Micro- and nanoparticle generation during nanosecond laser ablation: correlation between mass and optical emissions

The particulate emission during nanosecond ablation of gold targets was investigated at various fluences (10-100 Jcm(-2)) and vacuum levels (0.05-750 Torr). Atomic emission spectra were acquired during the ablation process and post-mortem characterization of particle spatial distribution was performed using scanning electron microscopy. The discussion of the results in the context of existing theoretical models permitted the identification of four distinct mass removal mechanisms. While the presence, shape and intensity of atomic emission lines is a telltale of the nanoparticle formation process, the fluctuations of the emission signal over a number of laser shots was linked to the production of microscopic debris

A Comparative Study of Power Distance of English Teachers and Non-English Teachers in Classroom Interaction in Iranian High Schools

This is the final version. Available on open access from Richtmann Publishing via the DOI in this recordSince cultural factors play a crucial role in creating behavioral patterns, investigating the relationship between English teachers and students can be a good index for discovering the level of power distance in the classroom environment with different cultures manifesting in their interactions. The current study has attempted to compare female high school students' viewpoints towards English teachers and non-English teachers in the Iran context to discover the difference in power distance between English and non-English teachers and their students. To this end, the present research was conducted in 3 high schools for females with female teachers, and the data was gathered through a five-item Likert scale questionnaire investigating students' viewpoints towards five main elements: Acceptability, Respect, Teaching method, behavioral patterns, and Friendship. The findings revealed a high power distance between English teachers and their students in an English class interaction than non-English teachers such as science teachers, math teachers, physics teachers, chemistry teachers, and art teachers and their students. In turn, the results implied positive viewpoints towards English teachers. Regarding four factors, Acceptability, Respect, Teaching method, and Behavior, there is a significant difference between the viewpoints towards English and non-English teachers. On the other hand, there is no significant difference between the two variables in terms of friendship

Prevalence of Soft Tissue Calcification in Panoramic Radiographs in Northern of Iran

BACKGROUND AND OBJECTIVE: Soft tissue calcification is a relatively common issue in panoramic radiography. Some of these calcifications may have non-specific clinical symptoms as feeling of foreign body, dysphagia, otalgia and non-reflective cough. Therefore, for correct diagnosis and avoiding incorrect and excess treatments it’s necessary to have information about prevalence of these calcifications in regional populations. This study aimed to determine the prevalence of soft tissue calcification in panoramic radiographs in a selected population in northern Iran. METHODS: In this cross sectional study, panoramic radiographs of 5000 patients referring to Oral & Maxillofacial radiology department of Babol dental school from 2014 to 2017 were examined. Radiographs were evaluated for the presence of any calcification, and their prevalence and their relationship with age were evaluated in two groups of under and over 40 years of age and gender. FINDING: The prevalence of the observed soft tissue calcifications including calcification of stylohyoid ligands was 484 cases (9.7%), tonsilolith 52 cases (1%), calcification of lymph nodes 9 cases (0.2%), calcification of carotid artery 22 cases (0.4%) and thyroid cartilage calcification was 17 cases (0.3%). No cases of rhinolith, antrolith, sialolith and phlebolitis were found. The amount of tonsilolith (34 to 18 cases) and lymph node calcification (7 versus 2 cases) were significantly higher in men. (p=0.002 and p =0.048). Also, the prevalence of calcification of stylohyoid ligament (290 versus 194 cases) (p=0.001), tonsilolith (13% vs. 39 cases) (p=0.001), calcification of carotid artery (18 versus 4) (p=0.001), and thyroid (14 versus 3) (p=0.003) were significantly relevant with age. CONCLUSION: The results of this study showed that soft tissue calcifications are prevalent and the most common is stylohyoid ligament calcification

Open-atmosphere structural depth profiling of multilayer samples of photovoltaic interest using laser-induced plasma spectrometry

The present work aims to assess Laser-Induced Plasma Spectrometry (LIPS) as a tool for the characterization of photovoltaic materials. Despite being a well-established technique with applications to many scientific and industrial fields, so far LIPS is little known to the photovoltaic scientific community. The technique allows the rapid characterization of layered samples without sample preparation, in open atmosphere and in real time. In this paper, we assess LIPS ability for the determination of elements that are difficult to analyze by other broadly used techniques, or for producing analytical information from very low-concentration elements. The results of the LIPS characterization of two different samples are presented: 1) a 90 nm, Al-doped ZnO layer deposited on a Si substrate by RF sputtering and 2) a Te-doped GaInP layer grown on GaAs by Metalorganic Vapor Phase Epitaxy. For both cases, the depth profile of the constituent and dopant elements is reported along with details of the experimental setup and the optimization of key parameters. It is remarkable that the longest time of analysis was ∼10 s, what, in conjunction with the other characteristics mentioned, makes of LIPS an appealing technique for rapid screening or quality control whether at the lab or at the production line

XPS as Characterization Tool for PV: From the Substrate to Complete III-V Multijunction Solar Cells

This contribution aims to illustrate the potential of the X-ray photoelectron spectroscopy (XPS) technique as a tool to analyze different parts of a solar cell (surface state, heterointerfaces, profile composition of ohmic contacts, etc). Here, the analysis is specifically applied to III-V multijunction solar cells used in concentrator systems. The information provided from such XPS analysis has helped to understand the physico-chemical nature of these surfaces and interfaces, and thus has guided the technological process in order to improve the solar cell performance

Analysis of the surface state of epi-ready Ge wafers

The surface state of Ge epi-ready wafers (such as those used on III-V multijunction solar cells) supplied by two different vendors has been studied using X-ray photoemission spectroscopy. Our experimental results show that the oxide layer on the wafer surface is formed by GeO and GeO2. This oxide layer thickness differs among wafers coming from different suppliers. Besides, several contaminants appear on the wafer surfaces, carbon and probably chlorine being common to every wafer, irrespective of its origin. Wafers from one of the vendors show the presence of carbonates at their surfaces. On such wafers, traces of potassium seem to be present too

Case study in failure analysis of accelerated life tests (ALT) on III-V commercial triple-junction concentrator solar cells

In this work the failure analysis carried out in III-V concentrator multijunction solar cells after a temperature accelerated life test is presented. All the failures appeared have been catastrophic since all the solar cells turned into low shunt resistances. A case study in failure analysis based on characterization by optical microscope, SEM, EDX, EQE and XPS is presented in this paper, revealing metal deterioration in the bus bar and fingers as well as cracks in the semiconductor structure beneath or next to the bus bar. In fact, in regions far from the bus bar the semiconductor structure seems not to be damaged. SEM images have dismissed the presence of metal spikes inside the solar cell structure. Therefore, we think that for these particular solar cells, failures appear mainly as a consequence of a deficient electrolytic growth of the front metallization which also results in failures in the semiconductor structure close to the bus bars

Angiotensin-converting enzyme genotype and late respiratory complications of mustard gas exposure

<p>Abstract</p> <p>Background</p> <p>Exposure to mustard gas frequently results in long-term respiratory complications. However the factors which drive the development and progression of these complications remain unclear. The Renin Angiotensin System (RAS) has been implicated in lung inflammatory and fibrotic responses. Genetic variation within the gene coding for the Angiotensin Converting Enzyme (ACE), specifically the Insertion/Deletion polymorphism (I/D), is associated with variable levels of ACE and with the severity of several acute and chronic respiratory diseases. We hypothesized that the ACE genotype might influence the severity of late respiratory complications of mustard gas exposure.</p> <p>Methods</p> <p>208 Kurdish patients who had suffered high exposure to mustard gas, as defined by cutaneous lesions at initial assessment, in Sardasht, Iran on June 29 1987, underwent clinical examination, spirometric evaluation and ACE Insertion/Deletion genotyping in September 2005.</p> <p>Results</p> <p>ACE genotype was determined in 207 subjects. As a continuous variable, FEV₁% predicted tended to be higher in association with the D allele 68.03 ± 20.5%, 69.4 ± 21.4% and 74.8 ± 20.1% for II, ID and DD genotypes respectively. Median FEV₁% predicted was 73 and this was taken as a cut off between groups defined as having better or worse lung function. The ACE DD genotype was overrepresented in the better spirometry group (Chi²4.9 p = 0.03). Increasing age at the time of exposure was associated with reduced FEV₁%predicted (p = 0.001), whereas gender was not (p = 0.43).</p> <p>Conclusion</p> <p>The ACE D allele is associated with higher FEV₁% predicted when assessed 18 years after high exposure to mustard gas.</p

Global, regional, and national levels and trends in burden of oral conditions from 1990 to 2017 : a systematic analysis for the Global Burden of Disease 2017 Study

Government and nongovernmental organizations need national and global estimates on the descriptive epidemiology of common oral conditions for policy planning and evaluation. The aim of this component of the Global Burden of Disease study was to produce estimates on prevalence, incidence, and years lived with disability for oral conditions from 1990 to 2017 by sex, age, and countries. In addition, this study reports the global socioeconomic pattern in burden of oral conditions by the standard World Bank classification of economies as well as the Global Burden of Disease Socio-demographic Index. The findings show that oral conditions remain a substantial population health challenge. Globally, there were 3.5 billion cases (95% uncertainty interval [95% UI], 3.2 to 3.7 billion) of oral conditions, of which 2.3 billion (95% UI, 2.1 to 2.5 billion) had untreated caries in permanent teeth, 796 million (95% UI, 671 to 930 million) had severe periodontitis, 532 million (95% UI, 443 to 622 million) had untreated caries in deciduous teeth, 267 million (95% UI, 235 to 300 million) had total tooth loss, and 139 million (95% UI, 133 to 146 million) had other oral conditions in 2017. Several patterns emerged when the World Bank’s classification of economies and the Socio-demographic Index were used as indicators of economic development. In general, more economically developed countries have the lowest burden of untreated dental caries and severe periodontitis and the highest burden of total tooth loss. The findings offer an opportunity for policy makers to identify successful oral health strategies and strengthen them; introduce and monitor different approaches where oral diseases are increasing; plan integration of oral health in the agenda for prevention of noncommunicable diseases; and estimate the cost of providing universal coverage for dental care