1,008 research outputs found
Controlled Morphological Structure of Ceria Nanoparticles Prepared by Spray Pyrolysis
AbstractCeria based materials have been widely used as catalyst supporters and electrolytes. Different applications require different morphologies, and the microstructural control during the synthesis is crucial. In the study, ceria particles were prepared from various precursors using a spray pyrolysis (SP). Comparing to the hollow and porous particles, the formation mechanism with solid spherical structure is not clarified readily. The ceria particles were characterized by transmission electron microscopy, thermogravimetry analysis and X-ray photoelectron spectroscopy. This experimental result suggests that the morphology is controlled by the precursors and could be related to their decomposed behavior during the heating process in SP
Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1097
NGC 1097 is a nearby barred spiral galaxy believed to be interacting with the
elliptical galaxy NGC 1097A located to its northwest. It hosts a Seyfert 1
nucleus surrounded by a circumnuclear starburst ring. Two straight dust lanes
connected to the ring extend almost continuously out to the bar. The other ends
of the dust lanes attach to two main spiral arms. To provide a physical
understanding of its structural and kinematical properties, two-dimensional
hydrodynamical simulations have been carried out. Numerical calculations reveal
that many features of the gas morphology and kinematics can be reproduced
provided that the gas flow is governed by a gravitational potential associated
with a slowly rotating strong bar. By including the self-gravity of the gas
disk in our calculation, we have found the starburst ring to be gravitationally
unstable which is consistent with the observation in \citet{hsieh11}. Our
simulations show that the gas inflow rate is 0.17 M_\sun yr into the
region within the starburst ring even after its formation, leading to the
coexistence of both a nuclear ring and a circumnuclear disk.Comment: 32 pages, 14 figures, 1 table, accepted for publication in the Ap
A Novel Two-Layer DAG-based Reactive Protocol for IoT Data Reliability in Metaverse
Many applications, e.g., digital twins, rely on sensing data from Internet of
Things (IoT) networks, which is used to infer event(s) and initiate actions to
affect an environment. This gives rise to concerns relating to data integrity
and provenance. One possible solution to address these concerns is to employ
blockchain. However, blockchain has high resource requirements, thereby making
it unsuitable for use on resource-constrained IoT devices. To this end, this
paper proposes a novel approach, called two-layer directed acyclic graph
(2LDAG), whereby IoT devices only store a digital fingerprint of data generated
by their neighbors. Further, it proposes a novel proof-of-path (PoP) protocol
that allows an operator or digital twin to verify data in an on-demand manner.
The simulation results show 2LDAG has storage and communication cost that is
respectively two and three orders of magnitude lower than traditional
blockchain and also blockchains that use a DAG structure. Moreover, 2LDAG
achieves consensus even when 49\% of nodes are malicious
How E-Servqual Affects Customer\u27s Online Purchase Intention?
With the boom of Internet, Internet has become one of the consumersâ online shopping channels. However, there is different in online shopping situation is because of consumers in different cultures and countries have different online shopping behavior is worth to discuss. This study is to explore the Internet usersâ online shopping situation in developing country, Malaysia, and 118 questionnaire respondents were collected. Statistical analysis software SPSS 17.0 and AMOS 6.0 were used to analyze the impact on e-service quality, satisfaction, trust, and purchase intention. The model fit of this study was in an acceptable level, and this indicates that the theoretical model of this study supports the description of e-service quality for e-retailers that online shopping situation will be effected by trust and satisfaction. The result of this study will be available for those who interested in developing a transnational e-retailer as a reference, as well as academic research on cross-cultural comparative analysis
Overcome Cancer Cell Drug Resistance Using Natural Products
Chemotherapy is one of the major treatment methods for cancer. However, failure in chemotherapy is not uncommon, mainly due to dose-limiting toxicity associated with drug resistance. Management of drug resistance is important towards successful chemotherapy. There are many reports in the Chinese literature that natural products can overcome cancer cell drug resistance, which deserve sharing with scientific and industrial communities. We summarized the reports into four categories: (1) in vitro studies using cell line models; (2) serum pharmacology; (3) in vivo studies using animal models; and (4) clinical studies. Fourteen single compounds were reported to have antidrug resistance activity for the first time. In vitro, compounds were able to overcome drug resistance at nontoxic or subtoxic concentrations, in a dose-dependent manner, by inhibiting drug transporters, cell detoxification capacity, or cell apoptosis sensitivity. Studies in vivo showed that single compounds, herbal extract, and formulas had potent antidrug resistance activities. Importantly, many single compounds, herbal extracts, and formulas have been used clinically to treat various diseases including cancer. The review provides comprehensive data on use of natural compounds to overcome cancer cell drug resistance in China, which may facilitate the therapeutic development of natural products for clinical management of cancer drug resistance
Fascia tissue engineering with human adipose-derived stem cells in a murine model: Implications for pelvic floor reconstruction
Background/PurposeMesh-augmented vaginal surgery for treatment of pelvic organ prolapse (POP) does not meet patients' needs. This study aims to test the hypothesis that fascia tissue engineering using adipose-derived stem cells (ADSCs) might be a potential therapeutic strategy for reconstructing the pelvic floor.MethodsHuman ADSCs were isolated, differentiated, and characterized in vitro. Both ADSCs and fibroblastic-differentiated ADSCs were used to fabricate tissue-engineered fascia equivalents, which were then transplanted under the back skin of experimental nude mice.ResultsADSCs prepared in our laboratory were characterized as a group of mesenchymal stem cells. In vitro fibroblastic differentiation of ADSCs showed significantly increased gene expression of cellular collagen type I and elastin (p < 0.05) concomitantly with morphological changes. By contrast, ADSCs cultured in control medium did not demonstrate these changes. Both of the engrafted fascia equivalents could be traced up to 12 weeks after transplantation in the subsequent animal study. Furthermore, the histological outcomes differed with a thin (111.0 ± 19.8 Όm) lamellar connective tissue or a thick (414.3 ± 114.9 Όm) adhesive fibrous tissue formation between the transplantation of ADSCs and fibroblastic-differentiated ADSCs, respectively. Nonetheless, the implantation of a scaffold without cell seeding (the control group) resulted in a thin (102.0 ± 17.1 Όm) fibrotic band and tissue contracture.ConclusionOur results suggest the ADSC-seeded implant is better than the implant alone in enhancing tissue regeneration after transplantation. ADSCs with or without fibroblastic differentiation might have a potential but different role in fascia tissue engineering to repair POP in the future
Overcome Cancer Cell Drug Resistance Using Natural Products
Chemotherapy is one of the major treatment methods for cancer. However, failure in chemotherapy is not uncommon, mainly due to dose-limiting toxicity associated with drug resistance. Management of drug resistance is important towards successful chemotherapy. There are many reports in the Chinese literature that natural products can overcome cancer cell drug resistance, which deserve sharing with scientific and industrial communities. We summarized the reports into four categories: (1) in vitro studies using cell line models; (2) serum pharmacology; (3) in vivo studies using animal models; and (4) clinical studies. Fourteen single compounds were reported to have antidrug resistance activity for the first time. In vitro, compounds were able to overcome drug resistance at nontoxic or subtoxic concentrations, in a dose-dependent manner, by inhibiting drug transporters, cell detoxification capacity, or cell apoptosis sensitivity. Studies in vivo showed that single compounds, herbal extract, and formulas had potent antidrug resistance activities. Importantly, many single compounds, herbal extracts, and formulas have been used clinically to treat various diseases including cancer. The review provides comprehensive data on use of natural compounds to overcome cancer cell drug resistance in China, which may facilitate the therapeutic development of natural products for clinical management of cancer drug resistance
Serum selenium concentration is associated with metabolic factors in the elderly: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Selenium is an essential micronutrient known for its antioxidant function. However, the association of serum selenium with lipid profiles and fasting glucose are inconsistent in populations with average intake of selenium. Furthermore, there were few studies conducted specifically for the elderly. This study examined the relationship of serum selenium concentration with serum lipids and fasting glucose in the Taiwanese elderly population.</p> <p>Methods</p> <p>This was a cross-sectional study of 200 males and females aged 65-85 years (mean 71.5 ± 4.6 years) from Taipei, Taiwan. Serum selenium was measured by inductively coupled plasma-mass spectrometer. The association between serum selenium and metabolic factors was examined using a multivariate linear regression analysis after controlling several confounders.</p> <p>Results</p> <p>The mean serum selenium concentration was 1.14 Όmol/L, without significant difference between sexes. Total cholesterol, triglycerides, and LDL cholesterol increased significantly with serum selenium concentration (<it>P </it>< 0.001, <it>P </it>< 0.05 and <it>P </it>< 0.001, respectively) after adjusting for age, gender, anthropometric indices, lifestyle factors, and cardio-vascular risk factors in several linear regression models. Furthermore, there was a significantly positive association between serum selenium and serum fasting glucose concentrations (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>Total cholesterol, triglycerides, and LDL cholesterol, and fasting serum glucose concentrations increased significantly with serum selenium concentration in the Taiwanese elderly. The underlying mechanism warrants further research.</p
Using the computer-based feedback (CBF) system to investigate the juniorphysiciansâs and clinical-instructors perceptions for the benefits of general medicine clinical-instructors training program
Background: The purpose of this study is to examine the clinical-instructors and junior-physicians (residents and interns) perceptions for the general-medicine training program by using bi-directional interactive and self-assessments computer-based feedback (CBF) and paper-based multisource feedback assessment (PBMFA) systems for the efficiency and benefit evaluation.Methods: Between 2011 January to 2013 December, junior-physicians and their clinical-instructors in the same medical team were enrolled consecutively for monitoring the CBF scores gave by each other after each clinical course. A total of 321 residents, 298 interns and 110 clinical-instructors who participated in the core competency general-medicine training program in 6-months period were included in the study. The CBF and PBMFA evaluations are undergone paralleled to gather the suggested information in different levels of Kirkpatrick evolutional theory.Results: The results showed that lecturers, being 5-10 years as attending physicians, internal medicine sub-specialty clinical-instructors are most benefit from the general medicine training program. Accordingly, the CBF scores of junior-physicians was positively correlated with the times (> 3-times) of exposure to the medical teams that leaded by qualified clinical-instructors. Both clinical-instructors and junior-physicians have positive attitude to the value of the general-medicine training program. Interestingly, a good consistency was existed between residents CBF scores and PBMFA grades for their core-competency performance. Comparatively, the overall perception of clinical-instructors and junior-physicians for the general-medicine training was very positive.Conclusions: Clinical-instructors and junior-physicians had positive perception of CBF and PBMFA systems which could give us different information to improve and strength the further core-competency general-medicine training program by appropriate utilization
Association between serum adipocyte fatty-acid binding protein concentrations, left ventricular function and myocardial perfusion abnormalities in patients with coronary artery disease
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