Investigation of paramagnetic response of metallic epoxies

The paramagnetic properties of epoxies which were impregnated with metal ions were examined as the primary task in this research. A major conclusion was that the quality control of the epoxies was insufficient to permit reliable evaluation. Subsequently, a new set of specimens is being prepared. As an additional task, a new method is investigated for estimating heats of combustion for saturated hydrocarbons. The results of that investigation have shown that the empirical approach is a promising method for on-line measurements

On-line measurement of heat of combustion

An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate at a level consistent with the desired oxygen concentration in the products. The heat of combustion is determined from a known correlation with the gas volumetric flow rate. An on-line microcomputer accesses the gas volumetric flow data, and displays the heat of combustion values at desired time intervals

Long-term effects of the coronavirus disease 2019 pandemic on the health and safety of children and mothers around the world

BACKGROUND: Coronavirus disease 2019 (COVID-19) epidemic is a global health disaster with significant effects on the health of children and mothers on a scale not seen in 100 years.METHODS: We searched in Google Scholar, PubMed, and Scopus databases with keywords of “COVID-19”, “children”, “mothers”, “health”, “impact”, “effect”, and “pandemic”. We found 33 related new studies and wrote a narrative review article. Some of them were full-text articles and others were organizational statistics or expert comments.RESULTS: Analyses showed that the COVID-19 epidemic led to widespread disruption of health systems and reduced access to food, and low- and middle-income countries should expect large increases in maternal and child mortality. The long-term effects of COVID-19 on the physical and mental health of children and mothers are very different and challenging compared to other people. During the pandemic, many mothers denied access to prenatal care. In addition to the many indirect effects, although most children have mild symptoms, they should be treated in the intensive care unit (ICU) if children are hospitalized with the same percentage of adults.CONCLUSION: It is very necessary for politicians and organizations in charge of children's health to have comprehensive and long-term plans to limit the destructive and unintended effects of the pandemic on children and mothers around the world, with a greater focus on underdeveloped and less developed countries

Lack of direct evidence for a functional role of voltage-operated calcium channels in juxtaglomerular cells

In this study we have examined the role of voltage-gated calcium channels in the regulation of calcium in juxtaglomerular cells. Using a combination of patch-clamp and single-cell calcium measurement we obtained evidence neither for voltage-operated calcium currents nor for changes of the intracellular calcium concentration upon acute depolarizations of the cell membrane. Increases of the extracellular concentration of potassium to 80 mmol/l depolarized the juxtaglomerular cells close to the potassium equilibrium potential, but did not alter the intracellular calcium concentration neither in patch-clamped nor in intact Furaester-loaded cells. Moreover, basal renin secretion from a preparation enriched in mouse juxtaglomerular cells and from rat glomeruli with attached juxtaglomerular cells was not inhibited when extracellular potassium was isoosmotically increased to 56 mmol/l. In mouse kidney slices, however, depolarizing potassium concentrations caused a delayed inhibition at 56 mmol/l and a delayed stimulation of renin secretion at 110 mmol/l. Taken together, our study does not provide direct evidence for a role of voltage-activated calcium channels in the regulation of calcium and renin secretion in renal juxtaglomerular cells

Measurement of viscosity of gaseous mixtures at atmospheric pressure

Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model

A simplified method for determining heat of combustion of natural gas

A simplified technique for determination of the heat of combustion of natural gas has been developed. It is a variation of the previously developed technique wherein the carrier air, in which the test sample was burnt, was oxygen enriched to adjust the mole fraction of oxygen in the combustion product gases up to that in the carrier air. The new technique eliminates the need for oxygen enrichment of the experimental mixtures and natural gas samples and has been found to predict their heats of combustion to an uncertainty of the order of 1 percent

The correlation of microstructure and mechanical properties of in-situ Al-Mg2Si cast composite processed by equal channel angular pressing

In this paper, the effect of equal channel angular pressing (ECAP) on microstructure and mechanical properties of hypereutectic Al-20%Mg2Si and Al-15%Mg2Si, as well as hypoeutectic Al-10%Mg2Si composites has been investigated. After fabricating the composites by in-situ casting, the composites were processed using the ECAP process up to two passes at room temperature. Microstructural studies have been carried out using a field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. Mechanical properties were also documented using Vickers microhardness and shear punch tests. In the hypereutectic composites, a decrease in the average size of pro-eutectic Mg2Si (Mg2Sip) particles, breakages in eutectic networks, and lengthening of the Al (α) phase in direction of shear bands were observed after the ECAP process. For instance, the average size of Mg2Sip Particles in Al-20%Mg2Si composite reduced from 40 to 17 μm after 2 passes of ECAP. Furthermore, a uniform distribution of Mg2Sip particles was developed in the matrix. In hypoeutectic composite, the ECAP process caused a uniform distribution of eutectic Mg2Si (Mg2SiE) in the matrix that considered a favorable microstructure. Microhardness measurements and shear punch results showed an ascending trend after each pass of ECAP for all specimens. For example, microhardness and shear strength of Al-20%Mg2Si increased from 88 HV and 109 MPa to 119 HV and 249 MPa after two passes indicating 35% and 34% increments, respectively. Density and porosity calculations by Archimedes principle revealed that the density of the composites increased after two passes of ECAP due to the reduction of porosity

The role of management participation in manufacturing companies of rasht city

Today, all successful organizations and companies around the world have found that intangible assets must be emphasized instead of an emphasis on raw materials. One of the most core assets is innovation and the lack of innovation is a fundamental barrier to the development of big organizations and companies. The purpose of the present study is to answer the key question that: can management participation affect organizational innovation? The present study is applied in terms of purpose and is descriptive-correlational in terms of method. It is also a field study in terms of data collection, the statistical population of this study includes all manufacturing companies in Rasht’s industrial town among which 20 companies were selected by convenience non-probability method. The instrument used for data collection is a standard questionnaire that was confirmed in terms of validity and reliability. The results of data analysis that was done by structural equations modeling show that all the hypotheses in the present study, except the effect of management participation on marketing innovation and product innovation were confirmed.Keywords: management participation, organizational innovation, technical innovation, marketing innovatio

THE IMPACT OF TASK-BASED METHOD ON TEACHING PHRASAL VERBS COLLOCATION AMONG IRANIAN INTERMEDIATE EFL LEARNERS

This study is going to investigate the effect of task-based method on teaching phrasal verbs collocation among Iranian intermediate EFL learners. To this end, 45 female EFL learners with the age range of 19 to 30 were selected from among 95 participants through Quick Placement Test. Its purpose was to homogenize the participants based on their proficiency level. Then they were randomly assigned into two experimental groups and one control group. The participants of the experimental groups were divided into two classes including 15 participants. Next, both experimental groups received task-based method for 15 sessions. During the treatment sessions some phrasal verbs pre-taught to the learners by the use of information-gap and opinion-gap tasks. Meanwhile, the control group received 15-session placebo that was the use of explicit instruction like Grammar Translation Method, and it was based on the structural syllabus. The related findings revealed that the experimental group who received the information-gap task performed better at learning phrasal verbs collocation. The findings showed that the role of information-gap of TBLT method leads the learners to more proficiency in learning phrasal verbs collocation, and it is more effective, because the learners have background knowledge. Consequently, the information-gap group had a better result in acquiring the phrasal verbs collocation.  Article visualizations