New telechelic polymers functionalized with terminal ethyl xanthate or vinyl groups were synthesized via cationic ring-opening polymerization (CROP). The polymerization of 2-ethyl-2-oxazoline (Etoxa) and 2-methoxycarbonylethyl-2-oxazoline (Esteroxa) was initiated by 1,4-trans-dibromobutene in acetonitrile at 78 ℃, with termination using either potassium ethyl xanthate or 4-vinylbenzyl-piperazine. Structural characterization by 1H and 13C NMR and FTIR spectroscopy confirmed the telechelic architecture. 1H NMR analysis revealed degrees of polymerization (DP) of 24–29 for ethyl xanthate-terminated polymers and 22–23 for vinyl-terminated polymers, consistent with theoretical values. The molar compositions of Etoxa and Esteroxa in all telechelic polymers matched the initial monomer feed ratios. End-group functionalization efficiency was quantified as follows: Ethyl xanthate-terminated polymers: 64%–82%, and vinyl-terminated polymers: 69% and 98% (for respective batches).
In this paper, a solar tracking device that can continuously track the sun by adjusting the direction and angle of the solar panel in real time is designed and fabricated to improve the power generation efficiency of the solar cell panel. The mechanical parts as well as the automatic control part of the passive sun-tracking system are described, and the efficiency enhancement with the sun-tracking solar panel is characterized in comparison with the fixed panel system. The test results show that in the spring season in Qingdao city of eastern China, the sun-tracking system can improve the solar cell power generation efficiency by 28.5%–42.9% when comparing to the direction and elevation angle fixed system in sunny days. Even in partly cloudy days, the PV power output can increased by 37% with using the passive sun-tracking system. Economic analysis results show the cost-benefit period is about 10 years, which indicates that the passive sun tracking device can substantially contribute to the solar energy harvest practices.
Iran has one of the oldest civilizations in the world, and many elements of today’s urban planning and design have their origins in the country. However, mass country-city migration from the 1960s onwards brought enormous challenges for the country’s main cities in the provision of adequate housing and associated services, resulting in a range of sub-standard housing solutions, particularly in Tehran, the capital city. At the same time, and notably in the past decade, Iran’s main cities have had significant involvement in the smart city movement. The Smart Tehran Program is currently underway, attempting to transition the capital towards a smart city by 2025. This study adopts a qualitative, inductive approach based on secondary sources and interview evidence to explore the current housing problems in Tehran and their relationship with the Smart Tehran Program. It explores how housing has evolved in Tehran and identifies key aspects of the current provision, and then assesses the main components of the Smart Tehran Program and their potential contribution to remedying the housing problems in the city. The article concludes that although housing related issues are at least being raised via the new smart city technology infrastructure, any meaningful change in housing provision is hampered by the over centralized and bureaucratic political system, an out of date planning process, lack of integration of planning and housing initiatives, and the limited scope for real citizen participation.
Public works (PWs) in Jordan seek to deliver public services that contribute to socio-economic growth and service provision. A clear framework for initiating PWs investments is lacking in Jordan to meet the required level of development of the country. This work sought to develop a framework for delivering the right PWs investments. The study found that there are several steps that need to be followed to deliver a desired project’s objectives. The study employed a qualitative method using semi-structured interviews. Besides the interviews, the document analysis approach was used and an extensive literature review was conducted. Experts in Jordan regarding PWs development were selected to participate in this study of developing a framework for the initiation of PWs investments. The study found that the framework should involve different steps and measures. They are integrated together to create a framework reflecting international practices in the context of Jordan.
The project finance scenario has changed significantly around the world after the 2008 financial crisis and following the subsequent Basel III recommendations. Project finance loans from commercial banks and financial institutions have largely dried up, leaving it mostly to the export credit agencies and the bilateral and multilateral development banks to provide the institutional credit. Unfortunately, those sources are not enough, given the huge needs for construction of new infrastructure and renovation of the old ones across Asia, Africa and Latin America. The need for capital markets, through market listed financial products across asset class, unlocking a large part of domestic and corporate savings, has never been felt as strongly before. This article seeks to analyze the development story of various Asian capital markets and examine financial products, which have succeeded in their short history in receiving investor interest. The article also delves into the challenges to market development, policy imperatives and the issues relating to market liquidity and credit rating, which are the most significant influencers for public market float and investor interest.
Phytomediation is an environmentally friendly green rehabilitation technology that is often incorporated with an application to improve calcium peroxide and phytohormones required for the growth of agricultural plants with the expectation to improve the effectiveness of plant rehabilitation. This study mainly consists of two parts: (1) water culture experiment and (2) pot culture experiment. In the water culture experiment, we attempt to understand the influence of the addition of calcium peroxide, phytohormones (IAA and GA3) and a chelating agent on the growth of sunflower plants. However, in the pot culture experiment, when hormones and the chelating agent EDTA are introduced to different plant groups at the same time, if the nutrition in the water required by plants is not available, the addition of the hormone cannot negate the toxicity caused by EDTA. In terms of calcium peroxide, due to quick release of oxygen in water, this study fails to apply calcium peroxide to the water culture experiment.
When the pot culture experiment is used to examine the influence of hormones at different concentration levels on the growth of sunflowers, GA3 10-8 M is reported to have the optimal effectiveness, followed by IAA 10-8 M; IAA 10-12 M has the lowest effectiveness. According to an accumulation analysis of heavy metals at different levels, GA3 concentrates in leaves to transport nutrition in soil to leaves. This results in an excellent TF value of 2.329G of GA3 than 1.845 of the control group indicating that the addition of the hormone and chelating agent to GA3 increases the TF value and the chelating agent is beneficial to the sunflower plant. If we examine phytoattenuation ability, the one-month experiment was divided into three stages for ten days each. The concentration level of heavy metals in the soil at each stage dropped continuously while that of the control group decreased from 31.63 mg/kg to 23.96 mg/kg, GA3 from 32.09 mg/kg to 23.04 mg/kg and EDTA from 30.65 mg/kg to 25.93 mg/kg indicating the quickest growth period of the sunflowers from the formation of the bud to blossom. During the stage, the quick upward transportation of nutrition results in quick accumulation of heavy metals; the accumulated speed of heavy metals is found higher than that of directly planted plants. This study shows an improvement in the effectiveness of the addition of hormones on plant extraction and when rehabilitation is incorporated with sunflowers with the beginning bud formation, better treatment effectiveness can be reached.
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