Electrical characterization of process induced defects in GaAs by Laplace deep level transient spectroscopy

In this study, we investigated defects introduced in n-GaAs with different carrier densities by electron irradiation and sputter deposition by means of conventional deep level transient spectroscopy (DLTS) as well as high resolution Laplace deep-level transient spectroscopy (LDLTS). In electron-irradiated material, we found that the well-known E3 defect, of which the origin has long been under discussion, consisted of three components (E3a, E3b and E3c). By constructing Arrhenius plots and performing annealing studies, and by comparing our results with literature, we could deduce that the E3a, the main component of the E3 is related to the VAs, while the E3b is related to the Asi and the E3c was related to the VGa-SiGa. In addition, the E3c was metastable and had a concentration that increased linearly with doping concentration. Further electrical characterization included I-V and C-V measurements, as well as measurements of the introduction rate, metastability, electric field emission mechanisms and capture cross-sections. For the sputter-deposited Schottky contacts, DLTS depth profiles showed that the defects were confined close to the surface and that their depth range depended strongly on the doping concentration, and corresponded roughly with the depletion depth of the Schottky diodes. We conclude that the diffusion of these defects was stronlgy enhanced by the conditions (free carrier density and electric field) in the depletion region. Six defects (S1, S2, S3, S4, S5 and S6) were observed by conventional DLTS and were further investigated by L-DLTS. One of these defects, the S6, could be split into two components while three of them (S1, S3 and S5) were metastable. The transformation kinetics of the metastable defects were investigated and we conclude that the prefactor of S5 to S3 transformation was related to free carrier emission but for the S3 to S5 transformation is larger than would be expected. The activation energy of these transformations was similar to that required for arsenic vacancy (VAs) diffusion. The real capture cross sections as well as capture barriers were measured for the S3, S4 and S5 defects.Thesis (PhD)--University of Pretoria, 2019.PhysicsPhDUnrestricte

Enhanced thermoelectric properties in phosphorene nanorings

Using the tight-binding approach, we investigate the thermoelectric (TE) properties of rectangular phosphorene nanorings for both symmetrically and asymmetrically attaching to phosphorene nanoribbon leads. We design our phosphorene-based nanostructures to enhance the TE performance in the absence and the presence of perpendicular magnetic fields. Our results show that when zigzag phosphorene nanoribbons (ZPNRs) are coupled symmetrically to rectangular rings, a comparatively large band gap is induced in the electronic conductance due to the suppression of the contribution of edge states. This gives rise to a remarkable increase in the thermopower response compared to the case of pristine ZPNRs. More intriguingly, we found that though the maximum power factor in this system is about the same as the one for its ZPNR counterpart, the much smaller electronic thermal conductance of this phosphorene-based nanostructure can remarkably contribute to the improvement of the figure of merit. Also, we found that the symmetry/asymmetry of our designed nanostructures, the geometrical characteristics of the ring, and the magnetic flux are three important factors that control the thermoelectric properties of phosphorene quantum rings. Our numerical calculations show that by changing the magnetic flux through the nanoring, a drastic increase in the thermopower is observed near an antiresonance point. We demonstrate the tunability of the thermopower and the possibility to switch on and off the TE response of phosphorene nanorings with the magnetic flux. Moreover, for asymmetric connection configurations with armchair-edged leads, we found that though the thermopower is almost intact, a remarkable reduction of the electronic thermal conductance can lead to a notable improvement in the figure of merit. Our results suggest phosphorene nanorings as promising candidate nanostructures for TE applications

An Overview of the Research Reports on Addiction in Iranian Journals from 2010 to 2015

Background: The articles and research reports presented in the scientific journals are selected without a proper critical appraisal in many cases. This is a major problem, as it leads to the opinions of the experts being neglected in many of these scientific journals. A descriptive study was done in fall and winter of 2016.Methods: Journals were identified searching the electronic databases, including PubMed, Medline, Scopus, Google Scholar, and national Persian databases of SID and Magiran. All the articles on addiction published in the time span of 2010-2015 in 8 psychiatry, psychology, and addiction journals were included in this study. The journals included Journal of Behavioral Sciences, Iranian Journal of Psychiatry and Clinical Psychology, Journal of Fundamentals of Mental Health, and Journal of Research on Addiction in Persian, and Health and Addiction Journal, International Journal of Psychiatry and Behavioral Sciences, Journal of Research in Behavioral Sciences, and International Journal of Psychological Studies in English. These journals were evaluated according to their research design and methodology, scientific writing style, and the validity of the references. For all of the 264 articles, the research design and references were thoroughly evaluated.Findings: The most frequent problems were seen in the introduction section, the sampling method of study, the exclusive criteria, analysis, and the limitations of the study.Conclusion: Major deficiencies in the articles on addiction in Iranian journals were seen. It can be prevented by including important items in the checklists published by some of the journals for reviewers

Efficacy of Smoking Cessation on Stress, Anxiety, and Depression in Smokers with Chronic Obstructive Pulmonary Disease: A Randomized Controlled Clinical Trial

Background: Stress, anxiety, and depression have been reported as very common comorbidities in smokers with chronic obstructive pulmonary disease (COPD). This study was aimed to investigate the effectiveness of smoking cessation on stress, anxiety, and depression in smokers with COPD. Methods: Three block-randomized controlled trial groups with a block size of 6 and 9 including guided self-change (GSC) (n = 19), nicotine replacement therapy (NRT) (n = 19), and combined GSC-NRT (n = 19) with a follow-up of 29 weeks were considered in this research. Participants included elderly adult smokers with COPD. The patients carried out 5 weekly GSC counseling sessions and NRT for smoking cessation. Transtheoretical Model (TTM) questionnaire, Fagerstrom Test for Nicotine Dependence (FTND), Depression Anxiety Stress Scale (DASS), the Beck Depression Inventory-II (BDI-II), and Hospital Anxiety and Depression Scale (HADS) as well as the exhaled carbon monoxide (CO) were evaluated over the baseline and 12 and 29 weeks following treatments. Findings: COPD participants with mean of 23 daily cigarette smoking completed the current study. The odds ratio (OR) of smoking cessation in GSC and GSC-NRT groups decreased more than NRT group. In addition, DASS, FTND, and the exhaled CO in GSC and GSC-NRT groups showed a better performance compared with the NRT group. Conclusion: The results showed that GSC and combined GSC-NRT therapy were significantly more effective than NRT alone. Also, the findings showed that GSC, NRT, and combined GSC-NRT were effective on stress, depression, and anxiety decreasing in smoking cessation. It seems that reducing smoking is associated with recovery in stress, anxiety, and depression in smokers with COPD

Effect of chitosan on propagation of zamiifolia as tropical ornamental indoor plant by leaf cutting

Zamiifolia (Zamioculcas zamiifolia) is an ornamental and perennial medicinal plant, which belongs to Araceae family. This plant holds a prominent place in the economic significance of this particular plant family. This study aimed to examine the process of root development and rhizome production through leaf cuttings of zamiifoliain the this experiment. This experiment was conducted as factorial design within a completely randomized framework design with three replications. Experimental treatments composed of chitosan application at three levels (0, 250 and 500 mg L-1), and the positioning of leaflet cuttings along the main axis of the mother leaf (apical, middle, and basal). After the application of the treatments, the leaflet cuttings were subjected to a four-month rooting period. This rooting process took place in a growth medium consisting of a balanced mixture of perlite and cocopeat mixed in a volume ratio of 1:1. The results exhibited significant effects of different chitosan concentrations on several parameters, including rhizome number, rhizome width, the number of roots, and the quality of the mother leaf. In addition, the type of leaflet cutting demonstrated a significant influence on the width and number of rhizomes. These results demonstrated that the application of chitosan at concentrations of 250 and 500 mg L-1 had a positive effect and resulted in increased rhizome number, rhizome width, and number of roots. Overall, it can be concluded that chitosan can promote the growth and development of zamiifolia by stimulating rhizome production and improving root proliferation

Baseline results of the first malaria indicator survey in Iran at household level

<p>Abstract</p> <p>Background</p> <p>Malaria is one of the leading causes of sickness and death in the developing world, causing more than a million deaths and around 250 million new cases annually worldwide. The aim of this comprehensive survey was to provide information on malaria indicators at household level in high-risk malaria areas in Iran.</p> <p>Methods</p> <p>In a cluster randomized cross-sectional survey data were collected from 5,456 households in both rural and urban areas of 20 malaria-affected districts of Iran. All the fieldwork was done by trained interviewers and a validated questionnaire. The questionnaire comprised baseline characteristics of the study population, the knowledge of people about different aspects of malaria (such as clinical symptoms, transmission and prevention) and their practice to prevent illness (such as using mosquito nets, spraying houses). The data were analysed and descriptive statistics (i.e. frequencies, percentages) were used to summarize the results.</p> <p>Results</p> <p>The results of this survey showed that 20% (95% CI: 17.36 - 22.24) of households owned at least one mosquito net, whether treated or untreated. Consequently, the use of mosquito nets was considerably low among both children under age five [5.90% (95% CI: 5.14 - 6.66)] and pregnant women [5.70% (95% CI: 3.07 - 8.33)]. Moreover, less than 10% of households reported that the interior walls of their dwelling had been sprayed in the previous year [8.70% (95% CI: 6.09 - 11.31)]. Data also suggest that 63.8% of the participants recognized fever as a sign of malaria, 56.4% reported that mosquito bites cause malaria and about 35% of participants mentioned that the use of mosquito nets could prevent malaria.</p> <p>Conclusion</p> <p>Findings from this study indicate that low access to treated nets along with low understanding of the role of nets in malaria prevention are the main barriers to utilization of bed nets. Therefore, the use of insecticide-treated mosquito nets should be encouraged through health education on the importance of the use along with increasing access to it.</p

Baseline results of the first malaria indicator survey in Iran at the health facility level

<p>Abstract</p> <p>Background</p> <p>Malaria continues to be a global public health challenge, particularly in developing countries. Delivery of prompt and effective diagnosis and treatment of malaria cases, detection of malaria epidemics within one week of onset and control them in less than a month, regular disease monitoring and operational classification of malaria are among the major responsibilities of the national malaria programme. The study was conducted to determine these indicators at the different level of primary health care facilities in malaria-affected provinces of Iran</p> <p>Methods</p> <p>In this survey, data was collected from 223 health facilities including health centres, malaria posts, health houses and hospitals as well as the profile of all 5, 836 recorded malaria cases in these facilities during the year preceding the survey. Descriptive statistics (i.e. frequencies, percentages) were used to summarize the results and Chi square test was used to analyse data.</p> <p>Results</p> <p>All but one percent of uncomplicated cases took appropriate and correctly-dosed of anti-malarial drugs in accordance to the national treatment guideline. A larger proportion of patients [85.8%; 95% CI: 84.8 - 86.8] were also given complete treatment including anti-relapse course, in line with national guidelines. About one third [35.0%; 95% CI: 33.6 - 36.4] of uncomplicated malaria cases were treated more than 48 hours after first symptoms onset. Correspondingly, half of severe malaria cases took recommended anti-malarial drugs for severe or complicated disease more than 48 hours of onset of first symptoms. The latter cases had given regular anti-malarial drugs promptly.</p> <p>The majority of malaria epidemics [97%; 95% CI: 90.6 - 100] in study areas were detected within one week of onset, but only half of epidemics were controlled within four weeks of detection. Just half of target districts had at least one health facility/emergency site with adequate supply and equipment stocks. Nevertheless, only one-third of them [33% (95% CI: 0.00 - 67.8)] had updated inventory of malaria foci on quarterly basis.</p> <p>Conclusion</p> <p>To sum up, malaria case management still constitutes a public health problem in Iran. Additionally, data suggest scarcity in management and evaluation of malaria foci, detection and control of malaria epidemics as well as assignment of emergency sites across different regions of the country. Consequently, massive and substantial investments need to be made at the Ministry of Health to coordinate national malaria control programmes towards achieving determined goals and targets.</p

Methadone Replacement Therapy and Sexual Disorders among Opium Dependent Iranian Men: A Meta-Analysis Study

Background: Evaluation of sexual disorders among persons receiving methadone replacement therapy is of great importance, because these problems may lead to non-compliance and relapse. This study aimed to estimate the effect of methadone maintenance therapy (MMT) on sexual function among addicted Iranian men using met-analysis.Methods: Investigating the available data banks, relevant studies were identified. After exclusion of duplicates, irrelevant papers and low quality articles, eligible papers were entered into the meta-analysis. Prevalence and standardized mean difference of sexual function scores were illustrated by forest plots based on sexual desire, orgasm and erectile function.Findings: During the primary search, 5341 evidences were identified. After application of the inclusion/exclusion criteria and quality assessment, nine papers were detected eligible for final meta-analysis. Total prevalence [95% confidence intervals (CI)] of sexual disorders and erectile dysfunction among Iranian men under methadone therapy were estimated as 66.3% (27.1-105.5) and 77.5% (61.9-93.1), respectively. The standardized mean differences (95% CI) of Sexual desire, orgasm and erection before and after methadone therapy were estimated as 0.16 (-0.68, 0.99), -0.01 (-0.75, 0.74) and 0.11 (-0.41, 0.64), respectively.Conclusion: This meta-analysis showed that methadone therapy did not significantly influence the sexual desire, erectile function and orgasm among opium dependent men