bluuebunny/crossref_metadata_2025 huggingface dataset:
Porosity Changes and Retention of Ginsenosides in North American Ginseng Root Using Different Dehydration Processes
Authors: Purnama Monica , Yaghmaee Parastoo , Durance Tim D. , Kitts David D.
Published: September 2010

Abstract:  Air drying (AD), freeze‐drying (FD), and vacuum‐microwave drying (VMD) were applied to fresh North American ginseng roots to evaluate the effect of different drying techniques on pore characteristics and the subsequent recovery of ginsenoside content. FD ginseng root produced the lowest reductions in both total moisture content and water activity (P < 0.05), with no differences noted between Ontario or British Columbia ginseng. Ginseng roots from Ontario and British Columbia sources were therefore pooled to conduct the root porosity and ginsenoside measurements. Among samples, FD ginseng obtained the highest total porosity followed by VMD and AD, respectively (P < 0.05). All dehydrated samples had a porous structure with sizes that ranged from 0.002 μm to 172 μm, dominated by macropores (>1.5 μm). Pore characteristics of dried ginseng root were shown to affect recovery of ginsenosides, with the general trend being an increase in total porosity resulting in an increase in total ginsenoside recovered. High performance liquid chromatography results obtained on specific ginsenosides showed that AD of ginseng root resulted in the lowest recovery of total ginsenosides, most notably, Rg1 and Rb1, followed by VMD and FD, respectively. There was no specific difference in total ginsenoside recovery from roots dried at increasing power of VMD.
Un essai d'évaluation de l'incidence des transferts publics sur les dynamiques de pauvreté: le cas de la Russie
Authors: Clément Matthieu
Published: September 2010

L'objet de cet article est de proposer une analyse d'incidence dynamique appliquée au système de transferts russe, qui repose sur la comparaison d'un indicateur de bien‐être pré‐intervention publique au bien‐être post‐intervention. Dans un premier temps nous estimons l'impact des transferts publics sur les formes de pauvreté et montrons que si le système participe à la réduction de la pauvreté chronique et transitoire, les mouvements entre catégories sont très limités. Dans un second temps, nous évaluons la capacité du système à protéger les ménages non pauvres contre un risque d'entrée dans la pauvreté (protection) et à aider les ménages pauvres à sortir de la pauvreté (promotion). Plusieurs investigations indiquent que le système de transferts russe semble adapté pour protéger les ménages, mais se révèle incapable de répondre à l'objectif de promotion. En d'autres termes, sous sa forme actuelle, il ne peut prétendre être un instrument efficace de lutte contre la pauvreté de longue durée.
Les enseignements tirés de l'expérience politique de l'étranger en matière de réforme des systèmes de santé: le cas des groupes homogènes de malades
Authors: Schmid Achim , Götze Ralf
Published: September 2010

L'observation des différentes convergences en matière de politiques et de la diffusion transnationale des idées, des connaissances et des politiques conduit à se poser des questions quant à la façon dont les pays peuvent tirer parti de ce qui se fait à l'étranger. Nous examinerons dans cet article le rôle des enseignements tirés de l'expérience étrangère en ce qui concerne les groupes homogènes de malades (GHM). Nous étudierons le champ d'application de cet instrument politique et nous analyserons sa mise en œuvre dans trois pays qui l'ont récemment adopté: l'Allemagne, la Suisse et les Pays‐Bas. Ces trois cas montrent que l'application des GHM a nécessité des études approfondies, une coopération avec les parties prenantes et un ajustement aux besoins spécifiques de chacun des pays concernés. Les pays ont tiré des enseignements de l'expérience étrangère, mais ce n'est qu'après l'instauration d'un cadre réglementaire pour la concurrence entre les caisses maladie que les GHM peuvent vraiment commencer à bénéficier d'une certaine attention au niveau politique. Alors que l'Allemagne et la Suisse se sont inspirées de modèles de GHM étrangers, les Pays‐Bas ont mis au point un système différent de classification des patients en fonction de la répartition des cas traités.
Reaktionen auf Reformvorschläge für Renten der sozialen Sicherheit in den Vereinigten Staaten
Authors: Becker Fred W.
Published: September 2010

Seit einiger Zeit befassen sich politische Entscheidungsträger, Analysten und Öffentlichkeit in den Vereinigten Staaten mit dem versicherungstechnischen Ungleichgewicht zwischen Einnahmen und Rentenzahlungen im Altersrentensystem der sozialen Sicherheit. Als Reaktion auf dieses Ungleichgewicht schlug Präsident George W. Bush im Jahr 2004 vor, das Verfahren zur Berechnung der Renten der sozialen Sicherheit zu ändern und im Rahmen der sozialen Sicherheit individuelle Investmentkonten einzurichten. Die Frage wurde intensiv debattiert, aber Mitte 2005 wurde es wieder still darum. Was von der Debatte 2004‐05 bleibt, sind die Grenzen, die künftigen Optionen zur Behandlung von Finanzproblemen des Programms der sozialen Sicherheit gesteckt sind. Der vorliegende Artikel beschreibt diese Zwänge, die zusammengenommen das neue ordnungs‐politische “Korsett” für künftige Debatten über das Altersrentenprogramm der sozialen Sicherheit in den Vereinigten Staaten bilden.
Fiktive Konten im Festbeitragssystem (NDC): Zahlungsfähigkeit und Risiken in Spanien
Authors: Boado‐Penas María del Carmen , Domínguez‐Fabián Inmaculada , Vidal‐Meliá Carlos
Published: September 2010

Diese Arbeit verfolgt ein doppeltes Ziel: Einerseits das versicherungsmathematische Ungleichgewicht des spanischen Rentensystems in seiner derzeitigen Gestalt aufzuzeigen; andererseits zu messen, welchem wirtschaftlichen Gesamtrisiko die Rentner ausgesetzt wären, wenn die Altersrenten auf der Basis von fiktiven Konten ermittelt würden. Das Modell arbeitet mit Szenarien für verschiedene Zeiträume und mit bis zu 10 000 veränderlichen Faktoren der Gesamtwirtschaft, um Parameter wie die Anfangsrente, die Ersatzquote (EQ) oder den internen Zinsfuß (IRR) und den Value at Risk (VaR) zu errechnen. Die Ergebnisse werden objektiv, aber auch subjektiv analysiert. Laut den wichtigsten Schlussfolgerungen würden sich im Rentensystem, wenn die Prognosen der verwendeten gesamtwirtschaftlichen Indikatoren nur im Geringsten realitätsnah sind, künftig ein solches finanzielles Ungleichgewicht ergeben, dass entweder eine deutliche Senkung der Anfangsrente oder eine Kombination von strikten Parameteranpassungen nötig würde. Bezogen auf die Risikobereitschaft, würden Leistungsempfänger mit geringer Risikobereitschaft eine Variante wählen, die unabhängig von den künftigen Schwankungen der Löhne eine real konstante Rente garantiert; während Leistungsempfänger mit höherer Risikobereitschaft Formeln bevorzugen würden mit einer geringeren Anfangsrente, die jedoch mit der künftigen Lohn‐entwicklung steigt.
Beurteilung der Geschlechterungleichheit im türkischen Rentensystem
Authors: Elveren Adem Y.
Published: September 2010

Auszug  Seit den 1990er Jahren wurde das Wohlfahrtsregime in der Türkei stärker marktwirtschaftlich ausgerichtet. Die Einführung des Individuellen Rentensystems (IRS), eines privat verwalteten Systems mit Beitragsprimat, ist ein Bestandteil dieser Entwicklung. In diesem Artikel wird ein autoregressives stochastisches Modell verwendet, um die Gesamtauswirkungen bestimmter Benachteiligungen auf die Rentenleistungen von Frauen in der Türkei aufzuzeigen. Zu diesen Benachteiligungen zählen ein kürzeres Erwerbsleben, geringerer Verdienst, längere Lebenserwartung, Reallohnwachstum, Verwaltungskosten und Risikoaversion. Mit der Analyse der geschlechtsspezifischen Unterschiede im türkischen beitragsbezogenen System versteht sich der Artikel, der ein versicherungsmathematisches Modell verwendet, als Beitrag zur Diskussion.
Charges for Oral Health Care During a Period of Economic Growth in the US: 1987‐96
Authors: Chattopadhyay Amit , Slade Gary D. , Shugars Daniel A.
Published: September 2010

Objectives: This study aimed to provide estimates of amounts charged for dental care during 1996 for the US adult population and its major sociodemographic subgroups, and to evaluate whether charges had increased since 1987. Methods: We used data from the 1996 Medical Expenditures Panel Survey and report results for 12,931 adults aged 19‐64 years. For comparison with previously published charges, we converted 1987 charges to their 1996 “constant dollar” value to control for inflation. Data were analyzed using SUDAAN and the results can be generalized to the US adult population. Results: In 1996, 43.) percent (95% CI=42.7%, 44.6%) of the US population incurred dental cart charges, which did not differ significantly from the 1987 estimate of 44.5 percent In 1996, mean per capita charge for dental care was $182 (95% CI=$171, $192) which did not differ significantly from the inflation‐adjusted 1987 estimate of $174 The average charge per patient who incurred charges in 1996 was $416 (95/, CI=$394, $438), which was only 7 percent greater than the inflation‐adjusted 1987 estimate of $389 (P=.08). Sociodemographic variations were observed in per capita charges, but were less apparent in mean charge per patient who incurred charges. Conclusions: During a period when economic growth and other market forces were expected to increase delivery of dental services, there was little or no change in percentage of US adults incurring charges or in mean per capita charges. The booming US economy did not raise dental charges significantly and did not increase utilization of dental care services.
Oral Cancer Examinations Among Adults at High Risk: Findings from the 1998 National Health Interview Survey
Authors: Macek Mark D. , Reid Britt C. , Yellowitz Janet A.
Published: September 2010

Objectives: Cigarette smoking and alcohol use are risk factors for oral and pharyngeal cancer. Recommendations for periodic oral cancer examinations highlight the importance of examining high‐risk smokers and alcohol users. This investigation assessed whether cigarette smoking and alcohol use were associated with receipt of an oral cancer examination. Methods: The cross‐sectional 1998 National Health Interview Survey was used. Covariates included age, sex, race/ethnicity, poverty status, and geographic region. Weighted bivariate and multivariate analyses were stratified by dentition status and limited to adults aged >40years. Results: Regardless of dentition status, current smokers werenomore likely to have received an examination than were never smokers. The associations between alcohol use and receipt of an examination were mixed, and were generally more favorable among those who had a dental visit in the last year. Dentate current and former alcohol users were more likely than abstainers to have received an examination. There was no statistically significant association between alcohol use and receipt of an oral cancer examination among edentulous adults. Conclusions: Practitioners should improve the provision rates of oral cancer examinations in accordance with published guidelines, especially among current smokers and edentulous alcohol users who have not been to the dentist in the last year. Recommendations for improvement are presented.
Enamel Fluorosis Prevalence after a 7‐year Interruption in Water Fluoridation in Jaú, São Paulo, Brazil
Authors: Buzalaf Manila A. R. , de Almeida Beatriz S. , Olympic Kelly P. K. , Cardoso Vanessa E. da S. , Peres Sílvia H. de C. S.
Published: September 2010

Objectives: This paper analyzes the impact of a 7‐year interruption in water fluoridation on the prevalence of enamel fluorosis in Jaú, state of São Paulo, Brazil. Methods: Fluorosis prevalence (TF index) was evaluated in permanent maxillary central incisors of children (9–14 years old) that were 36 (n=81; cohort ‐36), 27 (n=81; cohort ‐27), and 18 months old (± 1 month; n=89; cohort—18) in October 1991, when the break started, and 18 months old (± 1 month; n=70; cohort 18) after that date. Children brushed their teeth prior to examination, which was conducted under natural light by three calibrated examiners (agreement 87.8–93.8%, kappa 0.72–0.85). Results: The fluorosis prevalence (TF≥1) was 7.41 percent, 3.70 percent, 7.87 percent, and 18.57 percent, respectively, for cohorts ‐36, ‐27, ‐18, and 18. The difference between cohort 18 and the other groups was statistically significant (Kruskall‐Wallis test, P=.05). Conclusions: These results suggest that the fluoridated water is not an important risk factor for enamel fluorosis, since the prevalence of enamel fluorosis was low in the cohorts ‐36, ‐27, and ‐18 when fluoridated water was used. [J Public Health Dent 2004;64(4):205–8].
Past and Present Geographic Location as Oral Health Markers Among Older Adults
Authors: Adut Rina , Mann Jonathan , Sgan‐Cohen Harold D.
Published: September 2010

Objectives: This study evaluated the association between oral health status of community‐dwelling elderly adults visiting day health centers in Israel and geographic living location. Methods: Oral status was assessed through clinical examination, with additional data obtained using a questionnaire addressing demographic characteristics, dental utilization, and perceived oral health needs. Results: A representative sample of 338 subjects was examined. Fifty‐four percent of the sample was edentulous. Higher rates of edentulism were found among subjects living in urban areas compared to subjects living in rural areas (P <.01). More edentate subjects were found among European immigrants than among immigrants from North Africa or subjects born in Israel (P <.01). Among dentate subjects, the mean number of remaining teeth was 10.4. The mean periodontal loss of attachment was 5.8 mm. Less than 10 percent had mean attachment loss < 4 mm. Among subjects living in rural areas, mean attachment loss was higher than among those living in urban areas (P /.05). The mean DF score was 1.9. Forty‐seven percent had at least one tooth with untreated caries. Subjects living in urban areas tended to utilize dental services more than subjects living in rural areas (P <.01). Conclusion: Results indicate that present (urban or rural) and past (country of origin) geographic location represented a significant oral health risk marker. The implementation of a comprehensive program for this target population was clearly indicated.
Deposition of Potash‐Magnesium Salts in the Qarhan Playa, Qaidam Basin
Authors: Bihao Wu , Zhenghao Duan , Yuhua Guan , Wei Lian
Published: September 2010

Abstract The Qarhan potash‐magnesium salt deposit, which consists from east to west of four playa districts, namely Huobuxun, Qarhan, Dabuxun and Bieletan, may be divided from bottom to top into three salt beds (S1 S2 and S3), with potash salts mainly occurring in S3 The paper lays emphasis on the evolutionary history of the deposition of Salt Bed S3 and the modes of formation of potash salts in the Qarhan playa.

The analysis of the data obtained from more than 170 boreholes and the geochemical studies on bromine, magnesium and calcium reveal the existence of four concentration stages and three dilution stages during the formation of the Upper Salt Bed S3. In the process of concentration, evaporation of brine and precipitation of salt minerals dominated, which obeyed the regularity indicated by the phase diagram of the quaternary system Mg‐Na‐K/Cl−H2O. In the dilution stages, however, mixing of brines, dissolution of salts (especially the playa) and mechanical clastic deposition played the leading role. The prerequisite for mixing in the Qarhan salt deposit lies in that chloride type brine of the northeastern part coexists with magnesium sulfate type brine of the southwestern part in the same salt lake. The appearance of bassanite has verified the process of mixing. The dissolution refers to the partial dissolution of the salt beds originally deposited. Particularly in the last dilution process, approximately 200 km2 of the playa north of the Tuanjie Lake had been dissolved before a new‐born lake took form.

Solid potash salts were formed in three ways: (1) The surficial brine of the Dabuxun lake coexistent with the playa had an intercompensational relationship with the intercrystalline brine in the playa. As a result, K+ ions were collected into the lake, and layered carnallite precipitated from lake brine during the seasons of evaporation, which was accelerated by the action of wind. (2) Disseminated potash‐magnesium salts were formed by further concentration of intercrystalline brine. (3) Dissolution and reformation of the playa resulted in the formation of a new‐born salt lake, in the drying of which brine collected the potash‐magnesium salts originally dispersed over the playa into local low‐lying areas, forming finally stratoid potash‐magnesium salts.
Basic Characteristics of the Earth's Temperature Distribution in Southern China
Authors: Jun Wang , Shangyao Huang , Geshan Huang , Jiyang Wang
Published: September 2010

Abstract Sourthern China referred to in this paper embraces all the provinces to the south of latitude 32° N within the territory of China, exclusive of Tibet and Taiwan.

The paper is based on the data obtained from temperature measurements of 680 boreholes drilled for petroleum, coal and hydrogeology. The depth of these boreholes ranges between 1,000 and 2,000 m in most cases, being generally not less than 400 m and reaching 7,000 m in maximum.

Through the elaboration and analysis of the temperature data, isotherm maps showing the temperatures at depths of 1,000 m, 2,000 m and 3,000 m respectively and a geothermal gradient map of southern China have been compiled. These maps indicate that the earth's temperature distribution in southern China is characterized by a relatively low value in areas of its central part and those to the west of the Anning River valley of the western part (30°C, 40°C and 70°C at depths of 1,000 m, 2,000 m and 3,000 m respectively), and a comparatively high value in the southeastern coastal areas and western Yunnan (60°C, 80°C and over 120°C respectively), and that the geothermal gradient also increases from less than 1.5°C/100 m in the central part towards both the east and the west to 2.0‐3.0°C/100 m or even over 4.0°C/100 m.

The earth's temperature distribution is strictly controlled by the deep structure of the earth's crust and is very closely related to the character of the regional geological structure. The stable central areas remarkably differ in the earth's temperature distribution from the tectonically active areas such as the southeastern coastal areas and the Jinggu‐Tengchong area in western Yunnan, the former being Jower than the latter. Meanwhile, due to the well‐developed karst features in southern China, the strong groundwater flow may exert certain cooling effect on the temperature down to a depth of about 1,500 m.

According to the regularity of the earth's temperature distribution, regional deep structure of the earth's crust, regional geological structure and hydrogeological conditions, the following four models are proposed to explain the mechanism of formation and distribution of the earth's temperature fields in southern China: 1) conduction type; 2) convection type; 3) deep heat‐source conduction‐convection type; and 4) precipitation infiltration cooling type.
On the Post‐Variscan Global Tectonic Stages
Authors: Jishun Ren
Published: September 2010

Abstract

After the Variscan Cycle, the global tectonic framework underwent three major adjustments. The first occurred in the Late Triassic‐initial Jurassic, the second in the Late Jurassic‐early Early Cretaceous and the third in the Late Cretaceous‐Eogene. On that basis, the post‐Variscan tectonic history is divided into three tectonic cycles—the Indosinian, Yanshanian and Himalayan Cycles. The post‐Neocom ( k11 ) and pre‐Aptian ( k21) tectonic movement marks the end of the Yanshanian orogeny in eastern China and the initiation of the subduction of the Tethyan ocean in western China and represents the boundary between the Yanshanian and Himalayan Tectonic Cycles.
Stable Isotope Geochemistry of the Beishan Stratabound Sphalerite‐Pyrite Deposit, Guangxi
Authors: Haoshou Chen , Hong Lü , Huangqi Shi , Xiangchang Wang
Published: September 2010

Abstract

Based on lead isotope data, it has been shown that lead in the Beishan stratabound sphalerite‐pyrite deposit came mainly from the oldland and its underlying basement rocks and, subordinately, the Devonian itself or the sea water at that time. As to its primary source, upper crust lead was predominant, while lower crust lead or upper mantle lead was subordinate. Sulfur was formed mainly through bacterial reduction of marine carbonates. The carbon and oxygen isotopic analyses for carbonate rocks and minerals have demonstrated that carbonate rocks in the Beishan area are normal marine sediments. The isotopic characteristics of the carbonate rocks are intermediate between those of the northern Guangdong and central Hunan, but closer to those of the central Hunan basin. The formation of the Beishan deposit underwent: a depositional‐diagenetic mineralization stage and a successive post‐diagenetic enrichment‐remoulding one.
The Instability of Philosophical Intuitions: Running Hot and Cold on Truetemp
Authors: SWAIN STACEY , ALEXANDER JOSHUA , WEINBERG JONATHAN M.
Published: September 2010

A growing body of empirical literature challenges philosophers’ reliance on intuitions as evidence based on the fact that intuitions vary according to factors such as cultural and educational background, and socio‐economic status. Our research extends this challenge, investigating Lehrer’s appeal to the Truetemp Case as evidence against reliabilism. We found that intuitions in response to this case vary according to whether, and which, other thought‐experiments are considered first. Our results show that compared to subjects who receive the Truetemp Case first, subjects first presented with a clear case of knowledge are less willing to attribute knowledge in the Truetemp Case, and subjects first presented with a clear case of non‐knowledge are more willing to attribute knowledge in the Truetemp Case. We contend that this instability undermines the supposed evidential status of these intuitions, such that philosophers who deal in intuitions can no longer rest comfortably in their armchairs.
Protein kinase G‐dependent mechanisms modulate hypoglossal motoneuronal excitability and long‐term facilitation
Authors: Saywell Shane A. , Babiec Walter E. , Neverova Natalia V. , Feldman Jack L.
Published: September 2010

Since protein kinase‐dependent modulation of motoneuronal excitability contributes to adaptive changes in breathing, we hypothesized that cGMP‐dependent pathways activating protein kinase G (PKG) modulate motoneuronal inspiratory drive currents and long‐term plasticity. In a medullary slice preparation from neonatal rat (postnatal days 0–4) generating spontaneous respiratory‐related rhythm, hypoglossal (XII) motoneuronal inspiratory drive currents and respiratory‐related XII nerve activity were recorded. Focal application of a PKG activator, 8‐bromoguanosine‐3′,5′‐cyclomonophosphate (8‐Br‐cGMP), to voltage‐clamped XII motoneurones decreased inspiratory drive currents. In the presence of tetrodotoxin (TTX), 8‐Br‐cGMP decreased the exogenous postsynaptic inward currents induced by focal application of AMPA. Intracellular dialysis of XII motoneurones with an inhibitory peptide to PKG (PKGI) increased endogenous inspiratory‐drive currents and exogenous AMPA‐induced currents. Application of 8‐Br‐cGMP with PKGI had no further effect on spontaneous or evoked currents, confirming that the observed effects were induced by PKG. However, PKG differentially increased longer‐term plasticity. Three 3 min applications (separated by 5 min) of the α1‐adrenergic agonist phenylephrine (PE) in combination with 8‐Br‐cGMP yielded greater in vitro long‐term facilitation than PE alone. These data indicate the presence of a cGMP/PKG‐dependent signalling pathway in XII motoneurones that modulates inspiratory drive currents and plasticity of XII motoneurones, possibly contributing to their adaptation during physiological challenges, such as sleep and exercise.
Experimental Investigation on the Heat Transfer of a Leading Edge Impingement Cooling System for Low Pressure Turbine Vanes
Authors: de la Calzada Pedro , Alvarez Jose Javier
Published: September 2010

Impingement cooling through jet holes is a very attractive cooling system for heat rejection at high heat loaded areas as the leading edge of turbine vanes. Although some correlations and tools are available to dimension such systems, the variety and complexity of the flow features present in those systems still require experimental validation of real engine designs. Among the experimental techniques possible to be used, transient liquid crystal method offers good resolution as well as sufficient accuracy. Under this investigation, an impingement cooling system for the leading edge of a contrarotating power turbine (PT) representative of a small turboshaft engine was investigated experimentally. The PT vane features a very thin leading edge with high curvature and side channels rapidly turning backward. Constraints on cooling flow consumption and distribution led to a leading edge configuration with two rows of staggered jets. This particular configuration was experimentally investigated for three different Reynolds numbers around the design point by using a transient liquid crystal technique, which allows the measurement of surface distribution of heat transfer coefficient at the area of interest. Heat transfer results are presented in terms of surface distributions, impingement rows stagnation line local distributions, streamwise distributions along planes over the impingement stagnation points, span averaged streamwise local distributions, and surface averaged values. These results are then compared with available correlations from existing literature showing good matching for both maximum and averaged values. The results are also used as baseline data to discuss some of the flow features that can have effect on the heat transfer on this particular configuration.
Modeling and Characterization of Micro Optofluidic Lenses With Short Focal Length
Authors: Song Chaolong , Nguyen Nam-Trung , Asundi Anand Krishna
Published: September 2010

In this paper, fluidic models of liquid-core liquid-cladding lens formed in a circular chamber are reported. The models cover two cases: the circular chamber is symmetrical and asymmetrical to the channel axis. Experiments were also carried out to verify our models. The results agree well with the theoretical analysis. The test device with a circular lens chamber with 1-mm diameter and 100-μm height was fabricated in PDMS. The design of a circular chamber is demonstrated to develop a perfect arc shape of the lens interface, which can be mathematically pre-defined. The focusing abilities of lens formed in these two different geometries are compared. We found that the asymmetrical design, in which the channel is offseted from the axis of chamber, can develop a lens with shorter focal length. This design has an important significance for on-chip focusing.
Water Based Multiwalled Carbon Nanotube Nanofluids With Optimized Thermal Conductivity
Authors: Chen Li Fei , Xie Huaqing , Yu Wei , Li Yang
Published: September 2010

We report a method to prepare surfactant-free water based nanofluids containing multi-walled carbon nanotubes (CNTs). The as prepared CNTs with hard dispersibility, after being cut by mechanical ball-milling approach following strong acid treatment, can be directly dispersed into water. The thermal conductivity of the nanofluids is optimized by controlling the CNT length and straightness. It is realized by changed the ball-milling times. The thermal conductivity enhancement of water based CNT nanofluids with volume fraction of 1% attains 29.5% by controlling the CNT length and straightness when the temperature is 63.9°C.
A Honeycomb Micro Channel Cooling System for Electronics Cooling
Authors: Luo Xiaobing , Liu Yonglu , Liu Wei
Published: September 2010

A honeycomb porous micro channel cooling system for cooling of electronic chips is proposed in this paper. The design, fabrication, test system configuration of the micro channel heat sink is summarized. Preliminary experimental investigation is conducted to determine the heat transfer characteristics and cooling performance under steady single-phase flow of water liquid. In the experiments, the brass micro channel heat sink is attached to a test heater with 8cm2 area, the experimental results show that the cooling system can effectively remove the heat flux of 18.2W/cm2 under 2.4W pumping power, while the junction-wall temperature is 48.3°C at the room temperature of 26°C. The experimental results show that the present cooling system has good performance.
Gaseous Bubble Nucleation Under Shear Flow
Authors: Kwak Ho-Young , Kang Ki-Moon
Published: September 2010

A decompression experiment of a water solution, saturated with methane gas at about 68 atm at room temperature, was done to investigate gas bubble nucleation under shear flow. A pressure reduction from 68 atm to atmospheric pressure is well below the decompression pressure required for spontaneous bubble nucleation of the methane gas, about 120 atm. The application of a shear flow from 5 minutes before to 1 minute after the decompression induced active bubble formation and the final gas content in the solution was reduced substantially, even with the application of low shear rate of 25/s.
Study on Boiling Heat Transfer in Narrow Channel and Horizontal-Narrow-Flat Space
Authors: Koizumi Yasuo , Ohtake Hiroyasu , Oshikawa Takaaki
Published: September 2010

Boiling heat transfer experiments were preformed for narrow-horizontal-channels at 0.1 MPa. Test fluid was ethanol. The height and the width of the test channels were in a range of 1.0 mm ∼ 4.0 mm and 1.0 mm ∼ 3.0 mm, respectively. The channel length was 30 mm and 60 mm. The boiling surface was at the center of the bottom wall of the flow channel. Both ends of the channel were opened to wide space filled with liquid. Pool boiling experiments for the small heat transfer surfaces of the diameter of 1.0 mm ∼ 20.0 mm were also performed. Following conclusions were obtained. As the diameter of the boiling surface became small in pool boiling, boiling heat transfer was enhanced and the critical heat flux increased. The relation between the boiling heat flux and the wall superheat in the narrow rectangular channel was the same as that of the pool boiling for the same heat transfer surface size. As the channel height became narrow, the critical heat flux became low. In the case of the narrow-rectangular channel, large-coalescent bubbles occupied the top part of the flow channel. When the large bubble reached one outlet of the channel, almost all coalescent bubbles in the channel left from the outlet. After the selective departure of bubble from a specific outlet had established, the small reverse-inclination of the flow channel had no effect to alter the bubble departure outlet. It was suggested that the considerable steady-circulation flow had established. The CHF condition was not given only by the mass balance that the liquid supply to the channel was equal to the vapor generation rate. It was suggested that other effects such as the circulation flow should be included into the consideration for the CHF condition.
Novel Inorganic Polymer Derived Microfluidic Devices: Materials, Fabrication, Microchemical Performance
Authors: Li Ming , Yoon Tae-Ho , Kim Dong-Pyo
Published: September 2010

We introduce the successful fabrication of inorganic polymer derived microchannels with organic solvent resistance and optical transparency, via economic micro-molding process by using two types of source materials: commercial polyvinylsilazane (HTT1800 Kion Corp.), or allylhydropolycarbosilane (SMP-10, Starfire Co.). And we demonstrated the reliable microchemical performance in various organic solvents such as THF, DMF and acetonitrile at elevated temperatures. Knovenagel and Diels-Alder reactions were successfully run by pressured-driven flow in 2 cm and 16 cm long channel, respectively. It is proven that the developed inorganic polymer-based microchannels were obviously performed as a niche material-based microfluidic device between plastic and glass based device. In addition, we present the fabrication and characterization of ceramic microreactors composed of inverted beaded silicon carbide (SiC) monoliths with interconnected pores as catalyst supports, integrated within high-density alumina housings obtained via an optimized gel-casting procedure. These tailored macroporous SiC monoliths deposited Ru as a catalyst was run for the decomposition of ammonia with at temperatures between 450 and 1000 °C, which demonstrated a high temperature fuel cell reformer.
Microchannel Emulsification Devices for Generating Highly Uniform Droplets
Authors: Kobayashi Isao , Nakajima Mitsutoshi
Published: September 2010

Monodisperse emulsions consisting of uniform droplets have received a great deal of attentions over the past decade due to their high-tech applications, e.g., monodisperse microparticles as spacers for electronic devices and monodisperse micro-carriers for drug delivery systems (DDS). Our group proposed microchannel (MC) emulsification, which enables generating highly uniform droplets with the smallest coefficient of variation of below 5% using MC arrays of unique geometry. The resultant droplet size can be precisely controlled by MC geometry. Droplet generation for MC emulsification is very mild and does not require any external shear stress; a dispersed phase that passed through MCs is transformed spontaneously into uniform droplets inside a continuous-phase domain. The aim of this paper is to present recent developments in MC emulsification devices, particularly focusing on straight-through MC arrays consisting of uniform straight-through holes for large-scale production of monodisperse emulsions. A straight-through MC array device of a standard 24 × 24-mm size was made of single-crystal silicon, and a straight-through MC array consisting of numerous MCs was positioned within a 10 × 10-mm central region of the device. We initially designed symmetric straight-through MCs with circular and oblong sections. Highly uniform droplets with average sizes of 4 to 100 μm were generated using oblong straight-through MCs. The simulation results using CFD (computational fluid dynamics) agreed well with the experimental results and provided useful information, such as the movement of the oil-water interface around the MC outlet during droplet generation. Below the critical value of the dispersed phase flux, monodisperse emulsions were produced via suitable oblong straight-through MCs, with droplet size and size distribution independent of the flux value. The development of asymmetric straight-through MC arrays consisting of numerous pairs of microslots and circular MCs improved the productivity of highly uniform droplets and stability during droplet generation.
Liquid Film Thickness in Micro Tube Under Flow Boiling Condition
Authors: Han Youngbae , Shikazono Naoki
Published: September 2010

Slug flow is one of the representative flow regimes of flow boiling in micro tubes. It is well known that the thin liquid film formed between the tube wall and the vapor bubble plays an important role in micro scale heat transfer. In the previous study [1], liquid film thickness under adiabatic condition was investigated and an empirical correlation for the initial liquid film thickness based on capillary number, Reynolds number and Weber number was proposed. In the present study, the effects of wall superheat and bubble acceleration on the liquid film thickness are investigated. Under flow boiling condition, bubble velocity is not constant but accelerated, and it is necessary to consider this acceleration effect on the liquid film thickness, since it may affect the viscous, surface tension and inertia forces in the momentum equation. In addition, viscous boundary layer develops, and it may also affect the liquid film thickness. Besides, viscosity and surface tension coefficient are sensitive to temperature change. If wall superheat is high, it is crucial to consider the property change according to the temperature variation. In order to investigate these effects, laser focus displacement meter is used to measure the liquid film thickness. Ethanol, water and FC-40 are used as working fluids. Circular tubes with three different diameters, D = 0.5, 0.7 and 1.0 mm, are used. It is observed that when the wall superheat is larger than 5°C, liquid film thickness becomes thinner than the adiabatic case due to the decrease of viscosity near the wall. The increase of liquid film thickness with capillary number is restricted by bubble acceleration. Finally, an empirical correlation is proposed for accelerated flows in terms of capillary number and Bond number based on bubble acceleration.
DSMC Simalation of the Pressure and Temperature Driven Flows: Comparison With the Measurements
Authors: Ewart Timothe´e , Graur Irina A. , Firpo Jean-Luc , Polikarpov Alexey , Perrier Pierre , Me´olans J. Gilbert
Published: September 2010

A DSMC solver, adapted to the subsonic micro flow, is developed under the object-conception language (C++). Some technical details critical in these DSMC computations are provided. The numerical simulations of gas flow in micro channel are carried out using developed DSMC solver. Streamwise velocity distributions in the slip flow regime are compared with the analytical solution based on the Navier-Stokes equations with the velocity slip boundary condition. Satisfactory agreements have been achieved. Furthermore, the domain of the validity of this continuum approach is discussed. Simulations are then extended to transitional flow regime. Streamwise velocity distributions are also compared with the results of the numerical solutions of the linearized Boltzmann equation. We emphasize the influence of the accommodation coefficient on the velocity profiles and on the mass flow rate. The simulation results on the mass flow rate are compared with the experimental data, that allow us to validate the “experimental” technique of the determination of the accommodation coefficient.
Liquid-Liquid Extraction Based on Digital Microfluidics
Authors: Moon Hyejin , Kunchala Praveen , Nanayakkara Yasith , Armstrong Daniel W.
Published: September 2010

Liquid-liquid extraction techniques are one of the major tools in chemical engineering, analytical chemistry, and biology, especially in a system where two immiscible liquids have an interface solutes exchange between the two liquid phases along the interface up to a point where the concentration ratios in the two liquids reach their equilibrium values [1]. In this paper, we propose to use room temperature ionic liquid (RTIL) as a second liquid phase for extraction, which forms immiscible interface with aqueous solutions. We demonstrate liquid-liquid extraction with the EWOD digital microfluidic device, two model extraction systems were tested. One is organic dye extracted from RTIL(1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide or BMIMNTf2) to water and the other is iodine (I2) extracted from water to BMIMNTf2. Droplets of aqueous solution and BMIMNTf2 solution were generated on chip reservoir then transported for extraction and separated by EWOD actuation successfully.
An Experimental Investigation of Liquid Plug Flows in Polymeric Mini-Channels
Authors: Bhagavati Venkataramana Anant , Heiskanen Valtteri , Kallio Pasi
Published: September 2010

An accurate characterization of pressure driven flow in micro and mini-channels is essential for the design and development of passive-control based microfluidic systems. Polymeric cartridges are especially attractive for this purpose, due to their ease of fabrication and lower cost. The aim of this paper is to experimentally characterize liquid-plug flows in polymeric mini-channels at low velocities (< 2 mm/s) for potential applications in the development of Point-of-Care applications. This paper presents the characterization of the laminar flow behavior of liquid plugs in straight rectangular mini-channels fabricated from four different materials with inner hydraulic diameters ranging from 200 to 350 μm. The mini-channels were fabricated from Poly-Methylmethacrylate (PMMA), Polycarbonate (PC), and Methyl Methacrylate Acrylonitrile-Butadiene Styrene (MABS) using mechanical milling and from Polystyrene (PS) using injection molding All the tests in this study were performed with deionized water (DI) and an external pressure source (syringe pump) was used for actuation. The dynamic contact angles (DCA) of the front and rear menisci of liquid plugs were recorded in real time along with the experimental pressure-drop across the liquid plug(s) (ΔPexp) and the mean flow velocity of the liquid plug (V). The results are compared with a theoretical model which takes into account the surface-tension (capillary) forces and the hydrodynamic (viscous) forces acting on the liquid plug(s). The maximum error-margin between the experimentally measured values of the pressure-drop across the liquid plug (ΔPexp) and the theoretical values (ΔPth), is 13% among all the experiments in this study.
Nanostructuring Curved Surfaces Using a Flexible Stamp
Authors: Farshchian Bahador , Lee JaeJong , Park Sunggook
Published: September 2010

We report on a simple and effective process that allows direct imprinting of micro- and nanostructures on non-flat surfaces. A thin polydimethylsiloxane (PDMS) stamp having micro/nanogratings was placed between a metallic bar with a trapezoidal cross section or a metallic pellet and a flat polymethyl methacrylate (PMMA) substrate, followed by hot embossing at 200°C. During the hot embossing process, the metallic bar/pellet is pushed into the PMMA sheet forming a millimeter scale channel or a curved surface. Due to the presence of the PDMS stamp between the metallic object and the substrate, micro/nanostructures are produced into the channel or over the curved surface. With this method, we have successfully demonstrated micro- and nanostructures down to 300 nm wide gratings on non-flat substrates, as confirmed by scanning electron microscopy and atomic force microscopy. The process so developed will fill the gap in current micro- and nanofabrication technologies in that most of the technologies allow for patterning only on planar substrates.
Shock Wave Propagation and Spallation Study in Laser Shock Peening
Authors: Cao Yunfeng , Shin Yung C.
Published: September 2010

This paper deals with the spallation induced by shock wave propagation in targets during the laser shock peening process. Physical aspects concerning laser-matter interaction, shock wave propagation, and spallation are considered. A continuous kinetic model for the spallation process is included in a one-dimensional finite difference hydrodynamic code using Lagrangian coordinates in order to calculate the laser-induced spallation phenomena. Shock wave propagation in solids is calculated and validated by experimental data. The spallation zone location is then calculated for various materials with different thickness of foils and various laser shock peening parameters. The numerical simulations are compared with previously reported experimental results, and good agreement is obtained for the spallation threshold and damage zone location.
Formability Assessment in Stamping Die Face Morphing Using Strain Increment Method
Authors: Zhou Liang , Hu S. Jack , Stoughton Thomas B.
Published: September 2010

A strain increment method has been proposed for early formability assessment by predicting strain distribution directly from the part-to-part mapping process. This method consists of mapping the finite element mesh to the geometry of an existing part, solving the part-to-part mapping relation by adding bending energy and strain gradient penalty functions, and extracting strain increment from the part-to-part mapping related displacement field. Case studies show that the strain field obtained using the proposed strain increment method compares well with that from the finite element analysis. Since this method does not require the knowledge on new die surface, such formability assessment can serve as an early manufacturing feasibility analysis on the new part design.
Energy Pulse Modification of Electronic Materials: From Electronics via Photonics to Other Advanced Materials
Authors: Skorupa Wolfgang , Anwand Wolfgang , Gebel Thoralf
Published: September 2010

Regarding electronic materials there is a clear and increasing interest in energy pulse modification of materials, especially also thermal processing far below one second, i.e. the lower limit of RTP (Rapid Thermal Processing) called spike annealing. It is the world of processing in the millisecond or nanosecond range. In the past, this was mainly driven by the need of suppressing the so-called Transient Enhanced Diffusion for advanced boron-implanted shallow pn-junctions in the front-end silicon chip technology. Meanwhile the interest in flash lamp annealing (FLA) in the millisecond range spread out into other fields than just “classical” silicon electronics. This paper reports shortly about the restart in flash lamp annealing and further on recent experiments regarding shallow junction engineering in germanium and SOI (silicon-on-insulator), annealing of ITO (Indium Tin Oxide) layers on glass and plastic foil interesting for low cost electronics as well as investigations which we did during the last years in the field of wide band gap semiconductor materials (SiC, ZnO). Moreover recent achievements in the field of silicon-based light emission basing on Metal-Oxide-Semiconductor Light Emitting Devices will be reported. Finally it will be demonstrated that the basic principle of short time thermal processing, i.e. surface heating on a colder bulk, features also advantages regarding the casting of lead sheets to produce organ pipes in the spirit of the 17th century.
The Impact of Surface Forces on Particle Flow and Pore Blocking in the Microfiltration of Metalworking Fluids
Authors: Ham Seounghyun , Wentz John E. , Kapoor Shiv G. , DeVor Richard E.
Published: September 2010

Microfiltration is an in-process recycling method that shows great potential to extend fluid life and reduce bacterial concentrations in synthetic and semi-synthetic metalworking fluids (MWFs). The primary problem facing this use of microfiltration is membrane fouling, which is the blocking of membrane pores causing reduced flux. In this paper a fluid dynamic model of partial and complete blocking in sintered alumina membranes is developed that includes hydrodynamic, electrostatic, and Brownian forces. Model simulations are employed to study the impact of electrostatic and Brownian motion forces on the progression of partial blocking. The simulations also examine the effects of fluid velocity, particle size, and particle surface potential. The inclusion of electrostatic and Brownian forces is shown to significantly impact the progression of the partial blocking mechanism. The addition of a strong inter-particle electrostatic force is shown to eliminate the partial blocking build-up of small particles due to the presence of the repulsive forces between the particles. As a result, the time to complete blocking of the test pore was lengthened, suggesting that flux decline is reduced in the presence of electrostatic forces. Brownian motion is shown to have a large impact at low fluid velocities. The most effective parameter set is a low fluid velocity, small particle sizes, high microemulsion surface potential, and high membrane surface potential.