3,816 research outputs found
Method and apparatus for producing microshells
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
Some existing approaches to modeling the thermodynamics of moist air make
approximations that break , 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 in terms of their
, from which all thermodynamic quantities and
relationships are derived. In this paper, we develop this approach for
moist air thermodynamics and two widely used
approximations: the constant approximation and the dry heat capacities
approximation. The consistent constant approximation is particularly
attractive because it leads to, when using virtual potential temperature
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
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
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Anti-transpirant activity in xylem sap from flooded tomato (Lycopersicon esculentum Mill.) plants is not due to pH-mediated redistributions of root- or shoot-sourced ABA
In flooded soils, the rapid effects of decreasing oxygen availability on root metabolic activity are likely to generate many potential chemical signals that may impact on stomatal apertures. Detached leaf transpiration tests showed that filtered xylem sap, collected at realistic flow rates from plants flooded for 2 h and 4 h, contained one or more factors that reduced stomatal apertures. The closure could not be attributed to increased root output of the glucose ester of abscisic acid (ABA-GE), since concentrations and deliveries of ABA conjugates were unaffected by soil flooding. Although xylem sap collected from the shoot base of detopped flooded plants became more alkaline within 2 h of flooding, this rapid pH change of 0.5 units did not alter partitioning of root-sourced ABA sufficiently to prompt a transient increase in xylem ABA delivery. More shoot-sourced ABA was detected in the xylem when excised petiole sections were perfused with pH 7 buffer, compared with pH 6 buffer. Sap collected from the fifth oldest leaf of 'intact' well-drained plants and plants flooded for 3 h was more alkaline, by ~0.4 pH units, than sap collected from the shoot base. Accordingly, xylem [ABA] was increased 2-fold in sap collected from the fifth oldest petiole compared with the shoot base of flooded plants. However, water loss from transpiring, detached leaves was not reduced when the pH of the feeding solution containing 3-h-flooded [ABA] was increased from 6.7 to 7.1 Thus, the extent of the pH-mediated, shoot-sourced ABA redistribution was not sufficient to raise xylem [ABA] to physiologically active levels. Using a detached epidermis bioassay, significant non-ABA anti-transpirant activity was also detected in xylem sap collected at intervals during the first 24 h of soil flooding
Pengelolaan Teacher Capacity Building (Tcb) Untuk Meningkatkan Profesionalitas Guru (Studi Kasus Guru SMPN 2 Dan SMP Darul Hikam Bandung)
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
The selective liquid phase hydrogenation of furfural to furfuryl alcohol over Pt nanoparticles supported on SiOâ, ZnO, Îł-Al2Oâ, CeOâ 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, CeOâ and Îł-AlâOâ. 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
Introduction. Each year donation rates fall in the summer months straining blood banksâ 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 âToo busyâ (27.5 %) and âTraveling is a time for me to relax.â (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
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 50.2â59.1% (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 outcomeâa single-center study
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).<p></p>
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.<p></p>
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.<p></p>
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.<p></p>
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.<p></p>
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.<p></p>
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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