286 research outputs found

    Evaluation the Using of Local Aggregate in High Modulus Asphalt Concrete Layers

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    The performance of Hot Mix Asphalt (HMA) mixtures is greatly affected by the properties of the aggregate characteristics. The aggregate properties that significantly influence the performance of HMA mixtures are gradation, shape (angularity) and texture (roughness) .In 1990, the French Road Administration (LCPC) developed asphalt mixtures with a gradient "BBME", for the purpose of this new mixtures is to get a good resistance to rutting and good fatigue behavior. in Iraq, this type of the mixture is not used yet.The main purpose of this study is to evaluate the performance of asphalt mixtures with "BBME" gradient and compare them with the conventional mixture for binder course. To achieve this aim, one type of asphalt grade (40-50) from  Al-Nasiriyah refinery and two types of  local aggregates were used. First type of Al-nibaie area and the second from an area of ​​Badra and Jassan with two types of texture rounded and fully fracture. Physical tests on asphalt binder and aggregate, indirect tensile strength and wheel truck testing have been made in this work. Three asphalt contents (optimum asphalt content , optimum asphalt content ± 0.5) were used in indirect tensile strength test with one asphalt content (optimum asphalt content) in wheel truck testing under 60° temperature. The results of experimental work showed that the Marshall stability for BBME mixture were more than that for conventional(SCRB) mixture by 3, 3, 4 percent for al-nibaie half fracture, Badra and Jassan fully fracture and Badra and Jassan fully rounded aggregate mixture, respectively. The Indirect Tensile Strength resistance of the BBME mixes were approximately equal with comparison to the conventional mixes for all aggregate types, and showed that the mixes contain optimum asphalt content have a resistance to indirect tensile strength more than that mixes contain (optimum asphalt content ± 0.5) for BBME and conventional mixtures. As result, the both conventional and BBME mixes were failed at the same number of passing but less at rutting depth for the mixtures with BBME gradation.The mixtures that contain al-nibaie aggregate have an excellent resistance to Indirect Tensile Strength and permanent deformation in comparison with other types of aggregate.Based on AFNOR specification with using K formula and values of rutting percent, it was found that the mixture used in this study, Class III, is the type used in the roads with higher traffic. Keywords: BBME gradation, Marshall stability, Indirect Tensile Strength, Wheel Truck Testing, Optimum Asphalt Content

    7. Long term results of quadrangular autologous pericardial patch reconstruction of the pulmonary artery during arterial switch operation on post-

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    The aim of this retrospective study is to evaluate the technique of Quadrangular Fresh Autologous Pericardial Patch for the reconstruction of the pulmonary artery in Arterial Switch Operation (ASO) to prevent the post-operative pulmonary artery stenosis (PAS). A total of 287 consecutive infants with transposition of great arteries were treated with ASO in our center between January 2000 and September 2014. The mean age was (7.76days) and mean weight was (3.67kg). The new pulmonary arterial root was reconstructed with a fresh quadrangular autologous patch. The technique includes extensive mobilization of both pulmonary artery branches and direct suturing of the parch to 2/3 of the annulus of the new pulmonary artery trunk first, and then reconstruction finish by the re-suspension of the posterior commissure of the new pulmonary valve inside the patch. Patients were examined using trans-thoracic echocardiography consecutively at discharge form the hospital, and at 3–6 months and yearly after discharge. The mean follow up time was 78 months. The early mortality was 5.19% (17 patients), and there were no late mortality. The highest mortality was reported during the beginning of the pediatric surgical program. The mortality for the last 100 patients was 1%. The pressure gradient across the pulmonary valve in 249 patients (87%, was less than 20mmHg. Mild pulmonary stenosis (pressure gradient of 20–40mmHg) was present in 32 patients (11.14%) and moderate pulmonary stenosis with gradient 40–60mmHg was manifested in 4 patients (1.39%). Reconstruction of the new Pulmonary artery during the ASO, using the quadrangular autologous fresh pericardial patch, is effective and reproducible in reducing the incidence of post-operative pulmonary stenosis

    Nanohybrid Materials with Tunable Birefringence via Cation Exchange in Polymer Films

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    In this work, a nanohybrid material based on a freestanding polymeric liquid crystal network capable of postmodification via cation exchange to tune birefringence is proposed. The smectic liquid crystal films can be infiltrated with a variety of cations, thereby changing the refractive indices (ne and no) and the effective birefringence (Δn) of the nanohybrid material, with reversible cation infiltration occurring within minutes. Birefringence could be tuned between values of 0.06 and 0.19, depending on the cation infiltrated into the network. Upon infiltration, a decrease in the smectic layer spacing is found with layer contraction independent of the induced change in birefringence. Potential applications are in the field of specialty optical devices, such as flexible, retunable reflective filters

    Osteoporotic Bone Recovery by a Highly Bone-Inductive Calcium Phosphate Polymer-Induced Liquid-Precursor

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    Osteoporosis is an incurable chronic disease characterized by a lack of mineral mass in the bones. Here, the full recovery of osteoporotic bone is achieved by using a calcium phosphate polymer‐induced liquid‐precursor (CaP‐PILP). This free‐flowing CaP‐PILP material displays excellent bone inductivity and is able to readily penetrate into collagen fibrils and form intrafibrillar hydroxyapatite crystals oriented along the c‐axis. This ability is attributed to the microstructure of the material, which consists of homogeneously distributed ultrasmall (≈1 nm) amorphous calcium phosphate clusters. In vitro study shows the strong affinity of CaP‐PILP to osteoporotic bone, which can be uniformly distributed throughout the bone tissue to significantly increase the bone density. In vivo experiments show that the repaired bones exhibit satisfactory mechanical performance comparable with normal ones, following a promising treatment of osteoporosis by using CaP‐PILP. The discovery provides insight into the structure and property of biological nanocluster materials and their potential for hard tissue repair

    Erratum to: Concentric Multiple Rings by Droplet Epitaxy: Fabrication and Study of the Morphological Anisotropy

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    We present the Molecular Beam Epitaxy fabrication of complex GaAs/AlGaAs nanostructures by Droplet Epitaxy, characterized by the presence of concentric multiple rings. We propose an innovative experimental procedure that allows the fabrication of individual portions of the structure, controlling their diameter by only changing the substrate temperature. The obtained nanocrystals show a significant anisotropy between [110] and [1–10] crystallographic directions, which can be ascribed to different activation energies for the Ga atoms migration processes

    Establishment of LIF-Dependent Human iPS Cells Closely Related to Basic FGF-Dependent Authentic iPS Cells

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    Human induced pluripotent stem cells (iPSCs) can be divided into a leukemia inhibitory factor (LIF)-dependent naïve type and a basic fibroblast growth factor (bFGF)-dependent primed type. Although the former are more undifferentiated than the latter, they require signal transduction inhibitors and sustained expression of the transgenes used for iPSC production. We used a transcriptionally enhanced version of OCT4 to establish LIF-dependent human iPSCs without the use of inhibitors and sustained transgene expression. These cells belong to the primed type of pluripotent stem cell, similar to bFGF-dependent iPSCs. Thus, the particular cytokine required for iPSC production does not necessarily define stem cell phenotypes as previously thought. It is likely that the bFGF and LIF signaling pathways converge on unidentified OCT4 target genes. These findings suggest that our LIF-dependent human iPSCs could provide a novel model to investigate the role of cytokine signaling in cellular reprogramming

    Systematic review of MCDM approach applied to the medical case studies of COVID-19: trends, bibliographic analysis, challenges, motivations, recommendations, and future directions

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    When COVID-19 spread in China in December 2019, thousands of studies have focused on this pandemic. Each presents a unique perspective that reflects the pandemic’s main scientific disciplines. For example, social scientists are concerned with reducing the psychological impact on the human mental state especially during lockdown periods. Computer scientists focus on establishing fast and accurate computerized tools to assist in diagnosing, preventing, and recovering from the disease. Medical scientists and doctors, or the frontliners, are the main heroes who received, treated, and worked with the millions of cases at the expense of their own health. Some of them have continued to work even at the expense of their lives. All these studies enforce the multidisciplinary work where scientists from different academic disciplines (social, environmental, technological, etc.) join forces to produce research for beneficial outcomes during the crisis. One of the many branches is computer science along with its various technologies, including artificial intelligence, Internet of Things, big data, decision support systems (DSS), and many more. Among the most notable DSS utilization is those related to multicriterion decision making (MCDM), which is applied in various applications and across many contexts, including business, social, technological and medical. Owing to its importance in developing proper decision regimens and prevention strategies with precise judgment, it is deemed a noteworthy topic of extensive exploration, especially in the context of COVID-19-related medical applications. The present study is a comprehensive review of COVID-19-related medical case studies with MCDM using a systematic review protocol. PRISMA methodology is utilized to obtain a final set of (n = 35) articles from four major scientific databases (ScienceDirect, IEEE Xplore, Scopus, and Web of Science). The final set of articles is categorized into taxonomy comprising five groups: (1) diagnosis (n = 6), (2) safety (n = 11), (3) hospital (n = 8), (4) treatment (n = 4), and (5) review (n = 3). A bibliographic analysis is also presented on the basis of annual scientific production, country scientific production, co- occurrence, and co-authorship. A comprehensive discussion is also presented to discuss the main challenges, motivations, and recommendations in using MCDM research in COVID-19-related medial case studies. Lastly, we identify critical research gaps with their corresponding solutions and detailed methodologies to serve as a guide for future directions. In conclusion, MCDM can be utilized in the medical field effectively to optimize the resources and make the best choices particularly during pandemics and natural disasters

    Regulation of cAMP and GSK3 signaling pathways contributes to the neuronal conversion of glioma

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    Glioma is the most malignant type of primary central nervous system tumors, and has an extremely poor prognosis. One potential therapeutic approach is to induce the terminal differentiation of glioma through the forced expression of pro-neural factors. Our goal is to show the proof of concept of the neuronal conversion of C6 glioma through the combined action of small molecules. We investigated the various changes in gene expression, cell-specific marker expression, signaling pathways, physiological characteristics, and morphology in glioma after combination treatment with two small molecules (CHIR99021, a glycogen synthase kinase 3 [GSK3] inhibitor and forskolin, a cyclic adenosine monophosphate [cAMP] activator). Here, we show that the combined action of CHIR99021 and forskolin converted malignant glioma into fully differentiated neurons with no malignant characteristics; inhibited the proliferation of malignant glioma; and significantly down-regulated gene ontology and gene expression profiles related to cell division, gliogenesis, and angiogenesis in small molecule-induced neurons. In vivo, the combined action of CHIR99021 and forskolin markedly delayed neurological deficits and significantly reduced the tumor volume. We suggest that reprogramming technology may be a potential treatment strategy replacing the therapeutic paradigm of traditional treatment of malignant glioma, and a combination molecule comprising a GSK3 inhibitor and a cAMP inducer could be the next generation of anticancer drugs

    Identifying Human Disease Genes through Cross-Species Gene Mapping of Evolutionary Conserved Processes

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    Understanding complex networks that modulate development in humans is hampered by genetic and phenotypic heterogeneity within and between populations. Here we present a method that exploits natural variation in highly diverse mouse genetic reference panels in which genetic and environmental factors can be tightly controlled. The aim of our study is to test a cross-species genetic mapping strategy, which compares data of gene mapping in human patients with functional data obtained by QTL mapping in recombinant inbred mouse strains in order to prioritize human disease candidate genes.We exploit evolutionary conservation of developmental phenotypes to discover gene variants that influence brain development in humans. We studied corpus callosum volume in a recombinant inbred mouse panel (C57BL/6J×DBA/2J, BXD strains) using high-field strength MRI technology. We aligned mouse mapping results for this neuro-anatomical phenotype with genetic data from patients with abnormal corpus callosum (ACC) development.).This approach that exploits highly diverse mouse strains provides an efficient and effective translational bridge to study the etiology of human developmental disorders, such as autism and schizophrenia
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