1,371 research outputs found
Structural and functional characterization of S-adenosylmethionine (SAM) synthetase from Pichia ciferrii
No full textS-adenosylmethionine synthetase (SAM-s) catalyzes the synthesis of S-adenosylmethionine (SAM), which is essential for methylation, transcription, proliferation, and production of secondary metabolites. Here SAM-s from Pichia ciferrii were selectively cloned using RNA CapFishing and rapid amplification of cDNA ends (RACE). The putative full-length cDNA of SAM-s encoded a 383 amino acid protein (42.6 kDa), which has highly conserved metal binding sites, a phosphate-binding site, and functionally important motifs. The corresponding enzyme was over-expressed in a heterologous host of Pichia pastoris, and then purified to a homogenous form. Enzyme kinetics, immunoblotting, circular dichroism (CD), high performance liquid chromatography (HPLC), and molecular modeling were conducted to characterize the SAM-s from P. ciferrii. Structural and functional studies of SAM-s will provide important insights for industrial applications.open
Shape optimization of shear fracture specimen considering plastic anisotropy
No full textIt is important to fabricate fracture specimens with minimum variation of triaxiality in order to characterize the failure behaviors experimentally. Fracture in ductile materials is usually calibrated by uniaxial tensile, shear and plane strain tests. However, it is often observed that triaxiality for shear specimen changes severely during shear fracture test. The nonlinearity of triaxiality is most critical for shear test. In this study, a simple in-plane shear specimen is optimized by minimizing the variation of stress triaxiality in the shear zone. In the optimization, the Hill48 and Yld2000-2d criteria are employed to model the anisotropic plastic deformation of an aluminum alloy of 6k21. The evolution of the stress triaxiality of the optimized shear specimen is compared with that of the initial design of the shear specimen. The comparison reveals that the stress triaxiality changes much less for the optimized shear specimen than the evolution of the stress triaxiality with the original design of the shear specimen
Establishing strict dominance between alternatives with special type of incomplete information
No full textA special model for establishing dominance with decision maker's incomplete information is proposed in multi-attribute decision problem under certainty, Incomplete information is a set of linear inequalities about utilities as well as attribute weights. Since a general model presented in a prior work uses a linear programming technique, a number of linear programs should be solved for checking dominance, With the proposed method, we can check strict dominance between alternatives by simple matrix operation without solving linear programs, thus reducing computational time
Abstract 2899: Hypoxia-inducible factor 1-α maintains sarcoma stem-like cells in hypoxic regions of tumors and promotes migration and invasion via upregulation of platelet-derived growth factor receptors
No full textAbstract
Introduction: Sarcomas often thrive in hypoxic conditions to proliferate and metastasize. To survive in such an environment, sarcomas upregulate hypoxia inducible factor-1α (HIF-1α), which enhances the transcription of over 150 genes mediating tumor metabolism, angiogenesis, and metastasis. HIF-1α may be important for the maintenance of a subset of tumor cells referred to as “sarcoma stem-like cells” or SSCs. Platelet-derived growth factor receptor (PDGFR) is important in mesenchymal biology and may be a potential target of HIF-1α.
Methods: Three human sarcoma cell lines were examined: HT1080 (fibrosarcoma), SK-LMS-1 (leiomyosarcoma), and DDLS8817 (dedifferentiated liposarcoma). Cell lines were grown as spheroids on ultra-low attachment dishes to enrich for SSCs. The roles of HIF-1α and PDGFR-α/β in promoting SSC phenotypes, such as migratory/invasive capacity, were assessed via several in vitro assays under hypoxic conditions.
Results: Sarcoma cell lines grown as spheroids had increased levels of HIF-1α and increased phosphorylation of PDGFR-α/β as compared to when grown as monolayers; these effects were even more pronounced when sarcoma spheroids were grown under hypoxic conditions. Hypoxic conditions also increased migratory and invasive capacity in spheroid cells by 65-73% as compared to normoxic conditions. HIF-1α knockdown using shRNA in the three cell lines decreased expression of self-renewal proteins and decreased spheroid formation by 67-80%. HIF-1α knockdown decreased expression of epithelial-mesenchymal transition (EMT) transcription factors and reduced migratory and invasive capacity by 80-87% under normoxic conditions and 85-87% under hypoxic conditions. Phosphorylation of PDGFR-α/β was decreased in sarcoma cell lines following HIF-1α knockdown under normoxic and hypoxic conditions. PDGFR-α/β inhibition with imatinib reversed chemotherapy resistance in normally resistant SSCs, and treatment of HT1080 xenografts with doxorubicin chemotherapy and imatinib reduced tumor formation by 85% as compared to control and by 77% as compared to chemotherapy alone.
Conclusions: The HIF-1α/PDGFR axis supports the maintenance of SSCs, especially under hypoxic conditions, and promotes SSC phenotypes such as migratory/invasive capacity and chemotherapy resistance. Combining chemotherapy with PDGFR-α/β inhibition may be a promising strategy to reverse chemotherapy resistance and prevent metastasis in sarcomas.
Note: This abstract was not presented at the meeting.
Citation Format: Kevin K. Chang, Changhwan Yoon, Sam S. Yoon. Hypoxia-inducible factor 1-α maintains sarcoma stem-like cells in hypoxic regions of tumors and promotes migration and invasion via upregulation of platelet-derived growth factor receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2899. doi:10.1158/1538-7445.AM2017-2899</jats:p
Continuity and change in Yoon Suk Yeol's positioning of South Korea as a strong, proactive, and global middle power
No full textSouth Korean President Yoon Suk Yeol has stressed marked change with his predecessor in launching the nation as a strong, proactive, and globally oriented middle power. By way of testing four core assumptions on progressives and conservatives' policy proclivities, this article evaluates these (asserted) changes in South Korea's foreign security policy. It finds a sharp change in Seoul's policy toward the North's nuclear and missile program but continuity with the Moon administration in strengthening South Korea's force structure. Fearing potential American abandonment, the Yoon administration has further sought deeper integration with American forces on the Peninsula. Yoon breaking with China is a big policy shift, as is his taking incremental steps toward the tripartite alliance with the USA and Japan that is much-dreaded by Beijing. South Korea establishing ties with European countries and NATO on the other side of the world is also significant.Peer reviewe
The effectiveness of interventions to treat severe acute malnutrition in young children: a systematic review
No full textSevere acute malnutrition (SAM) arises as a consequence of a sudden period of food shortage and is associated with loss of a person’s body fat and wasting of their skeletal muscle. Many of those affected are already undernourished and are often susceptible to disease. Infants and young children are the most vulnerable as they require extra nutrition for growth and development, have comparatively limited energy reserves and depend on others. Undernutrition can have drastic and wide-ranging consequences for the child’s development and survival in the short and long term. Despite efforts made to treat SAM through different interventions and programmes, it continues to cause unacceptably high levels of mortality and morbidity. Uncertainty remains as to the most effective methods to treat severe acute malnutrition in young children.ObjectivesTo evaluate the effectiveness of interventions to treat infants and children aged < 5 years who have SAM.Data sourcesEight databases (MEDLINE, EMBASE, MEDLINE In-Process & Other Non-Indexed Citations, CAB Abstracts Ovid, Bioline, Centre for Reviews and Dissemination, EconLit EBSCO and The Cochrane Library) were searched to 2010. Bibliographies of included articles and grey literature sources were also searched. The project expert advisory group was asked to identify additional published and unpublished references.Review methodsPrior to the systematic review, a Delphi process involving international experts prioritised the research questions. Searches were conducted and two reviewers independently screened titles and abstracts for eligibility. Inclusion criteria were applied to the full texts of retrieved papers by one reviewer and checked independently by a second. Included studies were mapped to the research questions. Data extraction and quality assessment were undertaken by one reviewer and checked by a second reviewer. Differences in opinion were resolved through discussion at each stage. Studies were synthesised through a narrative review with tabulation of the results.ResultsA total of 8954 records were screened, 224 full-text articles were retrieved, and 74 articles (describing 68 studies) met the inclusion criteria and were mapped. No evidence focused on treatment of children with SAM who were human immunodeficiency virus sero-positive, and no good-quality or adequately reported studies assessed treatments for SAM among infants < 6 months old. One randomised controlled trial investigated fluid resuscitation solutions for shock, with none adequately treating shock. Children with acute diarrhoea benefited from the use of hypo-osmolar oral rehydration solution (H-ORS) compared with the standard World Health Organization-oral rehydration solution (WHO-ORS). WHO-ORS was not significantly different from rehydration solution for malnutrition (ReSoMal), but the safety of ReSoMal was uncertain. A rice-based ORS was more beneficial than glucose-based ORSs, and provision of zinc plus a WHO-ORS had a favourable impact on diarrhoea and need for ORS. Comparisons of different diets in children with persistent diarrhoea produced conflicting findings. For treating infection, comparison of amoxicillin with ceftriaxone during inpatient therapy, and routine provision of antibiotics for 7 days versus no antibiotics during outpatient therapy of uncomplicated SAM, found that neither had a significant effect on recovery at the end of follow-up. No evidence mapped to the next three questions on factors that affect sustainability of programmes, long-term survival and readmission rates, the clinical effectiveness of management strategies for treating children with comorbidities such as tuberculosis and Helicobacter pylori infection and the factors that limit the full implementation of treatment programmes. Comparison of treatment for SAM in different settings showed that children receiving inpatient care appear to do as well as those in ambulatory or home settings on anthropometric measures and response time to treatment. Longer-term follow-up showed limited differences between the different settings. The majority of evidence on methods for correcting micronutrient deficiencies considered zinc supplements; however, trials were heterogeneous and a firm conclusion about zinc was not reached. There was limited evidence on either supplementary potassium or nicotinic acid (each produced some benefits), and nucleotides (not associated with benefits). Evidence was identified for four of the five remaining questions, but not assessed because of resource limitation.LimitationsThe systematic review focused on key questions prioritised through a Delphi study and, as a consequence, did not encompass all elements in the management of SAM. In focusing on evidence from controlled studies with the most rigorous designs that were published in the English language, the systematic review may have excluded other forms of evidence. The systematic review identified several limitations in the evidence base for assessing the effectiveness of interventions for treating young children with severe acute malnutrition, including a lack of studies assessing the different interventions; limited details of study methods used; short follow-up post intervention or discharge; and heterogeneity in participants, interventions, settings, and outcome measures affecting generalisability.ConclusionsFor many of the most highly ranked questions evidence was lacking or inconclusive. More research is needed on a range of topic areas concerning the treatment of infants and children with SAM. Further research is required on most aspects of the management of SAM in children < 5 years, including intravenous resuscitation regimens for shock, management of subgroups (e.g. infants < 6 months old, infants and children with SAM who are human immunodeficiency virus sero-positive) and on the use of antibiotics.FundingThe National Institute for Health Research Technology Assessment programme.<br/
Uniform grafting of poly(1,5-dioxepan-2-one) by surface-initiated, ring-opening polymerization
No full textA polymeric film of a biodegradable poly(1,5-dioxepan-2-one) (PDXO) was formed on a gold surface by a combination of the formation of self-assembled monolayers (SAMs) presenting hydroxyl groups and the surface-initiated, ring-opening polymerization (SI-ROP) of 1,5-dioxepan-2-one (DXO). The SI-ROP of DXO was achieved by heating a mixture of Sn(Oct)(2), DXO, and the SAM-coated Substrate in anhydrous toluene at 55 degrees C. The resulting PDXO film was quite uniform. The PDXO film was characterized by polarized infrared external reflectance spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, atomic force microscopy, ellipsometry, and contact angle goniometry
Assessing Customer's Attitudes/Expectations Toward Online Grocery Businesses
No full textCustomer attitudes toward online purchasing behavior have relied on various factors, such as product category, price, and brand name awareness of the store. Customer attitudes toward online shopping are also greatly affected by the inherent limitation of virtual shopping: quality is not easily judged on the Web, particularly for products which the Web cannot deliver sensory experiences. The purpose of this study is to examine customer attitudes toward an online store that sells “look-and-feel” products with various qualities[1] that appear to grow and receive increased attention. In particular, the author investigated i) the factors affecting customer attitudes toward the online grocery store; ii) how those factors affected the perceived ease of use (EOU) and usefulness (U); and iii) the effects of the perceived ease of use (EOU) and usefulness (U) on overall expected customer satisfaction toward the online grocery store. Surveys were conducted and the major findings suggest that customers’ purchase decisions in the electronic marketplace are affected by how online stores apply strategies to maximize customer satisfaction. Furthermore, this study provides managerial implications and offers suggestions for e-businesses.1
High-frequency, high-pole count design for improving specific power density of electric machines
No full textThis thesis introduces the high frequency, high pole count (HFHP) design for improving specific power density of electric machines for weight and/or volume sensitive applications. Although electric machine designs have reached a limit in terms of efficiency, reliability, and cost, newer applications such as in aviation or the oil and gas industry are demanding next-generation motors to be lighter and more compact. The benefit of HFHP design is shown analytically by observing the effect of frequency and pole count on air-gap flux density and torque, while its adverse effects on magnetizing reactance, leakage reactance, and iron/copper losses are realized.
The concept is applied to two of the most ubiquitous electric machines today: induction machines and permanent magnet machines. Electrical equivalent circuits are utilized to analytically hypothesize the effect of HFHP designs, then finite element models (FEM) are built to verify the effects. For induction machines, significant reduction in magnetizing reactance is shown to result in growth in line current and low torque. For permanent magnet machines, however, reduction in magnetizing reactance is shown to not directly affect torque of the machine, thus increase in specific power density is shown.
The design of a 1 MW, 13 kW/kg motor is described, based on the shown benefit of HFHP design in permanent magnet machines. The motor proves that adverse effects of high frequency and high pole count are manageable by employing air-gap windings, halbach arrays, and outer rotor topology.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-05-01The student, Andy Yoon, accepted the attached license on 2016-04-13 at 11:23.The student, Andy Yoon, submitted this Thesis for approval on 2016-04-13 at 11:33.This Thesis was approved for publication on 2016-04-19 at 14:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #9203 on 2016-07-07 at 13:49:06Made available in DSpace on 2016-07-07T20:27:15Z (GMT). No. of bitstreams: 2
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Previous issue date: 2016-04-19Embargo set by: Seth Robbins for item 93101
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 93101
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Thermal and Thermoelectric Properties of SAM-Based Molecular Junctions
No full textIn
molecular thermoelectrics, the thermopower of molecular junctions
is closely interlinked with their thermal properties; however, the
detailed relationship between them remains uncertain. This study systematically
investigates the thermal properties of self-assembled monolayer (SAM)-based
molecular junctions and relates them to the thermoelectric performance
of the junctions. The electrode temperatures for the bare AuTS, AuTS/EGaIn, and AuTS/TPT SAM//Ga2O3/EGaIn samples placed on a hot chuck were measured under
different conditions, such as air vs vacuum and the presence and absence
of thermal grease, which generates a heat conduction channel from
a hot chuck to gold. It was revealed that the SAM was the most efficient
thermal resistor, which was responsible for the creation of a temperature
differential (ΔT) across the junction; ΔT in an air atmosphere is overestimated to some extent,
and air mainly contributes to large dispersions of thermovoltage (ΔV) data. While junction measurements in air were possible
at low ΔT (up to 13 K), the new optimal condition,
under a vacuum and with thermal grease, allowed us to examine a wide
temperature range up to ΔT = 40 K and obtain
a more reliable Seebeck coefficient (S, μV/K).
The value of S under the new condition was ∼1.4
times higher than that measured in air without thermal grease. Our
study shows the potential of liquid-metal-based junctions to reliably
investigate heat conduction across nanometer-thick organic films and
elaborates on how the thermal properties of molecular junctions affect
their thermoelectric performance
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