206 research outputs found
Experimental and Numerical Investigation of Fatigue behavior for Marine Clays and Offshore Monopile-Clay System
The design of foundations supporting offshore structures and subjected to excessive cyclic loading episodes become challenged when embedded in soft marine clays. A deterioration in the undrained shear strength of marine clays with the generation of excess pore water pressure under cyclic loading significantly affects the offshore infrastructure’s stability. It leads to large lateral deformations that might be failing both superstructure and infrastructural systems. Monopiles are extensively used in supporting offshore structures due to their high resistance to extensive lateral cyclic loading. The response of the Monopile-Clay system to lateral cyclic loading drew the attention of researchers over the years; they conducted experimental, field, and numerical studies to examine the suitability of the methods adopted in the design codes, which is still a controversial issue. This research aims to study the cyclic performance of marine clays and the monopile-clay system and measure the marine clay fatigue life and how it interferes with the system’s failure. A parametric sensitivity analysis using the Artificial Intelligence technique was proposed to highlight the complicated behavior of marine clays and to allocate the clay parameter(s) that primarily affect its behavior when subjected to cyclic loading. Datasets collected from the literature were used to measure the threshold cyclic stress ratio (CSR) for a wide range of marine clays worldwide. Moreover, a modified safe zone concept was proposed to predict the clay’s response, whether it fails or maintains equilibrium. The most significant clay parameters that impact its response were detected, and a predictive ANN model was proposed. The model successfully predicts the marine clay response to cyclic loading. The fatigue life estimation of marine clays was measured by performing a series of strain-controlled tests under different strain amplitudes. Three major turning points in the marine clay’s fatigue life were defined: (1) the crack initiation, (2) the crack propagation fatigue life, and (3) the transition point where the plastic strains become dominant and control the clay’s behavior. Furthermore, a new correlation of the degradation parameter (t) was proposed based on cycling the marine clays until failure. A 2D numerical investigation was performed under the same tested parameters of the strain-controlled tests to measure the monopile-clays system fatigue life. The system was analyzed under displacement-controlled loading amplitude to measure the actual clay’s response and deterioration over the embedded depth of the monopile and by increasing the number of cycling. The detected P-N profiles can be an efficient tool to develop new design criteria that fulfill the fatigue limit state (FLS) requirements
Umayyad epistolography, with special reference to the compositions ascribed to 'Abd al-Hamid al-Katib.
The object of this study, an analysis of Umayyad epistolography and chancery practice, is characterised by the more general problem of source material for the first century of Islamic history. The sources may be grouped as follows: (a) papyri; (b) insha, balaqha, and adab; (c) history, biography, and geography; (d) hadith, fiqh, and haeresiography. My approach to the problem delineated here will be set out in three chapters: (1) An examination of the Umayyad chancery: its structure, its adaptation to Arabic, and its technical development (2) A critical analysis of specimen letters reported to have been composed during the Umayyad period. (3) A study of the compositions ascribed to the dominant figure of 'Abd al-Hamid al-Katib, traditionally acknowledged as the major factor in the development of the Umayyad chancery. The conclusion of this study may be set out as follows: (1) It has been found that the Umayyad chancery format consists of (a) introductory formulae: the basmala, the inside address (al-unwan), the salam, the tahmid, and amma'd; (b) concluding formulae: dm sha Allah (if God wills), repeating the formula of salam with the definite article "al" the name of the scribe, and the date. (2) It has been noticed that the records of Kharaj in the conquered countries used to be written in Arabic, while the demand letters issued from the bureau of Kharaj were written in Persian, Greek, and Coptic until the reign of 'Abd al-Malik b. Marwan who ordered his secretaries to write them in Arabic. (3) With regard to the letters ascribed to 'Abd al-Hamid al-Katib, it has been found that they are not authentic and they could not be regarded as representative of the Umayyad chancery practice, for they involve considerable Abbasid characteristics
History and Genetics of Retinoblastoma
The history of retinoblastoma (RB) goes back to 1597 when Pieter Pawius of Amsterdam described a tumor that resembled retinoblastoma. “Fungus haematodes” was the first term used to describe retinoblastoma. Later, the American Ophthalmological Society approved the term retinoblastoma in 1926. The retinoblastoma protein is encoded by the RB1 gene located at 13q14. The functioning model of the tumor suppressor genes was first proposed by Alfred Knudson in the 1970s who precisely explained the hereditary mechanism of retinoblastoma. If both alleles of this gene are mutated, the protein is inactivated and this results in the development of retinoblastoma. One mutation can be either germline or somatic and the second one is always somatic. Differentiation between sporadic and germline retinoblastoma variants requires the identification of the RB1 germline status of the patient. This identification is important for assessing the risk of additional tumors in the same eye, the other eye, and the risk of secondary tumors. Thus, genetic testing is an important component of the management of all children diagnosed with retinoblastoma. In this chapter, we will go over the history, genetics, and counseling for patients with retinoblastoma
Is Gaza sandy shoreline region contaminated with human gastrointestinal parasites?
The study was implemented to test if the sandy shoreline of Gaza city is contaminated with human gastrointestinal parasites or not and to determine the types of intestinal parasites and the extent of contamination. A total of 104 sand samples (52 dry sand and 52 wet sand) were analyzed during the summer season period. Samples were collected from the study area of about 12km along the seashore region of Gaza City. Dry samples and wet sand samples were analyzed using water-sedimentation technique and a light microscope. The results showed that the percentage of the parasitic contamination was 40.4% of the wet sand samples and 34.6% of the dry sand samples along the shoreline region of the Gaza City. The human gastrointestinal parasites detected were the following: Ascaris lumbricoides, S. stercoralis, E. vermicularis, E. histolytica/dispar, G. lamblia, E. coli and Taenia. spp. The findings showed that
gamma-Diimine palladium(II) based complexes mediated polymerization of methyl methacrylate
The synthesis of new palladium(II) complexes of the type [Pd(A-N=C-ph-C=N-A) Cl-2] (4a-e) (A = cyclohexyl (a), 2-isoprpropyl (b), pyrenyl (c), naphthyl (d), and 2,6-diisopropyl (e)) is described. The isolated gamma-diimine ligands and their corresponding palladium(II) complexes were characterized by their physical properties, elemental analysis, H-1 NMR=, C-13 NMR, and infrared spectroscopy. The palladium(II) complexes (4a-e) were employed successfully as catalysts for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in the presence of ethyl-2-bromoisobutyrate (EBIB) as initiator at 90 degrees C. Polymerization with these catalyst systems afforded polymers with low molecular weight distribution (M-w/M-n) and syndio-rich atactic poly (MMA) with relatively higher [rr] diads. (C) 2013 Production and hosting by Elsevier B.V.Peer reviewe
Liposarcoma of the forearm in a man with type 1 neurofibromatosis: a case report
<p>Abstract</p> <p>Introduction</p> <p>The combination of neurofibromatosis and liposarcoma is very rare. We present a case of a dedifferentiated liposarcoma in the forearm, as a complication in a patient with neurofibromatosis type 1.</p> <p>Case presentation</p> <p>A Caucasian man with neurofibromatosis type 1 presented at our clinic complaining of a slow growing swelling on his left forearm over a period of one and a half years. Clinical examination and history pointed to malignancy. Radiological examination inclusive of magnetic resonance imaging and positron emission tomography confirmed our suspicion. A final diagnosis of dedifferentiated high-grade liposarcoma with axillary lymph node metastases was established after a pathological examination of a tumour biopsy. The consulting tumour board recommended either an elbow exarticulation or an accurate radical local resection including the metastatic axillary lymph nodes. Fortunately, we were able to perform an R-zero resection and the forearm could be saved. The treatment was completed with postoperative radiotherapy of the left forearm's operative bed, the left axillary and the supraclavicular regions. The patient decided against adjuvant chemotherapy.</p> <p>Conclusion</p> <p>Liposarcoma complicating neurofibromatosis type 1 is a very rare combination. Up to now, only five cases have been reported in the literature. We are adding a new case to this short list to stress the importance of early recognition. It is the first known case with this disease combination in an upper extremity. Liposarcoma is usually treated by surgery followed by radiotherapy. The role of chemotherapy is controversial and should be based on a decision made on a case-by-case basis.</p
4-(4-Chlorophenyl)-1-(2-hydroxy-2,2-diphenylacetyl)thiosemicarbazide
The asymmetric unit of the title compound, C21H18ClN3O2S, contains two molecules in which the bond lengths and angles are almost identical. Intramolecular N—H⋯S hydrogen bonds result in the formation of two five-membered rings. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers; these dimers are linked via intermolecular O—H⋯S hydrogen bonds, leading to infinite corrugated layers parallel to the bc plane through R
2
2(16) ring motifs
Novel palladium(II) and platinum(II) complexes with a fluoropiperazinyl based ligand exhibiting high cytotoxicity and anticancer activity in vitro
cis-Dichloro-palladium(II) and cis-dichloro-platinum(II) complexes (2, 4) of the general formula [M(N-N)Cl2] (M=Pd(II) and Pt(II), N-N= 1,2-diamino-4-fluoro-5-(4-methyl-1-piperazinyl) benzene, (DFMPB)) and the dicationic palladium(II) complex [Pd(N-N)(CH3CN)2](BF4)2 (3) have been prepared and characterized by elemental analysis, 1H-NMR-, mass spectroscopy, and IR spectroscopy. The cytotoxic effect of these complexes against MDA-231 and MCF-7 human breast cancer cell lines and K562 human leukemia cell line has been studied. The influence was dose dependent and varies with cell type. The palladium(II) complex (2) showed superior cytotoxic effect compared with the corresponding platinum(II) complex and the standard, cisplatin, when tested against all the above cell lines. 2016 Kayed A. Abu-Safieh et al.Scopu
Factors that influence a patient’s decision to engage in genetic research
IntroductionThe most challenging step in clinical research studies is patient recruitment. Many research studies do not reach their targets because of participant rejection. The purpose of this study was to assess patient as well as the community knowledge, motivation, and barriers to participate in genetic research.MethodsA cross-section study was conducted between September 2018 and February 2020 using face-to-face interviews with candidate patients from outpatient clinics at King Fahad Medical City (KFMC), Riyadh, Saudi Arabia. Additionally, an online survey was conducted to assess the community’s knowledge, motivation and barriers to participate in genetic research studies.ResultsIn total, 470 patients were interviewed for this study, with 341 being successfully recruited for the face to face interview, and the other patients being refused owing to time constraints. The majority percentage of the respondents were females. The respondents’ mean age was 30, and 52.6% reported having a college degree. The survey results from 388 participants illustrated that around 90% of the participants, participated voluntarily due to a good understanding of genetics studies. The majority held positive attitudes toward being part of genetic research, which exceeded the reported motivation score of >75%. The survey indicated that >90% of individuals were willing to participate to acquire therapeutic benefits or to receive continued aftercare. However, 54.6% of survey participants were worried about the side effects and the risks involved in genetic testing. A higher proportion (71.4%) of respondents reported that lack of knowledge about genetic research was one of the barriers to rejecting participation.ConclusionRespondents reported relatively high motivation and knowledge for participation in genetic research. However, study participants reported “do not know enough about genetic research” and “lack of time during clinic visit” as a barrier for participation in genetic research
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