88 research outputs found

    Bottomâ up vs reactive sintering of Al2O3â YAGâ YSZ composites via one or threeâ phase nanoparticles (NPs). Bottomâ up processing wins this time

    Full text link
    The bottomâ up approach describes the synthesis of bulk materials from the finest possible length scales to obtain the best global properties. This approach was adapted to the synthesis of multiâ phase ceramic composites produced from metal oxides produced by liquidâ feed flame spray pyrolysis (LFâ FSP). The effect of length scale of mixing was tested through two processing schemes, mixed single metalâ oxide nanopowders (NPs) and nanocomposite NPs having the desired composition within single particles. For the Al2O3â Y2O3â ZrO2 ternary system, composites prepared from nanostructured nanoparticles sinter to finer grain sizes (<410 nm) at equivalent densities of 95%TD than those prepared from mixed nanoparticle processing. These contrast with our previous studies in this area where mixed NP processing gave the best or equivalent results. The nanocomposite NPs produced in this study exhibit novel nanostructures with three phases contained within single particles <26 nm average particle size (APS). This nanostructure may directly explain the enhanced sintering of the nanocomposite NPs and may provide an impetus for future synthesis of similarly structured NPs.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137592/1/jace14761.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137592/2/jace14761_am.pd

    Processing YAG/뱉 Al2O3 composites via reactive sintering Y2O3/Al2O3 NP mixtures. A superior alternative to bottom up processing using atomically mixed YAlOx NPs

    Full text link
    This effort contrasts â bottomâ upâ processing of YAG/αâ Al2O3 composites where both elements (as 40â 50 nm APSs nanopowders) are present at close to atomic mixing with reactive sintering where ballâ milled mixtures of the individual nanopowders (40â 50 nm APSs) give uniform elemental mixing at length scales closer to 100â 800 nm with correspondingly much longer diffusion distances. In contrast to expectations, densification with control of final grain sizes is best effected using reactive sintering. Thus, reactive sintering to densities â ¥95% occurs at only 1500°C with final grain sizes of â 1000 nm for all samples. In contrast â bottom upâ processing to â ¥95% densities is only achieved at 1600°C, and with final grain sizes of 1700 nm. The reason for this unexpected behavior is that YAG phase forms early in the bottom up approach greatly inhibiting diffusion promoted densification. In contrast, in reactive sintering, YAG is prevented from forming because of the longer diffusion distances such that densification occurs prior to full conversion of the Y2O3 component to YAG. The found hardness values are statistically superior to literature values for composites near the known eutectic composition. In an accompanying paper, the addition of a third component reverses this behavior.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138233/1/jace14980_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138233/2/jace14980.pd

    Potensi Pengembangan Budidaya Ulat Sutera di Areal KPHP Model Awota

    Full text link
    The dialectics between local government interest versus the central government in forestry sector are the main topics of forestry today. Natural silk management is the interest of local government that has been assimilated into Forest Management Unit (KPH)in the form of KPHP Awota Model Awota. Until now, there is no scientific study on the potential of silkworm cultivation development in this areal. Therefore this study aims to analyze the potential of silkworm cultivation development. This potential in question is the institutional system, biophysical potential, environmental potential, market potential and financial value. The results showed that the development of silkworm cultivation in KPHP Awota Model area has the advantage of biophysical potential, environmental potential, marketing potential and financial value. However, this activity has an obstacles in the institutional issues primarily in the management of silkworm cultivation from upstream to downstream sectors

    Medullary sponge kidney: unusual finding in kidney transplant recipient

    Get PDF
    Background: Medullary sponge kidney is generally considered a benign condition, gold standard for the diagnosis is urography but it has almost been replaced by UroCT that did not present the same sensibility. Although it is really rare, our sonography's findings were consistent with medullary sponge kidney in the transplanted kidneys.Case presentation: A 45-year-old woman with a long history of double-kidney transplantation complained of frequent urinary tract infections, a history of vague loin pain and came to our attention for sonography follow-up. Her kidney function was normal, we did not find signs of infections in the transplanted kidneys and urinary findings were normal. Curiously, the transplanted kidneys came from a newborn and the patient received a double-kidney transplantation in order to guarantee a satisfactory renal function.Conclusions: Despite a long history of kidney transplantation, genetic disease should not be forgotten when symptoms and images recall to specific inherited alterations. Sonography has to be considered in diagnostic path of kidney cystic disease

    Utility of Doppler-Ultrasound and Liver Elastography in the Evaluation of Patients with Suspected Pregnancy-Related Liver Disease

    Get PDF
    Grayscale abdomen ultrasound (US) is routinely performed in pregnant women with suspected pregnancy-related liver dysfunction, but its diagnostic yield is very low. We aimed to investigate the association between Doppler-US findings, liver stiffness measurement (LSM) and different causes of pregnancy-related liver dysfunction. This is a prospective cohort study of pregnant women referred to our tertiary center for any suspected gastrointestinal disease between 2017 and 2019 and undergoing Doppler-US and liver elastography. Patients with previous liver disease were excluded from the analysis. For group comparisons of categorical and continuous variables, the chi-square test or Mann-Whitney test, and the McNemar test were used, as appropriate. A total of 112 patients were included in the final analysis, of whom 41 (36.6%) presented with suspected liver disease: 23 intrahepatic cholestasis of pregnancy (ICP), six with gestational hypertensive disorders and 12 cases with undetermined causes of elevated liver enzymes. Values of LSM were higher and significantly associated with a diagnosis of gestational hypertensive disorder (AUROC = 0.815). No significant differences at Doppler-US or LSM were found between ICP patients and controls. Patients with undetermined causes of hypertransaminasemia showed higher hepatic and splenic resistive indexes than controls, suggesting splanchnic congestion. The evaluation of Doppler-US and liver elastography is clinically useful in patients with suspected liver dysfunction during pregnancy. Liver stiffness represents a promising non-invasive tool for the assessment of patients with gestational hypertensive disorders

    Contemporary determinants of international relatioos

    Get PDF
    Z wprowadzenia: "Nauka o stosunkach międzynarodowych nie może się obejść bez systematyzowania i porządkowania omawianej przez siebie niezwykle szerokiej materii. Poszukując odpowiedzi na pytania związane z relacjami pomiędzy uczestnikami interakcji międzynarodowych, nie sposób nie dostrzegać czynników, jakie na nie wpływają, czy to w sposób pośredni czy też bezpośredni, zależny lub niezależny od nich. Wielość tych czynników i zmienność wagi przykładanej do poszczególnych, zależnie od epoki, stwarza konieczność gruntownego badania i wskazywania na najważniejsze z nich, decydujące w danym okresie."(...
    corecore