191 research outputs found

    Model arenes hydrogenation with silica-supported rhodium nanoparticles:The role of the silica grains and of the solvent on catalytic activities

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    Silica-supported rhodium-based nanoheterogeneous catalysts were easily prepared by impregnation with a pre-stabilized colloidal suspension. The resulting catalysts contain rhodium nanoparticles well-dispersed in the silica pores with a mean size of 5 nm. Influence of the silica grains size and of the solvent was investigated in arenes hydrogenation. It appeared that the size of the silica grains has a minimal influence on the reaction rate but the supported nanocatalysts displayed higher TOFs in hexane than in water

    Rhodium colloidal suspension deposition on porous silica particles by dry impregnation: Study of the influence of the reaction conditions on nanoparticles location and dispersion and catalytic reactivity

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    Rhodium composite nanomaterials were synthesized by an innovating process called dry impregnation in a fluidized bed. It consists in spraying an aqueous colloidal suspension of rhodium on silica porous particles. The use of this precursor solution containing preformed nanoparticles avoids calcination/activation step. Different composite nanomaterials were prepared displaying various metal loadings. The operating conditions were tuned to modify τs, the solvent vapour saturation rate value, in order to influence the deposit location: either uniform on the whole silica particles or at the particles surface like a coating. τs is defined as the ratio between solvent content in the bed atmosphere and the maximum solvent content. The obtained samples were investigated in catalytic hydrogenation of aromatic compounds under very mild conditions. Their catalytic performances were compared to those of the original colloidal suspension in one hand and of a similar catalyst prepared through wet impregnation in another hand. Interesting activity and selectivity were observed.This illustrates the interest of the dry impregnation method: this way allows an easy control of the metal loading as well as of the metal loading location in the support particles. Moreover, the support particle size and morphology are preserved

    Characterization of syneresis phenomena in stirred acid milk gel using low frequency nuclear magnetic resonance on hydrogen and image analyses

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    Water retention is an important quality attribute for yogurt. Classically, stirred yogurt water retention is investigated using induced syneresis measurement (centrifugation), which does not characterize spontaneous syneresis. Low-frequency nuclear magnetic resonance (1H-LF-NMR) is a non-destructive technique to detect spontaneous syneresis. Experimental yogurt from pasteurized skim milk, and commercial stirred yogurts were analyzed with 1H-LF-NMR. After Laplace's transformation of the signal, hydrogen atoms pools were differentiated according to their mobility. Each hydrogen pool stood for a type of water mobility in the matrices characterized by a relaxation time (T2(i)), and a signal intensity (I2(i)). Yogurt water retention was assessed by induced syneresis and their structure was characterized using microscopy. Low frequency 1H-NMR detected four different water mobility groups in the matrices. Among these, there was a signal from bulk water, and another attributed to the separated serum (spontaneous syneresis). In experimental yogurts, spontaneous syneresis was visible, resulting in induced syneresis higher than 50%. Moreover, induced syneresis and spontaneous syneresis detected by 1H-LF-NMR were similar. In commercial yogurts, bulk water mobility reduced with increasing protein content and protein network density. Induced syneresis and bulk-water mobility correlated only in yogurts without gelatin. In the presence of gelatin, the network was more open, probably favoring bulk water mobility. This study shows that 1H-LF-NMR associated with microscopy image analysis efficiently assesses and describes yogurts water retention and spontaneous syneresis

    Genetic compatibility exceeds possible ‘good genes’ effects of sexual selection in lake char

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    Mating is rarely random in nature, but the effects of mate choice on offspring performance are still poorly understood. We sampled in total 47 wild lake char (Salvelinus umbla) during two breeding seasons and used their gametes to investigate the genetic consequences of different mating scenarios. In a first study, 1,464 embryos that resulted from sperm competition trials were raised singly in either a stress- or non-stress environment. Offspring growth turned out to be strongly reduced with increased genetic relatedness between the parents while male coloration (that reveal aspects of male health) was no significant predictor of offspring performance. In a second experiment one year later, block-wise full-factorial in vitro breeding was used to produce 3,094 embryos that were raised singly after sublethal exposures to a pathogen or water only. Offspring growth was again strongly reduced with increased genetic relatedness between the parents while male coloration was no significant predictor of offspring performance. We conclude that the genetic benefits of mate choice would be strongest if females avoided genetic similarity, while male breeding colors seem more relevant in intra-sexual selection

    Neogene uplift of the Tian Shan Mountains observed in the magnetic record of the Jingou River section (northwest China)

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    The Tian Shan Mountains constitute central Asia's longest and highest mountain range. Understanding their Cenozoic uplift history thus bears on mountain building processes in general, and on how deformation has occurred under the influence of the India-Asia collision in particular. In order to help decipher the uplift history of the Tian Shan, we collected 970 samples for magnetostratigraphic analysis along a 4571-m-thick section at the Jingou River (Xinjiang Province, China). Stepwise alternating field and thermal demagnetization isolate a linear magnetization component that is interpreted as primary. From this component, a magnetostratigraphic column composed of 67 polarity chrons are correlated with the reference geomagnetic polarity timescale between ∼1 Ma and ∼23.6 Ma, with some uncertainty below ∼21 Ma. This correlation places precise temporal control on the Neogene stratigraphy of the southern Junggar Basin and provides evidence for two significant stepwise increases in sediment accumulation rate at ∼16–15 Ma and ∼11–10 Ma. Rock magnetic parameters also undergo important changes at ∼16–15 Ma and ∼11–10 Ma that correlate with changes in sedimentary depositional environments. Together with previous work, we conclude that growth history of the modern Tian Shan Mountains includes two pulses of uplift and erosion at ∼16–15 Ma and ∼11–10 Ma. Middle to upper Tertiary rocks around the Tian Shan record very young (<∼5 Ma) counterclockwise paleomagnetic rotations, on the order of 15° to 20°, which are interpreted as because of strain partitioning with a component of sinistral shear that localized rotations in the piedmont

    Social isolation and psychological distress among southern U.S. college students in the era of COVID-19

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    Background College students are at heightened risk for negative psychological outcomes due to COVID-19. We examined the prevalence of psychological distress and its association with social isolation among public university students in the southern United States. Methods A cross-sectional survey was emailed to all University of North Carolina-Chapel Hill students in June 2020 and was open for two weeks. Students self-reported if they were self-isolating none, some, most, or all of the time. Validated screening instruments were used to assess clinically significant symptoms of depression, loneliness, and increased perceived stress. The data was weighted to the complete student population. Results 7,012 completed surveys were included. Almost two-thirds (64%) of the students reported clinically significant depressive symptoms and 65% were categorized as lonely. An estimated 64% of students reported self-isolating most or all of the time. Compared to those self-isolating none of the time, students self-isolating some of the time were 1.78 (95% CI 1.37, 2.30) times as likely to report clinically significant depressive symptoms, and students self-isolating most or all of the time were 2.12 (95% CI 1.64, 2.74) and 2.27 (95% CI 1.75, 2.94) times as likely to report clinically significant depressive symptoms, respectively. Similar associations between self-isolation and loneliness and perceived stress were observed. Conclusions The prevalence of adverse mental health indicators among this sample of university students in June 2020 was exceptionally high. University responses to the COVID-19 pandemic should prioritize student mental health and prepare a range of support services to mitigate mental health consequences as the pandemic continues to evolve

    Patient with Total Hip Replacement: Bedside Simulation and its Implications for Collaborative Practice and Improved Patient Safety

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    Purpose – To share an experience that provides students with an authentic opportunity to perform, collaborate and learn roles and responsibilities during a simulated bedside experience with medical imaging (MI), nursing and physical therapy (PT) students. Background – Collaborative “practice ready” graduates are essential to the concept of patient-centered care and are dependent on the shared knowledge of one’s individual skills as well as the common skills within the team structure. This preparation cannot occur without the emphasis on roles and responsibilities, collaborative communication, and improved teamwork. Many interprofessional education (IPE) programs provide collaborative experiences between nursing and PT students, but opportunity for MI is not always present. This experience offers a unique model to allow integration of imaging as an important component of the team. Description – Collaborative student teams attended to a simulated patient at the bedside in a nursing lab. Students were provided with a patient chart. Nursing students initiated the introduction and evaluation, physical therapy students performed the pre-transfer assessments, and medical imaging students performed simulated post-operative x-rays. Each was charged with ensuring communication, teamwork and patient safety. Results – Qualitative feedback was positive. Common themes evolved around improved knowledge of the roles of others, similarities in assessment needs, and the importance of communication. A common thread was the role that communication and teamwork play in patient safety when positioning and mobilizing a patient with post-surgical precautions, the use of imaging to aid in diagnostic decision making, and the need to keep the patient at the center of collaborative care. Conclusion – This simulation offered students the opportunity to improve on the collaborative effort of nursing, PT and MI that is often part of the patient experience s/p a total hip arthroplasty. Relevance – Integration of multiple professions in simulated experiences broadens the discussion and highlights the commonalities of patient-centered care. Objectives Recognize opportunities and value to engage medical imaging, nursing and physical therapy students in a collaborative learning experience. Describe approaches for integrating different health professional students with the focus on communication and information sharing for patient safety initiatives. Describe an innovative interprofessional simulation activity with attention to cooperative clinical partnerships

    Generation of three induced pluripotent stem cell lines (UQACi003-A, UQACi004-A, and UQACi006-A) from three patients with KRT5 epidermolysis bullosa simplex mutations

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    Heterozygous mutations within Keratin 5 (KRT5) are common genetic causes of epidermolysis bullosa simplex (EBS), a skin fragility disorder characterized by blisters, which appear after minor trauma. Using CytoTune®Sendai virus, we generated three human induced pluripotent stem cell (iPSC) lines from three EBS patients carrying respectively the single heterozygous mutations in KRT5, c.449 T > C, c.980 T > C, and c.608 T > C. All lines display normal karyotype, expressed high levels of pluripotent markers, and can differentiate into derivatives of the three germ layers. These iPSCs are helpful for a better understanding of the EBS pathogenesis and developing novel therapeutic approaches

    Generation of two induced pluripotent stem cell lines (UQACi002-A and UQACi005-A) from two patients with KRT14 epidermolysis bullosa simplex mutations

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    More than 107 pathogenic variations were identified in Keratin 14 gene (KRT14) in patients affected by epidermolysis bullosa simplex (EBS), a rare skin disease with still no curative treatment. Disease models as human induced pluripotent stem cells (hiPSCs) are promising tool for further advance the knowledge about this disorder and accelerate therapies development. Here, two hiPSC lines were reprogrammed from skin fibroblasts of two EBS patients carrying mutations within KRT14 by using CytoTune®Sendai virus. These iPSCs display pluripotent cell morphology, pluripotent markers expression, and the capability to differentiate into the three germ layers
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