3,816 research outputs found

    Method and apparatus for producing microshells

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    A method is described for forming hollow particles, or shells, of extremely small size. The shell material is heated to a molten temperature in the presence of a gas that is at least moderately soluble in the shell material, to form a solution of the molten shell material and the soluble gas. The solution is atomized to form a multiplicity of separate droplets that are cooled while in free fall. Cooling of a droplet from the outside traps the desolved gas and forces it to form a gas bubble at the center of the droplet which now forms a gas filled shell. The shell is reheated and then cooled in free fall, in an environment having a lower pressure than the gas pressure in the shell. This causes expansion of the shell and the formation of a shell having a small wall thickness compared to its diameter

    Thermodynamically consistent versions of approximations used in modelling moist air

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    Some existing approaches to modeling the thermodynamics of moist air make approximations that break thermodynamic consistency\textit{thermodynamic consistency}, such that the resulting thermodynamics do not obey the 1st and 2nd laws or have other inconsistencies. Recently, an approach to avoid such inconsistency has been suggested: the use of thermodynamic potentials\textit{thermodynamic potentials} in terms of their natural variables\textit{natural variables}, from which all thermodynamic quantities and relationships are derived. In this paper, we develop this approach for unapproximated\textit{unapproximated} moist air thermodynamics and two widely used approximations: the constant Îș\kappa approximation and the dry heat capacities approximation. The consistent constant Îș\kappa approximation is particularly attractive because it leads to, when using virtual potential temperature Ξv\theta_v as the thermodynamic variable, adiabatic dynamics that depend only on total mass, independent of the breakdown between water forms. Additionally, a wide variety of material from different sources in the literature on thermodynamics in atmospheric modelling is brought together. It is hoped that this paper provides a comprehensive reference for the use of thermodynamic potentials in atmospheric modelling, especially for the three systems considered here.Comment: 22 page

    Reproductive Biology and Population Structure of the Plains Minnow, Hybognathus Placitus (Pisces: Cyprinidae), in Central Oklahoma

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    The main objective of this study was to describe several aspects of the life history of the plains minnow, Hybognathus placitus. This fish is small, not particularly attractive, and possesses no economic value, other than its occasional use as a bait fish. Like many other of our native, nongame fishes, it is not well known to the general public (if at all). However, plains minnows are an integral part of many prairie river ecosystems. In many rivers they are (or used to be) an extremely abundant species, providing a large forage base for "game species" and other piscine predators, as well as avian predators. Recently (the last 40 years or so), plains minnows have declined in range and abundance due to man's impact on their environment. Much riverine habitat has been replaced by a relatively new type of ecosystem to Oklahoma, ie., the many reservoirs found throughout the state. Water quality has suffered due to sewage effluent, hazardous chemicals, and feedlot wastes. Introduction of non-native fishes, intentional or not, has also taken its toll. These are some of the problems our native fishes are facing today. This study focuses on only one animal. In order to preserve our native fish fauna, baseline life history studies like this, as well as studies at the community level, are needed before long-term management decisions are made. The more we understand each component of an ecosystem and how the various components interact, the better that ecosystem can be managed to benefit man as well as its original inhabitants.Zoolog

    Pengelolaan Teacher Capacity Building (Tcb) Untuk Meningkatkan Profesionalitas Guru (Studi Kasus Guru SMPN 2 Dan SMP Darul Hikam Bandung)

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    Teacher Capacity Building (TCB) is a key point for a quality education service provided by a school. In the reality, schools have no standardize TCB system to ensure that their TCB is conducted effectivity and efficiently. The research was conducted to figure out the answers to four main questions related to the steps taken in determining the TCB policy at school, the TCB management, the quality assurance system, and the impacts of TCB either for the teacher as an individual, for learning quality, or for school quality. The location of the research were SMPN 2 Bandung and SMP Darul Hikam Bandung as the representation of school with their own school policy on TCB. The reasearch was a qualitative reaserch with descriptive method. The data was callected using three major techniques: observation, indeepth interview, and documentary study. The research revealed that the TCB in SMP Darul Hikam is basen on need analysis, the power of the leader, the tandardized recruitment, and teacher performance assessment. In SMPN 2 Bandung the TCB is empowered by the networking and a very health atmosphere for the teacher to show their best performances. The research also found that the aspects needs to be improved in the implementation of the TCB in both schools are the documentary and the quality assurance

    Highly selective hydrogenation of furfural over supported Pt nanoparticles under mild conditions

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    The selective liquid phase hydrogenation of furfural to furfuryl alcohol over Pt nanoparticles supported on SiO₂, ZnO, γ-Al2O₃, CeO₂ is reported under extremely mild conditions. Ambient hydrogen pressure, and temperatures as low as 50 °C are shown sufficient to drive furfural hydrogenation with high conversion and >99% selectivity to furfuryl alcohol. Strong support and solvent dependencies are observed, with methanol and n-butanol proving excellent solvents for promoting high furfuryl alcohol yields over uniformly dispersed 4 nm Pt nanoparticles over MgO, CeO₂ and γ-Al₂O₃. In contrast, non-polar solvents conferred poor furfural conversion, while ethanol favored acetal by-product formation. Furfural selective hydrogenation can be tuned through controlling the oxide support, reaction solvent and temperature

    Willingness To Donate Blood During the Summer

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    Introduction. Each year donation rates fall in the summer months straining blood banks’ capacities to meet local demands. In hopes of identifying factors to increase summer donations, our study investigated donor reported barriers which influence summer donations habits.Methods. An anonymous 16 question survey investigating various donation factors was administered across multiple American Red Cross (ARC) donation centers in Vermont. Questions addressed donor demographics, frequency of blood donation, preference in appointment making modalities including smartphone app use, summer travel habits, willingness to donate during vacation, and factors that deter donors from donating on vacation.Results. A total of 292 surveys were received. Survey respondents across multiple demographic groups cited similar barriers to summer donation, namely “Too busy” (27.5 %) and “Traveling is a time for me to relax.” (30.6 %). Of the respondents who travel in the summer, very few reported donating while traveling (3.4 %). Summer donation rates between summertime travelers (36.5 %) and non-travelers (36.4 %) were essentially equivalent. The most preferred methods of scheduling appointments were via ARC website (45.6 %) and phone (28.4%). Willingness to use the ARC app was highest among respondents ages of 18 to 34 (45-55%) and lowest among ages 55 and older (13-15%). Of respondents with no prior knowledge of summer seasonal shortages (22 %), 2/3rds indicated newfound motivation to donate.Conclusion. Regardless of travel, increasing awareness of summer shortages may increase summer donations. Use of donor websites and smartphone apps may be instrumented as part of recruitment efforts.https://scholarworks.uvm.edu/comphp_gallery/1239/thumbnail.jp

    Improved lung function and body mass index associated with long-term use of Macrolide antibiotics

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    AbstractBackground: A number of studies have suggested that the non-antimicrobial actions of macrolide antibiotics may be valuable in treating patients with cystic fibrosis. The use of long-term macrolide antibiotics for the management of CF patients colonised by Pseudomonas aeruginosa and progressive pulmonary disease was introduced into our clinic in 1997. A retrospective study was undertaken to assess of the impact of this therapy. Methods: Twenty patients with progressive pulmonary disease (>10% fall in FEV1 over 12 months despite optimising conventional therapy) were commenced on Azithromycin, 250 mg daily during a 21-month period. At the time of assessment they had remained on therapy for a mean of 0.9 years. Changes in lung function, weight, body mass index (BMI) and frequency of pulmonary exacerbations were assessed. A group of 20 patients with stable lung function and matched as far as possible for age and sex was identified for comparison. Results: Pulmonary function increased significantly in the Azithromycin group with FEV1% predicted increasing from a mean of 50.2–59.1% (P=0.001) while FVC% predicted increase from 64.5 to 76.1% (P=0.002). There was small but non-significant fall in lung function in the comparison group. Body mass index increased by a mean of 1.1 in the Azithromycin group but remained unchanged in the comparison group. The number of pulmonary exacerbations requiring intravenous antibiotics declined by 48.3% in macrolide treated subjects compared to the pre-treatment period (P<0.025); frequency of exacerbations in the control group was unchanged. Conclusion: Long-term Azithromycin treatment in patients with progressive deterioration in lung function appears to have led to an improvement in pulmonary function, increased body mass index and decreased the frequency of pulmonary exacerbations requiring intravenous antibiotics

    Effect of left atrial and ventricular abnormalities on renal transplant recipient outcome—a single-center study

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    Background: Premature cardiovascular (CV) death is the commonest cause of death in renal transplant recipients. Abnormalities of left ventricular (LV) structure (collectively termed uremic cardiomyopathy) and left atrial (LA) dilation, a marker of fluid status and diastolic function, are risk factors for reduced survival in patients with end stage renal disease (ESRD). In the present analysis, we studied the impact of pre-transplant LA and LV abnormalities on survival after successful renal transplantation (RT).&lt;p&gt;&lt;/p&gt; Methods: One hundred nineteen renal transplant recipients (first transplant, deceased donors) underwent cardiovascular MRI (CMR) as part of CV screening prior to inclusion on the waiting list. Data regarding transplant function and patient survival after transplantation were collected.&lt;p&gt;&lt;/p&gt; Results: Median post-transplant follow-up was 4.3 years (interquartile range (IQR) 1.9, 6.2). During the post-transplant period, 13 patients returned to dialysis after graft failure and 23 patients died with a functioning graft. Survival analyses, censoring for patients returning to dialysis, showed that pre-transplant LV hypertrophy and elevated LA volume were significantly associated with reduced survival after transplantation. Multivariate Cox regression analyses demonstrated that longer waiting time, poorer transplant function, presence of LV hypertrophy and higher LA volume on screening CMR and female sex were independent predictors of death in patients with a functioning transplant.&lt;p&gt;&lt;/p&gt; Conclusions: Presence of LVH and higher LA volume are significant, independent predictors of death in patients who are wait-listed and proceed with renal transplantation.&lt;p&gt;&lt;/p&gt; METHODS: One hundred nineteen renal transplant recipients (first transplant, deceased donors) underwent cardiovascular MRI (CMR) as part of CV screening prior to inclusion on the waiting list. Data regarding transplant function and patient survival after transplantation were collected.&lt;p&gt;&lt;/p&gt; RESULTS: Median post-transplant follow-up was 4.3 years (interquartile range (IQR) 1.9, 6.2). During the post-transplant period, 13 patients returned to dialysis after graft failure and 23 patients died with a functioning graft. Survival analyses, censoring for patients returning to dialysis, showed that pre-transplant LV hypertrophy and elevated LA volume were significantly associated with reduced survival after transplantation. Multivariate Cox regression analyses demonstrated that longer waiting time, poorer transplant function, presence of LV hypertrophy and higher LA volume on screening CMR and female sex were independent predictors of death in patients with a functioning transplant.&lt;p&gt;&lt;/p&gt; CONCLUSIONS: Presence of LVH and higher LA volume are significant, independent predictors of death in patients who are wait-listed and proceed with renal transplantation
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