. Untersuchung der Visualisierbarkeit knoecherner und hyalin knorpeliger Oberflaechenstrukturen des caput femoris mit Roentgen-Computertomographie

    Energy Technology Data Exchange (ETDEWEB)

    Laemmermann, G.

    1989-03-06

    This study investigates into the extent to which fine osseous structures in the head of the femur and hyaline cartilaginous surfaces of the hip joint are accessible to X-ray computed tomography as a method of diagnosis. At first, a true model of the femural head (post-mortem preparation embedded in methylacrylate) was tomographed to compare the sectional displays thus obtained with hard-microtome sections of similar thickness made at the same levels. This permitted preliminary evaluations to be carried out and confirmed that those structures can be visualised by high-resolution CT (1 mm sections). Methods using high-resolution sectional imaging have a role in examinations of congruence in the the hip joint. Particularly useful here are three-dimensional displays of osseous and cartilaginous surfaces of the joint parts examined. Further research is needed until a more refined method of reconstruction can be made available, the usefulness of which in actual practice will depend on the degree of geometrical congruence achieved between a patient's joint and its display on the screen. (orig./GDG).

  7. Electrostatic charging and control of droplets in microfluidic devices.

    Science.gov (United States)

    Zhou, Hongbo; Yao, Shuhuai

    2013-03-07

    Precharged droplets can facilitate manipulation and control of low-volume liquids in droplet-based microfluidics. In this paper, we demonstrate non-contact electrostatic charging of droplets by polarizing a neutral droplet and splitting it into two oppositely charged daughter droplets in a T-junction microchannel. We performed numerical simulation to analyze the non-contact charging process and proposed a new design with a notch at the T-junction in aid of droplet splitting for more efficient charging. We experimentally characterized the induced charge in droplets in microfabricated devices. The experimental results agreed well with the simulation. Finally, we demonstrated highly effective droplet manipulation in a path selection unit appending to the droplet charging. We expect our work could enable precision manipulation of droplets for more complex liquid handling in microfluidics and promote electric-force based manipulation in 'lab-on-a-chip' systems.

  8. The role of the droplet deformations in the bouncing droplet dynamics

    Science.gov (United States)

    Terwagne, D.; Ludewig, F.; Vandewalle, N.; Dorbolo, S.

    2013-12-01

    Droplets bouncing on a vibrated liquid bath open ways to methods of manipulating droplets, creating double emulsion, and performing pilot wave model experiments. In this work, we focus on the role of the droplet deformations in the vertical bouncing dynamics by neglecting the deformation of the surface of the bath. To be under this favorable condition, low viscous oil droplets are dropped over a highly viscous oil bath that is vibrated. These droplets bounce vertically on the surface of the bath and exhibit many periodic trajectories and resonant modes when tuning the forcing parameters, i.e., the oscillation of the bath. This complex dynamics emphasizes the interplay between elastic energy storage and energy dissipation in droplets at each bounce. We propose to model droplets using a bouncing mass-spring-damper system that mimics a deformable droplet bouncing on a non-deformable liquid bath. From the experimental measurements, we constructed bifurcation diagrams of the bouncing trajectories and challenged our bouncing spring model. The agreement between experiment and the spring model reveals that this model can be used to rationalize and predict a variety of bouncing droplets behaviors involving multi-periodicities.

  9. Droplet Microfluidics for Chip-Based Diagnostics

    Directory of Open Access Journals (Sweden)

    Karan V. I. S. Kaler

    2014-12-01

    Full Text Available Droplet microfluidics (DMF is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or passively control the shape and positioning of fluidic droplets over patterned substrates. In this review article, we focus on the operation and utility of electro-actuation-based DMF devices, which utilize one or more micro-/nano-patterned substrates to facilitate electric field-based handling of chemical and/or biological samples. The underlying theory of DMF actuations, device fabrication methods and integration of optical and opto-electronic detectors is discussed in this review. Example applications of such electro-actuation-based DMF devices have also been included, illustrating the various actuation methods and their utility in conducting chip-based laboratory and clinical diagnostic assays.

  10. Tetrachromacy, oil droplets and bird plumage colours.

    Science.gov (United States)

    Vorobyev, M; Osorio, D; Bennett, A T; Marshall, N J; Cuthill, I C

    1998-11-01

    There is a growing body of data on avian eyes, including measurements of visual pigment and oil droplet spectral absorption, and of receptor densities and their distributions across the retina. These data are sufficient to predict psychophysical colour discrimination thresholds for light-adapted eyes, and hence provide a basis for relating eye design to visual needs. We examine the advantages of coloured oil droplets, UV vision and tetrachromacy for discriminating a diverse set of avian plumage spectra under natural illumination. Discriminability is enhanced both by tetrachromacy and coloured oil droplets. Oil droplets may also improve colour constancy. Comparison of the performance of a pigeon's eye, where the shortest wavelength receptor peak is at 410 nm, with that of the passerine Leiothrix, where the ultraviolet-sensitive peak is at 365 nm, generally shows a small advantage to the latter, but this advantage depends critically on the noise level in the sensitivity mechanism and on the set of spectra being viewed.

  11. Janus droplet as a catalytic micromotor

    CERN Document Server

    Shklyaev, Sergey

    2015-01-01

    Self-propulsion of a Janus droplet in a solution of surfactant, which reacts on a half of a drop surface, is studied theoretically. The droplet acts as a catalytic motor creating a concentration gradient, which generates its surface-tension-driven motion; the self-propulsion speed is rather high, $60\\; {\\rm \\mu m/s}$ and more. This catalytic motor has several advantages over other micromotors: simple manufacturing, easily attained neutral buoyancy. In contrast to a single-fluid droplet, which demonstrates a self-propulsion as a result of symmetry breaking instability, for Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers. The paper was finalized and submitted by Denis S. Goldobin after Sergey Sklyaev had sadly passed away on June 2, 2014.

  12. Capillary droplets on Leidenfrost micro-ratchets

    CERN Document Server

    Marin, Alvaro G; Römer, Gertwillem R B E; Pathiraj, B; Veld, Albertus Huis in 't; Lohse, Detlef

    2012-01-01

    Leidenfrost ratchets are structures with the ability of transporting liquid droplets when heated over the critical Leidenfrost temperature. Once this temperature is reached, the droplet levitates over the surface and moves in the direction marked by the slope of the ratchet at terminal velocities around 10 cm/s. Here we provide new experiments with micron-sized ratchets, which have been produced with picosecond pulse laser ablation. In the following work, we use a simple method to measure the thrust driving droplets of capillary size over the micro-ratchets. The mechanism responsible for the force acting on the drop on superheated ratchets has been recently under debate. We extend the recently proposed 'viscous mechanism' proposed by Dupeaux et al. [Europhys. Lett., 96, 58001 (2011)] to capillary droplets and find good agreement with our measurements.

  13. Manipulation of microfluidic droplets by electrorheological fluid

    KAUST Repository

    Zhang, Menying

    2009-09-01

    Microfluidics, especially droplet microfluidics, attracts more and more researchers from diverse fields, because it requires fewer materials and less time, produces less waste and has the potential of highly integrated and computer-controlled reaction processes for chemistry and biology. Electrorheological fluid, especially giant electrorheological fluid (GERF), which is considered as a kind of smart material, has been applied to the microfluidic systems to achieve active and precise control of fluid by electrical signal. In this review article, we will introduce recent results of microfluidic droplet manipulation, GERF and some pertinent achievements by introducing GERF into microfluidic system: digital generation, manipulation of "smart droplets" and droplet manipulation by GERF. Once it is combined with real-time detection, integrated chip with multiple functions can be realized. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.

  14. Immersed Boundary Simulations of Active Fluid Droplets

    CERN Document Server

    Whitfield, Carl A

    2016-01-01

    We present numerical simulations of active fluid droplets immersed in an external fluid in 2-dimensions. We use an Immersed Boundary method to simulate the fluid droplet interface as a Lagrangian mesh. We present results from two example systems, firstly a droplet filled with an active polar fluid with polar anchoring at the droplet interface. Secondly, an active isotropic fluid consisting of particles that can bind and unbind from the interface and generate surface tension gradients through active contractility. These two systems demonstrate spontaneous symmetry breaking and steady state dynamics resembling cell motility and division and show complex feedback mechanisms with minimal degrees of freedom. The simulations outlined here will be useful for quantifying the wide range of dynamics observable in these active systems and modelling the effects of confinement in a consistent and adaptable way.

  15. Dispensing nano-pico droplets of ferrofluids

    Science.gov (United States)

    Irajizad, Peyman; Farokhnia, Nazanin; Ghasemi, Hadi

    2015-11-01

    Dispensing miniature volumes of a ferrofluid is of fundamental and practical importance for diverse applications ranging from biomedical devices, optics, and self-assembly of materials. Current dispensing systems are based on microfluidics flow-focusing approaches or acoustic actuation requiring complicated structures. A simple method is presented to continuously dispense the miniature droplets from a ferrofluid reservoir. Once a jet of the ferrofluid is subjected to a constrained flux through a membrane and an inhomogeneous magnetic field, the jet experiences a curvature-driven instability and transforms to a droplet. Ferrofluid droplets in the range of 0.1-1000 nl are dispensed with tunable dispensing frequencies. A model is developed that predicts the dispensed volume of the ferrofluid droplets with an excellent agreement with the measurements.

  16. Manipulation of microfluidic droplets by electrorheological fluid.

    Science.gov (United States)

    Zhang, Menying; Gong, Xiuqing; Wen, Weijia

    2009-09-01

    Microfluidics, especially droplet microfluidics, attracts more and more researchers from diverse fields, because it requires fewer materials and less time, produces less waste and has the potential of highly integrated and computer-controlled reaction processes for chemistry and biology. Electrorheological fluid, especially giant electrorheological fluid (GERF), which is considered as a kind of smart material, has been applied to the microfluidic systems to achieve active and precise control of fluid by electrical signal. In this review article, we will introduce recent results of microfluidic droplet manipulation, GERF and some pertinent achievements by introducing GERF into microfluidic system: digital generation, manipulation of "smart droplets" and droplet manipulation by GERF. Once it is combined with real-time detection, integrated chip with multiple functions can be realized.

  17. Dynamics of bouncing droplets in annular cavities

    Science.gov (United States)

    Lentz, Zachary Louis; Jalali, Mir Abbas; Alam, Mohammad-Reza

    2014-11-01

    In a cylindrical bath of silicon oil, vertically excited by a frequency of 45 Hz, we trace the motion of bouncing droplets as they fill an annular region. We compute the mean tangential and radial velocity components of the droplets and show that the maximum tangential velocity is larger than the maximum radial velocity by one order of magnitude. Velocity dispersions have almost equal levels in the radial and tangential directions, and their mean values are 1/4 times smaller than the mean tangential velocity. These results show that bouncing droplets undergo random motions within annular cavities determined by the interference patterns of self-induced circumferential waves. We derive analytical relations between the velocity dispersion and the wavelength of surface waves, and calculate the mean tangential velocity of droplets using the random kicks that they experience at the boundaries of the cavity by inward and outward traveling waves.

  18. Catching proteins in liquid helium droplets

    CERN Document Server

    Kupser, Peter; Meijer, Gerard; von Helden, Gert

    2010-01-01

    An experimental approach is presented that allows for the incorporation of large mass/charge selected ions in liquid helium droplets. It is demonstrated that droplets can be efficiently doped with a mass/charge selected amino acid as well as with the much bigger m$\\approx$12 000 amu protein Cytochrome C in selected charge states. The sizes of the ion-doped droplets are determined via electrostatic deflection. Under the experimental conditions employed, the observed droplet sizes are very large and range, dependent on the incorporated ion, from 10$^{10}$ helium atoms for protonated Phenylalanine to 10$^{12}$ helium atoms for Cytochrome C. As a possible explanation, a simple model based on the size- and internal energy-dependence of the pickup efficiency is given.

  19. Micro-droplets lubrication film thickness dynamics

    Science.gov (United States)

    Huerre, Axel; Theodoly, Olivier; Cantat, Isabelle; Leshansky, Alexander; Valignat, Marie-Pierre; Jullien, Marie-Caroline; MMN Team; LAI Team; IPR Team; Department of Chemical Engineering Team

    2014-11-01

    The motion of droplets or bubbles in confined geometries has been extensively studied; showing an intrinsic relationship between the lubrication film thickness and the droplet velocity. When capillary forces dominate, the lubrication film thickness evolves non linearly with the capillary number due to viscous dissipation between meniscus and wall. However, this film may become thin enough that intermolecular forces come into play and affect classical scalings. We report here the first experimental evidence of the disjoining pressure effect on confined droplets by measuring droplet lubrication film thicknesses in a microfluidic Hele-Shaw cell. We find and characterize two distinct dynamical regimes, dominated respectively by capillary and intermolecular forces. In the former case rolling boundary conditions at the interface are evidenced through film thickness dynamics, interface velocity measurement and film thickness profile.

  20. Subchondral chitosan/blood implant-guided bone plate resorption and woven bone repair is coupled to hyaline cartilage regeneration from microdrill holes in aged rabbit knees.

    Science.gov (United States)

    Guzmán-Morales, J; Lafantaisie-Favreau, C-H; Chen, G; Hoemann, C D

    2014-02-01

    Little is known of how to routinely elicit hyaline cartilage repair tissue in middle-aged patients. We tested the hypothesis that in skeletally aged rabbit knees, microdrill holes can be stimulated to remodel the bone plate and induce a more integrated, voluminous and hyaline cartilage repair tissue when treated by subchondral chitosan/blood implants. New Zealand White rabbits (13 or 32 months old, N = 7) received two 1.5 mm diameter, 2 mm depth drill holes in each knee, either left to bleed as surgical controls or press-fit with a 10 kDa (distal hole: 10K) or 40 kDa (proximal hole: 40K) chitosan/blood implant with fluorescent chitosan tracer. Post-operative knee effusion was documented. Repair tissues at day 0 (N = 1) and day 70 post-surgery (N = 6) were analyzed by micro-computed tomography, and by histological scoring and histomorphometry (SafO, Col-2, and Col-1) at day 70. All chitosan implants were completely cleared after 70 days, without increasing transient post-operative knee effusion compared to controls. Proximal control holes had worse osteochondral repair than distal holes. Both implant formulations induced bone remodeling and improved lateral integration of the bone plate at the hole edge. The 40K implant inhibited further bone repair inside 50% of the proximal holes, while the 10K implant specifically induced a "wound bloom" reaction, characterized by decreased bone plate density in a limited zone beyond the initial hole edge, and increased woven bone (WB) plate repair inside the initial hole (P = 0.016), which was accompanied by a more voluminous and hyaline cartilage repair (P hyaline cartilage repair can be promoted by treating acute drill holes with a biodegradable subchondral implant that elicits bone plate resorption followed by anabolic WB repair within a 70-day repair period. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  1. Programmable Electrowetting with Channels and Droplets

    OpenAIRE

    Ananda Banerjee; Joo Hyon Noh; Yuguang Liu; Philip D. Rack; Ian Papautsky

    2015-01-01

    In this work, we demonstrate continuous and discrete functions in a digital microfluidic platform in a programmed manner. Digital microfluidics is gaining popularity in biological and biomedical applications due to its ability to manipulate discrete droplet volumes (nL–pL), which significantly reduces the need for a costly and precious biological and physiological sample volume and, thus, diagnostic time. Despite the importance of discrete droplet volume handling, the ability of continuous mi...

  2. Combustion Behavior of Free Boron Slurry Droplets,

    Science.gov (United States)

    2014-09-26

    weak disruptive behavior while pure JP-1t burn quiescently, except for a flash extinction which occurs at the termination of combustion. The...I AD-R158 628 COMBUSTION BEHAVIOR OF FREE BORON SLURRY DROPLETS(U) i/i I PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENINEERIN., F TAKAHASHI...COMBUSTION BEHAVIOR OF FREE BORON SLURRY DROPLETS TAM by F. Takahashi, F.L. Dryer, and F.A. Williams Department of M~echanical and keyosase Engineering

  3. Numerical simulation of droplet impact on interfaces

    Science.gov (United States)

    Kahouadji, Lyes; Che, Zhizhao; Matar, Omar; Shin, Seungwon; Chergui, Jalel; Juric, Damir

    2015-11-01

    Simulations of three-dimensional droplet impact on interfaces are carried out using BLUE, a massively-parallel code based on a hybrid Front-Tracking/Level-Set algorithm for Lagrangian tracking of arbitrarily deformable phase interfaces. High resolution numerical results show fine details and features of droplet ejection, crown formation and rim instability observed under similar experimental conditions. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  4. Droplets climbing a rotating helical fiber

    CERN Document Server

    Texier, Baptiste Darbois

    2015-01-01

    A liquid droplet is placed on a rotating helical fiber. We find that the droplet may slide down, attach or climb up the fiber. We inspect experimentally the domain of existence of these three behaviors as a function of the geometrical characteristics of the fiber, its angle relatively to the horizontal, the wetting properties of the fluid and the rotating speed of the helix. A theoretical model is proposed in order to capture the boundaries of the experimental phase diagram.

  5. Engineering of Droplet Manipulation in Tertiary Junction Microfluidic Channels

    Science.gov (United States)

    2017-06-30

    in silico investigation of path selection by a single droplet inside a tertiary junction microchannel using oil-in-water as a model system. The...droplet was generated at a T-junction inside a microfluidic chip and its flow behaviour as a function of droplet size, streamline position, viscosity...investigation of path selection by a single droplet inside a tertiary- junction microchannel using oil-in-water as a model system. The droplet was generated at

  6. [Effects of in vitro continuous passaging on the phenotype of mouse hyaline chondrocytes and the balance of the extra- cellular matrix].

    Science.gov (United States)

    Linyi, Cai; Xiangli, Kong; Jing, Xie

    2016-06-01

    This study aimed to investigate the effects of in vitro continuous passaging on the morphological phenotype and differentiation characteristics of mouse hyaline chondrocytes, as well as on the balance of the extracellular matrix (ECM). Enzymatic digestion was conducted to isolate mouse hyaline chondrocytes, which expanded over five passages in vitro. Hematoxylin-eosin stain was used to show the changes in chondrocyte morphology. Semi-quantitative polymerase chain reaction was performed to analyze the mRNA changes in the marker genes, routine genes, matrix metalloproteinases (MMPs), and tissue inhibitors of MMPs (TIMPs) in chondrocytes. Zymography was carried out to elucidate changes in gelatinase activities. After continuous expansion in vitro, the morphology of round or polygonal chondrocytes changed to elongated and spindled shape. The expression of marker genes significantly decreased (P 0.05). Meanwhile, the ratio of MMPs/TIMPs was altered. At the protein level, the activities of gelatinases decreased after passaging, especially for P4 and P5 chondrocytes (P cartilage ECM became uncontrollable and led to the imbalance of ECM homeostasis. When hyaline chondrocytes are applied in research on relevant diseases or cartilage tissue engineering, P0-P2 chondrocytes should be used.

  7. Combustion of Interacting Droplet Arrays Being Studied

    Science.gov (United States)

    Dietrich, Daniel L.

    2002-01-01

    The combustion of liquid fuels is a major source of energy in the world today, and the majority of these fuels are burned in the form of a spray. This droplet combustion project at the NASA Glenn Research Center has the overall goal of providing a better understanding of spray combustion by extending existing studies of single droplets to a regime where droplet interactions are important (as occurs in a practical spray). The Combustion of Interacting Droplet Arrays is a collaborative effort between Glenn and the National Center for Microgravity Research. The group at Glenn also collaborates with scientists at the National Institute of Advanced Industrial Science and Technology in Hokkaido, Japan. The project is studying the combustion of a small number of droplets suspended on small quartz fibers in a 0.1-atm combustion chamber. Data consist primarily of video images of the flames and droplets. The tests are being conducted in Glenn's reduced-gravity facilities (2.2-sec and 5.2-sec drop towers) and in the Japan Microgravity Center's 10-sec drop tower (JAMIC).

  8. Mechanical vibrations of pendant liquid droplets.

    Science.gov (United States)

    Temperton, Robert H; Smith, Michael I; Sharp, James S

    2015-07-01

    A simple optical deflection technique was used to monitor the vibrations of microlitre pendant droplets of deuterium oxide, formamide, and 1,1,2,2-tetrabromoethane. Droplets of different volumes of each liquid were suspended from the end of a microlitre pipette and vibrated using a small puff of nitrogen gas. A laser was passed through the droplets and the scattered light was collected using a photodiode. Vibration of the droplets resulted in the motion of the scattered beam and time-dependent intensity variations were recorded using the photodiode. These time-dependent variations were Fourier transformed and the frequencies and widths of the mechanical droplet resonances were extracted. A simple model of vibrations in pendant/sessile drops was used to relate these parameters to the surface tension, density and viscosity of the liquid droplets. The surface tension values obtained from this method were found to be in good agreement with results obtained using the standard pendant drop technique. Damping of capillary waves on pendant drops was shown to be similar to that observed for deep liquid baths and the kinematic viscosities obtained were in agreement with literature values for all three liquids studied.

  9. Whole Teflon valves for handling droplets.

    Science.gov (United States)

    Cybulski, Olgierd; Jakiela, Slawomir; Garstecki, Piotr

    2016-06-21

    We propose and test a new whole-Teflon gate valve for handling droplets. The valve allows droplet plugs to pass through without disturbing them. This is possible due to the geometric design, the choice of material and lack of any pulses of flow generated by closing or opening the valve. The duct through the valve resembles a simple segment of tubing, without constrictions, change in lumen or side pockets. There are no extra sealing materials with different wettability or chemical resistance. The only material exposed to liquids is FEP Teflon, which is resistant to aggressive chemicals and fully biocompatible. The valve can be integrated into microfluidic systems: we demonstrate a complex system for culturing bacteria in hundreds of microliter droplet chemostats. The valve effectively isolates modules of the system to increase precision of operations on droplets. We verified that the valve allowed millions of droplet plugs to safely pass through, without any cross-contamination with bacteria between the droplets. The valve can be used in automating complex microfluidic systems for experiments in biochemistry, biology and organic chemistry.

  10. Programmable Electrowetting with Channels and Droplets

    Directory of Open Access Journals (Sweden)

    Ananda Banerjee

    2015-01-01

    Full Text Available In this work, we demonstrate continuous and discrete functions in a digital microfluidic platform in a programmed manner. Digital microfluidics is gaining popularity in biological and biomedical applications due to its ability to manipulate discrete droplet volumes (nL–pL, which significantly reduces the need for a costly and precious biological and physiological sample volume and, thus, diagnostic time. Despite the importance of discrete droplet volume handling, the ability of continuous microfluidics to process larger sample volumes at a higher throughput cannot be easily reproduced by merely using droplets. To bridge this gap, in this work, parallel channels are formed and programmed to split into multiple droplets, while droplets are programmed to be split from one channel, transferred and merged into another channel. This programmable handling of channels and droplets combines the continuous and digital paradigms of microfluidics, showing the potential for a wider range of microfluidic functions to enable applications ranging from clinical diagnostics in resource-limited environments, to rapid system prototyping, to high throughput pharmaceutical applications.

  11. Predicting Droplet Formation on Centrifugal Microfluidic Platforms

    Science.gov (United States)

    Moebius, Jacob Alfred

    Centrifugal microfluidics is a widely known research tool for biological sample and water quality analysis. Currently, the standard equipment used for such diagnostic applications include slow, bulky machines controlled by multiple operators. These machines can be condensed into a smaller, faster benchtop sample-to-answer system. Sample processing is an important step taken to extract, isolate, and convert biological factors, such as nucleic acids or proteins, from a raw sample to an analyzable solution. Volume definition is one such step. The focus of this thesis is the development of a model predicting monodispersed droplet formation and the application of droplets as a technique for volume definition. First, a background of droplet microfluidic platforms is presented, along with current biological analysis technologies and the advantages of integrating such technologies onto microfluidic platforms. Second, background and theories of centrifugal microfluidics is given, followed by theories relevant to droplet emulsions. Third, fabrication techniques for centrifugal microfluidic designs are discussed. Finally, the development of a model for predicting droplet formation on the centrifugal microfluidic platform are presented for the rest of the thesis. Predicting droplet formation analytically based on the volumetric flow rates of the continuous and dispersed phases, the ratios of these two flow rates, and the interfacial tension between the continuous and dispersed phases presented many challenges, which will be discussed in this work. Experimental validation was completed using continuous phase solutions of different interfacial tensions. To conclude, prospective applications are discussed with expected challenges.

  12. Lipid droplets, lipophagy, and beyond.

    Science.gov (United States)

    Wang, Chao-Wen

    2016-08-01

    Lipids are essential components for life. Their various structural and physical properties influence diverse cellular processes and, thereby, human health. Lipids are not genetically encoded but are synthesized and modified by complex metabolic pathways, supplying energy, membranes, signaling molecules, and hormones to affect growth, physiology, and response to environmental insults. Lipid homeostasis is crucial, such that excess fatty acids (FAs) can be harmful to cells. To prevent such lipotoxicity, cells convert excess FAs into neutral lipids for storage in organelles called lipid droplets (LDs). These organelles do not simply manage lipid storage and metabolism but also are involved in protein quality management, pathogenesis, immune responses, and, potentially, neurodegeneration. In recent years, a major trend in LD biology has centered around the physiology of lipid mobilization via lipophagy of fat stored within LDs. This review summarizes key findings in LD biology and lipophagy, offering novel insights into this rapidly growing field. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

  13. Cloud droplet activation: solubility revisited

    Directory of Open Access Journals (Sweden)

    L. T. Padró

    2007-02-01

    Full Text Available Soluble compounds present in atmospheric aerosol facilitate their transformation into cloud droplets by depressing the equilibrium vapor pressure required for activation. Their impact depends on the amount of dissolved substance in the aerosol aqueous phase, which in turn is controlled by its solubility. This study explores the impact of particle curvature on solubility, expressed in terms of a Kelvin enhancement. The augmented solubility, termed "Curvature Enhanced Solubility" (CES, is then introduced into Köhler theory for assessment of its impact on CCN activity for several organic compounds with a wide range of aqueous solubility. The interfacial energy between solute and aqueous phase required for quantification of CES is determined from existing correlations based on bulk solubility, and concurrent measurements of contact angle and surface tension. A number of important findings arise from this study: i CES can substantially increase solubility and impact CCN activity but only if the aerosol is initially wet, ii CES can stabilize highly supersaturated solutions, and provide a mechanism for retention of an aerosol aqueous phase even at very low relative humidity (RH, and, iii trace amounts of surfactant impurities can magnify the impact of CES.

  14. An Experimental Investigation of Vibration-Induced Single Droplet Ejection.

    Science.gov (United States)

    Range, Kai; Smith, Marc K.; Glezer, Ari

    1998-11-01

    Vibration-induced droplet atomization occurs when small secondary droplets are ejected from the free surface of a larger droplet placed on a vibrating membrane. To model a single ejection event, a liquid droplet is placed on a small piston and vibrated using an electromagnetic driver. The droplet oscillates in a characteristic mode shape that depends on the driving frequency and amplitude, the properties of the liquid, and the size of the droplet. When the excitation amplitude is large enough, a small secondary droplet is ejected from the primary droplet. Observations of this process using high-speed digital video imaging show that droplet ejection occurs when a small liquid column or jet appears on the primary droplet and a secondary droplet forms on the column by a capillary-pinching mechanism. The liquid column or jet emanates from a crater in the primary droplet. As the driving frequency increases, this crater becomes smaller and the diameter of the ejected droplet decreases. We shall present results showing how the ejected droplet diameter and speed depends on the driving frequency and amplitude, the liquid properties, and the primary droplet volume.

  15. Colonization of a Central Venous Catheter by the Hyaline Fungus Fusarium solani Species Complex: A Case Report and SEM Imaging

    Directory of Open Access Journals (Sweden)

    Alberto Colombo

    2013-01-01

    Full Text Available The incidence of opportunistic infections by filamentous fungi is increasing partly due to the widespread use of central venous catheters (CVC, indwelling medical devices, and antineoplastic/immunosuppressive drugs. The case of a 13-year-old boy under treatment for acute lymphoblastic leukemia is presented. The boy was readmitted to the Pediatric Ward for intermittent fever of unknown origin. Results of blood cultures drawn from peripheral venous sites or through the CVC were compared. CVC-derived bottles (but not those from peripheral veins yielded hyaline fungi that, based on morphology, were identified as belonging to the Fusarium solani species complex. Gene amplification and direct sequencing of the fungal ITS1 rRNA region and the EF-1alpha gene confirmed the isolate as belonging to the Fusarium solani species complex. Portions of the CVC were analyzed by scanning electron microscopy. Fungi mycelia with long protruding hyphae were seen into the lumen. The firm adhesion of the fungal formation to the inner surface of the catheter was evident. In the absence of systemic infection, catheter removal and prophylactic voriconazole therapy were followed by disappearance of febrile events and recovery. Thus, indwelling catheters are prone to contamination by environmental fungi.

  16. Laparoscopic treatment for retroperitoneal hyaline-vascular type localized Castleman's disease (LCD) in the iliac vessel region.

    Science.gov (United States)

    Le, Aiwen; Shan, Lili; Wang, Zhonghai; Dai, Xiaoyun; Xiao, Tianhui; Zhuo, Rong; Yuan, Rui

    2015-01-01

    To improve the understanding, diagnostic levels, and therapeutic levels of retroperitoneal hyaline vascular type LCD in the iliac vessel region. Diagnostic and therapeutic processes of 4 patients with retroperitoneal LCD in the iliac vessel region were retrospectively analyzed. The median ages of the research patients was 31.3 years old, Pelvic vascular dual-source computed tomography (CT) indicated an abnormal pelvic irregular cloddy intensity shadow with heterogeneous densities and punctate calcified lesions. The enhanced scanning showed significantly enhanced lesions and multiple tortuous vascular images inside and around the lesions. Patients' preoperative diagnoses were all "pelvic mass with unknown characteristics", and retroperitoneal masses were successfully stripped off after the laparoscopic surgery. Intra operative findings indicated 1 mass located at the left obturator nerve, 1 at the left internal iliac artery, and 2 at the right external iliac artery. The postoperative pathological reports suggest a diagnosis of Castleman's disease. Retroperitoneal LCD in the iliac vessel region is generally asymptomatic. Preoperative imaging data may help with the diagnosis, but a confirmed diagnosis depends on the results of the pathological examination. Iliac artery embolization is performed prior to laparoscopic mass stripping if the masses have abundant blood supply, while lymphadenectomy is also applied to those with enlarged lymph nodes.

  17. Biostable scaffolds of polyacrylate polymers implanted in the articular cartilage induce hyaline-like cartilage regeneration in rabbits.

    Science.gov (United States)

    Sancho-Tello, María; Forriol, Francisco; Martín de Llano, José J; Antolinos-Turpin, Carmen; Gómez-Tejedor, José A; Gómez Ribelles, José L; Carda, Carmen

    2017-07-05

    To study the influence of scaffold properties on the organization of in vivo cartilage regeneration. Our hypothesis was that stress transmission to the cells seeded inside the pores of the scaffold or surrounding it, which is highly dependent on the scaffold properties, determines the differentiation of both mesenchymal cells and dedifferentiated autologous chondrocytes. 4 series of porous scaffolds made of different polyacrylate polymers, previously seeded with cultured rabbit chondrocytes or without cells, were implanted in cartilage defects in rabbits. Subchondral bone was injured during the surgery to allow blood to reach the implantation site and fill the scaffold pores. At 3 months after implantation, excellent tissue regeneration was obtained, with a well-organized layer of hyaline-like cartilage at the condylar surface in most cases of the hydrophobic or slightly hydrophilic series. The most hydrophilic material induced the poorest regeneration. However, no statistically significant difference was observed between preseeded and non-preseeded scaffolds. All of the materials used were biocompatible, biostable polymers, so, in contrast to some other studies, our results were not perturbed by possible effects attributable to material degradation products or to the loss of scaffold mechanical properties over time due to degradation. Cartilage regeneration depends mainly on the properties of the scaffold, such as stiffness and hydrophilicity, whereas little difference was observed between preseeded and non-preseeded scaffolds.

  18. Hyaline articular cartilage: relaxation times, pulse-sequence parameters and MR appearance at 1.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Chalkias, S.M. [Dept. of Radiology, A.H.E.P.A. General Hospital of the Aristotelian Univ., Thessaloniki (Greece); Pozzi-Mucelli, R.S. [Dept. of Radiology, Univ. of Trieste (Italy); Pozzi-Mucelli, M. [Orthopaedic Clinic, Univ. of Trieste (Italy); Frezza, F. [Dept. of Radiology, Univ. of Trieste (Italy); Longo, R. [Dept. of Radiology, Univ. of Trieste (Italy)

    1994-08-01

    In order to optimize the parameters for the best visualization of the internal architecture of the hyaline articular cartilage a study both ex vivo and in vivo was performed. Accurate T1 and T2 relaxation times of articular cartilage were obtained with a particular mixed sequence and then used for the creation of isocontrast intensity graphs. These graphs subsequently allowed in all pulse sequences (spin echo, SE and gradient echo, GRE) the best combination of repetition time (TR), echo time (TE) and flip angle (FA) for optimization of signal differences between MR cartilage zones. For SE sequences maximum contrast between cartilage zones can be obtained by using a long TR (> 1,500 ms) with a short TE (< 30 ms), whereas for GRE sequences maximum contrast is obtained with the shortest TE (< 15 ms) combined with a relatively long TR (> 400 ms) and an FA greater than 40 . A trilaminar appearance was demonstrated with a superficial and deep hypointense zone in all sequences and an intermediate zone that was moderately hyperintense on SE T1-weighted images, slightly more hyperintense on proton density Rho and SE T2-weighted images and even more hyperintense on GRE images. (orig.)

  19. Injectable glycosaminoglycan-protein nano-complex in semi-interpenetrating networks: A biphasic hydrogel for hyaline cartilage regeneration.

    Science.gov (United States)

    Radhakrishnan, Janani; Subramanian, Anuradha; Sethuraman, Swaminathan

    2017-11-01

    Articular hyaline cartilage regeneration remains challenging due to its less intrinsic reparability. The study develops injectable biphasic semi-interpenetrating polymer networks (SIPN) hydrogel impregnated with chondroitin sulfate (ChS) nanoparticles for functional cartilage restoration. ChS loaded zein nanoparticles (∼150nm) prepared by polyelectrolyte-protein complexation were interspersed into injectable SIPNs developed by blending alginate with poly(vinyl alcohol) and calcium crosslinking. The hydrogel exhibited interconnected porous microstructure (39.9±5.8μm pore diameter, 57.7±5.9% porosity), 92% swellability and >350Pa elastic modulus. Primary chondrocytes compatibility, chondrocyte-matrix interaction with cell-cell clustering and spheroidal morphology was demonstrated in ChS loaded hydrogel and long-term (42days) proliferation was also determined. Higher fold expression of cartilage-specific genes sox9, aggrecan and collagen-II was observed in ChS loaded hydrogel while exhibiting poor expression of collagen-I. Immunoblotting of aggregan and collagen II demonstrate favorable positive influence of ChS on chondrocytes. Thus, the injectable biphasic SIPNs could be promising composition-mimetic substitute for cartilage restoration at irregular defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Deciphering chondrocyte behaviour in matrix-induced autologous chondrocyte implantation to undergo accurate cartilage repair with hyaline matrix.

    Science.gov (United States)

    Demoor, M; Maneix, L; Ollitrault, D; Legendre, F; Duval, E; Claus, S; Mallein-Gerin, F; Moslemi, S; Boumediene, K; Galera, P

    2012-06-01

    Since the emergence in the 1990s of the autologous chondrocytes transplantation (ACT) in the treatment of cartilage defects, the technique, corresponding initially to implantation of chondrocytes, previously isolated and amplified in vitro, under a periosteal membrane, has greatly evolved. Indeed, the first generations of ACT showed their limits, with in particular the dedifferentiation of chondrocytes during the monolayer culture, inducing the synthesis of fibroblastic collagens, notably type I collagen to the detriment of type II collagen. Beyond the clinical aspect with its encouraging results, new biological substitutes must be tested to obtain a hyaline neocartilage. Therefore, the use of differentiated chondrocytes phenotypically stabilized is essential for the success of ACT at medium and long-term. That is why researchers try now to develop more reliable culture techniques, using among others, new types of biomaterials and molecules known for their chondrogenic activity, giving rise to the 4th generation of ACT. Other sources of cells, being able to follow chondrogenesis program, are also studied. The success of the cartilage regenerative medicine is based on the phenotypic status of the chondrocyte and on one of its essential component of the cartilage, type II collagen, the expression of which should be supported without induction of type I collagen. The knowledge accumulated by the scientific community and the experience of the clinicians will certainly allow to relief this technological challenge, which influence besides, the validation of such biological substitutes by the sanitary authorities. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  1. Modeling of Droplet Evaporation on Superhydrophobic Surfaces.

    Science.gov (United States)

    Fernandes, Heitor C M; Vainstein, Mendeli H; Brito, Carolina

    2015-07-14

    When a drop of water is placed on a rough surface, there are two possible extreme regimes of wetting: the one called Cassie-Baxter (CB) with air pockets trapped underneath the droplet and the one called the Wenzel (W) state characterized by the homogeneous wetting of the surface. A way to investigate the transition between these two states is by means of evaporation experiments, in which the droplet starts in a CB state and, as its volume decreases, penetrates the surface's grooves, reaching a W state. Here we present a theoretical model based on the global interfacial energies for CB and W states that allows us to predict the thermodynamic wetting state of the droplet for a given volume and surface texture. We first analyze the influence of the surface geometric parameters on the droplet's final wetting state with constant volume and show that it depends strongly on the surface texture. We then vary the volume of the droplet, keeping the geometric surface parameters fixed to mimic evaporation and show that the drop experiences a transition from the CB to the W state when its volume reduces, as observed in experiments. To investigate the dependency of the wetting state on the initial state of the droplet, we implement a cellular Potts model in three dimensions. Simulations show very good agreement with theory when the initial state is W, but it disagrees when the droplet is initialized in a CB state, in accordance with previous observations which show that the CB state is metastable in many cases. Both simulations and the theoretical model can be modified to study other types of surfaces.

  2. Vibration-Induced Droplet Atomization --- A Theoretical Investigation.

    Science.gov (United States)

    James, Ashley; Smith, Marc K.; Glezer, Ari

    1997-11-01

    The atomization of a liquid droplet placed on a vibrating membrane starts with the development of Faraday free surface waves. As the excitation amplitude increases, the waves grow in amplitude and ultimately begin to eject smaller secondary droplets from the wave crests. The rate of droplet ejection can be large enough to completely drain the primary droplet, an event we call bursting. The evolution of the droplet ejection process depends on a coupled system dynamic between the droplet and the membrane. When droplets are ejected the resonant frequency of the system increases. This changes the acceleration felt by the droplet and, in turn, the rate of droplet ejection. Depending on the excitation frequency and amplitude, various types of bursting or droplet ejection processes may occur. A simple, single degree-of-freedom model of this coupled system is presented. The model is used to illustrate the effect of the excitation frequency and amplitude and the initial droplet size on the acceleration of the membrane and the droplet ejection rate. The results of the model will be compared to our experimental data on droplet ejection. Additional work is directed towards an understanding of the mechanism behind the droplet ejection process.

  3. Thermocapillary migration of an isolated droplet and interaction of two droplets in zero gravity

    Science.gov (United States)

    Alhendal, Yousuf; Turan, Ali; Kalendar, Abdulrahim

    2016-09-01

    Fluid transfer within a stagnant liquid presents a significant challenge in zero-gravity conditions due to the lack of buoyancy effects. This challenge can be overcome by the utilisation of the Marangoni effect, or more specifically thermocapillary migration. The thermocapillary migration of droplets is driven by temperature gradients within the multiphase system which bring about a surface tension gradient driving the flow from the cold to the hot region. The migration speed of the droplet is significantly impacted by the heat transfer both inside the droplet and in its surroundings. This paper presents the analysis of drop movement in a stagnant liquid using computational fluid dynamics (CFD). The commercial software package Ansys-Fluent v.13 [1] is used to solve the governing continuum conservation equations for two-phase flow using the Volume of Fluid (VOF) method to track the liquid/liquid interface in 2D domain. This approach has been shown to be a valuable tool for studying the phenomena of liquid-liquid interaction. A strong agreement has been found with experimental observations conducted in microgravity. The inherent velocity of drops has been found to decrease with increasing Marangoni number. This finding is in line with the previous space experiments of Xie et al. (2005) [2] and in contrast to the numerical results of Ma (1999) [3] using the same liquid for the droplet and the host liquid. Data obtained in the present numerical study has been used to derive an expression predicting the scaled droplet velocity as a function of Marangoni number. A numerical study of the interaction of two spherical droplets undergoing thermocapillary migration in microgravity is also presented. The temperature thrust from the leading droplet towards the trailing droplet was found to disturb its migration velocity, but the trailing droplet was found to have no influence on the migration of the leading droplet.

  4. Droplet impact on soft viscoelastic surfaces

    Science.gov (United States)

    Chen, Longquan; Bonaccurso, Elmar; Deng, Peigang; Zhang, Haibo

    2016-12-01

    In this work, we experimentally investigate the impact of water droplets onto soft viscoelastic surfaces with a wide range of impact velocities. Several impact phenomena, which depend on the dynamic interaction between the droplets and viscoelastic surfaces, have been identified and analyzed. At low We , complete rebound is observed when the impact velocity is between a lower and an upper threshold, beyond which droplets are deposited on the surface after impact. At intermediate We , entrapment of an air bubble inside the impinging droplets is found on soft surfaces, while a bubble entrapment on the surface is observed on rigid surfaces. At high We , partial rebound is only identified on the most rigid surface at We ≳92 . Rebounding droplets behave similarly to elastic drops rebounding on superhydrophobic surfaces and the impact process is independent of surface viscoelasticity. Further, surface viscoelasticity does not influence drop spreading after impact—as the surfaces behave like rigid surfaces—but it does affect drop recoiling. Also, the postimpact drop oscillation on soft viscoelastic surfaces is influenced by dynamic wettability of these surfaces. Comparing sessile drop oscillation with a damped harmonic oscillator allows us to conclude that surface viscoelasticity affects the damping coefficient and liquid surface tension sets the spring constant of the system.

  5. Structural Transitions in Cholesteric Liquid Crystal Droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ye; Bukusoglu, Emre; Martinez-Gonzalez, Jose A.; Rahimi, Mohammad; Roberts, Tyler F.; Zhang, Rui; Wang, Xiaoguang; Abbott, Nicholas L.; de Pablo, Juan J.

    2016-07-01

    Confinement of cholesteric liquid crystals (ChLC) into droplets leads to a delicate interplay between elasticity, chirality, and surface energy. In this work, we rely on a combination of theory and experiments to understand the rich morphological behavior that arises from that balance. More specifically, a systematic study of micrometer-sized ChLC droplets is presented as a function of chirality and surface energy (or anchoring). With increasing chirality, a continuous transition is observed from a twisted bipolar structure to a radial spherical structure, all within a narrow range of chirality. During such a transition, a bent structure is predicted by simulations and confirmed by experimental observations. Simulations are also able to capture the dynamics of the quenching process observed in experiments. Consistent with published work, it is found that nanoparticles are attracted to defect regions on the surface of the droplets. For weak anchoring conditions at the nanoparticle surface, ChLC droplets adopt a morphology similar to that of the equilibrium helical phase observed for ChLCs in the bulk. As the anchoring strength increases, a planar bipolar structure arises, followed by a morphological transition to a bent structure. The influence of chirality and surface interactions are discussed in the context of the potential use of ChLC droplets as stimuli-responsive materials for reporting molecular adsorbates.

  6. Simulation of sliding of liquid droplets

    Science.gov (United States)

    Alen, Saif Khan; Farhat, Nazia; Rahman, Md. Ashiqur

    2016-07-01

    Numerical simulations of sliding behavior of liquid droplets on flat and periodic microgrooved surfaces with a range of groove geometry are conducted. A numerical model is developed which is capable of predicting the critical sliding angle of the drop by comparing the advancing and the receding angles obtained from numerical and experimental findings. The effect of microgroove topography, droplet size and inclination angle on the droplet sliding characteristics is analysed. Using an open-source platform (Surface Evolver), a 3D drop-shape model is developed to numerically determine the drop stability and contact angle hysteresis on tilted surfaces. In this numerical model, the three phase contact line of the drop is obtained by numerically calculating the vertex force and local contact angle at each vertex of the base contour. Several numerical models are developed based on various assumptions of base contour shape (circular or elliptical) and implementation of gravitational force to the droplet. Droplet shapes and critical sliding angles, obtained from these numerical models, are compared with those of experimental results and are found to be in very good agreement.

  7. Bouncing droplets on a billiard table

    CERN Document Server

    Shirokoff, David

    2012-01-01

    In a set of experiments, Couder et. al. demonstrate that an oscillating fluid bed may propagate a bouncing droplet through the guidance of the surface waves. We present a dynamical systems model, in the form of an iterative map, for a droplet on an oscillating bath. We examine the droplet bifurcation from bouncing to walking, and prescribe general requirements for the surface wave to support stable walking states. We show that in addition to walking, there is a region of large forcing that may support the chaotic bouncing of the droplet. Using the map, we then investigate the droplet trajectories for two different wave responses in a square (billiard ball) domain. We show that for waves which are quickly damped in space, the long time trajectories in a square domain are either non-periodic dense curves, or approach a quasiperiodic orbit. In contrast, for waves which extend over many wavelengths, at low forcing, trajectories tend to approach an array of circular attracting sets. As the forcing increases, the a...

  8. Bead mediated separation of microparticles in droplets

    Science.gov (United States)

    Sung, Ki-Joo; Lin, Xiaoxia Nina; Burns, Mark A.

    2017-01-01

    Exchange of components such as particles and cells in droplets is important and highly desired in droplet microfluidic assays, and many current technologies use electrical or magnetic fields to accomplish this process. Bead-based microfluidic techniques offer an alternative approach that uses the bead’s solid surface to immobilize targets like particles or biological material. In this paper, we demonstrate a bead-based technique for exchanging droplet content by separating fluorescent microparticles in a microfluidic device. The device uses posts to filter surface-functionalized beads from a droplet and re-capture the filtered beads in a new droplet. With post spacing of 7 μm, beads above 10 μm had 100% capture efficiency. We demonstrate the efficacy of this system using targeted particles that bind onto the functionalized beads and are, therefore, transferred from one solution to another in the device. Binding capacity tests performed in the bulk phase showed an average binding capacity of 5 particles to each bead. The microfluidic device successfully separated the targeted particles from the non-targeted particles with up to 98% purity and 100% yield. PMID:28282412

  9. Droplet breakup dynamics of weakly viscoelastic fluids

    Science.gov (United States)

    Marshall, Kristin; Walker, Travis

    2016-11-01

    The addition of macromolecules to solvent, even in dilute quantities, can alter a fluid's response in an extensional flow. For low-viscosity fluids, the presence of elasticity may not be apparent when measured using a standard rotational rheometer, yet it may still alter the response of a fluid when undergoing an extensional deformation, especially at small length scales where elastic effects are enhanced. Applications such as microfluidics necessitate investigating the dynamics of fluids with elastic properties that are not pronounced at large length scales. In the present work, a microfluidic cross-slot configuration is used to study the effects of elasticity on droplet breakup. Droplet breakup and the subsequent iterated-stretching - where beads form along a filament connecting two primary droplets - were observed for a variety of material and flow conditions. We present a relationship on the modes of bead formation and how and when these modes will form based on key parameters such as the properties of the outer continuous-phase fluid. The results are vital not only for simulating the droplet breakup of weakly viscoelastic fluids but also for understanding how the droplet breakup event can be used for characterizing the extensional properties of weakly-viscoelastic fluids.

  10. Jumping-droplet electrostatic energy harvesting

    Science.gov (United States)

    Miljkovic, Nenad; Preston, Daniel J.; Enright, Ryan; Wang, Evelyn N.

    2014-07-01

    Micro- and nanoscale wetting phenomena have been an active area of research due to its potential for improving engineered system performance involving phase change. With the recent advancements in micro/nanofabrication techniques, structured surfaces can now be designed to allow condensing coalesced droplets to spontaneously jump off the surface due to the conversion of excess surface energy into kinetic energy. In addition to being removed at micrometric length scales (˜10 μm), jumping water droplets also attain a positive electrostatic charge (˜10-100 fC) from the hydrophobic coating/condensate interaction. In this work, we take advantage of this droplet charging to demonstrate jumping-droplet electrostatic energy harvesting. The charged droplets jump between superhydrophobic copper oxide and hydrophilic copper surfaces to create an electrostatic potential and generate power during formation of atmospheric dew. We demonstrated power densities of ˜15 pW/cm2, which, in the near term, can be improved to ˜1 μW/cm2. This work demonstrates a surface engineered platform that promises to be low cost and scalable for atmospheric energy harvesting and electric power generation.

  11. The dynamics of laser droplet generation.

    Science.gov (United States)

    Krese, Blaz; Perc, Matjaz; Govekar, Edvard

    2010-03-01

    We propose an experimental setup allowing for the characterization of laser droplet generation in terms of the underlying dynamics, primarily showing that the latter is deterministically chaotic by means of nonlinear time series analysis methods. In particular, we use a laser pulse to melt the end of a properly fed vertically placed metal wire. Due to the interplay of surface tension, gravity force, and light-metal interaction, undulating pendant droplets are formed at the molten end, which eventually completely detach from the wire as a consequence of their increasing mass. We capture the dynamics of this process by employing a high-speed infrared camera, thereby indirectly measuring the temperature of the wire end and the pendant droplets. The time series is subsequently generated as the mean value over the pixel intensity of every infrared snapshot. Finally, we employ methods of nonlinear time series analysis to reconstruct the phase space from the observed variable and test it against determinism and stationarity. After establishing that the observed laser droplet generation is a deterministic and dynamically stationary process, we calculate the spectra of Lyapunov exponents. We obtain a positive largest Lyapunov exponent and a negative divergence, i.e., sum of all the exponents, thus indicating that the observed dynamics is deterministically chaotic with an attractor as solution in the phase space. In addition to characterizing the dynamics of laser droplet generation, we outline industrial applications of the process and point out the significance of our findings for future attempts at mathematical modeling.

  12. MODEL OF LASER INTERACTION WITH LIQUID DROPLET

    Directory of Open Access Journals (Sweden)

    K. N. Volkov,

    2016-09-01

    Full Text Available Subject of Research. A mathematical model of optical breakdown in the dielectric liquid droplets when exposed to pulsed laser radiation was developed. The process is considered in several stages: heating, evaporation of the particle, forming a steam halo, ionization of the steam halo. Numerical study was carried out on the basis of the mathematical model to determine the threshold characteristics of the laser pulse. Main Results.Distributions of pressure, density and temperature of the particle steam halo were obtained by means of a calculation. The temperature field around the liquid droplet was determined. It has been found that at high energies in the gas bubble, the conditions are provided for thermal gas ionization and start of the electron avalanche, leading to plasma formation. Due to the volumetric heat generation, the droplet is overheated and is in a metastable state. The plasma cloud is almost opaque to radiation that causes an abrupt increase of temperature. As a result, an explosion occurs inside the droplet with the formation of a shock wave that is propagating outward. Practical Relevance.The results can be used to assess the performance of high-power laser scanning (LIDAR under the presence of liquid droplets in the atmosphere and other suspensions. Lasers can be used in fire and explosion aerospace systems. Obtained findings can be applied also in the systems of laser ignition and detonation initiation.

  13. Bioeffects due to acoustic droplet vaporization

    Science.gov (United States)

    Bull, Joseph

    2015-11-01

    Encapsulated micro- and nano-droplets can be vaporized via ultrasound, a process termed acoustic droplet vaporization. Our interest is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular microdroplets. Additionally, the microdroplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Early timescale vaporization events, including phase change, are directly visualized using ultra-high speed imaging, and the influence of acoustic parameters on droplet/bubble dynamics is discussed. Acoustic and fluid mechanics parameters affecting the severity of endothelial cell bioeffects are explored. These findings suggest parameter spaces for which bioeffects may be reduced or enhanced, depending on the objective of the therapy. This work was supported by NIH grant R01EB006476.

  14. Single Mobile Micro Droplet-Particle Pairs Spatially Captured by Macro Host Droplets on a Superhydrophobic Surface

    Directory of Open Access Journals (Sweden)

    Gregory S. Watson

    2015-01-01

    Full Text Available In this preliminary study, we demonstrate how small single water droplets can be spatially captured on the surface of individual micron sized hydrophobic coated particles (C18 which adhere to the surface of a nonmobile larger host water droplet resting on a superhydrophobic surface. The formation of the larger droplet, particle adhesion to that droplet, and smaller droplet formation on the particle all take place spontaneously from condensation conditions. These micro droplet-particle pairs are confined to the surface (liquid-air interface of the larger host droplet; however, they are free to engage with external forces to promote mobility. This response may find applications for particle pair transport on liquid surfaces. We also demonstrate that droplets can be captured or removed from the larger droplet surface via a self-propulsion mechanism.

  15. Dynamics of Coalescence-Induced Jumping Water Droplets

    CERN Document Server

    Miljkovic, Nenad; Enright, Ryan; Wang, Evelyn N

    2013-01-01

    This fluid dynamics video shows the different interaction mechanisms of coalescence-induced droplet jumping during condensation on a nanostructured superhydrophobic surface. High speed imaging was used to show jumping behavior on superhydrophobic copper oxide and carbon nanotube surfaces. Videos demonstrating multi-jumping droplets, jumping droplet return to the surface, and droplet-droplet electrostatic repulsions were analyzed. Experiments using external electric fields in conjunction with high speed imaging in a custom built experimental chamber were used to show that all coalescence-induced jumping droplets on superhydrophobic surfaces become positively charged upon leaving the surface, which is detailed in the video.

  16. Possible transmission experiments with low-velocity helium droplets

    Science.gov (United States)

    Wynveen, A.; Lidke, K. A.; Lutsyshyn, Y.; Halley, J. W.

    2007-02-01

    We show that very low velocity droplets can be used to carry out an experiment to test whether condensate mediated transmission processes can occur in a superfluid droplet of He4 . By appropriately choosing the droplet radius and temperature, we can eliminate the competing roton, phonon, and ripplon mediated elastic transmission events. Then a calculation shows that if a few percent or more of the incident atoms experience anomalous condensate mediated transmission, the effects should be detectable in the droplet trajectories. We consider two forms of the experiment, involving a freely falling droplet in ambient vapor in the first instance and an oscillating droplet in a magnetic trap in the second.

  17. SPH Modeling of Droplet Impact on Solid Boundary

    Institute of Scientific and Technical Information of China (English)

    李大鸣; 白玲; 李玲玲; 赵明宇

    2014-01-01

    A droplet undergoes spreading, rebounding or splashing when it impacts solid boundary, which is a typical phenomenon of free surface flow that exists widely in modern industry. Smoothed particle hydrodynamics (SPH) method is applied to numerically study the dynamical behaviors of the droplet impacting solid boundary, and both the spreading and rebounding phenomena of the droplet are reproduced in the simulation. The droplet deformation, flow fields and pressure fields inside the droplet at different moments are analyzed. Two important factors, the initial veloc-ity and diameter, are discussed in determining the maximum spreading factor, revealing that the maximum spreading factor increases with the increase of the impact velocity and droplet diameter respectively.

  18. Hyalinizing trabecular tumor of the thyroid: Diagnosed of a rare tumor using ultrasonography, cytology, and intraoperative frozen sections

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hyun Sik; Kim, Eun Kyung; Kwak, Jin Young; Moon, Hee Jung; Yoon, Jung Hyun [Dept. of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul (Korea, Republic of); Park, Cheol Keun; Son, Eun Ju [Gangnam Severance Hospital, Yonsei University, College of Medicine, Seoul (Korea, Republic of)

    2016-03-15

    The goal of this study was to evaluate the clinicopathological and imaging features of thyroid nodules surgically diagnosed as hyaline trabecular tumor (HTT), and to assess the role of cytology and frozen sections (FS) in the diagnosis of HTT. This study included 21 thyroid nodules in 21 patients treated from August 2005 to March 2015 (mean age, 53.3 years) who were either diagnosed as HTT or had HTT suggested as a possible diagnosis based on cytology, FS, or the final pathology report. Patients' medical records were retrospectively reviewed for cytopathologic results and outcomes during the course of follow-up. Sonograms were reviewed and categorized. Twelve nodules from 12 patients were surgically confirmed as HTT. Ultrasonography (US)-guided fine needle aspiration (FNA) was performed on 11 nodules, of which six (54.5%) were papillary thyroid carcinoma (PTC) or suspicious for PTC and three (27.3%) were HTT or suspicious for HTT. Intraoperative FS suggested the possibility of HTT in seven nodules, of which four (57.1%) were confirmed as HTT. US-FNA suggested the diagnosis of HTT in 10 nodules, of which three (30.0%) were confirmed as HTT. Common US features of the 12 pathologically confirmed cases of HTT were hypoechogenicity or marked hypoechogenicity (83.4%), absence of calcifications (91.7%), parallel shape (100.0%), presence of vascularity (75.0%), and probable benignity (58.3%). HTT should be included in the differential diagnosis of solid tumors with hypoechogenicity or marked hypoechogenicity and otherwise benign US features that have been diagnosed as PTC through cytology.

  19. Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities

    Directory of Open Access Journals (Sweden)

    CJ Ley

    2014-03-01

    Full Text Available Osteochondral lesions in the joints of the distal tarsal region of young Icelandic horses provide a natural model for the early stages of osteoarthritis (OA in low-motion joints. We describe and characterise mineralised and non-mineralised osteochondral lesions in left distal tarsal region joint specimens from twenty-two 30 ±1 month-old Icelandic horses. Combinations of confocal scanning light microscopy, backscattered electron scanning electron microscopy (including, importantly, iodine staining and three-dimensional microcomputed tomography were used on specimens obtained with guidance from clinical imaging. Lesion-types were described and classified into groups according to morphological features. Their locations in the hyaline articular cartilage (HAC, articular calcified cartilage (ACC, subchondral bone (SCB and the joint margin tissues were identified and their frequency in the joints recorded. Associations and correlations between lesion-types were investigated for centrodistal joints only. In centrodistal joints the lesion-types HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest and ACC advance had significant associations and strong correlations. These lesion-types had moderate to high frequency in centrodistal joints but low frequencies in tarsometatarsal and talocalcaneal-centroquartal joints. Joint margin lesion-types had no significant associations with other lesion-types in the centrodistal joints but high frequency in both the centrodistal and tarsometatarsal joints. The frequency of SCB lesion-types in all joints was low. Hypermineralised infill phase lesion-types were detected. Our results emphasise close associations between HAC and ACC lesions in equine centrodistal joints and the importance of ACC lesions in the development of OA in low-motion compression-loaded equine joints.

  20. Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities.

    Science.gov (United States)

    Ley, C J; Ekman, S; Hansson, K; Björnsdóttir, S; Boyde, A

    2014-03-25

    Osteochondral lesions in the joints of the distal tarsal region of young Icelandic horses provide a natural model for the early stages of osteoarthritis (OA) in low-motion joints. We describe and characterise mineralised and non-mineralised osteochondral lesions in left distal tarsal region joint specimens from twenty-two 30 ±1 month-old Icelandic horses. Combinations of confocal scanning light microscopy, backscattered electron scanning electron microscopy (including, importantly, iodine staining) and three-dimensional microcomputed tomography were used on specimens obtained with guidance from clinical imaging. Lesion-types were described and classified into groups according to morphological features. Their locations in the hyaline articular cartilage (HAC), articular calcified cartilage (ACC), subchondral bone (SCB) and the joint margin tissues were identified and their frequency in the joints recorded. Associations and correlations between lesion-types were investigated for centrodistal joints only. In centrodistal joints the lesion-types HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest and ACC advance had significant associations and strong correlations. These lesion-types had moderate to high frequency in centrodistal joints but low frequencies in tarsometatarsal and talocalcaneal-centroquartal joints. Joint margin lesion-types had no significant associations with other lesion-types in the centrodistal joints but high frequency in both the centrodistal and tarsometatarsal joints. The frequency of SCB lesion-types in all joints was low. Hypermineralised infill phase lesion-types were detected. Our results emphasise close associations between HAC and ACC lesions in equine centrodistal joints and the importance of ACC lesions in the development of OA in low-motion compression-loaded equine joints.

  1. Hyalinizing trabecular tumor of the thyroid: diagnosis of a rare tumor using ultrasonography, cytology, and intraoperative frozen sections

    Directory of Open Access Journals (Sweden)

    Hyunsik Jang

    2016-04-01

    Full Text Available Purpose: The goal of this study was to evaluate the clinicopathological and imaging features of thyroid nodules surgically diagnosed as hyaline trabecular tumor (HTT, and to assess the role of cytology and frozen sections (FS in the diagnosis of HTT. Methods: This study included 21 thyroid nodules in 21 patients treated from August 2005 to March 2015 (mean age, 53.3 years who were either diagnosed as HTT or had HTT suggested as a possible diagnosis based on cytology, FS, or the final pathology report. Patients’ medical records were retrospectively reviewed for cytopathologic results and outcomes during the course of follow-up. Sonograms were reviewed and categorized. Results: Twelve nodules from 12 patients were surgically confirmed as HTT. Ultrasonography (US-guided fine needle aspiration (FNA was performed on 11 nodules, of which six (54.5% were papillary thyroid carcinoma (PTC or suspicious for PTC and three (27.3% were HTT or suspicious for HTT. Intraoperative FS suggested the possibility of HTT in seven nodules, of which four (57.1% were confirmed as HTT. US-FNA suggested the diagnosis of HTT in 10 nodules, of which three (30.0% were confirmed as HTT. Common US features of the 12 pathologically confirmed cases of HTT were hypoechogenicity or marked hypoechogenicity (83.4%, absence of calcifications (91.7%, parallel shape (100.0%, presence of vascularity (75.0%, and probable benignity (58.3%. Conclusion: HTT should be included in the differential diagnosis of solid tumors with hypoechogenicity or marked hypoechogenicity and otherwise benign US features that have been diagnosed as PTC through cytology.

  2. A Unique Case of Pulmonary Hyalinizing Granuloma Associated With FDG-avid PET Scan and Deep Venous Thrombosis.

    Science.gov (United States)

    Khalid, Imran; Stone, Chad; Kvale, Paul

    2009-04-01

    An 83-year-old obese woman with a 60-pack-year smoking history was referred for evaluation of an abnormal chest radiograph [chest x-ray (CXR)]. Her past medical history was significant for recurrent deep venous thrombosis without any predisposing factors. CXR showed a large mass in the right mid lung and another nodule at the right apex, highly suspicious for a neoplastic process. These were not present on a CXR from 2 years earlier. An fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scan revealed that all lesions were strongly FDG-avid. Six CT-guided core-needle lung biopsy specimens were obtained from the lung mass and all contained dense, lamellar, or "ropy" keloid-like collagen bundles arranged in a haphazard pattern. The biopsy specimens lacked significant necrosis and granulomas. Congo red stain with polarization was also negative for amyloid. The diagnosis of pulmonary hyalinizing granuloma (PHG) was made. A complete hypercoagulable workup was performed but no underlying abnormalities were found, including a negative lupus anticoagulant and malignancy workup. The patient was maintained on warfarin and followed with serial CT scans for 1 year, with spontaneous regression in the lung mass. The case is unique as it is the first case that reports an association of PHG with recurrent deep venous thrombosis in the absence of autoimmune or procoagulant factors and emphasizes the need for life-long anticoagulation in such scenarios. Also, we report the FDG-avid PET scan findings here that are novel for this disease in adults and add PHG to the list of diseases causing false-positive PET scans when malignancy is suspected.

  3. The dynamics of laser droplet generation

    CERN Document Server

    Krese, Blaz; Govekar, Edvard

    2010-01-01

    We propose an experimental setup allowing for the characterization of laser droplet generation in terms of the underlying dynamics, primarily showing that the latter is deterministically chaotic by means of nonlinear time series analysis methods. In particular, we use a laser pulse to melt the end of a properly fed vertically placed metal wire. Due to the interplay of surface tension, gravity force and light-metal interaction, undulating pendant droplets are formed at the molten end, which eventually completely detach from the wire as a consequence of their increasing mass. We capture the dynamics of this process by employing a high-speed infrared camera, thereby indirectly measuring the temperature of the wire end and the pendant droplets. The time series is subsequently generated as the mean value over the pixel intensity of every infrared snapshot. Finally, we employ methods of nonlinear time series analysis to reconstruct the phase space from the observed variable and test it against determinism and stati...

  4. Droplet Manipulations in Two Phase Flow Microfluidics

    Directory of Open Access Journals (Sweden)

    Arjen M. Pit

    2015-11-01

    Full Text Available Even though droplet microfluidics has been developed since the early 1980s, the number of applications that have resulted in commercial products is still relatively small. This is partly due to an ongoing maturation and integration of existing methods, but possibly also because of the emergence of new techniques, whose potential has not been fully realized. This review summarizes the currently existing techniques for manipulating droplets in two-phase flow microfluidics. Specifically, very recent developments like the use of acoustic waves, magnetic fields, surface energy wells, and electrostatic traps and rails are discussed. The physical principles are explained, and (potential advantages and drawbacks of different methods in the sense of versatility, flexibility, tunability and durability are discussed, where possible, per technique and per droplet operation: generation, transport, sorting, coalescence and splitting.

  5. Versatile microfluidic droplets array for bioanalysis.

    Science.gov (United States)

    Hu, Shan-Wen; Xu, Bi-Yi; Ye, Wei-Ke; Xia, Xing-Hua; Chen, Hong-Yuan; Xu, Jing-Juan

    2015-01-14

    We propose a novel method to obtain versatile droplets arrays on a regional hydrophilic chip that is fabricated by PDMS soft lithography and regional plasma treatment. It enables rapid liquid dispensation and droplets array formation just making the chip surface in contact with solution. By combining this chip with a special Christmas Tree structure, the droplets array with concentrations in gradient is generated. It possesses the greatly improved performance of convenience and versatility in bioscreening and biosensing. For example, high throughput condition screening of toxic tests of CdSe quantum dots on HL-60 cells are conducted and cell death rates are successfully counted quickly and efficiently. Furthermore, a rapid biosensing approach for cancer biomarkers carcinoma embryonic antigen (CEA) is developed via magnetic beads (MBs)-based sandwich immunoassay methods.

  6. A study of oil droplet coalescence.

    Science.gov (United States)

    Boyson, T K; Pashley, R M

    2007-12-01

    Oil droplets dispersed in water can be readily studied when they are coated with surfactants, which lower their interfacial tension and enhance their stability. Pure oil droplets are more difficult to study because of their high interfacial tension, which facilitates coalescence and the adsorption of contaminants. In this study, we have characterised the surface charging properties of a water insoluble oil, bromododecane, which has a density close to water. The small density difference allows us to study relatively large drops of this oil and to analyse its coalescence behaviour. The results obtained with this simple, surfactant-free, system suggest that an additional attractive force, such as the long range hydrophobic interaction, might be required to explain oil droplet coalescence behaviour.

  7. Lattice-Boltzmann simulations of droplet evaporation

    KAUST Repository

    Ledesma-Aguilar, Rodrigo

    2014-09-04

    © the Partner Organisations 2014. We study the utility and validity of lattice-Boltzmann (LB) simulations to explore droplet evaporation driven by a concentration gradient. Using a binary-fluid lattice-Boltzmann algorithm based on Cahn-Hilliard dynamics, we study the evaporation of planar films and 3D sessile droplets from smooth solid surfaces. Our results show that LB simulations accurately reproduce the classical regime of quasi-static dynamics. Beyond this limit, we show that the algorithm can be used to explore regimes where the evaporative and diffusive timescales are not widely separated, and to include the effect of boundaries of prescribed driving concentration. We illustrate the method by considering the evaporation of a droplet from a solid surface that is chemically patterned with hydrophilic and hydrophobic stripes. This journal is

  8. Effect of water droplet in solvent sublation

    Institute of Scientific and Technical Information of China (English)

    Peng Yu Bi; Hui Ru Dong; Nan Nan Wang

    2008-01-01

    Aqueous phase layer around bubble and water droplet are two additional processes in solvent sublation. In the dynamic processof mass transfer, they are always neglected, but they are very important in the investigation of thermodynamic equilibrium. In thispaper, the effect of water droplet in solvent sublation was discussed in detail, and the previous mathematical model of solventsubaltion was improved. Matlab 6.5 was used to simulate the process of water droplets, and the comparison between the previoushypothesis and the improvement in this paper showed the superiority, especially in the investigation of thermodynamic equilibrium.Moreover, the separation and concentration of the complex compound dithizone-Co(Ⅱ) from aqueous phase to n-octanol by solventsublation also proved the improved mathematical model was reasonable.2008 Hui Ru Dong. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  9. Rebound of continuous droplet streams from an immiscible liquid pool

    Science.gov (United States)

    Doak, William J.; Laiacona, Danielle M.; German, Guy K.; Chiarot, Paul R.

    2016-05-01

    We report on the rebound of high velocity continuous water droplet streams from the surface of an immiscible oil pool. The droplets have diameters and velocities of less than 90 μm and 15 m/s, respectively, and were created at frequencies up to 60 kHz. The impact and rebound of continuous droplet streams at this scale and velocity have been largely unexplored. This regime bridges the gap between single drop and jet impacts. The impinging droplets create a divot at the surface of the oil pool that had a common characteristic shape across a wide-range of droplet and oil properties. After impact, the reflected droplets maintain the same uniformity and periodicity of the incoming droplets but have significantly lower velocity and kinetic energy. This was solely attributed to the generation of a flow induced in the viscous oil pool by the impacting droplets. Unlike normally directed impact of millimeter-scale droplets with a solid surface, our results show that an air film does not appear to be maintained beneath the droplets during impact. This suggests direct contact between the droplets and the surface of the oil pool. A ballistic failure limit, correlated with the Weber number, was identified where the rebound was suppressed and the droplets were driven through the oil surface. A secondary failure mode was identified for aperiodic incoming streams. Startup effects and early time dynamics of the rebounding droplet stream were also investigated.

  10. Droplet sizes, dynamics and deposition in vertical annular flow

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, J C.B.; Dukler, A E

    1985-10-01

    The role of droplets in vertical upwards annular flow is investigated, focusing on the droplet size distributions, dynamics, and deposition phenomena. An experimental program was performed based on a new laser optical technique developed in these laboratories and implemented here for annular flow. This permitted the simultaneous measurement of droplet size, axial and radial velocity. The dependence of droplet size distributions on flow conditions is analyzed. The Upper-Log Normal function proves to be a good model for the size distribution. The mechanism controlling the maximum stable drop size was found to result from the interaction of the pressure fluctuations of the turbulent flow of the gas core with the droplet. The average axial droplet velocity showed a weak dependence on gas rates. This can be explained once the droplet size distribution and droplet size-velocity relationship are analyzed simultaneously. The surprising result from the droplet conditional analysis is that larger droplet travel faster than smaller ones. This dependence cannot be explained if the drag curves used do not take into account the high levels of turbulence present in the gas core in annular flow. If these are considered, then interesting new situations of multiplicity and stability of droplet terminal velocities are encountered. Also, the observed size-velocity relationship can be explained. A droplet deposition is formulated based on the particle inertia control. This permitted the calculation of rates of drop deposition directly from the droplet size and velocities data.

  11. Optical droplet vaporization of micron-sized perfluorocarbon droplets and their photoacoustic detection

    Science.gov (United States)

    Strohm, Eric; Rui, Min; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael

    2011-03-01

    An acoustic and photoacoustic characterization of micron-sized perfluorocarbon (PFC) droplets is presented. PFC droplets are currently being investigated as acoustic and photoacoustic contrast agents and as cancer therapy agents. Pulse echo measurements at 375 MHz were used to determine the diameter, ranging from 3.2 to 6.5 μm, and the sound velocity, ranging from 311 to 406 m/s of nine droplets. An average sound velocity of 379 +/- 18 m/s was calculated for droplets larger than the ultrasound beam width of 4.0 μm. Optical droplet vaporization, where vaporization of a single droplet occurred upon laser irradiation of sufficient intensity, was verified using pulse echo acoustic methods. The ultrasonic backscatter amplitude, acoustic impedance and attenuation increased after vaporization, consistent with a phase change from a liquid to gas core. Photoacoustic measurements were used to compare the spectra of three droplets ranging in diameter from 3.0 to 6.2 μm to a theoretical model. Good agreement in the spectral features was observed over the bandwidth of the 375 MHz transducer.

  12. Burning of droplets and particles of explosives

    Energy Technology Data Exchange (ETDEWEB)

    Kondrikov, B.N. [Mendeleev University of Chemical Technology, Moscow (Russian Federation)

    1996-12-31

    Small droplets of organic diazides investigated by C.K. Law and coworkers burn in hot gas at 1 atm with rates inversely proportional to the droplet diameter presumably owing to leading chemical reaction proceeds in gas phase. These burning rates are obviously much lower than those obtained by extrapolation of the results measured for the some substances in glass tubes (at pressure of about 10{sup -2}-10{sup -1} atm, and temperature 0-100 deg C) on the burning conditions of the droplets. Kinetic constants estimated using Zel`dovich equation for the burning rate in gas phase and Semenov relation for delay time of the droplets micro-explosion in liquid phase are about the same: E {approx_equal} 0.17 MJ/mol, log{sub 10}k{sub o} {approx_equal} 15(S{sup -1}). In both of the cases the leading chemical reaction is supposed to be of the first order. Landau instability is assumed to be reflected in distortion of the droplets at burning but, as opposed to the liquids pools or columns burning, it is not followed by the burning rate augmentation or (as it is observed sometimes) by the combustion extinguishment. Simple dependence of burning rate of droplets of diazides of the row of normal alkanes on their enthalpy of formation is obtained. Burning rate of ball-shaped particles of polyvinyl-nitrate estimated by A. Merzhanov and collaborators is about the same as measured by the data E.I. Maximov, the member of the same team, for PVN strands, at extrapolation of his results on the suggested preheating temperature of the particle. Probably it is a result of the leading chemical reaction proceeding in condensed phase. (author) 10 refs.

  13. Simulation of Droplet Trains in Microfluidic Networks

    CERN Document Server

    Behzad, Mehran Djalali; Ejtehadi, Mohammad Reza

    2009-01-01

    In this work we show that in a microfluidic network and in low Reynolds numbers a system can be irreversible because of hysteresis effects.The network, which is employed in our simulations, is taken from recent experiments. The network consists of one loop connected to input and output pipes. A train of droplets enter the system at a uniform rate, but they may leave it in different patterns, e.g. periodic or even chaotic. The out put pattern depends on the time interval among the incoming droplets as well as the network geometry and for some parameters the system is not reversible.

  14. O(^3 p) Doped Helium Droplets

    Science.gov (United States)

    Brice, Joseph T.; Douberly, Gary E.

    2017-06-01

    Atomic oxygen (^3 P) is generated via thermolysis in a commerical thermal gas cracker (Mantis Ltd. MGC-75). Complexes with HCN were investigated to qualitatively assess the doping efficiency of O(^3 P) into a helium droplet. Theoretical calculations of a linear O \\cdot\\cdot\\cdot HCN (^3 Σ) complex at the CCSD(T)/aug-cc-pVTZ level are consistent with the rotational constants extracted from the rotational substructure in the experimental spectra, and with dipole moments approximated from Stark spectra. The thermal source will be used to study reactions between O(^3 P) and hydrocarbons in helium droplets, and preliminary data on this topic will be presented.

  15. Free running droplets on packed powder beds

    Science.gov (United States)

    Whitby, Catherine P.; Bian, Xun; Sedev, Rossen

    2013-06-01

    We observed that water drops placed on horizontal beds of fine molybdenite particles move freely over the bed surface for about 1 second. The drops collect an irregular coating of unevenly distributed particles as they bounce and roll. We manipulated the distance that the drops travel, and hence the area of the droplet surface coated with particles, by varying the water surface tension and the kinetic energy of the initial droplet impact on the bed surface. Our results highlight the role of contact angle hysteresis in particle encapsulation of liquid drops.

  16. Vitrification and devitrification of micro-droplets

    Science.gov (United States)

    Ryoun Youn, Jae; Song, Young Seok

    2012-11-01

    Vitrification can be achieved by flash freezing and thawing (i.e. quenching) when ice crystal formation is inhibited in a cryogenic environment. Such ultra-rapid cooling and rewarming occurs due to the large temperature difference between the liquid and its surrounding medium. Here, we analyze the crystallization behavior of a droplet (i.e. vitrification and devitrification) by using a numerical model. The numerical results were found to explain the experimental observations successfully. The findings showed that for successful cryopreservation not only sufficiently fast cooling, but also rewarming processes should be designed and controlled to avoid devitrification of a droplet.

  17. Recent Advances in Applications of Droplet Microfluidics

    Directory of Open Access Journals (Sweden)

    Wei-Lung Chou

    2015-09-01

    Full Text Available Droplet-based microfluidics is a colloidal and interfacial system that has rapidly progressed in the past decade because of the advantages of low fabrication costs, small sample volumes, reduced analysis durations, high-throughput analysis with exceptional sensitivity, enhanced operational flexibility, and facile automation. This technology has emerged as a new tool for many recently used applications in molecular detection, imaging, drug delivery, diagnostics, cell biology and other fields. Herein, we review recent applications of droplet microfluidics proposed since 2013.

  18. Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100

    Directory of Open Access Journals (Sweden)

    J. K. Spiegel

    2012-05-01

    Full Text Available Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the evaluation of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100: first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of Mie theory. We deduced error assumptions and proposed how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we derived corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We show that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient windspeeds below 4.4 m s−1 and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. As a consequence, for further LWC measurements with the FM-100 we strongly recommend to consider (1 the error arising due to Mie

  19. Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100

    Directory of Open Access Journals (Sweden)

    J. K. Spiegel

    2012-09-01

    Full Text Available Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the error analysis of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100: first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of the Mie theory. We deduced error assumptions and proposed a new method on how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we summarized corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We showed that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the new stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient wind speeds below 4.4 m s−1 and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. Consequently, for further LWC measurements with the FM-100 we strongly recommend to consider (1 the

  20. Droplet motion driven by electro-elasto-capillary effects

    Science.gov (United States)

    Shah, Jaymeen; Yang, Xin; Sun, Ying

    2013-11-01

    The motion of droplets on natural and synthetic fibers underlines many technological applications including flexible displays, insulation, and smart filters. However, there is a lack of fundamental understanding of the coupled electrical, elastic, and capillary forces on droplets in fiber networks. In the present study, the motion of a water droplet suspended between two electrically insulated fibers of different Young's modulus, lengths and diameters are examined under electric fields. The results on rigid fibers reveal a critical voltage, under which the droplet remain stationary. Above this critical voltage, droplet self-propulsion is observed as a result of the interplay of electro, elasto and capillary forces on the droplet. The effects of the inter-fiber distance and Young's modulus on droplet motion are also discussed. The controllable motion of droplets can be used to manipulate or transport liquid at small scales.

  1. Encapsulation of emulsion droplets by organo–silica shells

    NARCIS (Netherlands)

    Zoldesi, C.; Steegstra, Patrick; Imhof, Arnout

    2007-01-01

    Surfactant-stabilized emulsion droplets were used as templates for the synthesis of hollow colloidal particles. Monodisperse silicone oil droplets were prepared by hydrolysis and polymerization of dimethyldiethoxysiloxane monomer, in the presence of surfactant: sodium dodecyl sulphate (SDS, anionic)

  2. Velocity and rotation measurements in acoustically levitated droplets

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Abhishek [University of Central Florida, Orlando, FL 32816 (United States); Basu, Saptarshi [Indian Institute of Science, Bangalore 560012 (India); Kumar, Ranganathan, E-mail: ranganathan.kumar@ucf.edu [University of Central Florida, Orlando, FL 32816 (United States)

    2012-10-01

    The velocity scale inside an acoustically levitated droplet depends on the levitator and liquid properties. Using Particle Imaging Velocimetry (PIV), detailed velocity measurements have been made in a levitated droplet of different diameters and viscosity. The maximum velocity and rotation are normalized using frequency and amplitude of acoustic levitator, and droplet viscosity. The non-dimensional data are fitted for micrometer- and millimeter-sized droplets levitated in different levitators for different viscosity fluids. It is also shown that the rotational speed of nanosilica droplets at an advanced stage of vaporization compares well with that predicted by exponentially fitted parameters. -- Highlights: ► Demonstrates the importance of rotation in a levitated droplet that leads to controlled morphology. ► Provides detailed measurements of Particle Image Velocimetry inside levitated droplets. ► Shows variation of vortex strength with the droplet diameter and viscosity of the liquid.

  3. Droplets Fusion in a Microchannel on a Piezoelectric Substrate

    Directory of Open Access Journals (Sweden)

    Fu Xiang-ting

    2013-07-01

    Full Text Available Fusion droplets is a key operation in a microfluidic device for microfluidic analysis. A new fusion method for droplets was presented. An interditigal transducer and a reflector were fabricated on 1280-yx LiNbO3 piezoelectric substrate using microelectric technology. A poly-dimethyl silicone micro-channel was made by soft lithography technology and mounted on the piezoelectric substrate. Droplets in the microchannel were actuated by surface acoustic wave and fussed each other. Coloured dye solution droplets were used to fusion experiments. Results show that the two droplets in the microchannel can be fused by help of surface acoustic wave, and size of droplets, distance of droplets and RF signal power can affect successful fusion of the droplets. The fusion method is valuable for microlfuidic biological and chemical analysis in a microfluidic device.

  4. Droplet Velocity in an Electrowetting on Dielectric Digital Microfluidic Device

    Directory of Open Access Journals (Sweden)

    Mun Mun Nahar

    2016-04-01

    Full Text Available In many electrowetting on dielectric (EWOD based microfluidics devices, droplet actuation speed is a crucial performance-controlling parameter. Our present study aims to characterize and study droplet speed in a typical EWOD device. First, a practical droplet speed measurement method has been methodically demonstrated and some related velocity terms have been introduced. Next, influence of electrode shape on droplet speed has been studied and a new design to enhance droplet speed has been proposed and experimentally demonstrated. Instead of using square shaped electrodes, rectangular electrodes with smaller widths are used to actuate droplets. Additionally, different schemes of activating electrodes are studied and compared for the same applied voltage. The experiments show that a particular scheme of activating the array of rectangular electrodes enhances the droplet speed up to 100% in comparison to the droplet speed in a conventional device with square shaped electrodes.

  5. A novel coarsening mechanism of droplets in immiscible fluid mixtures.

    Science.gov (United States)

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-06-16

    In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with inter-droplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian-coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of individual droplets, causing accidental collisions and subsequent interface-tension-driven coalescence. Contrary to this, here we demonstrate that the droplet motion is not random, but hydrodynamically driven by the composition Marangoni force due to an interfacial tension gradient produced in each droplet as a consequence of composition correlation among droplets. This alters our physical understanding of droplet coarsening in immiscible liquid mixtures on a fundamental level.

  6. Microfluidic droplet generator with controlled break-up mechanism

    KAUST Repository

    Gonzalez, David Conchouso

    2017-04-13

    Droplet generation devices and systems that parallelize droplet generation devices are provided. The droplet generation devices can include a symmetric block-and-break system and a tapered droplet generation zone. The symmetric block-and-break system can include a pair of break channels and a pair of bypass channels symmetrically arranged with respect to the dispersed-phase input channel and the output channel. The droplet generation devices can generate monodisperse droplets with a predefined volume over a range of flow rates, pressures, and fluid properties. The droplet generation devices are therefore capable of parallelization to achieve large-capacity droplet generation, e.g. greater than 1 L/hr, with small overall coefficients of variation.

  7. Droplet sorting in a loop of flat microfluidic channels

    Science.gov (United States)

    Kadivar, Erfan; Herminghaus, Stephan; Brinkmann, Martin

    2013-07-01

    Motivated by recent experiments, we numerically study the droplet traffic in microfluidic channels forming an asymmetric loop with a long and a short arm. The loop is connected to an inlet and an outlet channel by two right angled T-junctions. Assuming flat channels, we employ the boundary element method (BEM) to numerically solve the two-dimensional Darcy equation that governs two phase flow in the Hele-Shaw limit. The occurrence of different sorting regimes is summarized in sorting diagrams in terms of droplet size, distance between consecutive droplets in the inlet channel, and loop asymmetry for mobility ratios of the liquid phases larger and smaller than one. For large droplet distances, the traffic is regulated by the ratio of the total hydraulic resistances of the long and short arms. At high droplet densities and below a critical droplet size, droplet-droplet collisions are observed for both mobility ratios.

  8. Heat transfer and phase change in an impinging droplet

    Science.gov (United States)

    Rangchian, Aysan; Shirazi, Nikki L.; Kavehpour, H. Pirouz

    2016-11-01

    Non isothermal droplet impact on solid surfaces has several industrial applications such as spray cooling and 3D printing. Impinging of a droplet on a surface involves an initial phase of spreading followed by a subsequent return to the equilibrium shape. Thermal energy exchanged within the droplet fluid as well as between liquid/solid during the impact has been studied using an ultra high speed infrared camera. Variable parameters in the experiment include droplet temperature and kinetic energy of the droplet during the impact. The evolution of droplet shape viewed by IR camera is similar to what previously observed by high speed photography. The thermal map of droplet over time in these experiments agrees with previously reported numerical simulation. In addition, spacial and temporal temperature variations of liquid droplets on a surface as they solidify are presented. IR camera provides an accurate temperature diagram as the phase change occurs, which is essential for understanding the physics of 3D printing.

  9. Combinatorial microfluidic droplet engineering for biomimetic material synthesis

    Science.gov (United States)

    Bawazer, Lukmaan A.; McNally, Ciara S.; Empson, Christopher J.; Marchant, William J.; Comyn, Tim P.; Niu, Xize; Cho, Soongwon; McPherson, Michael J.; Binks, Bernard P.; deMello, Andrew; Meldrum, Fiona C.

    2016-01-01

    Although droplet-based systems are used in a wide range of technologies, opportunities for systematically customizing their interface chemistries remain relatively unexplored. This article describes a new microfluidic strategy for rapidly tailoring emulsion droplet compositions and properties. The approach uses a simple platform for screening arrays of droplet-based microfluidic devices and couples this with combinatorial selection of the droplet compositions. Through the application of genetic algorithms over multiple screening rounds, droplets with target properties can be rapidly generated. The potential of this method is demonstrated by creating droplets with enhanced stability, where this is achieved by selecting carrier fluid chemistries that promote titanium dioxide formation at the droplet interfaces. The interface is a mixture of amorphous and crystalline phases, and the resulting composite droplets are biocompatible, supporting in vitro protein expression in their interiors. This general strategy will find widespread application in advancing emulsion properties for use in chemistry, biology, materials, and medicine.

  10. Sensitive and predictable separation of microfluidic droplets by size using in-line passive filter.

    Science.gov (United States)

    Ding, Ruihua; Ung, W Lloyd; Heyman, John A; Weitz, David A

    2017-01-01

    Active manipulation of droplets is crucial in droplet microfluidics. However, droplet polydispersity decreases the accuracy of active manipulation. We develop a microfluidic "droplet filter" that accurately separates droplets by size. The droplet filter has a sharp size cutoff and is capable of distinguishing droplets differing in volume by 20%. A simple model explains the behavior of the droplets as they pass through the filter. We show application of the filter in improving dielectric sorting efficiency.

  11. Intra-articular administration of hyaluronic acid increases the volume of the hyaline cartilage regenerated in a large osteochondral defect by implantation of a double-network gel.

    Science.gov (United States)

    Fukui, Takaaki; Kitamura, Nobuto; Kurokawa, Takayuki; Yokota, Masashi; Kondo, Eiji; Gong, Jian Ping; Yasuda, Kazunori

    2014-04-01

    Implantation of PAMPS/PDMAAm double-network (DN) gel can induce hyaline cartilage regeneration in the osteochondral defect. However, it is a problem that the volume of the regenerated cartilage tissue is gradually reduced at 12 weeks. This study investigated whether intra-articular administration of hyaluronic acid (HA) increases the volume of the cartilage regenerated with the DN gel at 12 weeks. A total of 48 rabbits were used in this study. A cylindrical osteochondral defect created in the bilateral femoral trochlea was treated with DN gel (Group DN) or left without any implantation (Group C). In both Groups, we injected 1.0 mL of HA in the left knee, and 1.0 mL of saline solution in the right knee. Quantitative histological evaluations were performed at 2, 4, and 12 weeks, and PCR analysis was performed at 2 and 4 weeks after surgery. In Group DN, the proteoglycan-rich area was significantly greater in the HA-injected knees than in the saline-injected knees at 12 weeks (P = 0.0247), and expression of type 2 collagen, aggrecan, and Sox9 mRNAs was significantly greater in the HA-injected knees than in the saline-injected knees at 2 weeks (P = 0.0475, P = 0.0257, P = 0.0222, respectively). The intra-articular administration of HA significantly enhanced these gene expression at 2 weeks and significantly increased the volume of the hyaline cartilage regenerated by implantation of a DN gel at 12 weeks. This information is important to develop an additional method to increase the volume of the hyaline cartilage tissue in a potential cartilage regeneration strategy using the DN gel.

  12. Spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect created in the femoral condyle using a novel double-network hydrogel.

    Science.gov (United States)

    Yokota, Masashi; Yasuda, Kazunori; Kitamura, Nobuto; Arakaki, Kazunobu; Onodera, Shin; Kurokawa, Takayuki; Gong, Jian-Ping

    2011-02-22

    Functional repair of articular osteochondral defects remains a major challenge not only in the field of knee surgery but also in tissue regeneration medicine. The purpose is to clarify whether the spontaneous hyaline cartilage regeneration can be induced in a large osteochondral defect created in the femoral condyle by means of implanting a novel double-network (DN) gel at the bottom of the defect. Twenty-five mature rabbits were used in this study. In the bilateral knees of each animal, we created an osteochondral defect having a diameter of 2.4-mm in the medial condyle. Then, in 21 rabbits, we implanted a DN gel plug into a right knee defect so that a vacant space of 1.5-mm depth (in Group I), 2.5-mm depth (in Group II), or 3.5-mm depth (in Group III) was left. In the left knee, we did not apply any treatment to the defect to obtain the control data. All the rabbits were sacrificed at 4 weeks, and the gross and histological evaluations were performed. The remaining 4 rabbits underwent the same treatment as used in Group II, and real-time PCR analysis was performed at 4 weeks. The defect in Group II was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen. The Wayne's gross appearance and histology scores showed that Group II was significantly greater than Group I, III, and Control (p hyaline cartilage regeneration can be induced in vivo in an osteochondral defect created in the femoral condyle by means of implanting the DN gel plug at the bottom of the defect so that an approximately 2-mm deep vacant space was intentionally left in the defect. This fact has prompted us to propose an innovative strategy without cell culture to repair osteochondral lesions in the femoral condyle.

  13. Spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect created in the femoral condyle using a novel double-network hydrogel

    Directory of Open Access Journals (Sweden)

    Onodera Shin

    2011-02-01

    Full Text Available Abstract Background Functional repair of articular osteochondral defects remains a major challenge not only in the field of knee surgery but also in tissue regeneration medicine. The purpose is to clarify whether the spontaneous hyaline cartilage regeneration can be induced in a large osteochondral defect created in the femoral condyle by means of implanting a novel double-network (DN gel at the bottom of the defect. Methods Twenty-five mature rabbits were used in this study. In the bilateral knees of each animal, we created an osteochondral defect having a diameter of 2.4-mm in the medial condyle. Then, in 21 rabbits, we implanted a DN gel plug into a right knee defect so that a vacant space of 1.5-mm depth (in Group I, 2.5-mm depth (in Group II, or 3.5-mm depth (in Group III was left. In the left knee, we did not apply any treatment to the defect to obtain the control data. All the rabbits were sacrificed at 4 weeks, and the gross and histological evaluations were performed. The remaining 4 rabbits underwent the same treatment as used in Group II, and real-time PCR analysis was performed at 4 weeks. Results The defect in Group II was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen. The Wayne's gross appearance and histology scores showed that Group II was significantly greater than Group I, III, and Control (p Conclusions This study demonstrated that spontaneous hyaline cartilage regeneration can be induced in vivo in an osteochondral defect created in the femoral condyle by means of implanting the DN gel plug at the bottom of the defect so that an approximately 2-mm deep vacant space was intentionally left in the defect. This fact has prompted us to propose an innovative strategy without cell culture to repair osteochondral lesions in the femoral condyle.

  14. Response of two-phase droplets to intense electromagnetic radiation

    Science.gov (United States)

    Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

    1993-04-01

    The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.

  15. Dynamic Melting of Freezing Droplets on Ultraslippery Superhydrophobic Surfaces.

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli

    2017-03-08

    Condensed droplet freezing and freezing droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the freezing delay performance of the surface is common, the melting of the freezing droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.

  16. Lattice Boltzmann simulations of droplet formation during microchannel emulsification

    NARCIS (Netherlands)

    Zwan, van der E.A.; Sman, van der R.G.M.; Schroën, C.G.P.H.; Boom, R.M.

    2009-01-01

    In this study, we compared microchannel droplet formation in a microfluidics device with a two phase lattice Boltzmann simulation. The droplet formation was found to be qualitatively described, with a slightly smaller droplet in the simulation. This was due to the finite thickness of the interface i

  17. Dynamics of droplet breakup in a T-junction

    NARCIS (Netherlands)

    Hoang, D.A.; Portela, L.M.; Kleijn, C.R.; Kreutzer, M.T.; Van Steijn, V.

    2013-01-01

    The breakup of droplets due to creeping motion in a confined microchannel geometry is studied using three-dimensional numerical simulations. Analogously to unconfined droplets, there exist two distinct breakup phases: (i) a quasi-steady droplet deformation driven by the externally applied flow; and

  18. An extension of dynamic droplet deformation models to secondary atomization

    NARCIS (Netherlands)

    Bartz, F.O.; Schmehl, R.; Koch, R.; Bauer, H.J.

    2010-01-01

    A detailed model for secondary atomization of liquid droplets by aerodynamic forces is presented. As an empirical extension of dynamic droplet deformation models, it accounts for temporal variations of the relative velocity between droplet and gas phase during the deformation and breakup process and

  19. Current status of droplet evaporation in turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Birouk, Madjid [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB (Canada); Goekalp, Iskender [Laboratoire de Combustion et Systemes Reactifs, Centre National de la Recherche Scientifique, 45071 Orleans Cedex 2 (France)

    2006-07-01

    This article reviews the available literature results concerning the effects of turbulence on the transport (heat and mass transfer) rates from a droplet. The survey emphasizes recent findings related specifically to physical models and correlations for predicting turbulence effects on the vaporization rate of a droplet. In addition, several research challenges on the vaporization of fuel droplets in turbulent flow environments are outlined. (author)

  20. Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

    Directory of Open Access Journals (Sweden)

    C. L. A. Berli

    2007-06-01

    Full Text Available The present work deals with the relationship between colloidal interactions and physical properties of emulsions, in particular rheology and gel transition. Experimental data on protein-stabilized oil-in-water emulsions are considered. In this system, the excess of protein in the aqueous phase yields reversible droplet aggregation by the mechanism of depletion. Thus both phase and flow behaviors can be controlled by changing protein concentration, ionic strength and temperature. Calculations of the potential of interaction between droplets are carried out in the framework of colloid science. Particular emphasis is placed on the role that droplet-droplet interaction plays in defining the morphology of the aggregates, hence the microstructure and finally, the bulk physical properties. This understanding offers new perspectives in the study of complex food systems.

  1. Adjuvants for single droplet application of glyphosate

    DEFF Research Database (Denmark)

    Mathiassen, Solvejg Kopp; Kudsk, Per; Lund, Ivar

    2016-01-01

    Retention and biological activity of droplets of glyphosate deposited onto plant leaves using a Drop on Demand inkjet printer application system, was examined on pot-grown Brassica napus, Solanum nigrum, Chenopodium album, Silene noctiflora and Echinocloa crus-galli plants. Retention was measured...... but the biological activity of glyphosate was not improved....

  2. Droplets for ultrasmall-volume analysis.

    Science.gov (United States)

    Chiu, Daniel T; Lorenz, Robert M; Jeffries, Gavin D M

    2009-07-01

    By using methods that permit the generation and manipulation of ultrasmall-volume droplets, researchers are pushing the boundaries of ultrasensitive chemical analyses. (To listen to a podcast about this feature, please go to the Analytical Chemistry Web site at pubs.acs.org/ancham.).

  3. Superheated Droplet Detector Response for Temperature

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Superheated droplet detector has the following advantages: Used repeatedly, recording the cumulative dose, using both indoors and outdoors, compacting; relatively low cost, direct reading of the bubbles using the naked eye, and working in gamma-neutron mixed-field well

  4. Surface tension of evaporating nanofluid droplets

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ruey-Hung [Univ. of Central Florida, Orlando, FL (United States); Phuoc, Tran X. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Martello, Donald [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2011-05-01

    Measurements of nanofluid surface tension were made using the pendant droplet method. Three different types of nanoparticles were used - laponite, silver and Fe2O3 - with de-ionized water (DW) as the base fluid. The reported results focus on the following categories; (1) because some nanoparticles require surfactants to form stable colloids, the individual effects of the surfactant and the particles were investigated; (2) due to evaporation of the pendant droplet, the particle concentration increases, affecting the apparent surface tension; (3) because of the evaporation process, a hysteresis was found where the evaporating droplet can only achieve lower values of surface tension than that of nanofluids at the same prepared concentrations: and (4) the Stefan equation relating the apparent surface tension and heat of evaporation was found to be inapplicable for nanofluids investigated. Comparisons with findings for sessile droplets are also discussed, pointing to additional effects of nanoparticles other than the non-equilibrium evaporation process.

  5. The Physics of Foams, Droplets and Bubbles

    Science.gov (United States)

    Sarker, Dipak K.

    2013-01-01

    Foams or bubble dispersions are common to milkshakes, bread, champagne froth, shaving mousse, shampoo, crude oil extraction systems, upholstery packing and bubble wrap, whereas the term droplet is often synonymous with either a small drop of water or a drop of oil--a type of coarse dispersion. The latter are seen in butter and milk, household…

  6. CFD Simulations of Vibration Induced Droplet Ejection.

    Science.gov (United States)

    James, Ashley; Smith, Marc K.; Glezer, Ari

    1998-11-01

    Vibration-induced droplet ejection is a process that occurs when a liquid droplet is placed on a vibrating membrane. Above a critical value of the excitation amplitude, Faraday waves form on the surface of the drop. As the amplitude is increased secondary drops are ejected from the wave crests. A Navier-Stokes solver designed to simulate the transient fluid mechanics of the process is presented. The solver is based on a MAC method on a staggered grid. A volume of fluid method is implemented to track the free surface. The volume fraction is advected via a second-order, unsplit method that minimizes numerical diffusion of the interface. Surface tension is incorporated as a continuum surface force. This work is intended to provide a comprehensive description of the fluid dynamics involved in vibration-induced droplet ejection, with the aim of understanding the mechanism behind the ejection process. The evolution of the interface through droplet ejection will be simulated. The dependence of the ejection process on the driving parameters will be evaluated and the resonance characteristics of the drop will be determined. The results of the computations will be compared with experimental results.

  7. Moving droplets: The measurement of contact lines

    NARCIS (Netherlands)

    Poelma, C.; Franken, M.J.Z.; Kim, H.; Westerweel, J.

    2014-01-01

    Contact lines are the locations where a gas, liquid and a solid meet. From everyday experience we know that such contact lines can be mobile, for example in the case of a water droplet sliding over a glass surface. However, the continuum description of the flow towards or away from a contact line im

  8. High-Genus nematic liquid crystal droplets

    Science.gov (United States)

    Jayalakshmi, V.; Ekapop, P.; Fernandez-Nieves, Alberto

    2017-05-01

    We will discuss the defect structures that originate in nematic droplets with two or more handles. In these cases, the topology of the bounding surface requires the presence of defects. Our experiments elucidate where do these defects locate and how many of them populated the ground state of the system.

  9. Adjuvants for single droplet application of glyphosate

    DEFF Research Database (Denmark)

    Mathiassen, Solvejg K.; Kudsk, Per; Lund, Ivar

    2016-01-01

    Retention and biological activity of droplets of glyphosate deposited onto plant leaves using a Drop on Demand inkjet printer application system, was examined on pot-grown Brassica napus, Solanum nigrum, Chenopodium album, Silene noctiflora and Echinocloa crus-galli plants. Retention was measured...... but the biological activity of glyphosate was not improved....

  10. Prediction on Droplet Sauter Mean Diameter in Gas-Liquid Mist Flow Based on Droplet Fractal Theory

    OpenAIRE

    Jian-Yi Liu; Xiao-Hua Tan; Zhou Fan; Xu-Tao You; Zhou Li; Jia-Hui Zhao

    2015-01-01

    We present a fractal model for droplet Sauter mean diameter in gas-liquid mist flow, based on the droplet fractal theory and the balance relationship between total droplet surface energy and total gas turbulent kinetic energy. The present model is expressed as functions of the droplet fractal dimension, gas superficial velocity, liquid superficial velocity, and other fluid characteristics. Agreement between the present model predictions and experimental measurements is obtained. Results verif...

  11. Prediction on Droplet Sauter Mean Diameter in Gas-Liquid Mist Flow Based on Droplet Fractal Theory

    Directory of Open Access Journals (Sweden)

    Jian-Yi Liu

    2015-01-01

    Full Text Available We present a fractal model for droplet Sauter mean diameter in gas-liquid mist flow, based on the droplet fractal theory and the balance relationship between total droplet surface energy and total gas turbulent kinetic energy. The present model is expressed as functions of the droplet fractal dimension, gas superficial velocity, liquid superficial velocity, and other fluid characteristics. Agreement between the present model predictions and experimental measurements is obtained. Results verify the reliability of the present model.

  12. Reflectivity of NaK Droplets

    Science.gov (United States)

    Wiedemann, C.; Oswald, M.; Stabroth, S.; Klinkrad, H.; Vörsmann, P.

    An important contribution to the space debris population near 900 km orbital altitude are the NaK droplets. Sixteen nuclear powered satellites of the type RORSAT launched between 1980 and 1988 activated a reactor core ejection system close to this altitude. The core ejection causes an opening of the primary coolant circuit. The liquid coolant has been released into space during these core ejections, forming droplets up to a diameter of 5.5 cm. These droplets consist of an alloy of two alkali metals, sodium and potassium (NaK). In this paper the monochromatic and the total reflectivity of NaK is calculated using theoretical models. The reflectivity depends on the alloy composition and temperature of a droplet. The alloy composition may change due to evaporation, resulting in an enrichment of sodium especially at the droplet surface. According to the literature, there is only a limited number of available measurement data concerning the optical properties of NaK alloys. Furthermore the published data for pure sodium and potassium are controversial. Thus it is necessary to investigate the optical properties of alkali metals and their alloys. Mainly two types of optical absorption, the intraband and the interband absorption, are considered. The intraband absorption is calculated using the Drude-model which uses electrical properties to derive the optical constants of pure metals or alloys. Drude assumes that the valence electrons can be treated as free electrons. The electrons behave like an ideal gas of uncharged particles. The theory of free electrons is a very simple model for the description of the valence electrons in metals. This assumption is sufficient for alkali metals, because they show a nearly free electron behavior. For the interband absorption the classical Butcher-model is used. Furthermore an absorption anomaly which has been observed in some alkali metals is discussed. Especially for potassium, some measurements revealed an unexpected absorption in the

  13. Hyaline cartilage calcification of the first metatarsophalangeal joint is associated with osteoarthritis but independent of age and BMI.

    Science.gov (United States)

    Hubert, Jan; Hawellek, Thelonius; Hischke, Sandra; Bertrand, Jessica; Krause, Matthias; Püschel, Klaus; Rüther, Wolfgang; Niemeier, Andreas

    2016-11-15

    Hyaline cartilage calcification (CC) is associated with osteoarthritis (OA) in hip and knee joints. The first metatarsophalangeal joint (1(st)MTPJ) is frequently affected by OA, but it is unclear if CC occurs in the 1(st)MTPJ. The aim of the present study was to analyze the prevalence of CC of the 1(st)MTPJ in the general population by high-resolution digital contact radiography (DCR) and to determine its association with histological OA severity, age and body mass index (BMI). 168 metatarsal heads of 84 donors (n = 47 male, n = 37 female; mean age 62.73 years, SD ±18.8, range 20-93) were analyzed by DCR for the presence of CC. Histological OA grade (hOA) by OARSI was analyzed in the central load-bearing zone of the first metatarsal head (1(st) MH). Structural equation modeling (SEM) was performed to analyze the interrelationship between CC, hOA, age and BMI. The prevalence of CC of 1(st)MH was 48.8 % (41/84) (95 %-CI [37.7 %, 60.0 %]), independent of the affected side (p = 0.42), gender (p = 0.41) and BMI (p = 0.51). The mean amount of CC of one MH correlated significantly with that of the contralateral side (rs = 0.4, 95 %-CI [0.26, 0.52], p cartilage area) of the MH correlated significantly with the severity of hOA (rs = 0.51, 95 %-CI [0.32, 0.65], p < 0.001). SEM revealed significant associations between CC and hOA (r = 0.74, p < 0.001) and between hOA and age (β = 0.62, p = 0.001), but not between CC and age (p = 0.15). There was no significant influence of BMI on either CC (p = 0.37) or hOA (p = 0.16). The observation that CC of the 1(st)MH is significantly associated with the severity of OA but independent of age and BMI, suggests an intimate relationship between CC and the pathogenesis of OA, the exact nature of which will have to be explored by future studies.

  14. An interface tracking model for droplet electrocoalescence.

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, Lindsay Crowl

    2013-09-01

    This report describes an Early Career Laboratory Directed Research and Development (LDRD) project to develop an interface tracking model for droplet electrocoalescence. Many fluid-based technologies rely on electrical fields to control the motion of droplets, e.g. microfluidic devices for high-speed droplet sorting, solution separation for chemical detectors, and purification of biodiesel fuel. Precise control over droplets is crucial to these applications. However, electric fields can induce complex and unpredictable fluid dynamics. Recent experiments (Ristenpart et al. 2009) have demonstrated that oppositely charged droplets bounce rather than coalesce in the presence of strong electric fields. A transient aqueous bridge forms between approaching drops prior to pinch-off. This observation applies to many types of fluids, but neither theory nor experiments have been able to offer a satisfactory explanation. Analytic hydrodynamic approximations for interfaces become invalid near coalescence, and therefore detailed numerical simulations are necessary. This is a computationally challenging problem that involves tracking a moving interface and solving complex multi-physics and multi-scale dynamics, which are beyond the capabilities of most state-of-the-art simulations. An interface-tracking model for electro-coalescence can provide a new perspective to a variety of applications in which interfacial physics are coupled with electrodynamics, including electro-osmosis, fabrication of microelectronics, fuel atomization, oil dehydration, nuclear waste reprocessing and solution separation for chemical detectors. We present a conformal decomposition finite element (CDFEM) interface-tracking method for the electrohydrodynamics of two-phase flow to demonstrate electro-coalescence. CDFEM is a sharp interface method that decomposes elements along fluid-fluid boundaries and uses a level set function to represent the interface.

  15. Influence of Liquid Viscosity on Droplet Impingement on Superhydrophobic Surfaces

    CERN Document Server

    Pearson, John T; Webb, Brent W

    2010-01-01

    This fluid dynamics video describes droplet impingement experiments performed on superhydrophobic surfaces. When droplets of pure water are impinged upon superhydrophobic surfaces, a region of thin coherent jets are observed for Weber numbers between 5 and 15. Also, peripheral splashing is observed for Weber numbers above about 200. When the viscosity of the droplet is increased by mixing glycerol with the water, the thin jets are not observed and peripheral splashing is delayed somewhat. In the Weber number range where pure water droplets are observed to splash peripherally, the water/glycerol droplets are observed to have two-pronged jets.

  16. An Oil Droplet That Spontaneously Climbs up Stairs

    Science.gov (United States)

    Sumino, Y.; Magome, N.; Yoshikawa, K.

    It has been reported that an oil droplet on a glass surface moves spontaneously in an oil-water system. This motion of an oil droplet can be understood as the spreading of a reactive droplet, which is induced by the interfacial tension gradient at the glass surface. In this paper, we focus on the spontaneous motion of an oil droplet climbing up stairs. We found that an oil droplet tends to move up the stairs rather than to step down. We describe some of the mechanisms of this unique behavior.

  17. Photophoretic trampoline - Interaction of single airborne absorbing droplets with light

    CERN Document Server

    Esseling, Michael; Alpmann, Christina; Denz, Cornelia

    2012-01-01

    We present the light-induced manipulation of absorbing liquid droplets in air. Ink droplets from a printer cartridge are used to demonstrate that absorbing liquids - just like their solid counterparts - can interact with regions of high light intensity due to the photophoretic force. It is shown that droplets follow a quasi-ballistic trajectory after bouncing off a high intensity light sheet. We estimate the intensities necessary for this rebound of airborne droplets and change the droplet trajectories through a variation of the manipulating light field.

  18. Investigations of Abrupt Movements of Optically Trapped Water Droplets

    Science.gov (United States)

    Murphy, Shawntel; McCann, Lowell I.

    2007-03-01

    We have used a single beam optical trap (optical tweezers) to capture individual water droplets in air. A 3-dimensional viewing system consisting of a two axis microscope allows the trapped droplet to be viewed from the top and the side simultaneously. The position of the droplet is determined with a digital camera at a rate up to 700Hz. We have observed abrupt movements along the beam in two situations: As a pure water droplet evaporates, the movements occur at specific size intervals as the diameter decreases. For non-evaporating saltwater droplets the movements rapidly occur for certain ranges of beam power, and not at all for other ranges of power.

  19. A soft microchannel decreases polydispersity of droplet generation.

    Science.gov (United States)

    Pang, Yan; Kim, Hyoungsoo; Liu, Zhaomiao; Stone, Howard A

    2014-10-21

    We study the effect of softness of the microchannel on the process of droplet generation in two-phase flows in a T-junction microchannel. One side of the microchannel has a flexible thin PDMS layer, which vibrates naturally while droplets are generated; the deformation frequency coincides with the frequency of droplet formation. Furthermore, we compare the polydispersity of water-in-oil droplets formed with a microchannel with one soft wall with those formed in a conventional rigid microchannel. We show that deformation of the soft wall reduces the polydispersity in the droplet size.

  20. Nonaxisymmetric shapes of a magnetically levitated and spinning water droplet.

    Science.gov (United States)

    Hill, R J A; Eaves, L

    2008-12-05

    The shape of a weightless spinning liquid droplet is governed by the balance between the surface tension and centrifugal forces. The axisymmetric shape for slow rotation becomes unstable to a nonaxisymmetric distortion above a critical angular velocity, beyond which the droplet progresses through a series of 2-lobed shapes. Theory predicts the existence of a family of 3- and 4-lobed equilibrium shapes at higher angular velocity. We investigate the formation of a triangular-shaped magnetically levitated water droplet, driven to rotate by the Lorentz force on an ionic current within the droplet. We also study equatorial traveling waves which give the droplet threefold, fourfold, and fivefold symmetry.

  1. Electric-Field-Enhanced Jumping-Droplet Condensation

    Science.gov (United States)

    Miljkovic, Nenad; Preston, Daniel; Enright, Ryan; Limia, Alexander; Wang, Evelyn

    2013-11-01

    When condensed droplets coalesce on a superhydrophobic surface, the resulting droplet can jump due to the conversion of surface energy into kinetic energy. This frequent out-of-plane droplet jumping has the potential to enhance condensation heat and mass transfer. In this work, we demonstrated that these jumping droplets accumulate positive charge that can be used to further increase condensation heat transfer via electric fields. We studied droplet jumping dynamics on silanized nanostructured copper oxide surfaces. By characterizing the droplet trajectories under various applied external electric fields (0 - 50 V/cm), we show that condensation on superhydrophobic surfaces results in a buildup of negative surface charge (OH-) due to dissociated water ion adsorption on the superhydrophobic coating. Consequently, the opposite charge (H3O +) accumulates on the coalesced jumping droplet. Using this knowledge, we demonstrate electric-field-enhanced jumping droplet condensation whereby an external electric field opposes the droplet vapor flow entrainment towards the condensing surface to increase the droplet removal rate and overall surface heat transfer by 100% when compared to state-of-the-art dropwise condensing surfaces. This work not only shows significant condensation heat transfer enhancement through the passive charging of condensed droplets, but promises a low cost approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification.

  2. Hydrodynamics of Leidenfrost droplets in one-component fluids

    KAUST Repository

    Xu, Xinpeng

    2013-04-24

    Using the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)], we numerically investigate the hydrodynamics of Leidenfrost droplets under gravity in two dimensions. Some recent theoretical predictions and experimental observations are confirmed in our simulations. A Leidenfrost droplet larger than a critical size is shown to be unstable and break up into smaller droplets due to the Rayleigh-Taylor instability of the bottom surface of the droplet. Our simulations demonstrate that an evaporating Leidenfrost droplet changes continuously from a puddle to a circular droplet, with the droplet shape controlled by its size in comparison with a few characteristic length scales. The geometry of the vapor layer under the droplet is found to mainly depend on the droplet size and is nearly independent of the substrate temperature, as reported in a recent experimental study [Phys. Rev. Lett. 109, 074301 (2012)]. Finally, our simulations demonstrate that a Leidenfrost droplet smaller than a characteristic size takes off from the hot substrate because the levitating force due to evaporation can no longer be balanced by the weight of the droplet, as observed in a recent experimental study [Phys. Rev. Lett. 109, 034501 (2012)].

  3. Modeling of sea spray droplets in the ocean

    Directory of Open Access Journals (Sweden)

    Zhu Jian-Bin

    2014-01-01

    Full Text Available Droplets are known to play an important role in momentum, heat, and moisture transfer between the ocean and atmosphere. A lot of scholars and experts aim to investigate the effects of droplets on the climate and make precise forecast for hurricane conditions. So the profiles of droplets concentration at different heights above the sea surface are important. For a better study of the momentum and energy transport among the boundary layer, we also need to know the distribution of droplets with different radii. After wave break, with the coupled effects of inertia, gravity, wind updraught, and turbulent mixing, droplets can be transported to certain heights above the sea surface. In the present study, we develop a modified subgrid-scale flow field model coupled with the large eddy simulation to investigate the profiles of spay droplets concentration after wave break. The results in our simulation show that, the distribution of the droplets with the same radii in vertical direction is roughly Gaussian distribution, and the maximum appears at the height nearly above the significant wave height. For different radii, the concentration of droplets with larger radii can be higher than that of the smaller ones at some heights. Since the droplets in our model only include the spay droplets generated by wave break, the data will not be identical with the measurement in the open ocean and laboratory, which include all the kinds of droplets above the ocean.

  4. Vibration-Induced Droplet Atomization --- An Experimental Investigation.

    Science.gov (United States)

    Vukasinovic, Bojan; Smith, Marc K.; Glezer, Ari

    1997-11-01

    The atomization of a liquid droplet placed on a vibrating membrane starts with the development of Faraday free surface waves. As the excitation amplitude increases, the waves grow in amplitude and ultimately begin to eject smaller secondary droplets from the wave crests. The rate of droplet ejection can be large enough to completely drain the primary droplet, an event we call bursting. The evolution of the droplet ejection process depends on a coupled system dynamic between the droplet and the membrane. When droplets are ejected the resonant frequency of the system increases. This changes the acceleration felt by the droplet and, in turn, the rate of droplet ejection. Depending on the excitation frequency and amplitude, various types of bursting or droplet ejection processes may occur. In the present experiments, the high acceleration needed to attain ejection (typically 300g) is achieved by driving a light-weight membrane near its resonant frequency (nominally 1000 Hz). The resonant characteristics and the acceleration during the ejection process for various droplet sizes and excitation amplitudes are investigated using a surface-mounted microfabricated accelerometer and a laboratory computer system.

  5. Non-equilibrium solidification of undercooled droplets during atomization process

    Indian Academy of Sciences (India)

    Prashant Shukla; R K Mandal; S N Ojha

    2001-10-01

    Thermal history of droplets associated with gas atomization of melt has been investigated. A mathematical model, based on classical theory of heterogeneous nucleation and volume separation of nucleants among droplets size distribution, is described to predict undercooling of droplets. Newtonian heat flow condition coupled with velocity dependent heat transfer coefficient is used to obtain cooling rate before and after nucleation of droplets. The results indicate that temperature profile of droplets in the spray during recalescence, segregated and eutectic solidification regimes is dependent on their size and related undercooling. The interface temperature during solidification of undercooled droplets rapidly approaches the liquidus temperature of the alloy with a subsequent decrease in solid–liquid interface velocity. A comparison in cooling rates of atomized powder particles estimated from secondary dendrite arm spacing measurements are observed to be closer to those predicted from the model during segregated solidification regime of large size droplets.

  6. Impact of Droplets on Inclined Flowing Liquid Films

    CERN Document Server

    Che, Zhizhao; Matar, Omar K

    2015-01-01

    The impact of droplets on an inclined falling liquid film is studied experimentally using high-speed imaging. The falling film is created on a flat substrate with controllable thicknesses and flow rates. Droplets with different sizes and speeds are used to study the impact process under various Ohnesorge and Weber numbers, and film Reynolds numbers. A number of phenomena associated with droplet impact are identified and analysed, such as bouncing, partial coalescence, total coalescence, and splashing. The effects of droplet size, speed, as well the film flow rate are studied culminating in the generation of an impact regime map. The analysis of the lubrication force acted on the droplet via the gas layer shows that a higher flow rate in the liquid film produces a larger lubrication force, slows down the drainage process, and increases the probability of droplet bouncing. Our results demonstrate that the flowing film has a profound effect on the droplet impact process and associated phenomena, which are marked...

  7. Evaporation dynamics of water droplets on inclined surfaces

    Science.gov (United States)

    Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

    2016-11-01

    When a water droplet is gently placed on a flat substrate, particularly which is tilted at an inclined angle, usually there are advancing and receding angles inside the droplet formed by inclination under gravitational force. Evaporation dynamics of an nonspherical inclined droplet at inclinations would deviate from that of a spherical droplet. Here we study on evaporation dynamics rates of inclined droplets by measuring mass changes with time and their lifetimes. We find that the lifetime of an evaporating inclined droplets becomes longer as the gravitational influence becomes stronger. The lifetime depends on the pinning-depinning transitions and the depinning onset times, which are changed by the gravitational influence. This The dependence inclination-induced evaporation behavior would be useful important in understanding evaporation dynamics of inclined droplets. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1B01007133).

  8. Sorting and Manipulation of Magnetic Droplets in Continuous Flow

    Science.gov (United States)

    Al-Hetlani, Entesar; Hatt, Oliver J.; Vojtíšek, Martin; Tarn, Mark D.; Iles, Alexander; Pamme, Nicole

    2010-12-01

    We report the rapid on-chip generation and subsequent manipulation of magnetic droplets in continuous flow. Magnetic droplets were formed using aqueous-based ferrofluid as the dispersed phase and fluorocarbon oil as the continuous phase. Droplet manipulation was demonstrated with simple permanent magnets using two microfluidic platforms: (i) flow focusing droplet generation followed by their splitting into daughter droplets containing different amounts of magnetic nanoparticles, and (ii) droplet generation at a T-junction and their downstream deflection across a chamber for sorting based on the applied magnetic field and magnetite loading of the droplet. Both systems show great potential for performing a wide range of high throughput continuous flow processes including sample dilution, cell sorting and screening, and microparticle fabrication.

  9. Stick-jump mode in surface droplet dissolution

    CERN Document Server

    Dietrich, Erik; Zhang, Xuehua; Zandvliet, Harold J W; Lohse, Detlef

    2016-01-01

    The analogy between evaporating surface droplets in air to dissolving long-chain alcohol droplets in water is worked out. We show that next to the three known modi for surface droplet evaporation or dissolution (constant contact angle mode, constant contact radius mode, and stick-slide mode), a fourth mode exists for small droplets on supposedly smooth substrates, namely the stick-jump mode: intermittent contact line pinning causes the droplet to switch between sticking and jumping during the dissolution. We present experimental data and compare them to theory to predict the dissolution time in this stick-jump mode. We also explain why these jumps were easily observed for microscale droplets but not for larger droplets.

  10. Magnetohydrodynamic actuation of droplets for millimetric planar fluidic systems

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, A., E-mail: ali.ahmadi@ubc.ca; McDermid, C. M.; Markley, L. [School of Engineering, University of British Columbia, Kelowna, British Columbia V1V 1V7 (Canada)

    2016-01-04

    In this work, a magnetohydrodynamic method is proposed for the actuation of droplets in small-scale planar fluidic systems, providing an alternative to commonly used methods such as electrowetting-on-dielectric. Elementary droplet-based operations, including transport, merging, and mixing, are demonstrated. The forces acting on millimetric droplets are carefully investigated, with a primary focus on the magnetic actuation force and on the unbalanced capillary forces that arise due to hysteresis. A super-hydrophobic channel is 3D printed to guide the droplets, with thin wires installed as contact electrodes and permanent magnets providing a static magnetic field. It is shown that droplet motion is enhanced by increasing the droplet size and minimizing the electrode contact surface. The effects of channel geometry on threshold voltage and minimum moveable droplet volume are characterized. Finally, the presence of electrolysis is investigated and mitigating strategies are discussed.

  11. Structure formation by nanosilica particles suspended in levitated droplet

    CERN Document Server

    Saha, Abhishek; Kumar, Ranganathan; Basu, Saptarshi

    2010-01-01

    Vaporization of liquid droplets containing particles has been studied extensively for its applications in combustion, thermal coating, ink-jet printing, spray cooling, drug delivery, and surface patterning. Droplets containing solid particles show a preferential solute-migration during drying process. Recently we carried out experiments with vaporizing droplet suspended in an acoustic levitator. In this work, we present detailed study of a laser irradiated droplet containing nanosilica particles. Infrared and High speed imaging of the heating process for different concentrations of nanosilica revealed an interesting solute migration pattern. Further investigation with Particle Image Velocimetry shows presence of strong recirculation within the levitated droplet. It also reveals that with increasing viscosity of the liquid the strength of this recirculation decreases. Due to the droplets rotation about the levitator axis, a centrifugal force also dominated the flow field within the droplet. High speed imaging ...

  12. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  13. Effect of slip on circulation inside a droplet

    CERN Document Server

    Thalakkottor, Joseph J

    2013-01-01

    Internal recirculation in a moving droplet plays an important role in several droplet-based microfluidic devices as it enhances mixing, chemical reaction and heat transfer. The occurrence of fluid slip at the wall, which becomes prominent at high shear rates and lower length scales, results in a significant change in droplet circulation. Using molecular dynamics (MD) simulations, the presence of circulation in droplets is demonstrated and quantified. Circulation is shown to vary inversely with slip length, which is a measure of interface wettability. A simple circulation model is established that captures the effect of slip on droplet circulation. Scaling parameters for circulation and slip length are identified from the circulation model which leads to the collapse of data for droplets with varying aspect ratio (AR) and slip length. The model is validated using continuum and MD simulations and is shown to be accurate for droplets with high AR.

  14. Image-based analysis of droplets in microfluidics.

    Science.gov (United States)

    Zantow, Miné; Dendere, Ronald; Douglas, Tania S

    2013-01-01

    In order to design a microfluidic device that can produce monodispersed encapsulated enzymes as droplets, it is essential to be able to evaluate the system during its development. An automated method to determine the size of the droplets as well as a method to tag and track droplets as they move in the system is desirable for system evaluation. We apply the Hough transform for circles to determine droplet size. Most of the droplets in the images are detected, and the best results are obtained at 20x magnification. We also test the ability of the ImageJ 'particle tracker' plugin to determine the behaviour of the droplets as they move in microfluidic systems. It is effective in tracking droplets that travel less than 50 pixels between frames.

  15. Effective doping of low energy ions into superfluid helium droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie; Chen, Lei; Freund, William M.; Kong, Wei, E-mail: wei.kong@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States)

    2015-08-21

    We report a facile method of doping cations from an electrospray ionization (ESI) source into superfluid helium droplets. By decelerating and stopping the ion pulse of reserpine and substance P from an ESI source in the path of the droplet beam, about 10{sup 4} ion-doped droplets (one ion per droplet) can be recorded, corresponding to a pickup efficiency of nearly 1 out of 1000 ions. We attribute the success of this simple approach to the long residence time of the cations in the droplet beam. The resulting size of the doped droplets, on the order of 10{sup 5}/droplet, is measured using deflection and retardation methods. Our method does not require an ion trap in the doping region, which significantly simplifies the experimental setup and procedure for future spectroscopic and diffraction studies.

  16. Separation of Iron Droplets From Titania Bearing Slag

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-yu; LOU Tai-ping; ZHANG Li; SUI Zhi-tong

    2008-01-01

    Owing to smelting vanadium-titanium magnetite ore, the amount of iron entrainment in slag as droplets is far higher than that in conventional BF slag. However, the iron droplets can be easily settled by blowing air into the molten slag. The results show that more than 80% of iron droplets in titania bearing slag can be settled and separated after treatment. The temperature rise of molten slag during the oxidizing process and the decreased viscosity caused by the component change of slag as well as air stirring in slag both accelerate the iron droplets settling. The vanadium content in the settled iron droplets and the original iron droplets was obtained by chemical analysis. The possible reason for the increased vanadium in the settled iron droplets was discussed by thermodynamic principles.

  17. Programmed Application of Transforming Growth Factor β3 and Rac1 Inhibitor NSC23766 Committed Hyaline Cartilage Differentiation of Adipose-Derived Stem Cells for Osteochondral Defect Repair.

    Science.gov (United States)

    Zhu, Shouan; Chen, Pengfei; Wu, Yan; Xiong, Si; Sun, Heng; Xia, Qingqing; Shi, Libing; Liu, Huanhuan; Ouyang, Hong Wei

    2014-10-01

    Hyaline cartilage differentiation is always the challenge with application of stem cells for joint repair. Transforming growth factors (TGFs) and bone morphogenetic proteins can initiate cartilage differentiation but often lead to hypertrophy and calcification, related to abnormal Rac1 activity. In this study, we developed a strategy of programmed application of TGFβ3 and Rac1 inhibitor NSC23766 to commit the hyaline cartilage differentiation of adipose-derived stem cells (ADSCs) for joint cartilage repair. ADSCs were isolated and cultured in a micromass and pellet culture model to evaluate chondrogenic and hypertrophic differentiation. The function of Rac1 was investigated with constitutively active Rac1 mutant and dominant negative Rac1 mutant. The efficacy of ADSCs with programmed application of TGFβ3 and Rac1 inhibitor for cartilage repair was studied in a rat model of osteochondral defects. The results showed that TGFβ3 promoted ADSCs chondro-lineage differentiation and that NSC23766 prevented ADSC-derived chondrocytes from hypertrophy in vitro. The combination of ADSCs, TGFβ3, and NSC23766 promoted quality osteochondral defect repair in rats with much less chondrocytes hypertrophy and significantly higher International Cartilage Repair Society macroscopic and microscopic scores. The findings have illustrated that programmed application of TGFβ3 and Rac1 inhibitor NSC23766 can commit ADSCs to chondro-lineage differentiation and improve the efficacy of ADSCs for cartilage defect repair. These findings suggest a promising stem cell-based strategy for articular cartilage repair. ©AlphaMed Press.

  18. Assessment of apoptosis and MMP-1, MMP-3 and TIMP-2 expression in tibial hyaline cartilage after viable medial meniscus transplantation in the rabbit.

    Science.gov (United States)

    Zwierzchowski, Tomasz J; Stasikowska-Kanicka, Olga; Danilewicz, Marian; Fabiś, Jarosław

    2012-12-20

    The porpuse of this animal study was to assess chondrocyte apoptosis and MMP-1, MMP-3 and TIMP-2 expression in rabbit tibial cartilage 6 months after viable medial meniscal autografts and allografts. Twenty white male New Zealand rabbits were chosen for the study. The medial meniscus was excised from 14 animals and stored under tissue culture conditions for 2 weeks, following which t of them were implantated as autografts and 7 as allografts. The control group consisted of 6 animals which underwent arthtrotomy. When the animals were eutanized, the tibial cartilage was used for immunohisochemical examination. Apoptosis (TUNEL method) and MMP-1, MMP-3 and TIMP-2 expression were estimated semiquantatively. An increased level of chodrocyte apoptosis in the tibail cartilage was observed after both kinds of transplants (p hyaline cartilage against excessive apoptosis. The results of experimantal studies on humans indicate the need to device a method of apoptosis inhibition in the hyaline cartilage to improve long-term results of meniscal transplantation.

  19. A Case of Hyalinizing Clear Cell Carcinoma, So-Called Clear Cell Carcinoma, Not Otherwise Specified, of the Minor Salivary Glands of the Buccal Mucosa

    Directory of Open Access Journals (Sweden)

    Takahiro Yamanishi

    2015-01-01

    Full Text Available Hyalinizing clear cell carcinoma (HCCC, so-called clear cell carcinoma, not otherwise specified (CCC (NOS, of the salivary glands is a rare and low-grade malignant tumor. We report a case of HCCC so-called CCC (NOS (referred to as HCCC of the minor salivary gland of the buccal mucosa. A 52-year-old woman had presented with a gradually growing and indolent mass in the right buccal mucosa for about two years. The first biopsy histopathologically suggested the possibility of malignancy derived from the minor salivary glands. A month later, she visited our hospital. The tumor measured approximately 1.5 cm in diameter and was elastic hard, smooth, and well movable. Image examinations demonstrated internal homogeneity of the lesion, which had a smooth margin, in the right buccal mucosa. Complete tumor resection followed by covering with a polyglycolic acid sheet and fibrin glue spray was performed without surgical flap reconstruction. Histopathological findings revealed proliferating tumor cells with clear cytoplasm surrounded by hyalinizing stroma in the submucosal minor salivary glands. Immunohistochemical stains revealed these tumor cells to be positive for epithelial cell markers but negative for myoepithelial ones. These findings confirmed the diagnosis of HCCC. Good wound healing and no evidence of local recurrence and metastasis have been shown since surgery.

  20. Hyalinizing cholecystitis and associated carcinomas: clinicopathologic analysis of a distinctive variant of cholecystitis with porcelain-like features and accompanying diagnostically challenging carcinomas.

    Science.gov (United States)

    Patel, Samip; Roa, Juan Carlos; Tapia, Oscar; Dursun, Nevra; Bagci, Pelin; Basturk, Olca; Cakir, Asli; Losada, Hector; Sarmiento, Juan; Adsay, Volkan

    2011-08-01

    We describe a clinicopathologically distinct subtype of cholecystitis, the extensively calcific version of which has been presented in the clinical literature as "porcelain gallbladder (PG)." This cholecystitis, which we propose to refer to as hyalinizing cholecystitis (HC), is characterized by dense, paucicellular hyaline fibrosis transforming the gallbladder (GB) wall into a relatively thin and uniform band. The process diffusely effaces most of the normal structures of GB, and some cases show calcifications. To determine the clinicopathologic associations of HC, we systematically analyzed 4231 cholecystectomies (606 of which had carcinoma) histopathologically, in addition to a targeted search in our databases. Ninety-six cases of HC were identified (1.6% of cholecystectomies). Patients with HC were a decade older than ordinary cholecystitis patients (56 vs. 47; Pcholecystitis, HC with minimal or no calcifications (incomplete PG), is associated with invasive carcinoma. Thus, imaging protocols ought to focus on the correlates of HC rather than fixating on calcifications. Further studies into the pathogenesis of this process and its mechanisms of progression to carcinoma are warranted.

  1. 鼻塞式CPAP治疗新生儿肺透明膜病疗效观察%Efficacy of Hyaline Membrane Disease Nasal CPAP Treatment

    Institute of Scientific and Technical Information of China (English)

    艾力甫

    2015-01-01

    目的:观察鼻塞式CPAP(NCPAP)治疗新生儿肺透明膜病的疗效。方法对20例早期新生儿肺透明膜病进行X线检查,根据血气分析结果调整呼吸机参数。结果20例患儿放弃治疗1例,转上级医院治疗1例,余18例顺利撤除鼻塞式CPAP。结论鼻塞式CPAP治疗早期新生儿肺透出明膜病能明显的提高治疗效果,对早产儿非常适用。%Objective To observe the nasal CPAP (NCPAP)therapy hyaline membrane disease.Methods 20 cases of early neonatal hyaline membrane disease,X-ray inspection,adjustment of ventilator parameters based on the results of blood gas analysis.Results 20 patients gave up treatment one case,turn higher hospital one case,more than 18 cases of successful removal of nasal CPAP.Conclusion Nasal CPAP treatment early neonatal lung disease,revealed a clear film can significantly improve the therapeutic ef ect,very suitable for preterm children.

  2. Global rainbow refractometry for droplet temperature measurement

    Energy Technology Data Exchange (ETDEWEB)

    Pascal Lemaitre; Emmanuel Porcheron; Amandine Nuboer; Philippe Brun; Pierre Cornet; Jeanne Malet; Jacques Vendel; Laurent Bouilloux [Institut de Radioprotection et de Surete Nucleaire DSU/SERAC, BP 68, 91192 Gif-sur-Yvette Cedex (France); Gerard Grehan [UMR 6614 CORIA, Laboratoire d' Electromagnetisme et Systemes Particulaires Site Universitaire du Madrillet, Avenue de l' universite BP 12, 76 801 Saint Etienne du Rouvray Cedex, (France)

    2005-07-01

    Full text of publication follows: In order to establish an accurate database to characterize the heat and mass transfers between a spray and the atmosphere with thermal-hydraulic conditions representative of a hypothetical nuclear reactor accident in the containment enclosure of a pressurized water reactor (PWR), the French Institut de Radioprotection et de Surete Nucleaire (IRSN) has developed the TOSQAN experimental facility. This experiment is highly instrumented with non-intrusive diagnostics allowing to measure droplet size and velocity and gas concentrations [1]. The aim of this work is to present the Global Rainbow Thermometry (GRT), which is an advanced non-intrusive optical diagnostic, developed to measure the mean temperature of a set of falling droplets, in a measurement volume of 1 cm{sup 3}. The final paper will be divided in three parts. In the first one, we will explain the principle of the rainbow formation and how droplet temperature can be deduced from the rainbow analysis [2]. This part will be illustrated with the theoretical background on the rainbow and numerical simulations of the global rainbow. The second part will be devoted to present the global rainbow experimental set-up we have developed on optical table, its experimental qualification and finally its implementation on the TOSQAN facility [3]. Finally, we will present the temperature measurements achieved in TOSQAN for thermal-hydraulic conditions representative of a hypothetical nuclear reactor accident. These measurements are useful to characterize the heat and mass transfers between the spraying droplets and the air-steam mixture composing the atmosphere. This analysis will be exposed in a two companion papers. References: [1] E. Porcheron, P. Brun, P. Cornet, J. Malet, J. Vendel. Optical diagnostics applied for single and multi-phase flow characterization in the TOSQAN facility dedicated for thermal hydraulic containment studies. NURETH-10 Seoul, Korea, October 5-9, 2003. [2] P

  3. Encapsulation of single cells into monodisperse droplets by fluorescence-activated droplet formation on a microfluidic chip.

    Science.gov (United States)

    Hu, Rui; Liu, Pian; Chen, Pu; Wu, Liang; Wang, Yao; Feng, Xiaojun; Liu, Bi-Feng

    2016-06-01

    Random compartmentalization of cells by common droplet formation methods, i.e., T-junction and flow-focusing, results in low occupancy of droplets by single cells. To resolve this issue, a fluorescence-activated droplet formation method was developed for the on-command generation of droplets and encapsulation of single cells. In this method, droplets containing one cell were generated by switching on/off a two-phase hydrodynamic gating valve upon optical detection of single cells. To evaluate the developed method, flow visualization experiments were conducted with fluorescein. Results indicated that picoliter droplets of uniform sizes (RSDdroplets contained one bead. Further application of the developed methods to the compartmentalization of individual HeLa cells indicated 82.5% occupancy of droplets by single cells, representing a 3 fold increase in comparison to random compartmentalization.

  4. Fundamental thermal noise in droplet microresonators

    CERN Document Server

    Giorgini, Antonio; Malara, Pietro; De Natale, Paolo; Gagliardi, Gianluca

    2016-01-01

    Liquid droplet whispering-gallery-mode microresonators open a new research frontier for optomechanics and photonic devices. At visible wavelengths, where most liquids are transparent, a major contribution to a droplet optical quality factor is expected theoretically from thermal surface distortions and capillary waves. Here, we investigate experimentally these predictions using transient cavity ring-down spectroscopy. In this way, the optical out-coupling and intrinsic loss are measured independently while any perturbation induced by thermal, acoustic and laser-frequency noise is avoided thanks to the ultra-short light-cavity interaction time. The measurements reveal a photon lifetime ten times longer than the thermal limit and suggest that capillary fluctuations activate surface scattering effects responsible for light coupling.

  5. Mechanism of supercooled droplet freezing on surfaces

    Science.gov (United States)

    Jung, Stefan; Tiwari, Manish K.; Doan, N. Vuong; Poulikakos, Dimos

    2012-01-01

    Understanding ice formation from supercooled water on surfaces is a problem of fundamental importance and general utility. Superhydrophobic surfaces promise to have remarkable 'icephobicity' and low ice adhesion. Here we show that their icephobicity can be rendered ineffective by simple changes in environmental conditions. Through experiments, nucleation theory and heat transfer physics, we establish that humidity and/or the flow of a surrounding gas can fundamentally switch the ice crystallization mechanism, drastically affecting surface icephobicity. Evaporative cooling of the supercooled liquid can engender ice crystallization by homogeneous nucleation at the droplet-free surface as opposed to the expected heterogeneous nucleation at the substrate. The related interplay between droplet roll-off and rapid crystallization is also studied. Overall, we bring a novel perspective to icing and icephobicity, unveiling the strong influence of environmental conditions in addition to the accepted effects of the surface conditions and hydrophobicity.

  6. Dancing droplets: Chemical space, substrates, and control

    Science.gov (United States)

    Cira, Nate; Benusiglio, Adrien; Prakash, Manu

    2015-11-01

    Previously we showed that droplets of propylene glycol and water display remarkable properties when placed on clean glass due to an interplay between surface tension and evaporation. (Cira, Benusiglio, Prakash: Nature, 2015). We showed that these mechanisms apply to a range of two-component mixtures of miscible liquids where one component has both higher surface tension and higher vapor pressure on a variety of high energy surfaces. We now show how this rule can be cheated using a simple trick. We go on to demonstrate applications for cleaning, and show how this system works on substrates prepared only with sunlight. We finish by demonstrating active control of droplets, allowing access to a host of new possibilities.

  7. Single Molecule Sensitive FRET in Attoliter Droplets

    CERN Document Server

    Milas, Peker; Gamari, Ben D; Goldner, Lori S

    2013-01-01

    Single molecular-pair fluorescence resonance energy transfer (spFRET) has become an cross-disciplinary tool for understanding molecular folding and interactions. While providing detailed information about the individual members of a molecular ensemble, this technique is always limited by fluorophore brightness and stability. In the case of diffusing molecules, the experiment is further limited by the number of photons that can be collected during the time it takes for a molecule to diffuse across the detection volume. To maximize the number of photons it is common to either increase the detection volume at the expense of increased background, or increase the diffusion time by adding glycerol or sucrose to increase viscosity. Here we demonstrate that FRET from attoliter volume (100 nm radius) aqueous droplets in perfluorinated oil has significantly higher signal-to-noise and a much wider dynamic range than FRET from molecules diffusing in solution. However, our measurements also reveal a droplet environment th...

  8. Sessile droplet evaporation on superheated superhydrophobic surfaces

    CERN Document Server

    Hays, Robb C; Maynes, Daniel; Webb, Brent W

    2013-01-01

    This fluid dynamics video depicts the evaporation of sessile water droplets placed on heated superhydrophobic (SH) surfaces of varying cavity fraction, F_c, and surface temperature, T_s, above the saturation temperature, T_sat. Images were captured at 10,000 FPS and are played back at 30 FPS in this video. Teflon-coated silicon surfaces of F_c = 0, 0.5, 0.8, and 0.95 were used for these experiments. T_s ranging from 110{\\deg}C to 210{\\deg}C were studied. The video clips show how the boiling behavior of sessile droplets is altered with changes in surface microstructure. Quantitative results from heat transfer rate experiments conducted by the authors are briefly discussed near the end of the video.

  9. Solute-mediated interactions between active droplets

    Science.gov (United States)

    Moerman, Pepijn G.; Moyses, Henrique W.; van der Wee, Ernest B.; Grier, David G.; van Blaaderen, Alfons; Kegel, Willem K.; Groenewold, Jan; Brujic, Jasna

    2017-09-01

    Concentration gradients play a critical role in embryogenesis, bacterial locomotion, as well as the motility of active particles. Particles develop concentration profiles around them by dissolution, adsorption, or the reactivity of surface species. These gradients change the surface energy of the particles, driving both their self-propulsion and governing their interactions. Here, we uncover a regime in which solute gradients mediate interactions between slowly dissolving droplets without causing autophoresis. This decoupling allows us to directly measure the steady-state, repulsive force, which scales with interparticle distance as F ˜1 /r2 . Our results show that the dissolution process is diffusion rather than reaction rate limited, and the theoretical model captures the dependence of the interactions on droplet size and solute concentration, using a single fit parameter, l =16 ±3 nm , which corresponds to the length scale of a swollen micelle. Our results shed light on the out-of-equilibrium behavior of particles with surface reactivity.

  10. Engineering particle morphology with microfluidic droplets

    Science.gov (United States)

    Kang, Zhanxiao; Kong, Tiantian; Lei, Leyan; Zhu, Pingan; Tian, Xiaowei; Wang, Liqiu

    2016-07-01

    The controlled generation of microparticles with non-spherical features is of increasing importance. Such particles are useful for fundamental studies in areas such as self-assembly, as well as biomedical applications from drug carriers to photonic devices. We propose a simple model that captures the dominating factors controlling the size and morphology of non-spherical particles from phase separated droplets. The validity of our model is verified by comparing the generated non-spherical microparticles by droplet microfluidics. This simple relationship between the dominating factors and the final morphologies enables the production of non-spherical particles with well-defined shapes and tightly-controlled dimensions for a variety of applications from drug delivery vehicles to structural materials.

  11. Lipid Structure in Triolein Lipid Droplets

    DEFF Research Database (Denmark)

    Chaban, Vitaly V; Khandelia, Himanshu

    2014-01-01

    Lipid droplets (LDs) are primary repositories of esterified fatty acids and sterols in animal cells. These organelles originate on the lumenal or cytoplasmic side of endoplasmic reticulum (ER) membrane and are released to the cytosol. In contrast to other intracellular organelles, LDs are composed...... of a mass of hydrophobic lipid esters coved by phospholipid monolayer. The small size and unique architecture of LDs makes it complicated to study LD structure by modern experimental methods. We discuss coarse-grained molecular dynamics (MD) simulations of LD formation in systems containing 1-palmitoyl-2...... to coarse-grained simulations, the presence of PE lipids at the interface has a little impact on distribution of components and on the overall LD structure. (4) The thickness of the lipid monolayer at the surface of the droplet is similar to the thickness of one leaflet of a bilayer. Computer simulations...

  12. Droplet Impact Dynamics on Micropillared Hydrophobic Surfaces

    CERN Document Server

    Patil, Nagesh D; Sharma, Atul

    2016-01-01

    The effect of pitch of the pillars and impact velocity are studied for the impact dynamics of a microliter water droplet on a micropillared hydrophobic surface. The results are presented qualitatively by the high-speed photography and quantitatively by the temporal variation of wetted diameter and droplet height. A characterization of the transient quantitative results is a novel aspect of our work. Three distinct regimes, namely, non-bouncing, complete bouncing and partial bouncing are presented. A critical pitch as well as impact velocity exists for the transition from one regime to another. This is explained with a demonstration of Cassie to Wenzel wetting transition in which the liquid penetrates in the grooves between the pillars at larger pitch or impact velocity. The regimes are demarcated on a map of pitch and impact velocity. A good agreement is reported between the present measurements and published analytical models.

  13. Ballistic model to estimate microsprinkler droplet distribution

    Directory of Open Access Journals (Sweden)

    Conceição Marco Antônio Fonseca

    2003-01-01

    Full Text Available Experimental determination of microsprinkler droplets is difficult and time-consuming. This determination, however, could be achieved using ballistic models. The present study aimed to compare simulated and measured values of microsprinkler droplet diameters. Experimental measurements were made using the flour method, and simulations using a ballistic model adopted by the SIRIAS computational software. Drop diameters quantified in the experiment varied between 0.30 mm and 1.30 mm, while the simulated between 0.28 mm and 1.06 mm. The greatest differences between simulated and measured values were registered at the highest radial distance from the emitter. The model presented a performance classified as excellent for simulating microsprinkler drop distribution.

  14. Droplets and modes of respiratory disease transmission

    Science.gov (United States)

    Bourouiba, Lydia

    2014-11-01

    Direct observation of violent expirations such as sneezes and coughs events reveal that such flows are multiphase turbulent buoyant clouds with suspended droplets of various sizes. The effects of ambient conditions indoors, such as moisture and temperature, coupled with the water content of such clouds are key in shaping the pathogen footprint emitted by potentially sick individuals. Such pathogen footprint can change the patterns of respiratory disease transmission. We discuss how the fluid dynamics of violent expirations can help inform how.

  15. Spreading of charged micro-droplets

    Directory of Open Access Journals (Sweden)

    Joseph Iaia

    2013-09-01

    Full Text Available We consider the spreading of a charged microdroplet on a flat dielectric surface whose spreading is driven by surface tension and electrostatic repulsion. This leads to a third order nonlinear partial differential equation that gives the evolution of the height profile. Assuming the droplets are circular we are able to prove existence of solutions with infinite contact angle and in many cases we are able to prove nonexistence of solutions with finite contact angle.

  16. Computational Fluid Dynamics of rising droplets

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Matthew [Lake Superior State University; Francois, Marianne M. [Los Alamos National Laboratory

    2012-09-05

    The main goal of this study is to perform simulations of droplet dynamics using Truchas, a LANL-developed computational fluid dynamics (CFD) software, and compare them to a computational study of Hysing et al.[IJNMF, 2009, 60:1259]. Understanding droplet dynamics is of fundamental importance in liquid-liquid extraction, a process used in the nuclear fuel cycle to separate various components. Simulations of a single droplet rising by buoyancy are conducted in two-dimensions. Multiple parametric studies are carried out to ensure the problem set-up is optimized. An Interface Smoothing Length (ISL) study and mesh resolution study are performed to verify convergence of the calculations. ISL is a parameter for the interface curvature calculation. Further, wall effects are investigated and checked against existing correlations. The ISL study found that the optimal ISL value is 2.5{Delta}x, with {Delta}x being the mesh cell spacing. The mesh resolution study found that the optimal mesh resolution is d/h=40, for d=drop diameter and h={Delta}x. In order for wall effects on terminal velocity to be insignificant, a conservative wall width of 9d or a nonconservative wall width of 7d can be used. The percentage difference between Hysing et al.[IJNMF, 2009, 60:1259] and Truchas for the velocity profiles vary from 7.9% to 9.9%. The computed droplet velocity and interface profiles are found in agreement with the study. The CFD calculations are performed on multiple cores, using LANL's Institutional High Performance Computing.

  17. Detachment force of particles from fluid droplets.

    Science.gov (United States)

    Ettelaie, Rammile; Lishchuk, Sergey V

    2015-06-07

    We calculate the deformation of a spherical droplet, resulting from the application of a pair of opposite forces to particles located diametrically opposite at the two ends of the droplet. The free-energy analysis is used to calculate the force-distance curves for the generated restoring forces, arising from the displacement of the particles relative to each other. While the logarithmic dependence of the "de Gennes-Hooke" constant on the particle to droplet size ratio, ν, is rather well known in the limit of very small ν, we find that for more realistic particle to droplet size ratios, i.e. ν = 0.001 to 0.01, the additional constant terms of O(1) constitute a significant correction to previously reported results. We derive the restoring force constant to be 2πγ[0.5 - ln (ν/2)](-1), in perfect agreement with the exact semi-numerical analysis of the same problem. The deviation from the linear force-displacement behaviour, occurring close to the point of detachment, is also investigated. A study of the energy dissipated shows it to be an increasingly dominant component of the work done during the detachment of the particles, as ν decreases. This indicates the existence of a significantly higher energy barrier to desorption of very small particles, compared to the one suggested by their adsorption energy alone. The influence of the line tension on the detachment force is also considered. It is shown that where line tension is important, the contact angle is no longer a constant but instead alters with the displacement of the particles from their equilibrium positions.

  18. Splashing onset in dense suspension droplets

    OpenAIRE

    Peters, Ivo; Xu, Qin; Jaeger, Heinrich M.

    2013-01-01

    We investigate the impact of droplets of dense suspensions onto a solid substrate. We show that a global hydrodynamic balance is unable to predict the splash onset and propose to replace it by an energy balance at the level of the particles in the suspension. We experimentally verify that the resulting, particle-based Weber number gives a reliable, particle size and density dependent splash onset criterion. We further show that the same argument also explains why, in bimodal systems, smaller ...

  19. Droplet Microfluidic System with On-Demand Trapping and Releasing of Droplet for Drug Screening Applications.

    Science.gov (United States)

    Courtney, Matthew; Chen, Xiaoming; Chan, Sarah; Mohamed, Tarek; Rao, Praveen P N; Ren, Carolyn L

    2017-01-03

    96-Well plate has been the traditional method used for screening drug compounds libraries for potential bioactivity. Although this method has been proven successful in testing dose-response analysis, the microliter consumption of expensive reagents and hours of reaction and analysis time call for innovative methods for improvements. This work demonstrates a droplet microfluidic platform that has the potential to significantly reduce the reagent consumption and shorten the reaction and analysis time by utilizing nanoliter-sized droplets as a replacement of wells. This platform is evaluated by applying it to screen drug compounds that inhibit the tau-peptide aggregation, a phenomena related to Alzheimer's disease. In this platform, sample reagents are first dispersed into nanolitre-sized droplets by an immiscible carrier oil and then these droplets are trapped on-demand in the downstream of the microfluidic device. The relative decrease in fluorescence through drug inhibition is characterized using an inverted epifluorescence microscope. Finally, the trapped droplets are released on-demand after each test by manipulating the applied pressures to the channel network which allows continuous processing. The testing results agree well with that obtained from 96-well plates with much lower sample consumption (∼200 times lower than 96-well plate) and reduced reaction time due to increased surface volume ratio (2.5 min vs 2 h).

  20. Development of an imaging system for single droplet characterization using a droplet generator.

    Science.gov (United States)

    Minov, S Vulgarakis; Cointault, F; Vangeyte, J; Pieters, J G; Hijazi, B; Nuyttens, D

    2012-01-01

    The spray droplets generated by agricultural nozzles play an important role in the application accuracy and efficiency of plant protection products. The limitations of the non-imaging techniques and the recent improvements in digital image acquisition and processing increased the interest in using high speed imaging techniques in pesticide spray characterisation. The goal of this study was to develop an imaging technique to evaluate the characteristics of a single spray droplet using a piezoelectric single droplet generator and a high speed imaging technique. Tests were done with different camera settings, lenses, diffusers and light sources. The experiments have shown the necessity for having a good image acquisition and processing system. Image analysis results contributed in selecting the optimal set-up for measuring droplet size and velocity which consisted of a high speed camera with a 6 micros exposure time, a microscope lens at a working distance of 43 cm resulting in a field of view of 1.0 cm x 0.8 cm and a Xenon light source without diffuser used as a backlight. For measuring macro-spray characteristics as the droplet trajectory, the spray angle and the spray shape, a Macro Video Zoom lens at a working distance of 14.3 cm with a bigger field of view of 7.5 cm x 9.5 cm in combination with a halogen spotlight with a diffuser and the high speed camera can be used.

  1. Adaptive Liquid Lens Actuated by Droplet Movement

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2014-08-01

    Full Text Available In this paper we report an adaptive liquid lens actuated by droplet movement. Four rectangular PMMA (Polymethyl Methacrylate substrates are stacked to form the device structure. Two ITO (Indium Tin Oxide sheets stick on the bottom substrate. One PMMA sheet with a light hole is inserted in the middle of the device. A conductive droplet is placed on the substrate and touches the PMMA sheet to form a small closed reservoir. The reservoir is filled with another immiscible non-conductive liquid. The non-conductive liquid can form a smooth concave interface with the light hole. When the device is applied with voltage, the droplet stretches towards the reservoir. The volume of the reservoir reduces, changing the curvature of the interface. The device can thus achieve the function of an adaptive lens. Our experiments show that the focal length can be varied from −10 to −159 mm as the applied voltage changes from 0 to 65 V. The response time of the liquid lens is ~75 ms. The proposed device has potential applications in many fields such as information displays, imaging systems, and laser scanning systems.

  2. Dynamics of nanoscale droplets on moving surfaces.

    Science.gov (United States)

    Ritos, Konstantinos; Dongari, Nishanth; Borg, Matthew K; Zhang, Yonghao; Reese, Jason M

    2013-06-11

    We use molecular dynamics (MD) simulations to investigate the dynamic wetting of nanoscale water droplets on moving surfaces. The density and hydrogen bonding profiles along the direction normal to the surface are reported, and the width of the water depletion layer is evaluated first for droplets on three different static surfaces: silicon, graphite, and a fictitious superhydrophobic surface. The advancing and receding contact angles, and contact angle hysteresis, are then measured as a function of capillary number on smooth moving silicon and graphite surfaces. Our results for the silicon surface show that molecular displacements at the contact line are influenced greatly by interactions with the solid surface and partly by viscous dissipation effects induced through the movement of the surface. For the graphite surface, however, both the advancing and receding contact angles values are close to the static contact angle value and are independent of the capillary number; i.e., viscous dissipation effects are negligible. This finding is in contrast with the wetting dynamics of macroscale water droplets, which show significant dependence on the capillary number.

  3. A frictional sliding algorithm for liquid droplets

    Science.gov (United States)

    Sauer, Roger A.

    2016-12-01

    This work presents a new frictional sliding algorithm for liquid menisci in contact with solid substrates. In contrast to solid-solid contact, the liquid-solid contact behavior is governed by the contact line, where a contact angle forms and undergoes hysteresis. The new algorithm admits arbitrary meniscus shapes and arbitrary substrate roughness, heterogeneity and compliance. It is discussed and analyzed in the context of droplet contact, but it also applies to liquid films and solids with surface tension. The droplet is modeled as a stabilized membrane enclosing an incompressible medium. The contact formulation is considered rate-independent such that hydrostatic conditions apply. Three distinct contact algorithms are needed to describe the cases of frictionless surface contact, frictionless line contact and frictional line contact. For the latter, a predictor-corrector algorithm is proposed in order to enforce the contact conditions at the contact line and thus distinguish between the cases of advancing, pinning and receding. The algorithms are discretized within a monolithic finite element formulation. Several numerical examples are presented to illustrate the numerical and physical behavior of sliding droplets.

  4. Water droplet evaporation from sticky superhydrophobic surfaces

    Science.gov (United States)

    Lee, Moonchan; Kim, Wuseok; Lee, Sanghee; Baek, Seunghyeon; Yong, Kijung; Jeon, Sangmin

    2017-07-01

    The evaporation dynamics of water from sticky superhydrophobic surfaces was investigated using a quartz crystal microresonator and an optical microscope. Anodic aluminum oxide (AAO) layers with different pore sizes were directly fabricated onto quartz crystal substrates and hydrophobized via chemical modification. The resulting AAO layers exhibited hydrophobic or superhydrophobic characteristics with strong adhesion to water due to the presence of sealed air pockets inside the nanopores. After placing a water droplet on the AAO membranes, variations in the resonance frequency and Q-factor were measured throughout the evaporation process, which were related to changes in mass and viscous damping, respectively. It was found that droplet evaporation from a sticky superhydrophobic surface followed a constant contact radius (CCR) mode in the early stage of evaporation and a combination of CCR and constant contact angle modes without a Cassie-Wenzel transition in the final stage. Furthermore, AAO membranes with larger pore sizes exhibited longer evaporation times, which were attributed to evaporative cooling at the droplet interface.

  5. Characteristics of droplet motion in effervescent sprays

    Directory of Open Access Journals (Sweden)

    Jedelský Jan

    2014-03-01

    Full Text Available Time resolved droplet size and velocity measurement was made using Phase-Doppler anemometry in an effervescent spray at GLR of 6 % and operation pressure drops 21 – 52 kPa. The spray shows a size dependent variation of mean as well as fluctuating axial and radial velocities of droplets similarly for all operation regimes. Particles under 13 μm follow the gas flow, axially decelerated due to gas expansion. Velocity of medium sized particles is positively size correlated and larger particles keep high velocity, given them during discharge. Fluctuating radial velocity of small particles is larger than that of large particles while fluctuating axial velocity increases with size. Small particles thus reach a ratio of radial to axial velocity fluctuations ~ 0.6 but large particles only ~ 0.1, which indicates large transverse dispersion of small particles. Overall fluctuating velocity ratios smaller than 0.5 document an anisotropic character of the liquid mass fluctuations. Power spectral density (PSD of axial velocity fluctuations of large droplets is uniform up to 1 kHz, while PSD of smaller particles drops down with frequency for frequencies > 100 Hz. Large particles thus preserve the fluctuations imposed during discharge while the gas turbulence drops with frequency. Turbulence intensity reaches 14 to 21 % depending on pressure. Such high-turbulence character of the flow probably results from a heterogeneous gas–liquid mixture at the discharge.

  6. Decreasing luminescence lifetime of evaporating phosphorescent droplets

    Science.gov (United States)

    van der Voort, D. D.; Dam, N. J.; Sweep, A. M.; Kunnen, R. P. J.; van Heijst, G. J. F.; Clercx, H. J. H.; van de Water, W.

    2016-12-01

    Laser-induced phosphorescence has been used extensively to study spray dynamics. It is important to understand the influence of droplet evaporation in the interpretation of such measurements, as it increases luminescence quenching. By suspending a single evaporating n-heptane droplet in an acoustic levitator, the properties of lanthanide-complex europium-thenoyltrifluoroacetone-trioctylphosphine oxide (Eu-TTA-TOPO) phosphorescence are determined through high-speed imaging. A decrease was found in the measured phosphorescence decay coefficient (780 → 200 μs) with decreasing droplet volumes (10-9 → 10-11 m3) corresponding to increasing concentrations (10-4 → 10-2 M). This decrease continues up to the point of shell-formation at supersaturated concentrations. The diminished luminescence is shown not to be attributable to triplet-triplet annihilation, quenching between excited triplet-state molecules. Instead, the pure exponential decays found in the measurements show that a non-phosphorescent quencher, such as free TTA/TOPO, can be attributable to this decay. The concentration dependence of the phosphorescence lifetime can therefore be used as a diagnostic of evaporation in sprays.

  7. Lattice Boltzmann Simulations of Evaporating Droplets with Nanoparticles

    Science.gov (United States)

    Zhao, Mingfei; Yong, Xin

    2016-11-01

    Elucidating the nanoparticle dynamics in drying droplets provides fundamental hydrodynamic insight into the evaporation-induced self-assembly, which is of great importance to materials printing and thin film processing. We develop a free-energy-based multiphase lattice Boltzmann model coupled with Lagrangian particle tracking to simulate evaporating particle-laden droplets on a solid substrate with specified wetting behavior. This work focuses on the interplay between the evaporation-driven advection and the self-organization of nanoparticles inside the droplet and at the droplet surface. For static droplets, the different parameters, fluid-particle interaction strength and particle number, governing the nanoparticle-droplet dynamics are systematically investigated, such as particle radial and circumferential distribution. We clarify the effect of nanoparticle presence on the droplet surface tension and wetting behavior. For evaporating droplets, we observe how droplet evaporation modulates the self-assembly of nanoparticles when the droplet has different static contact angles and hysteresis windows. We also confirm that the number of nanoparticles at the liquid-vapor interface influences the evaporation flux at the liquid-vapor interface.

  8. Droplet ejection and sliding on a flapping film

    Science.gov (United States)

    Chen, Xi; Doughramaji, Nicole; Betz, Amy Rachel; Derby, Melanie M.

    2017-03-01

    Water recovery and subsequent reuse are required for human consumption as well as industrial, and agriculture applications. Moist air streams, such as cooling tower plumes and fog, represent opportunities for water harvesting. In this work, we investigate a flapping mechanism to increase droplet shedding on thin, hydrophobic films for two vibrational cases (e.g., ± 9 mm and 11 Hz; ± 2 mm and 100 Hz). Two main mechanisms removed water droplets from the flapping film: vibrational-induced coalescence/sliding and droplet ejection from the surface. Vibrations mobilized droplets on the flapping film, increasing the probability of coalescence with neighboring droplets leading to faster droplet growth. Droplet departure sizes of 1-2 mm were observed for flapping films, compared to 3-4 mm on stationary films, which solely relied on gravity for droplet removal. Additionally, flapping films exhibited lower percentage area coverage by water after a few seconds. The second removal mechanism, droplet ejection was analyzed with respect to surface wave formation and inertia. Smaller droplets (e.g., 1-mm diameter) were ejected at a higher frequency which is associated with a higher acceleration. Kinetic energy of the water was the largest contributor to energy required to flap the film, and low energy inputs (i.e., 3.3 W/m2) were possible. Additionally, self-flapping films could enable novel water collection and condensation with minimal energy input.

  9. In vitro characterization of perfluorocarbon droplets for focused ultrasound therapy

    Science.gov (United States)

    Schad, Kelly C.; Hynynen, Kullervo

    2010-09-01

    Focused ultrasound therapy can be enhanced with microbubbles by thermal and cavitation effects. However, localization of treatment is difficult as bioeffects can occur outside of the target region. Spatial control of bubbles can be achieved by ultrasound-induced conversion of liquid perfluorocarbon droplets to gas bubbles. This study was undertaken to determine the acoustic parameters for bubble production by droplet conversion and how it depends on the acoustic conditions and droplet physical parameters. Lipid-encapsulated droplets containing dodecafluoropentane were manufactured with sizes ranging from 1.9 to 7.2 µm in diameter and diluted to a concentration of 8 × 106 droplets mL-1. The droplets were sonicated in vitro with a focused ultrasound transducer and varying frequency and exposure under flow conditions through an acoustically transparent vessel. The sonications were 10 ms in duration at frequencies of 0.578, 1.736 and 2.855 MHz. The pressure threshold for droplet conversion was measured with an active transducer operating in pulse-echo mode and simultaneous measurements of broadband acoustic emissions were performed with passive acoustic detection. The results show that droplets cannot be converted at low frequency without broadband emissions occurring. However, the pressure threshold for droplet conversion decreased with increasing frequency, exposure and droplet size. The pressure threshold for broadband emissions was independent of the droplet size and was 2.9, 4.4 and 5.3 MPa for 0.578, 1736 and 2.855 MHz, respectively. In summary, we have demonstrated that droplet conversion is feasible for clinically relevant sized droplets and acoustic exposures.

  10. Inertial migration of deformable droplets in a microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaodong; Xue, Chundong; Hu, Guoqing, E-mail: guoqing.hu@imech.ac.cn, E-mail: sunjs@nanoctr.cn [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Li [Research and Development Center, Synfuels China Technology Co., Ltd., Beijing 101407 (China); Jiang, Xingyu; Sun, Jiashu, E-mail: guoqing.hu@imech.ac.cn, E-mail: sunjs@nanoctr.cn [Beijing Engineering Research Center for BioNanotechnology and Key Lab for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190 (China)

    2014-11-15

    The microfluidic inertial effect is an effective way of focusing and sorting droplets suspended in a carrier fluid in microchannels. To understand the flow dynamics of microscale droplet migration, we conduct numerical simulations on the droplet motion and deformation in a straight microchannel. The results are compared with preliminary experiments and theoretical analysis. In contrast to most existing literature, the present simulations are three-dimensional and full length in the streamwise direction and consider the confinement effects for a rectangular cross section. To thoroughly examine the effect of the velocity distribution, the release positions of single droplets are varied in a quarter of the channel cross section based on the geometrical symmetries. The migration dynamics and equilibrium positions of the droplets are obtained for different fluid velocities and droplet sizes. Droplets with diameters larger than half of the channel height migrate to the centerline in the height direction and two equilibrium positions are observed between the centerline and the wall in the width direction. In addition to the well-known Segré-Silberberg equilibrium positions, new equilibrium positions closer to the centerline are observed. This finding is validated by preliminary experiments that are designed to introduce droplets at different initial lateral positions. Small droplets also migrate to two equilibrium positions in the quarter of the channel cross section, but the coordinates in the width direction are between the centerline and the wall. The equilibrium positions move toward the centerlines with increasing Reynolds number due to increasing deformations of the droplets. The distributions of the lift forces, angular velocities, and the deformation parameters of droplets along the two confinement direction are investigated in detail. Comparisons are made with theoretical predictions to determine the fundamentals of droplet migration in microchannels. In

  11. In vitro characterization of perfluorocarbon droplets for focused ultrasound therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schad, Kelly C; Hynynen, Kullervo, E-mail: khynynen@sri.utoronto.c [Imaging Research, Sunnybrook Health Sciences Centre, 2075 Bayview Ave, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto (Canada)

    2010-09-07

    Focused ultrasound therapy can be enhanced with microbubbles by thermal and cavitation effects. However, localization of treatment is difficult as bioeffects can occur outside of the target region. Spatial control of bubbles can be achieved by ultrasound-induced conversion of liquid perfluorocarbon droplets to gas bubbles. This study was undertaken to determine the acoustic parameters for bubble production by droplet conversion and how it depends on the acoustic conditions and droplet physical parameters. Lipid-encapsulated droplets containing dodecafluoropentane were manufactured with sizes ranging from 1.9 to 7.2 {mu}m in diameter and diluted to a concentration of 8 x 10{sup 6} droplets mL{sup -1}. The droplets were sonicated in vitro with a focused ultrasound transducer and varying frequency and exposure under flow conditions through an acoustically transparent vessel. The sonications were 10 ms in duration at frequencies of 0.578, 1.736 and 2.855 MHz. The pressure threshold for droplet conversion was measured with an active transducer operating in pulse-echo mode and simultaneous measurements of broadband acoustic emissions were performed with passive acoustic detection. The results show that droplets cannot be converted at low frequency without broadband emissions occurring. However, the pressure threshold for droplet conversion decreased with increasing frequency, exposure and droplet size. The pressure threshold for broadband emissions was independent of the droplet size and was 2.9, 4.4 and 5.3 MPa for 0.578, 1736 and 2.855 MHz, respectively. In summary, we have demonstrated that droplet conversion is feasible for clinically relevant sized droplets and acoustic exposures.

  12. Evaporation of Droplets on Superhydrophobic Surfaces: Surface Roughness and Small Droplet Size Effects

    Science.gov (United States)

    Chen, Xuemei; Ma, Ruiyuan; Li, Jintao; Hao, Chonglei; Guo, Wei; Luk, B. L.; Li, Shuai Cheng; Yao, Shuhuai; Wang, Zuankai

    2012-09-01

    Evaporation of a sessile droplet is a complex, nonequilibrium phenomenon. Although evaporating droplets upon superhydrophobic surfaces have been known to exhibit distinctive evaporation modes such as a constant contact line (CCL), a constant contact angle (CCA), or both, our fundamental understanding of the effects of surface roughness on the wetting transition remains elusive. We show that the onset time for the CCL-CCA transition and the critical base size at the Cassie-Wenzel transition exhibit remarkable dependence on the surface roughness. Through global interfacial energy analysis we reveal that, when the size of the evaporating droplet becomes comparable to the surface roughness, the line tension at the triple line becomes important in the prediction of the critical base size. Last, we show that both the CCL evaporation mode and the Cassie-Wenzel transition can be effectively inhibited by engineering a surface with hierarchical roughness.

  13. 新生儿肺透明膜病的多层螺旋CT诊断%The MSCT Diagnosis of Neonatal Hyaline Membrane Disease

    Institute of Scientific and Technical Information of China (English)

    韦学; 谭俊扬; 胡琪琳; 廖保荣

    2011-01-01

    Objective To explore the Spiral CT signs of neonatal hyaline membrane disease .Analysis its Pathogenesis and clinical manifestation through literature review in order to improve the understanding of the disease. Methods Analyze our hospital 18 cases of neonatal hyaline membrane disease from May 2008 to March 2011 especially focus on the multislice CT imaging features. Results Grinding glass phenomenon of double lung among all cases, including air-filled bronchi imaging levy in 12 cases, white lung change 1 case, pneumothorax 4 cases, pneumomediastinum 2 cases, among them, including Neck soft tissue emphysema 2 cases, pulmonary hemorrhage 1 case. Conclusion The MDCT performance of neonatal hyaline membrane disease has certain characteristic, and can supply the evidence for imaging diagnosis this lesion.%目的 探讨新生儿肺透明膜病的螺旋CT征象特点,分析其发病机制及临床表现,通过复习文献,提高对该病的认识.方法 分析我院自2008年5月至2011年3月具有完整资料的肺透明膜病18例,着重分析多层螺旋CT对其肺部的病灶显示能力及影像学特征.结果 本组病例中全部出现双肺透亮度降低的磨玻璃样影及小颗粒样影,其中合并出现支气管充气造影征12例,白肺改变1例,气胸4例,纵隔气肿2例,其中1例合并颈部软组织内气肿.合并肺出血1例.结论 新生儿肺透明膜病多层螺旋CT表现有一定的特征性,可为临床提供重要的影像学依据.

  14. Hands-off preparation of monodisperse emulsion droplets using a poly(dimethylsiloxane) microfluidic chip for droplet digital PCR.

    Science.gov (United States)

    Tanaka, Hironari; Yamamoto, Shunsuke; Nakamura, Arichika; Nakashoji, Yuta; Okura, Naoaki; Nakamoto, Norimitsu; Tsukagoshi, Kazuhiko; Hashimoto, Masahiko

    2015-04-21

    A fully autonomous method of creating highly monodispersed emulsion droplets with a low sample dead volume was realized using a degassed poly(dimethylsiloxane) (PDMS) microfluidic chip possessing a simple T-junction channel geometry with two inlet reservoirs for oil and water to be loaded and one outlet reservoir for the collection of generated droplets. Autonomous transport of oil and water phases in the channel was executed by permeation of air confined inside the outlet reservoir into the degassed PDMS. The only operation required for droplet creation was simple pipetting of oil and aqueous solutions into the inlet reservoirs. Long-lasting fluid transport in the current system enabled us to create ca. 51,000 monodispersed droplets (with a coefficient of variation of droplet diameter) in 80 min with a maximum droplet generation rate of ca. 12 Hz using a PDMS chip that had been degassed overnight. With multiple time-course measurements, the reproducibility in the current method of droplet preparation was confirmed, with tunable droplet sizes achieved simply by changing the cross-sectional dimensions of the microchannel. Furthermore, it was verified that the resultant droplets could serve as microreactors for digital polymerase chain reactions. This hands-free technique for preparing monodispersed droplets in a very facile and inexpensive fashion is intended for, but not limited to, bioanalytical applications and is also applicable to material syntheses.

  15. Formation of droplets of alternating composition in microfluidic channels and applications to indexing of concentrations in droplet-based assays.

    Science.gov (United States)

    Zheng, Bo; Tice, Joshua D; Ismagilov, Rustem F

    2004-09-01

    For screening the conditions for a reaction by using droplets (or plugs) as microreactors, the composition of the droplets must be indexed. Indexing here refers to measuring the concentration of a solute by addition of a marker, either internal or external. Indexing may be performed by forming droplet pairs, where in each pair the first droplet is used to conduct the reaction, and the second droplet is used to index the composition of the first droplet. This paper characterizes a method for creating droplet pairs by generating alternating droplets, of two sets of aqueous solutions in a flow of immiscible carrier fluid within PDMS and glass microfluidic channels. The paper also demonstrates that the technique can be used to index the composition of the droplets, and this application is illustrated by screening conditions of protein crystallization. The fluid properties required to form the steady flow of the alternating droplets in a microchannel were characterized as a function of the capillary number Ca and water fraction. Four regimes were observed. At the lowest values of Ca, the droplets of the two streams coalesced; at intermediate values of Ca the alternating droplets formed reliably. At even higher values of Ca, shear forces dominated and caused formation of droplets that were smaller than the cross-sectional dimension of the channel; at the highest values of Ca, coflowing laminar streams of the two immiscible fluids formed. In addition to screening of protein crystallization conditions, understanding of the fluid flow in this system may extend this indexing approach to other chemical and biological assays performed on a microfluidic chip.

  16. Phase rainbow refractometry for accurate droplet variation characterization.

    Science.gov (United States)

    Wu, Yingchun; Promvongsa, Jantarat; Saengkaew, Sawitree; Wu, Xuecheng; Chen, Jia; Gréhan, Gérard

    2016-10-15

    We developed a one-dimensional phase rainbow refractometer for the accurate trans-dimensional measurements of droplet size on the micrometer scale as well as the tiny droplet diameter variations at the nanoscale. The dependence of the phase shift of the rainbow ripple structures on the droplet variations is revealed. The phase-shifting rainbow image is recorded by a telecentric one-dimensional rainbow imaging system. Experiments on the evaporating monodispersed droplet stream show that the phase rainbow refractometer can measure the tiny droplet diameter changes down to tens of nanometers. This one-dimensional phase rainbow refractometer is capable of measuring the droplet refractive index and diameter, as well as variations.

  17. Effects of induced vibration modes on droplet sliding phenomena

    Science.gov (United States)

    Mejia, Jose Eduardo; Alvarado, Jorge; Yao, Chun-Wei; Dropwise Condensation Collaboration; Engineered Surfaces Collaboration

    2016-11-01

    An analytical and experimental investigation has been undertaken to understand the effects of induced vibration modes on droplet sliding phenomena. A mathematical model has been postulated which is capable of estimating accurately droplet sliding angles when using hydrophobic and hydrophilic surfaces. The model, which takes into account equilibrium contact angle, contact angle hysteresis, and droplet volume, has been validated using experimental data. The model has been modified to be able to estimate droplet sliding angle when different modes of vibrations are imposed on the surfaces. Experimental results to date reveal that when resonance modes of vibrations are imposed, the droplet sliding angles decrease considerably. The results also indicate that the modified model can be used effectively to relate imposed resonance frequencies to the critical sliding angle of droplets. LSAMP sponsored NSF Fellowship.

  18. Bouncing dynamics of impact droplets on the convex superhydrophobic surfaces

    Science.gov (United States)

    Shen, Yizhou; Liu, Senyun; Zhu, Chunling; Tao, Jie; Chen, Zhong; Tao, Haijun; Pan, Lei; Wang, Guanyu; Wang, Tao

    2017-05-01

    Bouncing dynamics of impact droplets on solid surfaces intensively appeal to researchers due to the importance in many industrial fields. Here, we found that droplets impacting onto dome convex superhydrophobic surfaces could rapidly bounce off with a 28.5% reduction in the contact time, compared with that on flat superhydrophobic surfaces. This is mainly determined by the retracting process of impact droplets. Under the action of dome convexity, the impact droplet gradually evolves into an annulus shape with a special hydrodynamic distribution. As a consequence, both the inner and external rims of the annulus shape droplet possess a higher retracting velocity under the actions of the inertia force and the surface energy change, respectively. Also, the numerical simulation provides a quantitative evidence to further verify the interpretation on the regimes behind the rapidly detached phenomenon of impact droplets.

  19. Generation and mixing of subfemtoliter aqueous droplets on demand.

    Science.gov (United States)

    Tang, Jianyong; Jofre, Ana M; Kishore, Rani B; Reiner, Joseph E; Greene, Mark E; Lowman, Geoffrey M; Denker, John S; Willis, Christina C C; Helmerson, Kristian; Goldner, Lori S

    2009-10-01

    We describe a novel method of generating monodisperse subfemtoliter aqueous droplets on demand by means of piezoelectric injection. Droplets with volumes down to 200 aL are generated by this technique. The droplets are injected into a low refractive index perfluorocarbon so that they can be optically trapped. We demonstrate the use of optical tweezers to manipulate and mix droplets. For example, using optical tweezers we bring two droplets, one containing a calcium sensitive dye and the other calcium chloride, into contact. The droplets coalesce with a resulting reaction time of about 1 ms. The monodispersity, manipulability, repeatability, small size, and fast mixing afforded by this system offer many opportunities for nanochemistry and observation of chemical reactions on a molecule-by-molecule basis.

  20. Numerical simulation of droplet formation in a microchannel device

    Directory of Open Access Journals (Sweden)

    K Granado

    2016-09-01

    Full Text Available The formation of droplets is a phenomenon of particular importance in the development of industrial emulsions. The quality of these compounds is associated with droplet size and stability over time. Anna et al.(2003 developed a methodology named "flow focusing" to improve droplet formation processes for engineering applications. In this work, Computational Fluid Dynamics (CFD based techniques are used to assess the capacity of a pseudo-2D numerical model to reproduce the formation of water droplets within silicon oil, as obtained during experiments. Average time of droplet onset obtained via numerical analysis was 1.5 times larger than observed experimentally, whereas droplets convection velocity and diameter predictions differed by 40-45% and 60%, respectively. Nevertheless, the calculated velocity profiles downstream of the discharge slot reproduced the expected free-jet shear layer according to outer/inner flow ratio.

  1. Droplet actuation induced by coalescence: experimental evidences and phenomenological modeling

    CERN Document Server

    Sellier, Mathieu; Gaubert, Cécile; Verdier, Claude

    2012-01-01

    This paper considers the interaction between two droplets placed on a substrate in immediate vicinity. We show here that when the two droplets are of different fluids and especially when one of the droplet is highly volatile, a wealth of fascinating phenomena can be observed. In particular, the interaction may result in the actuation of the droplet system, i.e. its displacement over a finite length. In order to control this displacement, we consider droplets confined on a hydrophilic stripe created by plasma-treating a PDMS substrate. This controlled actuation opens up unexplored opportunities in the field of microfluidics. In order to explain the observed actuation phenomenon, we propose a simple phenomenological model based on Newton's second law and a simple balance between the driving force arising from surface energy gradients and the viscous resistive force. This simple model is able to reproduce qualitatively and quantitatively the observed droplet dynamics.

  2. Single-molecule emulsion PCR in microfluidic droplets.

    Science.gov (United States)

    Zhu, Zhi; Jenkins, Gareth; Zhang, Wenhua; Zhang, Mingxia; Guan, Zhichao; Yang, Chaoyong James

    2012-06-01

    The application of microfluidic droplet PCR for single-molecule amplification and analysis has recently been extensively studied. Microfluidic droplet technology has the advantages of compartmentalizing reactions into discrete volumes, performing highly parallel reactions in monodisperse droplets, reducing cross-contamination between droplets, eliminating PCR bias and nonspecific amplification, as well as enabling fast amplification with rapid thermocycling. Here, we have reviewed the important technical breakthroughs of microfluidic droplet PCR in the past five years and their applications to single-molecule amplification and analysis, such as high-throughput screening, next generation DNA sequencing, and quantitative detection of rare mutations. Although the utilization of microfluidic droplet single-molecule PCR is still in the early stages, its great potential has already been demonstrated and will provide novel solutions to today's biomedical engineering challenges in single-molecule amplification and analysis.

  3. Droplet microfluidics--a tool for single-cell analysis.

    Science.gov (United States)

    Joensson, Haakan N; Andersson Svahn, Helene

    2012-12-03

    Droplet microfluidics allows the isolation of single cells and reagents in monodisperse picoliter liquid capsules and manipulations at a throughput of thousands of droplets per second. These qualities allow many of the challenges in single-cell analysis to be overcome. Monodispersity enables quantitative control of solute concentrations, while encapsulation in droplets provides an isolated compartment for the single cell and its immediate environment. The high throughput allows the processing and analysis of the tens of thousands to millions of cells that must be analyzed to accurately describe a heterogeneous cell population so as to find rare cell types or access sufficient biological space to find hits in a directed evolution experiment. The low volumes of the droplets make very large screens economically viable. This Review gives an overview of the current state of single-cell analysis involving droplet microfluidics and offers examples where droplet microfluidics can further biological understanding.

  4. Compound Droplet Levitation for Lab-on-a-Chip

    Science.gov (United States)

    Black, James; Neitzel, G. Paul

    2016-11-01

    A fluid transport mechanism utilizing thermocapillarity has been previously shown to successfully levitate and translate both microliter- and nanoliter-volume droplets of silicone oil. The surface flow required to drive levitation and transport has not been achieved for aqueous droplets, and encapsulation of samples within a layer of silicone oil is necessary. A droplet-on-demand generator capable of producing nanoliter-volume compound droplets has been developed and previously reported. The work presented here discusses efforts to demonstrate the applicability of this microfluidic transport mechanism to lab-on-a-chip systems. We elaborate on translation speeds of single-phase, nanoliter-volume, silicone-oil droplets. Compound droplets of varying compositions of oil and water are then generated, captured, levitated, and merged to explore the composition limits thereof. Work supported by NSF and NASA.

  5. Collective waves in dense and confined microfluidic droplet arrays

    Science.gov (United States)

    Schiller, Ulf D.; Fleury, Jean-Baptiste; Seemann, Ralf; Gompper, Gerhard

    Excitation mechanisms for collective waves in confined dense one-dimensional microfluidic droplet arrays are investigated by experiments and computer simulations. We demonstrate that distinct modes can be excited by creating specific `defect' patterns in flowing droplet trains. Excited longitudinal modes exhibit a short-lived cascade of pairs of laterally displacing droplets. Transversely excited modes obey the dispersion relation of microfluidic phonons and induce a coupling between longitudinal and transverse modes, whose origin is the hydrodynamic interaction of the droplets with the confining walls. Moreover, we investigate the long-time behaviour of the oscillations and discuss possible mechanisms for the onset of instabilities. Our findings demonstrate that the collective dynamics of microfluidic droplet ensembles can be studied particularly well in dense and confined systems. Experimentally, the ability to control microfluidic droplets may allow to modulate the refractive index of optofluidic crystals which is a promising approach for the production of dynamically programmable metamaterials.

  6. Electromagnetic emission of a strongly charged oscillating droplet

    Science.gov (United States)

    Grigor'ev, A. I.; Kolbneva, N. Yu.; Shiryaeva, S. O.

    2016-08-01

    Analytical expressions for electric field in the vicinity of an oscillating strongly charged droplet of nonviscous conducting liquid and intensity of electromagnetic radiation are derived in the linear approximation with respect to perturbation amplitude of the droplet surface. Order-of-magnitude estimations of the radiation intensity are presented. The intensity of electromagnetic radiation of a ball lightning that can be simulated using a charged droplet is not related to the surface oscillations.

  7. Capillary effects during droplet impact on a solid surface

    Science.gov (United States)

    Pasandideh-Fard, M.; Qiao, Y. M.; Chandra, S.; Mostaghimi, J.

    1996-03-01

    Impact of water droplets on a flat, solid surface was studied using both experiments and numerical simulation. Liquid-solid contact angle was varied in experiments by adding traces of a surfactant to water. Impacting droplets were photographed and liquid-solid contact diameters and contact angles were measured from photographs. A numerical solution of the Navier-Stokes equation using a modified SOLA-VOF method was used to model droplet deformation. Measured values of dynamic contact angles were used as a boundary condition for the numerical model. Impacting droplets spread on the surface until liquid surface tension and viscosity overcame inertial forces, after which they recoiled off the surface. Adding a surfactant did not affect droplet shape during the initial stages of impact, but did increase maximum spread diameter and reduce recoil height. Comparison of computer generated images of impacting droplets with photographs showed that the numerical model modeled droplet shape evolution correctly. Accurate predictions were obtained for droplet contact diameter during spreading and at equilibrium. The model overpredicted droplet contact diameters during recoil. Assuming that dynamic surface tension of surfactant solutions is constant, equaling that of pure water, gave predicted droplet shapes that best agreed with experimental observations. When the contact angle was assumed constant in the model, equal to the measured equilibrium value, predictions were less accurate. A simple analytical model was developed to predict maximum droplet diameter after impact. Model predictions agreed well with experimental measurements reported in the literature. Capillary effects were shown to be negligible during droplet impact when We≫Re1/2.

  8. Grooved organogel surfaces towards anisotropic sliding of water droplets.

    Science.gov (United States)

    Zhang, Pengchao; Liu, Hongliang; Meng, Jingxin; Yang, Gao; Liu, Xueli; Wang, Shutao; Jiang, Lei

    2014-05-21

    Periodic micro-grooved organogel surfaces can easily realize the anisotropic sliding of water droplets attributing to the formed slippery water/oil/solid interface. Different from the existing anisotropic surfaces, this novel surface provides a versatile candidate for the anisotropic sliding of water droplets and might present a promising way for the easy manipulation of liquid droplets for water collection, liquid-directional transportation, and microfluidics.

  9. Measurement of electric properties of the single supersaturated aerosol droplet

    Institute of Scientific and Technical Information of China (English)

    HE KeJuan; CHENG Hua; ZHU YanYing; WANG LiangYu; ZHANG YunHong

    2008-01-01

    A system for measuring the electric properties of single aerosol droplet is designed and applied to the NaCIO4 aerosol droplet in different relative humidity (RH). The conductance and capacitance are obtained within the whole RH range, especially in the supersaturated state which cannot be acquired from the bulk solution. These results reflect the situation of ions in the droplet macroscopically and supply useful information for other relative study fields, such as crystallogeny and aerography.

  10. Electrostatic charge on spray droplets of aqueous surfactant solutions

    OpenAIRE

    POLAT, Mehmet; Polat, Hürriyet; Chander, Subhash

    2000-01-01

    Electrostatic charges on individual spray droplets were measured using a refined form of the Millikan oil drop method. The measurement system consisted of three main sections; a droplet generation cell, a settling column and a charge measurement chamber. The trajectories required for calculation of charge were determined using a high-speed motion analyzer coupled to a long-focal-length microscope. Charges on droplets were manipulated by the addition of surface-active agents into the spray sol...

  11. Droplets Fusion in a Microchannel on a Piezoelectric Substrate

    OpenAIRE

    Fu Xiang-ting; Zha Yan; Zhang An-liang

    2013-01-01

    Fusion droplets is a key operation in a microfluidic device for microfluidic analysis. A new fusion method for droplets was presented. An interditigal transducer and a reflector were fabricated on 1280-yx LiNbO3 piezoelectric substrate using microelectric technology. A poly-dimethyl silicone micro-channel was made by soft lithography technology and mounted on the piezoelectric substrate. Droplets in the microchannel were actuated by surface acoustic wave and fussed each other. Coloured dye so...

  12. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Change in the optical properties of hyaline cartilage heated by the near-IR laser radiation

    Science.gov (United States)

    Bagratashvili, Viktor N.; Bagratashvili, N. V.; Gapontsev, V. P.; Makhmutova, G. Sh; Minaev, V. P.; Omel'chenko, A. I.; Samartsev, I. E.; Sviridov, A. P.; Sobol', E. N.; Tsypina, S. I.

    2001-06-01

    The in vitro dynamics of the change in optical properties of hyaline cartilage heated by fibre lasers at wavelengths 0.97 and 1.56 μm is studied. The laser-induced bleaching (at 1.56 μm) and darkening (at 0.97 μm) of the cartilage, caused by the heating and transport of water as well as by a change in the cartilage matrix, were observed and studied. These effects should be taken into account while estimating the depth of heating of the tissue. The investigated dynamics of light scattering in the cartilage allows one to choose the optimum radiation dose for laser plastic surgery of cartilage tissues.

  13. Recombinant Bone Morphogenetic Protein 2 Stimulates the Remodeling Chitosan-Based Porous Scaffold Into Hyaline-like Cartilage: Study in Heterotopic Implantation

    Directory of Open Access Journals (Sweden)

    Nurshat M. Gaifullin

    2013-09-01

    Full Text Available To study the morphology of remodeling the chitosan-based three-dimensional porous scaffold, containing bone morphogenetic protein-2 (BMP-2 for chondroinduction, the experiments with heterotopic implantation using 28 Wistar rats were carried out. Scaffolds with growth factor (n=12 or without it (n=12, against intact control (n=4 were implanted subcutaneously. Classical methods of histology and morphometry as well as immune histochemical markers (CD-68, CD-31, MMP-9, TIMP-1, and osteonectin expression, one used to investigate zone of remodeling in euthanized animals at 4 and 8 weeks after implantation. The BMP-2 application provides more intensive and rapid new cartilage formation from the scaffold matter. The additional chondroinductive effect proved more intensive settlement and proliferation of chondral cells in the regenerate, expression of chondral phenotype with the building the hyaline-like matrix, and the supporting necessary balance between the matrix metalloproteinases and their tissue inhibitors.

  14. Scaling Laws for Inter-droplet Ice Bridging

    Science.gov (United States)

    Nath, Saurabh; Ahmadi, Farzad; Boreyko, Jonathan

    2016-11-01

    In this work, we study the dynamics of an ice bridge growing from a frozen droplet towards its neighboring supercooled liquid droplet. Experiments were done on a Peltier stage inside a humidity chamber with deposited or condensed droplets where the substrate temperature and ambient humidity could be controlled. Following a quasi-steady diffusion-driven model, we develop scaling laws to show how the growth rate depends on the substrate temperature, droplet sizes and inter-droplet distances over and above other environmental parameters such as air temperature and humidity. The growth rate as well as the success or failure of an ice bridge to connect to its neighboring liquid droplet depend on a nondimensional number called the separation parameter S*, defined as the ratio of the initial inter-droplet spacing to the diameter of the evaporating liquid droplet. It is shown that the maximum value of S* for connection scales as 1 as long as frozen drop is larger than the liquid droplet. For the converse case of a larger water drop, there are at least three separate regimes of critical S*, depending on whether the water drop is a puddle, a spherical cap or if the frozen drop is a puddle.

  15. Evaluation of droplet size distributions using univariate and multivariate approaches.

    Science.gov (United States)

    Gaunø, Mette Høg; Larsen, Crilles Casper; Vilhelmsen, Thomas; Møller-Sonnergaard, Jørn; Wittendorff, Jørgen; Rantanen, Jukka

    2013-01-01

    Pharmaceutically relevant material characteristics are often analyzed based on univariate descriptors instead of utilizing the whole information available in the full distribution. One example is droplet size distribution, which is often described by the median droplet size and the width of the distribution. The current study was aiming to compare univariate and multivariate approach in evaluating droplet size distributions. As a model system, the atomization of a coating solution from a two-fluid nozzle was investigated. The effect of three process parameters (concentration of ethyl cellulose in ethanol, atomizing air pressure, and flow rate of coating solution) on the droplet size and droplet size distribution using a full mixed factorial design was used. The droplet size produced by a two-fluid nozzle was measured by laser diffraction and reported as volume based size distribution. Investigation of loading and score plots from principal component analysis (PCA) revealed additional information on the droplet size distributions and it was possible to identify univariate statistics (volume median droplet size), which were similar, however, originating from varying droplet size distributions. The multivariate data analysis was proven to be an efficient tool for evaluating the full information contained in a distribution.

  16. Droplet Mobility Manipulation on Porous Media Using Backpressure.

    Science.gov (United States)

    Vourdas, N; Pashos, G; Kokkoris, G; Boudouvis, A G; Stathopoulos, V N

    2016-05-31

    Wetting phenomena on hydrophobic surfaces are strongly related to the volume and pressure of gas pockets residing at the solid-liquid interface. In this study, we explore the underlying mechanisms of droplet actuation and mobility manipulation when backpressure is applied through a porous medium under a sessile pinned droplet. Reversible transitions between the initially sticky state and the slippery states are thus incited by modulating the backpressure. The sliding angles of deionized (DI) water and ethanol in DI water droplets of various volumes are presented to quantify the effect of the backpressure on the droplet mobility. For a 50 μL water droplet, the sliding angle decreases from 45 to 0° when the backpressure increases to ca. 0.60 bar. Significantly smaller backpressure levels are required for lower surface energy liquids. We shed light on the droplet actuation and movement mechanisms by means of simulations encompassing the momentum conservation and the continuity equations along with the Cahn-Hilliard phase-field equations in a 2D computational domain. The droplet actuation mechanism entails depinning of the receding contact line and movement by means of forward wave propagation reaching the front of the droplet. Eventually, the droplet skips forward. The contact line depinning is also corroborated by analytical calculations based on the governing vertical force balance, properly modified to incorporate the effect of the backpressure.

  17. Efficient transport of droplet sandwiched between saw-tooth plates.

    Science.gov (United States)

    Wang, Liya; Wu, Hengan; Wang, Fengchao

    2016-01-15

    The transport of droplet sandwiched between smooth and saw-tooth plates was investigated using molecular dynamics method. The repeated opening and closing of the plates result in sequential stretching and squeezing of the droplet, which provide the driving force. The asymmetrical saw tooth obstructs the backward motion of the droplet, and gives rise to a net forward displacement of the droplet in every opening and closing cycle. This unidirectional motion facilitates the efficient droplet transport, which is referred to as the ratchet-like effect in this work. Our simulations also reveal that the influence of the surface wettability on the droplet transport is different for saw-tooth and smooth plates. Droplet transport efficiency exhibits monotonic decrease with the increase of the solid-liquid interactions for saw-tooth plates. While for smooth plates, unidirectional droplet movement was only observed for certain solid-liquid interactions. Taken together these simulation results and theoretical analysis, we demonstrate that hydrophobic saw-tooth plates can improve the transport efficiency significantly. These findings not only enhance our understanding of the droplet transport from atomistic scale, but also are beneficial to practical applications in designing of micro- and nano-fluidic systems.

  18. Droplet microfluidics for high-throughput biological assays.

    Science.gov (United States)

    Guo, Mira T; Rotem, Assaf; Heyman, John A; Weitz, David A

    2012-06-21

    Droplet microfluidics offers significant advantages for performing high-throughput screens and sensitive assays. Droplets allow sample volumes to be significantly reduced, leading to concomitant reductions in cost. Manipulation and measurement at kilohertz speeds enable up to 10(8) samples to be screened in one day. Compartmentalization in droplets increases assay sensitivity by increasing the effective concentration of rare species and decreasing the time required to reach detection thresholds. Droplet microfluidics combines these powerful features to enable currently inaccessible high-throughput screening applications, including single-cell and single-molecule assays.

  19. Instabilities, motion and deformation of active fluid droplets

    Science.gov (United States)

    Whitfield, Carl A.; Hawkins, Rhoda J.

    2016-12-01

    We consider two minimal models of active fluid droplets that exhibit complex dynamics including steady motion, deformation, rotation and oscillating motion. First we consider a droplet with a concentration of active contractile matter adsorbed to its boundary. We analytically predict activity driven instabilities in the concentration profile, and compare them to the dynamics we find from simulations. Secondly, we consider a droplet of active polar fluid of constant concentration. In this system we predict, motion and deformation of the droplets in certain activity ranges due to instabilities in the polarisation field. Both these systems show spontaneous transitions to motility and deformation which resemble dynamics of the cell cytoskeleton in animal cells.

  20. Dynamics of droplet entrapment in a constricted microchannel

    Science.gov (United States)

    Nekouei, Mehdi; Bithi, Swastika; Vanapalli, Siva

    2016-11-01

    Droplet migration and clogging in confined geometries is a problem of fundamental importance in oil recovery and droplet microfluidics. A confined droplet flowing through a conduit can either be arrested at the constriction or squeeze through it. The dynamics of the trapped and squeezed states are expected to depend on capillary number, drop size, viscosity ratio. Although there have been a number of studies on the dynamics of droplets passing through a constriction, investigations of dynamics of trapped droplets in constricted microchannels is lacking. In this work, we performed three-dimensional simulations of droplet trapping and squeezing process in a constricted microchannel. We also conducted experiments to validate the key results of the simulations. We investigated the impact of different system parameters on the onset of droplet immobilization at the constriction. We found that the continuous phase flows through the corners of the droplet, i.e. gutter flows to play an important role in determining the transition between trapping and squeezing. Therefore we evaluated the effect of different system parameters on gutter flows and found that the hydrodynamic resistance of gutters depends on the viscosity, size and confinement of the droplet.

  1. Electric field mediated spraying of miniaturized droplets inside microchannel.

    Science.gov (United States)

    Timung, Seim; Chaudhuri, Joydip; Borthakur, Manash Pratim; Mandal, Tapas Kumar; Biswas, Gautam; Bandyopadhyay, Dipankar

    2016-10-17

    We report a facile and noninvasive way to disintegrate a microdroplet into a string of further miniaturized ones under the influence of an external electrohydrodynamic field inside a microchannel. The deformation and breakup of the droplet was engendered by the Maxwell's stress originating from the accumulation of induced and free charges at the oil-water interface. While at smaller field intensities, for example less than 1 MV/m, the droplet deformed into a plug, at relatively higher field intensities, e.g. ∼1.16 MV/m, a pair of droplets having opposite surface charge was formed. The charged droplets showed an interesting periodic bridging and breakup during their translation motion across the channel. For even higher field intensities, for example more than 1.2 MV/m, the entire droplet underwent dielectrophoresis toward one of the electrodes before experiencing a strong attractive force from the other electrode to deform into a shape of a Taylor cone. With progress in time, mimicking the electrospraying phenomenon, the cone tip periodically ejected a string of miniaturized water droplets to form a microemulsion inside the channel. The frequency and size of the droplet ejection could be tuned by varying the applied field intensity. A water droplet of ∼214 μm diameter could continuously eject droplets of size ∼10 μm or even smaller to form a microemulsion inside the channel.

  2. Numerical simulation of filler metal droplets spreading in laser brazing

    Science.gov (United States)

    Chen, Yanbin; Feng, Xiaosong; Li, Liqun

    2007-11-01

    A finite element model was constructed using a commercial software Fidap to analyze the Cu-base filler metal droplet spreading process in laser brazing, in which the temperature distribution, droplet geometry, and fluid flow velocity were calculated. Marangoni and buoyancy convection and gravity force were considered, and the effects of laser power and spot size on the spreading process were evaluated. Special attention was focused on the free surface of the droplet, which determines the profile of the brazing spot. The simulated results indicate that surface tension is the dominant flow driving force and laser spot size determines the droplet spreading domain.

  3. Targeting the motor regulator Klar to lipid droplets

    Directory of Open Access Journals (Sweden)

    Einstein Jenifer

    2011-02-01

    Full Text Available Abstract Background In Drosophila, the transport regulator Klar displays tissue-specific localization: In photoreceptors, it is abundant on the nuclear envelope; in early embryos, it is absent from nuclei, but instead present on lipid droplets. Differential targeting of Klar appears to be due to isoform variation. Droplet targeting, in particular, has been suggested to occur via a variant C-terminal region, the LD domain. Although the LD domain is necessary and sufficient for droplet targeting in cultured cells, lack of specific reagents had made it previously impossible to analyze its role in vivo. Results Here we describe a new mutant allele of klar with a lesion specifically in the LD domain; this lesion abolishes both droplet localization of Klar and the ability of Klar to regulate droplet motion. It does not disrupt Klar's function for nuclear migration in photoreceptors. Using a GFP-LD fusion, we show that the LD domain is not only necessary but also sufficient for droplet targeting in vivo; it mediates droplet targeting in embryos, in ovaries, and in a number of somatic tissues. Conclusions Our analysis demonstrates that droplet targeting of Klar occurs via a cis-acting sequence and generates a new tool for monitoring lipid droplets in living tissues of Drosophila.

  4. Sessile multidroplets and salt droplets under high tangential electric fields

    Science.gov (United States)

    Xie, Guoxin; He, Feng; Liu, Xiang; Si, Lina; Guo, Dan

    2016-01-01

    Understanding the interaction behaviors between sessile droplets under imposed high voltages is very important in many practical situations, e.g., microfluidic devices and the degradation/aging problems of outdoor high-power applications. In the present work, the droplet coalescence, the discharge activity and the surface thermal distribution response between sessile multidroplets and chloride salt droplets under high tangential electric fields have been investigated with infrared thermography, high-speed photography and pulse current measurement. Obvious polarity effects on the discharge path direction and the temperature change in the droplets in the initial stage after discharge initiation were observed due to the anodic dissolution of metal ions from the electrode. In the case of sessile aligned multidroplets, the discharge path direction could affect the location of initial droplet coalescence. The smaller unmerged droplet would be drained into the merged large droplet as a result from the pressure difference inside the droplets rather than the asymmetric temperature change due to discharge. The discharge inception voltages and the temperature variations for two salt droplets closely correlated with the ionization degree of the salt, as well as the interfacial electrochemical reactions near the electrodes. Mechanisms of these observed phenomena were discussed. PMID:27121926

  5. Synchronized reinjection and coalescence of droplets in microfluidics.

    Science.gov (United States)

    Lee, Manhee; Collins, Jesse W; Aubrecht, Donald M; Sperling, Ralph A; Solomon, Laura; Ha, Jong-Wook; Yi, Gi-Ra; Weitz, David A; Manoharan, Vinothan N

    2014-02-07

    Coalescence of two kinds of pre-processed droplets is necessary to perform chemical and biological assays in droplet-based microfluidics. However, a robust technique to accomplish this does not exist. Here we present a microfluidic device to synchronize the reinjection of two different kinds of droplets and coalesce them, using hydrostatic pressure in conjunction with a conventional syringe pump. We use a device consisting of two opposing T-junctions for reinjecting two kinds of droplets and control the flows of the droplets by applying gravity-driven hydrostatic pressure. The hydrostatic-pressure operation facilitates balancing the droplet reinjection rates and allows us to synchronize the reinjection. Furthermore, we present a simple but robust module to coalesce two droplets that sequentially come into the module, regardless of their arrival times. These re-injection and coalescence techniques might be used in lab-on-chip applications requiring droplets with controlled numbers of solid materials, which can be made by coalescing two pre-processed droplets that are formed and sorted in devices.

  6. Microfluidic droplet sorting using integrated bilayer micro-valves

    Science.gov (United States)

    Chen, Yuncong; Tian, Yang; Xu, Zhen; Wang, Xinran; Yu, Sicong; Dong, Liang

    2016-10-01

    This paper reports on a microfluidic device capable of sorting microfluidic droplets utilizing conventional bilayer pneumatic micro-valves as sorting controllers. The device consists of two micro-valves placed symmetrically on two sides of a sorting area, each on top of a branching channel at an inclined angle with respect to the main channel. Changes in transmitted light intensity, induced by varying light absorbance by each droplet, are used to divert the droplet from the sorting area into one of the three outlet channels. When no valve is activated, the droplet flows into the outlet channel in the direction of the main channel. When one of the valves is triggered, the flexible membrane of valve will first be deflected. Once the droplet leaves the detection point, the deflected membrane will immediately return to its default flattened position, thereby exerting a drawing pressure on the droplet and deviating it from its original streamline to the outlet on the same side as the valve. This sorting method will be particularly suitable for numerous large-scale integrated microfluidic systems, where pneumatic micro-valves are already used. Only few structural modifications are needed to achieve droplet sorting capabilities in these systems. Due to the mechanical nature of diverting energy applied to droplets, the proposed sorting method may induce only minimal interference to biological species or microorganisms encapsulated inside the droplets that may accompany electrical, optical and magnetic-based techniques.

  7. Investigation on Electrostatical Breakup of Bio-Oil Droplets

    Directory of Open Access Journals (Sweden)

    John Z. Wen

    2012-10-01

    Full Text Available In electrostatic atomization, the input electrical energy causes breaking up of the droplet surface by utilizing a mutual repulsion of net charges accumulating on that surface. In this work a number of key parameters controlling the bio-oil droplet breakup process are identified and these correlations among the droplet size distribution, specific charges of droplets and externally applied electrical voltages are quantified. Theoretical considerations of the bag or strip breakup mechanism of biodiesel droplets experiencing electrostatic potential are compared to experimental outcomes. The theoretical analysis suggests the droplet breakup process is governed by the Rayleigh instability condition, which reveals the effects of droplets size, specific charge, surface tension force, and droplet velocities. Experiments confirm that the average droplet diameters decrease with increasing specific charges and this decreasing tendency is non-monotonic due to the motion of satellite drops in the non-uniform electrical field. The measured specific charges are found to be smaller than the theoretical values. And the energy transformation from the electrical energy to surface energy, in addition to the energy loss, Taylor instability breakup, non-excess polarization and some system errors, accounts for this discrepancy. The electrostatic force is the dominant factor controlling the mechanism of biodiesel breakup in electrostatic atomization.

  8. Mechanical stability of ordered droplet packings in microfluidic channels

    Science.gov (United States)

    Fleury, Jean-Baptiste; Claussen, Ohle; Herminghaus, Stephan; Brinkmann, Martin; Seemann, Ralf

    2011-12-01

    The mechanical response and stability of one and two-row packing of monodisperse emulsion droplets are studied in quasi 2d microchannels under longitudinal compression. Depending on the choice of parameter, a considered droplet arrangement is either transformed continuously into another packing under longitudinal compression or becomes mechanically unstable and segregates into domains of higher and lower packing fraction. Our experimental results are compared to analytical calculations for 2d-droplet arrangements with good quantitative agreement. This study also predicts important consequences for the stability of droplet arrangements in flowing systems.

  9. Spreading dynamics of droplet on an inclined surface

    Science.gov (United States)

    Shen, Chaoqun; Yu, Cheng; Chen, Yongping

    2016-06-01

    A three-dimensional unsteady theoretical model of droplet spreading process on an inclined surface is developed and numerically analyzed to investigate the droplet spreading dynamics via the lattice Boltzmann simulation. The contact line motion and morphology evolution for the droplet spreading on an inclined surface, which are, respectively, represented by the advancing/receding spreading factor and droplet wetted length, are evaluated and analyzed. The effects of surface wettability and inclination on the droplet spreading behaviors are examined. The results indicate that, dominated by gravity and capillarity, the droplet experiences a complex asymmetric deformation and sliding motion after the droplet comes into contact with the inclined surfaces. The droplet firstly deforms near the solid surface and mainly exhibits a radial expansion flow in the start-up stage. An evident sliding-down motion along the inclination is observed in the middle stage. And the surface-tension-driven retraction occurs during the retract stage. Increases in inclination angle and equilibrium contact angle lead to a faster droplet motion and a smaller wetted area. In addition, increases in equilibrium contact angle lead to a shorter duration time of the middle stage and an earlier entry into the retract stage.

  10. Dynamic response of vaporizing droplet to pressure oscillation

    Science.gov (United States)

    Yuan, Lei; Shen, Chibing; Zhang, Xinqiao

    2017-02-01

    Combustion instability is a major challenge in the development of the liquid propellant engines, and droplet vaporization is viewed as a potential mechanism for driving instabilities. Based on the previous work, an unsteady droplet heating and vaporization model was developed. The model and numerical method are validated by experimental data available in literature, and then the oscillatory vaporization of n-Heptane droplet exposed to unsteady harmonic nitrogen atmosphere was numerically investigated over a wide range of amplitudes and frequencies. Also, temperature variations inside the droplet were demonstrated under oscillation environments. It was found that the thermal wave is attenuated with significantly reduced wave intensities as it penetrates deep into droplet from the ambient gas. Droplet surface temperature exhibits smaller fluctuation than that of the ambient gas, and it exhibits a time lag with regard to the pressure variation. Furthermore, the mechanism leading to phase lag of vaporization rate with respect to pressure oscillation was unraveled. Results show that this phase lag varies during the droplet lifetime and it is strongly influenced by oscillation frequency, indicating droplet vaporization is only capable of driving combustion instability in some certain frequency domains. Instead, the amplitude of the oscillation does not have very significant effects. It is noteworthy that thermal inertia of the droplet also plays a considerable role in determining the phase lag.

  11. Electric-Field-Assisted Droplet Dispensing on Immiscible Fluids

    Science.gov (United States)

    Uhm, Taewoong; Hong, Jiwoo; Lee, Sang Joon; Kang, In Seok

    2014-11-01

    Dispensing tiny droplets is a basic and crucial process in numerous practical applications, such as printed electronics, DNA microarray, and digital microfluidics. The precise positioning with demanded size of droplets is the main issue of dispensing tiny droplets. Furthermore, capability of dispensing charged droplets on the immiscible fluids could bring out more utilities. In this work, we demonstrate the droplet dispensing on immiscible fluids by means of electrical charge concentration (ECC). This results from the fact that the droplet is generated by electric force caused by electric induction between the surface of droplet and the immiscible fluid. The temporal evolution of the droplet-dispensing process was observed consecutively with a high-speed camera. In addition, the relationship between the size of dispensed droplet and the parameters, such as physical properties of fluids and electrical field strength, is established. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant Number: 2013R1A1A2011956).

  12. Numerical simulation of filler metal droplets spreading in laser brazing

    Institute of Scientific and Technical Information of China (English)

    Yanbin Chen; Xiaosong Feng; Liqun Li

    2007-01-01

    A finite element model was constructed using a commercial software Fidap to analyze the Cu-base filler metal droplet spreading process in laser brazing, in which the temperature distribution, droplet geometry,and fluid flow velocity were calculated. Marangoni and buoyancy convection and gravity force were considered, and the effects of laser power and spot size on the spreading process were evaluated. Special attention was focused on the free surface of the droplet, which determines the profile of the brazing spot.The simulated results indicate that surface tension is the dominant flow driving force and laser spot size determines the droplet spreading domain.

  13. Digitally controlled droplet microfluidic system based on electrophoretic actuation

    Science.gov (United States)

    Im, Do Jin; Yoo, Byeong Sun; Ahn, Myung Mo; Moon, Dustin; Kang, In Seok

    2012-11-01

    Most researches on direct charging and the subsequent manipulation of a charged droplet were focused on an on-demand sorting in microchannel where carrier fluid transports droplets. Only recently, an individual actuation of a droplet without microchannel and carrier fluid was tried. However, in the previous work, the system size was too large and the actuation voltage was too high (1.5 kV), which limits the applicability of the technology to mobile use. Therefore, in the current research, we have developed a miniaturized digital microfluidic system based on the electrophoresis of a charged droplet (ECD). By using a pin header socket for an array of electrodes, much smaller microfluidic system can be made from simple fabrication process with low cost. A full two dimensional manipulation (0.4 cm/s) of a droplet (300 nL) suspended in silicone oil (6 cSt) and multiple droplet actuation have been performed with reasonable actuation voltage (300 V). By multiple droplet actuation and coalescence, a practical biochemical application also has been demonstrated. We hope the current droplet manipulation method (ECD) can be a good alternative or complimentary technology to the conventional ones and therefore contributes to the development of droplet microfluidics. This work has been supported by BK21 program of the Ministry of Education, Science and Technology (MEST) of Korea.

  14. Enhanced hyaline cartilage matrix synthesis in collagen sponge scaffolds by using siRNA to stabilize chondrocytes phenotype cultured with bone morphogenetic protein-2 under hypoxia.

    Science.gov (United States)

    Legendre, Florence; Ollitrault, David; Hervieu, Magalie; Baugé, Catherine; Maneix, Laure; Goux, Didier; Chajra, Hanane; Mallein-Gerin, Frédéric; Boumediene, Karim; Galera, Philippe; Demoor, Magali

    2013-07-01

    Cartilage healing by tissue engineering is an alternative strategy to reconstitute functional tissue after trauma or age-related degeneration. However, chondrocytes, the major player in cartilage homeostasis, do not self-regenerate efficiently and lose their phenotype during osteoarthritis. This process is called dedifferentiation and also occurs during the first expansion step of autologous chondrocyte implantation (ACI). To ensure successful ACI therapy, chondrocytes must be differentiated and capable of synthesizing hyaline cartilage matrix molecules. We therefore developed a safe procedure for redifferentiating human chondrocytes by combining appropriate physicochemical factors: hypoxic conditions, collagen scaffolds, chondrogenic factors (bone morphogenetic protein-2 [BMP-2], and insulin-like growth factor I [IGF-I]) and RNA interference targeting the COL1A1 gene. Redifferentiation of dedifferentiated chondrocytes was evaluated using gene/protein analyses to identify the chondrocyte phenotypic profile. In our conditions, under BMP-2 treatment, redifferentiated and metabolically active chondrocytes synthesized a hyaline-like cartilage matrix characterized by type IIB collagen and aggrecan molecules without any sign of hypertrophy or osteogenesis. In contrast, IGF-I increased both specific and noncharacteristic markers (collagens I and X) of chondrocytes. The specific increase in COL2A1 gene expression observed in the BMP-2 treatment was shown to involve the specific enhancer region of COL2A1 that binds the trans-activators Sox9/L-Sox5/Sox6 and Sp1, which are associated with a decrease in the trans-inhibitors of COL2A1, c-Krox, and p65 subunit of NF-kappaB. Our procedure in which BMP-2 treatment under hypoxia is associated with a COL1A1 siRNA, significantly increased the differentiation index of chondrocytes, and should offer the opportunity to develop new ACI-based therapies in humans.

  15. Theoretical and Experimental Investigations on Droplet Evaporation and Droplet Ignition at High Pressures

    Science.gov (United States)

    Ristau, R.; Nagel, U.; Iglseder, H.; Koenig, J.; Rath, H. J.; Normura, H.; Kono, M.; Tanabe, M.; Sato, J.

    1993-01-01

    The evaporation of fuel droplets under high ambient pressure and temperature in normal gravity and microgravity has been investigated experimentally. For subcritical ambient conditions, droplet evaporation after a heat-up period follows the d(exp 2)-law. For all data the evaporation constant increases as the ambient temperature increases. At identical ambient conditions the evaporation constant under microgravity is smaller compared to normal gravity. This effect can first be observed at 1 bar and increases with ambient pressure. Preliminary experiments on ignition delay for self-igniting fuel droplets have been performed. Above a 1 s delay time, at identical ambient conditions, significant differences in the results of the normal and microgravity data are observed. Self-ignition occurs within different temperature ranges due to the influence of gravity. The time dependent behavior of the droplet is examined theoretically. In the calculations two different approaches for the gas phase are applied. In the first approach the conditions at the interface are given using a quasi steady theory approximation. The second approach uses a set of time dependent governing equations for the gas phase which are then evaluated. In comparison, the second model shows a better agreement with the drop tower experiments. In both cases a time dependent gasification rate is observed.

  16. Propagation of capillary waves and ejection of small droplets in rapid droplet spreading

    KAUST Repository

    Ding, Hang

    2012-03-12

    A new regime of droplet ejection following the slow deposition of drops onto a near-complete wetting solid substrate is identified in experiments and direct numerical simulations; a coalescence cascade subsequent to pinch-off is also observed for the first time. Results of numerical simulations indicate that the propagation of capillary waves that lead to pinch-off is closely related to the self-similar behaviour observed in the inviscid recoil of droplets, and that motions of the crests and troughs of capillary waves along the interface do not depend on the wettability and surface tension (or Ohnesorge number). The simulations also show that a self-similar theory for universal pinch-off can be used for the time evolution of the pinching neck. However, although good agreement is also found with the double-cone shape of the pinching neck for droplet ejection in drop deposition on a pool of the same liquid, substantial deviations are observed in such a comparison for droplet ejection in rapid drop spreading (including the newly identified regime). This deviation is shown to result from interference by the solid substrate, a rapid downwards acceleration of the top of the drop surface and the rapid spreading process. The experiments also confirm non-monotonic spreading behaviour observed previously only in numerical simulations, and suggest substantial inertial effects on the relation between an apparent contact angle and the dimensionless contact-line speed. © 2012 Cambridge University Press.

  17. Quark matter droplets in neutron stars

    Science.gov (United States)

    Heiselberg, H.; Pethick, C. J.; Staubo, E. F.

    1993-01-01

    We show that, for physically reasonable bulk and surface properties, the lowest energy state of dense matter consists of quark matter coexisting with nuclear matter in the presence of an essentially uniform background of electrons. We estimate the size and nature of spatial structure in this phase, and show that at the lowest densities the quark matter forms droplets embedded in nuclear matter, whereas at higher densities it can exhibit a variety of different topologies. A finite fraction of the interior of neutron stars could consist of matter in this new phase, which would provide new mechanisms for glitches and cooling.

  18. Quark matter droplets in neutron stars

    Science.gov (United States)

    Heiselberg, H.; Pethick, C. J.; Staubo, E. F.

    1993-01-01

    We show that, for physically reasonable bulk and surface properties, the lowest energy state of dense matter consists of quark matter coexisting with nuclear matter in the presence of an essentially uniform background of electrons. We estimate the size and nature of spatial structure in this phase, and show that at the lowest densities the quark matter forms droplets embedded in nuclear matter, whereas at higher densities it can exhibit a variety of different topologies. A finite fraction of the interior of neutron stars could consist of matter in this new phase, which would provide new mechanisms for glitches and cooling.

  19. Droplet migration in a Hele-Shaw microchannel: Effect of the lubrication film on the droplet dynamics

    CERN Document Server

    Ling, Yue; Popinet, Stéphane; Josserand, Christophe

    2016-01-01

    Droplet migration in a Hele-Shaw microchannel is a fundamental multiphase flow problem which is crucial to many microfluidics applications. We focus on the regime at low capillary number, where the droplet keeps a circular shape in the horizontal plane. Parametric studies are performed on the droplet horizontal radius and the capillary number, and particular attention is paid to the effect of the lubrication film on the droplet velocity. For droplets with an horizontal radius larger than half of the channel height, the droplet overfills the channel and a lubrication film is formed between the droplet and the wall. The lubrication film is shown to have a strong impact on the droplet migration velocity and the three-dimensional flow structure. The droplet velocity in the present simulation is shown to be lower than the average inflow velocity, in contrast with the Taylor-Saffman theory for Hele-Shaw flows, but in agreement with experimental measurements. Both the strong shear induced by the lubrication film and...

  20. Effect of viscosity on droplet-droplet collision outcome: Experimental study and numerical comparison

    Science.gov (United States)

    Gotaas, Cecilie; Havelka, Pavel; Jakobsen, Hugo A.; Svendsen, Hallvard F.; Hase, Matthias; Roth, Norbert; Weigand, Bernhard

    2007-10-01

    The influence of viscosity on droplet-droplet collision behavior at ambient conditions was studied experimentally and numerically. N-decane, monoethyleneglycol (MEG), diethyleneglycol (DEG), and triethyleneglycol were used as liquid phase providing viscosities in the range from 0.9to48mPas. Collision Weber numbers ranged approximately from 10 to 420. A direct numerical simulation code, based on the volume-of-fluid concept, was used for the simulations. Experimentally, observations of two droplet streams using a modified stroboscopic technique (aliasing method) were used to investigate the whole range of impact parameters during one experimental run. The experimental method has previously been verified for the water/air system [C. Gotaas et al., Phys. Fluids 19, 102105 (2007)]. In the present work, it was tested and validated for the n-decane/air system. Measured data agree well with those published in the literature. Well-defined regions of stretching separation and coalescence were identified, while reflexive separation regions were not found by using a single sinusoidal disturbance. However, the onset of reflexive separation was identified for MEG and DEG using an amplitude modulation technique. The results show that the criteria for onset of reflexive separation for viscous fluids provided by Y. I. Jiang et al. [J. Fluid Mech. 234, 177 (1992)] are not valid. This is consistent with the results given by K. D. Willis and M. Orme [Exp. Fluids 34, 28 (2003)]. A new empirical correlation for the onset of reflexive separation for high viscosity fluids is presented. The borders between coalescing and stretching separation were shifted toward higher Weber numbers with increasing viscosity. The lack of occurrence of reflexive separation for the single sinusoidal disturbance (small droplets), as well as the stretching separation boundary shift, can be explained by dissipation of collision kinetic energy in viscous flows inside the merged droplet after collision. Results