Compatibilization of polycarbonate/poly (ethylene terephthalate) blends by addition of their transesterification product

In this study, poly carbonate (PC) and poly (ethylene terephthalate) (PET) were reactive melt-blended under two different conditions to produce PC/PET copolymers. For each condition, samples were taken at specified mixing times representative a specific structure of copolymers and each one employed to physically compatibilize a PC/PET blend with a fixed composition. Reactive blending and copolymer structure are described by solubility analysis results. Continues declining and going through a minimum are two trends of solubility versus mixing time depending on reactive blending condition. Decreasing and increasing patterns of solubility curves were attributed to the formation of copolymers with longer and shorter block lengths, respectively, and the level of solubility was related to the amount of produced copolymers. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques were employed to investigate blend compatibility. The content and structure of copolymers showed favorable correlation of Tg differences of blend components and PET crystallinity. As expected, Tg of blend components approached to each other by the addition of copolymers, and the copolymers with longer block length caused less Tg differences. The melting point and crystallinity of PET were affected by introducing the copolymers too. In addition to the main melting endotherm, melting endotherm peaks of compatibilized blends had a shoulder that its corresponding melting point and crystallinity are related to the copolymer structure so that the longer length of block copolymer or higher its amount leads to the higher melting points. The SEM micrographs showed that, after the addition of the copolymer, smaller PET particles formed and uniformly dispersed in the PC matrix. A strong correlation between the blend morphology and the level of blend compatibility was demonstrated. The more compatibilized PC/PET blend, the better dispersion of PET particles in the PC matrix was obtained. The results of this study could be a basis for designing and production of compatibilizers suitable to achieve a desired level of compatibility in PC and polyester blends, specially in PC/PET blend

On a Bounded Budget Network Creation Game

We consider a network creation game in which each player (vertex) has a fixed budget to establish links to other players. In our model, each link has unit price and each agent tries to minimize its cost, which is either its local diameter or its total distance to other players in the (undirected) underlying graph of the created network. Two versions of the game are studied: in the MAX version, the cost incurred to a vertex is the maximum distance between the vertex and other vertices, and in the SUM version, the cost incurred to a vertex is the sum of distances between the vertex and other vertices. We prove that in both versions pure Nash equilibria exist, but the problem of finding the best response of a vertex is NP-hard. We take the social cost of the created network to be its diameter, and next we study the maximum possible diameter of an equilibrium graph with n vertices in various cases. When the sum of players' budgets is n-1, the equilibrium graphs are always trees, and we prove that their maximum diameter is Theta(n) and Theta(log n) in MAX and SUM versions, respectively. When each vertex has unit budget (i.e. can establish link to just one vertex), the diameter of any equilibrium graph in either version is Theta(1). We give examples of equilibrium graphs in the MAX version, such that all vertices have positive budgets and yet the diameter is Omega(sqrt(log n)). This interesting (and perhaps counter-intuitive) result shows that increasing the budgets may increase the diameter of equilibrium graphs and hence deteriorate the network structure. Then we prove that every equilibrium graph in the SUM version has diameter 2^O(sqrt(log n)). Finally, we show that if the budget of each player is at least k, then every equilibrium graph in the SUM version is k-connected or has diameter smaller than 4.Comment: 28 pages, 3 figures, preliminary version appeared in SPAA'1

Mechanochemical Characterisation of Calcined Impure Kaolinitic Clay as a Composite Binder in Cementitious Mortars

The availability of some supplementary cementitious materials, especially fly ash, is of imminent concern in Europe due to the projected closure of several coal-fired power generation plants. Pure kaolinitic clays, which arguably have the potential to replace fly ash, are also scarce and expensive due to their use in other industrial applications. This paper examines the potential utilisation of low-grade kaolinitic clays for construction purposes. The clay sample was heat-treated at a temperature of 800 °C and evenly blended with Portland cement in substitutions of 10–30% by weight. The physical, chemical, mineralogical and mechanical characteristics of the blended calcined clay cement were determined. The Frattini test proved the pozzolanic potential of the calcined impure clay, as a plot of its CaO and OH− was found below the lime solubility curve. The 28 days compressive strengths trailed the reference cement by 5.1%, 12.3% and 21.7%, respectively, at all replacement levels. The optimum replacement level between the three blends was found to be 20 wt.%

Influence of Calcining Temperature on the Mineralogical and Mechanical Performance of Calcined Impure Kaolinitic Clays in Portland Cement Mortars

In this work, the effects of calcination temperatures ranging from 600°C to 1,000°C on the changes in mineralogical phases and mechanical characteristics of calcined impure kaolinite clay blended cement mortars were investigated. The impact of calcining temperature on pozzolanic activity of impure kaolinite clay was evaluated using direct and indirect methods. The findings demonstrated that at 700°C, kaolinite changed from a crystalline to an amorphous metakaolin phase. Specific surface, water demand, and setting time of the blended cements decreased as calcining temperature increased. The compressive strengths of blended cement mortar containing low-grade clay calcined at 700°C, 800°C, and 900°C were found to be greater than that of 600°C and 1,000°C. Based on the results of pozzolanic reactivity evaluations and compressive strength development, the most effective calcining temperature was shown to be between 800°C and 900°C

Removal of the Cefazolin Antibiotic Using Polyaniline Resin-Polyethylene Glycol from Aqueous Medium

Cefazolin is a widely used antibiotic in the treatment of bacterial infections that enters the water sources in original or metabolized form through the discharge of sewage and effluents. The presence of antibiotics in the environment can affect non-target pathogens, change the structure, enrich the algae in water sources, interfere with photosynthesis in plants and cause morphological abnormalities in plants. Various methods have been studied to remove antibiotics. Among these, surface adsorption is one of the appropriate methods. Therefore, in this study, the synthesis of polyaniline-polyethylene glycol resin and its evaluation in the removal of cefazolin by the adsorption process were investigated. Polyanyylene-polyethylene glycol resin was prepared by chemical polymerization method. Transfer electron microscope, thermometer and infrared spectrometer were used to determine the properties of the synthesized resin. In this study, the effect of pH parameters in the range of 2 to 8, the amount of adsorbent 0.1 to 5 g, the initial concentration of antibiotics in the amount of 10 to 100 mg/L, contact time 15 to 120 minutes and the temperature range of 20 to 70 °C, adsorbent desorption with nitric acid and sodium hydroxide, the interfering compounds of chloride and sulfate were investigated. The adsorption isotherms of Langmuir, Freundlich, Tamkin and adsorption kinetics were determined. In all stages, spectrophotometer was used to determine the concentration of cefazolin and HPLC was used to determine the effect of interfering ions on the removal of cefazolin and to confirm the results of spectra to determine the effect of interfering ions. The contact time of 60 minutes of adsorbent and cefazolin was selected as the optimal time due to the completion of the adsorption capacity of polyaniline-polyethylene glycol resin and high removal efficiency. Due to the high removal efficiency of cefazolin at (pH = 5), cefazolin was selected as the optimal pH due to the competition between OH- ions and negatively charged molecules. Adsorbent (3 g) was selected as the optimal adsorbent due to the increase in removal efficiency with increasing adsorbent consumption and the presence of a large number of adsorption sites. Elimination of cefazolin was tested in the concentration range (10, 20, 50, 70 and 100 mg/L) and the results showed that with increasing the concentration of cefazolin, the removal efficiency decreased from 69% to 50% due to more adsorption sites on the adsorbent surface in concentrations. Low concentration of cefazolin causes to be rapidly absorbed and the removal efficiency increases. The results of experiments of the effect of disturbing compounds showed that the removal percentage of cefazolin in distilled water from 98.46% to 72.72% in municipal water despite the disturbing compounds of chloride and sulfate due to the formation of anions with the adsorbent surface and the formation of stable complexes and barriers to cefazolin uptake decreased. The results of adsorbent reduction showed that the percentage of removal of cefazolin after 6 steps by nitric acid decreased from 93.99 to 74.55% and decreased by profit from 41.25 to 21.56%

Mapping 123 million neonatal, infant and child deaths between 2000 and 2017

Since 2000, many countries have achieved considerable success in improving child survival, but localized progress remains unclear. To inform efforts towards United Nations Sustainable Development Goal 3.2—to end preventable child deaths by 2030—we need consistently estimated data at the subnational level regarding child mortality rates and trends. Here we quantified, for the period 2000–2017, the subnational variation in mortality rates and number of deaths of neonates, infants and children under 5 years of age within 99 low- and middle-income countries using a geostatistical survival model. We estimated that 32% of children under 5 in these countries lived in districts that had attained rates of 25 or fewer child deaths per 1,000 live births by 2017, and that 58% of child deaths between 2000 and 2017 in these countries could have been averted in the absence of geographical inequality. This study enables the identification of high-mortality clusters, patterns of progress and geographical inequalities to inform appropriate investments and implementations that will help to improve the health of all populations

Global injury morbidity and mortality from 1990 to 2017 : results from the Global Burden of Disease Study 2017

Correction:Background Past research in population health trends has shown that injuries form a substantial burden of population health loss. Regular updates to injury burden assessments are critical. We report Global Burden of Disease (GBD) 2017 Study estimates on morbidity and mortality for all injuries. Methods We reviewed results for injuries from the GBD 2017 study. GBD 2017 measured injury-specific mortality and years of life lost (YLLs) using the Cause of Death Ensemble model. To measure non-fatal injuries, GBD 2017 modelled injury-specific incidence and converted this to prevalence and years lived with disability (YLDs). YLLs and YLDs were summed to calculate disability-adjusted life years (DALYs). Findings In 1990, there were 4 260 493 (4 085 700 to 4 396 138) injury deaths, which increased to 4 484 722 (4 332 010 to 4 585 554) deaths in 2017, while age-standardised mortality decreased from 1079 (1073 to 1086) to 738 (730 to 745) per 100 000. In 1990, there were 354 064 302 (95% uncertainty interval: 338 174 876 to 371 610 802) new cases of injury globally, which increased to 520 710 288 (493 430 247 to 547 988 635) new cases in 2017. During this time, age-standardised incidence decreased non-significantly from 6824 (6534 to 7147) to 6763 (6412 to 7118) per 100 000. Between 1990 and 2017, age-standardised DALYs decreased from 4947 (4655 to 5233) per 100 000 to 3267 (3058 to 3505). Interpretation Injuries are an important cause of health loss globally, though mortality has declined between 1990 and 2017. Future research in injury burden should focus on prevention in high-burden populations, improving data collection and ensuring access to medical care.Peer reviewe