Novel nanostructured carbon films for high performance devices

The next generation of advance technologies require novel materials to meet demands in the energy and high performance device sectors. Novel carbon materials, such as nanostructured carbon films, are promising since they can exhibit a wide range of desirable properties depending on their structure and they are generally low-cost which is vital for industrial applications. Whilst functionalized CNTs and graphene based devices offer good performance and low power consumption their preparation typically includes the manipulation of individual sheets/tubes, precluding compatibility with large scale silicon device processing. In addition, large scale production of CNTs having the necessary degree of ordering between each tube so that properties can be optimised for device applications is problematic. By using a filtered cathodic vacuum arc (FCVA) deposition system, it is possible to synthesise carbon thin films with a variety of microstructures including diamond-like amorphous, graphite-like oriented or carbon nitride (CNx). However, it is a challenge to find the deposition parameters which can produce films with the desired microstructure on any given substrate type. This first aim of this thesis is to map out the microstructures that are possible in CNx films as the most important deposition conditions of temperature, gas pressure and substrate bias are varied. While some work has been done previously in this area, this is the first comprehensive study and will allow researchers in the field to choose the most appropriate conditions in order to synthesise CNx films with a particular microstructure. The second aim of this thesis is to find an alternative method to direct substrate biasing in order to alter the deposition energy, a key parameter which determines microstructure and properties in carbon based films prepared using FCVA. An alternative method is urgently required since direct substrate biasing is problematic if electrically insulating substrate are required. The use of a biased mesh placed in front of the substrate within the plasma stream was found to be an effective alternative to direct substrate biasing for varying the energy of the depositing flux. This opens the way for the deposition of the full range of carbon film types that are possible on electrically conducting substrates to be deposited on any substrate type. While the excellent properties of carbon based films are well known, there is the opportunity to extend their use in a range of real world applications. In this thesis, the use of carbon films with a microstructure consisting of highly oriented graphitic carbon as thermal and electrical interconnects is investigated. This thesis also investigates the use of carbon based films for use in hydrogen gas sensing. In the latter case, it was found that hydrogen exposure increases the resistance between two catalytic metal contacts placed on the carbon material. The mechanism for gas sensing was found to involve hydrogen “spillover” from the catalytic metal into the carbon leading to carbon-hydrogen bonding, the removal of free electrons and an increase in resistance

Content analysis of secondary school chemistry textbooks based on components of resistance economy: Shannon Entropy Methodod

Background and Objectives:The present study aims to analyze the content of second grade chemistry textbooks based on the emphasis on the goals of resistance economy. Methods: The research method in this study was descriptive content analysis. In this study, after collecting quantitative data, Shannon entropy technique was used for anarysis. The statistical population of this study formed the content of all secondary high school chemistry textbooks. The sampling method in this study was census; Therefore, all second grade chemistry textbooks were analyzed. The registration unit in this study was the subject. In this study, the frequency of components and themes of resistance economy in chemistry curricula were examined. Findings: The findings of the content analysis showed that in secondary high school chemistry books, the most attention was paid to the goals of resistance economy in the field of consumption the field of skills and the field of production attitude. Conclusion: From the present study, it can be concluded that in the second grade chemistry textbooks, very little attention has been paid to the goals of the resistance economy. Also, in secondary school chemistry curricula, little attention has been paid to the goals and components of the resistance economy and the amount of attention to the goals of the resistance economy do not have a normal distribution and only some components of the resistance economy in the second secondary school (three dimensions and three areas) are consi dered

Unusual sites of bone involvement in Langerhans cell histiocytosis: a systematic review of the literature

Background: Langerhans cell histiocytosis (LCH) is a rare disease that originates from the uncontrolled proliferation and accumulation of bone marrow-derived immature myeloid dendritic cells. Dendritic cells are a type of histiocyte that play an important role in the human immune system and are found in the bone, skin, stomach, eyes, intestines, and lungs. Objective: This systematic review aimed to collect and report published case reports of rare bone disease caused by LCH to avoid misdiagnoses or delays in diagnosis. Methods: We systematically searched Scopus, PubMed, Embase, and Web of Sciences from August 1, 2000 to December 31, 2019. Studies reporting cases of LCH with rare bone involvement were included. Results: We identified 60 articles including 64 cases. Of the identified cases, 31 (48.4) involved children, and 33 (51.6) involved adults. Additionally, 46.9 (30 individuals) were from Asian countries. The mean age of the children was 7.6 ± 4.3 years and that of the adults was 36 ± 12 years. The findings indicated that unifocal bone involvements were the most prevalent form of the disease (68.7), and, overall, the skull and chest wall were the most commonly affected bones in both adults and children. The spine and long bones were the second most commonly affected bones in children, and the spine and jaw were the second most commonly affected bones in adults. Pain and swelling were the most frequent presenting signs among the investigated cases, and loss of consciousness, myelopathy, nerve palsy, visual loss, torticollis and clicking sounds were rare signs. Osteolytic lesions were the most frequent radiologic feature (62.5), and intracranial hemorrhage, fluid�fluid level, dura and intracranial extension and pathologic fractures were rare radiological features. Total excision, curettage and observation in the unifocal group of patients and systemic chemotherapy in the other groups (i.e., multifocal and multisystem) were the most frequent management approaches. The recovery rates of the unifocal and multifocal groups were 77.3 and 81.8, respectively, while that of the multisystem group was 55.5. The rates of recurrence and mortality in the multisystem group were 11 and were higher than those in the other groups. Conclusions: LCH is a rare disease that can affect any organ in the human body. However, bone is the most commonly involved organ, and rare bone involvements may be the first or only symptom of the disease due to the rarity of such lesions; a lack of familiarity with them may result in misdiagnosis or delayed diagnosis. © 2021, The Author(s)

Association between (GT)n repeats in heme oxygenase-1 gene promoter and 3-year survival of patients with acute leukemia: A controlled, cross-sectional study

Background: Acute leukemia is a common pediatric cancer. Novel strategies for treatment of acute leukemia have been developed, but treatment resistance is remained as the most problematic issue. It is hypothesized that the HO-1 gene up-regulation is responsible for tumor resistance to chemotherapy or radiotherapy-induced apoptosis. HO-1 expression levels are related to (GT)n microsatellite polymorphisms in the location of its promoter.This study designed to compare allelic frequencies of (GT)n microsatellite polymorphisms in HO-1 gene between acute leukemia patients and healthy controls. Indeed, 3-year disease-free survival was also evaluated. Materials and Methods: Sixty-three patients with acute leukemia and 70 healthy infants were included in this study. We used patient�s medical records to collect data about survival after chemotherapy. The number of GT repeats in HO-1 promoter was determined by an ABI 3100 sequencer. Results: The HO-1 GT repeats ranged from 14 to 34 with peaks at 27 repeats in both cases and controls. Children with longer alleles ((GT)n � 27) had enhanced 3-year survival rate after treatment with chemotherapy or radiotherapy (P<0.05). Conclusion: Although no significant differences were observed between leukemia patients and controls regarding allelic frequency, we found elevated frequency of �LL� genotype in leukemia patients with good prognosis and 3-year surveillance. Radiotherapy and chemotherapy might elevate the expression levels of HO-1 with subsequent increased resistance of leukemia patients to therapy. © 2018, Tehran University of Medical Sciences (TUMS). All rights reserved

Association between (GT)n repeats in heme oxygenase-1 gene promoter and 3-year survival of patients with acute leukemia: A controlled, cross-sectional study

Background: Acute leukemia is a common pediatric cancer. Novel strategies for treatment of acute leukemia have been developed, but treatment resistance is remained as the most problematic issue. It is hypothesized that the HO-1 gene up-regulation is responsible for tumor resistance to chemotherapy or radiotherapy-induced apoptosis. HO-1 expression levels are related to (GT)n microsatellite polymorphisms in the location of its promoter.This study designed to compare allelic frequencies of (GT)n microsatellite polymorphisms in HO-1 gene between acute leukemia patients and healthy controls. Indeed, 3-year disease-free survival was also evaluated. Materials and Methods: Sixty-three patients with acute leukemia and 70 healthy infants were included in this study. We used patient�s medical records to collect data about survival after chemotherapy. The number of GT repeats in HO-1 promoter was determined by an ABI 3100 sequencer. Results: The HO-1 GT repeats ranged from 14 to 34 with peaks at 27 repeats in both cases and controls. Children with longer alleles ((GT)n � 27) had enhanced 3-year survival rate after treatment with chemotherapy or radiotherapy (P<0.05). Conclusion: Although no significant differences were observed between leukemia patients and controls regarding allelic frequency, we found elevated frequency of �LL� genotype in leukemia patients with good prognosis and 3-year surveillance. Radiotherapy and chemotherapy might elevate the expression levels of HO-1 with subsequent increased resistance of leukemia patients to therapy. © 2018, Tehran University of Medical Sciences (TUMS). All rights reserved

Association between (GT)n repeats in heme oxygenase-1 gene promoter and 3-year survival of patients with acute leukemia: A controlled, cross-sectional study

Background: Acute leukemia is a common pediatric cancer. Novel strategies for treatment of acute leukemia have been developed, but treatment resistance is remained as the most problematic issue. It is hypothesized that the HO-1 gene up-regulation is responsible for tumor resistance to chemotherapy or radiotherapy-induced apoptosis. HO-1 expression levels are related to (GT)n microsatellite polymorphisms in the location of its promoter.This study designed to compare allelic frequencies of (GT)n microsatellite polymorphisms in HO-1 gene between acute leukemia patients and healthy controls. Indeed, 3-year disease-free survival was also evaluated. Materials and Methods: Sixty-three patients with acute leukemia and 70 healthy infants were included in this study. We used patient�s medical records to collect data about survival after chemotherapy. The number of GT repeats in HO-1 promoter was determined by an ABI 3100 sequencer. Results: The HO-1 GT repeats ranged from 14 to 34 with peaks at 27 repeats in both cases and controls. Children with longer alleles ((GT)n � 27) had enhanced 3-year survival rate after treatment with chemotherapy or radiotherapy (P<0.05). Conclusion: Although no significant differences were observed between leukemia patients and controls regarding allelic frequency, we found elevated frequency of �LL� genotype in leukemia patients with good prognosis and 3-year surveillance. Radiotherapy and chemotherapy might elevate the expression levels of HO-1 with subsequent increased resistance of leukemia patients to therapy. © 2018, Tehran University of Medical Sciences (TUMS). All rights reserved