285 research outputs found
Recycling of Waste Plastics into Pyrolytic Fuels and Their Use in IC Engines
The energy crisis and environmental destruction are the principal problems in the present day due to the rapid industrialization and growing population. Degradation of solid waste such as plastic bottles, grocery bags, etc. in nature takes many years. Besides, plastic disposing methods like landfill, reusing, and burning can create severe risks to the human health and environment. Therefore, plastic must be kept under control from damaging the environment. One of the most favorable and effective disposing methods is pyrolysis, which is an environmentally friendly and efficient way. Pyrolysis is the thermal degradation of solid wastes at high temperatures to produce pyrolytic oil. The pyrolytic oil produced is converted into pyrolytic fuel very similar to diesel or gasoline by upgrading. The calorific value of the pyrolytic fuel is similar to that of diesel and gasoline. Pyrolytic fuel can be used in internal combustion engines without significant loss in engine performance. Besides, some engine emissions, especially smoke opacity and CO and HC emissions, improve when used with additives or when the engine’s operating conditions such as compression ratio and ignition timing are changed. However, NOx emission is very similar to diesel fuel, too
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Determination of Aggregate Shape Properties Using X-ray Tomographic Methods and the Effect of Shape on Concrete Rheology
The shape of aggregate particles can significantly influence certain properties of concrete, both in its fresh and hardened states. Therefore, there is a need to be able to completely characterize the shape of aggregate particles, in three dimensions, in order to develop computational models that accurately predict properties. In the past, numerous methods have been suggested for this task. However, these methods are often only applicable to two-dimensional images of particles, they output a single or a few values, and fail to characterize the true shape of the particle. X-ray tomographic techniques allow the capturing of the true shape of particles and have been applied to concrete aggregates. Computed tomography has been used to characterize coarse and fine aggregate particles, while X-ray microtomography has been used to characterize particles passing the 75 m sieve. Sample preparation methods and scanning parameters applicable to concrete aggregates have been developed. The spherical harmonic method was used to efficiently store shape information, and to calculate useful parameters for individual particles, such as volume and surface area. Comparisons of the results to properties determined using other techniques were made and it was determined that the results of indirect or two-dimensional shape and size characterization methods can be misleading.Aggregates Foundation for Technology, Research, and Education (AFTRE)Civil, Architectural, and Environmental Engineerin
The Convergence Behavior of CO2 Emissions in Seven Regions under Multiple Structural Breaks
The aim of this paper is to examine the convergence behavior of carbon dioxide emissions per capita (co) in seven regions for 1960-2011 period by using recently developed the second generation panel data methods. Empirical results are as follows: i) there exists cross-sectional dependency for co variable ii) the CADF unit root test without structural breaks shows that the co variable is stationary at its first differences, iii) but the PANKPSS unit root test with structural breaks the co variable is stationary at its level. The overall results indicate that the regional stochastic convergence of carbon emission per capita is valid for the seven regions under structural breaks and any environmental shock has temporary effect.
Keywords: Carbon Emissions, Stochastic Convergence, Panel Data.
JEL Classifications: C33, Q53, Q5
The Relationship between Institutional Structure and Economic Growth: A Comparative Analysis for Selected Countries
This study explores the long-run relationship between institutional structure and economic growth for selected countries for 1993-2012 period by using dynamic panel data analysis. The results can be summarized as follows: i) There exists a cross-sectional dependence for variables and models ii) All variables are stationary at their first difference except for institutional indicator of second group. iii) There exists a cointegration relationship between non-stationary variables. iv) Institutional structure has positive and statistically significant impact on economic growth in First group of countries. v) There is no significant relationship between institutional structure and economic growth in second group of countries. vi) Gross capital formation has positive impact on economic growth in both groups.
Keywords: Institutional Economics, Institutional Structure, Economic Growth, Panel Data Analysis, International Country Risk Guide.
JEL Classifications: C33, D72, O5
Rapid Recovery of Visual Acuity after Lumboperitoneal Shunt Operation in Malignant Idiopathic Intracranial Hypertension
Background. Idiopathic intracranial hypertension can cause rapid deterioration of visual acuity in some severe cases, and these cases are usually thought to have “malignant” form of this disease. Case. In this paper, we report on a 16-year-old girl who is a typical example for malignant idiopathic intracranial hypertension with a rapid recovery of visual acuity after lumboperitoneal shunt operation. Observations and Conclusions. Malignant form of idiopathic intracranial hypertension must be kept in mind in selected patients to avoid irreversible visual loss
Assessment of the prevalence and characteristics of dens invaginatus in a sample of Turkish Anatolian population
Objective: The objective of this study was to assess the prevalence and characteristics of dens invaginatus in anterior teeth and to classify the type of dens invaginatus in a sample of Turkish Anatolian population. Study design: A retrospective study was performed using full-mouth periapical and panoramic radiographs of 1012 patients. Maxillary and mandibular anterior teeth were evaluated for the presence and characteristics of dens invaginatus. Statistical evaluation of the presence of dens invaginatus related to gender was performed by the Pearson chi-squared test. Results: Dens invaginatus was observed in 13 out of 1012 subjects and in only maxillary lateral incisors. There were no periapical lesions in teeth with types I and II, whereas both of the subjects with type III had apical periodontitis at the time of referral. Males and females were almost equally affected by dens invaginatus (P= 0.98). Conclusion: The anomaly was detected in only maxillary lateral incisors with no gender difference and the most commonly observed type of dens invaginatus was type I (81.25%)
Intratympanic Steroid Treatment in Méniére Disease
Méniére disease (MD) is characterized by vertigo attacks, hearing loss, tinnitus, and aural fullness. Although the exact treatment of MD is lacking, several treatment options including conservative, medical, and surgical aim to control symptoms. Recently, an increasingly used treatment method called intratympanic steroid (ITS) treatment is applied to patients suffering from MD. In which step the ITS takes part for MD treatment protocol is not certain. But common wisdom is that ITS can be used in patients with intractable MD to conservative and medical treatment before applying intratympanic gentamicin and surgical treatments
Co-culture of cryopreserved healthy sertoli cells with testicular tissue of non-obstructive azoospermia (NOA) patients in culture media containing follicle-stimulating hormone (FSH)/testosterone has no advantage in germ cell maturation
Different cell culture conditions and techniques have been used to mature spermatogenic cells to increase the success of in vitro fertilization. Sertoli cells (SCs) are essential in maintaining spermatogenesis and FSH stimulation exerts its effect through direct or indirect actions on SCs. The effectiveness of FSH and testosterone added to the co-culture has been demonstrated in other studies to provide microenvironment conditions of the testicular niche and to contribute to the maturation and meiotic progression of spermatogonial stem cells (SSCs). In the present study, we investigated whether co-culture of healthy SCs with the patient's testicular tissue in the medium supplemented with FSH/testosterone provides an advantage in the differentiation and maturation of germ cells in NOA cases (N = 34). In men with obstructive azoospermia (N = 12), healthy SCs from testicular biopsies were identified and purified, then cryopreserved. The characterization of healthy SCs was done by flow cytometry (FC) and immunohistochemistry using antibodies specific for GATA4 and vimentin. FITC-conjugated annexin V/PI staining and the MTT assay were performed to compare the viability and proliferation of SCs before and after freezing. In annexin V staining, no difference was found in percentages of live and apoptotic SCs, and MTT showed that cryopreservation did not inhibit SC proliferation compared to the pre-freezing state. Then, tissue samples from NOA patients were processed in two separate environments containing FSH/testosterone and FSH/testosterone plus co-culture with thawed healthy SCs for 7 days. FC was used to measure 7th-day levels of specific markers expressed in spermatogonia (VASA), meiotic cells (CREM), and post-meiotic cells (protamine-2 and acrosin). VASA and acrosin basal levels were found to be lower in infertile patients compared to the OA group (8.2% vs. 30.6% and 12.8% vs. 30.5%, respectively; p < 0.05). Compared to pre-treatment measurements, on the 7th day in the FSH/testosterone environment, CREM levels increased by 58.8% and acrosin levels increased by 195.5% (p < 0.05). Similarly, in medium co-culture with healthy SCs, by day 7, CREM and acrosin levels increased to 92.2% and 204.8%, respectively (p < 0.05). Although VASA and protamine levels increased in both groups, they did not reach a significant level. No significant difference was found between the day 7 increase rates of CREM, VASA, acrosin and protamine-2 in either FSH/testosterone-containing medium or in medium additionally co-cultured with healthy SCs (58.8% vs. 92.2%, 120.6% vs. 79.4%, 195.5% vs. 204.8%, and 232.3% vs. 198.4%, respectively; p > 0.05). Our results suggest that the presence of the patient's own SCs for maturation of germ cells in the culture medium supplemented with FSH and testosterone is sufficient, and co-culture with healthy SCs does not have an additional advantage. In addition, the freezing-thawing process would not impair the viability and proliferation of SCs.</p
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