Search results for "LED"
showing 10 items of 8768 documents
Monolayer graphene doping and strain dynamics induced by thermal treatments in controlled atmosphere
2018
Time dynamics of doping and strain induced in single layer graphene by thermal treatments up to 300 degrees C in vacuum, nitrogen, carbon dioxide and oxygen controlled atmosphere are deeply studied by Raman spectroscopy and they are compared with its morphological evolution investigated by Atomic Force Microscopy. The reaction dynamics in oxygen treatments is determined down to a time scale of few minutes as well as that of dedoping process made by water vapor treatment. The interplay of strain modification and doping effects is separated. The strain is clarified to be strongly influenced by the cooling time. The doping removal is dominated by the water vapor, showing that the concentration…
Determination of selenium, zinc and cadmium in antidandruff shampoos by atomic spectrometry after microwave assisted sample digestion
2000
Microwave assisted pre-treatments for atomic spectrometric determination (inductive coupled plasma-optical emission spectrometry, ICP-OES or flame atomic absorption spectrometry, FAAS) of metallic elements, usually present in antidandruff shampoos, are proposed. They are based on the digestion of the sample with HNO(3) into a closed reactor, which is irradiated at 800 W for a few minutes. Selenium was determined by ICP-OES. The limit of detection was 0.11 mg l(-1); the relative standard deviation (R.S.D.) for the selenium content in the samples was in the 0.6-3.6% range. The results obtained were in agreement with the label contents and the recovery of the proposed method was in the 100-106…
[Is ICD-programming for double intraoperative defibrillation threshold energy safe and effective during long-time follow-up? Results of a prospective…
1999
The aim of this prospective and randomized study was to evaluate the safety and efficacy of a reduced shock strength in transvenous implantable defibrillator therapy. So far clinical data concerning the safety margin of the shock energy in ICD therapy do not exist. The shock energy tested during long-term follow-up in this study was twice the intraoperatively measured defibrillation threshold (DFT). A total number of 176 consecutive patients representing a typical cohort of ICD patients were evaluated. All patients received a non-thoracotomy lead system (CPI, Endotak 0070, 0090) and a biphasic cardioverter-defibrillator with the ability to store episodes (Cardiac Pacemakers Inc., Ventac TM …
Calcium Pre-Rinse: Effect on permeability of dentin tubules by fluoride rinse
2019
Background The aim of this study was to evaluate whether calcium (CaL) solution would enhance the capacity of sodium fluoride (NaF) solution in reducing the permeability of hypersensitive dentin. Material and Methods Thirty-two Wistar rats ingested for 45 days acidic isotonic drink (Gatorade, pH 2.7) ad libitum to induce dental erosion. Then, molar teeth received a cold stimulus to confirm the presence and score the intensity of dentin hypersensitivity based on body contraction and noise. Animals were allocated to four groups (n=8), according to the solution(s) applied in the oral cavity: NaF (12 mmol/L, 1 min); CaL (150 mmol/L, 1 min); CaL followed by NaF (CaF+NaF, 1 min each); distilled w…
Cisplatin plus weekly vinorelbine versus cisplatin plus vinorelbine on days 1 and 8 in advanced non-small cell lung cancer: a prospective randomized …
2008
Summary Purpose A phase III randomized trial was carried out to compare two schedules of the vinorelbine (VNR)–cisplatin (CDDP) regimen in patients with locally advanced unresectable poor prognosis stage IIIB or metastatic stage IV non-small cell lung cancer. The primary endpoints were overall survival (OS) and analysis of toxicity, while secondary endpoints included response rates, time-to-progression (TTP) and quality of life (QoL). Patients and methods Eligible patients were randomized to receive: (a) VNR 25 mg/m 2 on day 1, 8 and 15 plus CDDP 100 mg/m 2 on day 1 every 4 weeks or (b) VNR 30 mg/m 2 on day 1 and 8 plus CDDP 80 mg/m 2 on day 1 every 3 weeks. All patients were chemotherapy-n…
Determination of copper, iron, molybdenum and silicon in hydrometallurgically roasted molybdenite concentrate solution by inductively coupled plasma …
1997
Abstract Inductively coupled plasma atomic emission spectrometry has been applied for the estimation of major constituents in molybdenite concentrate solutions produced by hydrometallurgical alkaline digestion. Copper, iron, molybdenum and silicon were considered as major constituents to be determined. Multiple linear regression was utilized for the control of matrix effects. Using simple acid-based standards, all the elements investigated could be determined with satisfactory results using an appropriate method of calculation.
The measurement of impurities in silicon for solar cell production
2012
The power conversion efficiency of solar cells is largely dependent on impurity levels in silicon. In the current investigations two sample preparation methods of silicon had been used before analysis - acid dissolution at atmospheric pressure and pressured microwave assisted technique. Quantification of impurities in solar silicon was done by inductively coupled plasma mass spectrometry and electrothermal atomic spectrometry. Microwave assisted dissolution of solar silicon was more effective compared to the traditional dissolution method on the hot plate, but complete dissolution of impurities and silicon matrix was achieved with a nitric and hydrofluoric acid mixture. The mass of solar si…
Self-Efficacy Between Previous and Current Mathematics Performance of Undergraduate Students: An Instrumental Variable Approach to Exposing a Causal …
2021
PurposeSelf-efficacy has been argued theoretically and shown empirically to be an essential construct for students’ improved learning outcomes. However, there is a dearth of studies on its causal effects on performance in mathematics among university students. Meanwhile, it will be erroneous to assume that results from other fields of studies generalize to mathematics learning due to the task-specificity of the construct. As such, attempts are made in the present study to provide evidence for a causal relationship between self-efficacy and performance with a focus on engineering students following a mathematics course at a Norwegian university.MethodThe adopted research design in the presen…
Intellectual Capital – The Key for Sustainable Competitive Advantage for the SME's Sector
2015
Abstract With the adoption of the Lisbon Agenda and its major objective, namely that the EU would become the most dynamic and competitive knowledge based economy in the world, it became clear the Small and Medium Enterprises (SME's) are the especially affected by these plans, because they represent the driving force for the European economy. In this context of creating and maintaining a competitive advantage for the SME's, it is crucial for them to make good use of the intellectual capital of their employees, in an efficient and proficient manner, in order to increase their potential for innovation. The aim of this article is to show, through an original argumentation, based on the analysis…
Postawy rodzicielskie reprezentowane przez rodziców uczniów szkół integracyjnych
2016
Family perceived as a basic environment conditioning the overall develoment of a child is important not only for healthy, normally developing children; in the upbringing of a child with a disability the role and importance of the family are greatly increased. Children with disabilities are particularly at risk of the consequences of negative attitudes of parents, because the attitudes of relatives, especially the parents', determine a child's proper development, and they are crucial for the effects obtained in the process of rehabilitation.