Friction and wear performance analysis of hydrofluoroether-7000 refrigerant as lubricant

The disquiet about global warming has triggered the formulation and introduction of new generation of refrigerants. Hydrofluoroethers (HFEs) are within the family of newly developed environmentally friendly refrigerants with a wide range of application areas. Hydrofluoroethers reportedly have better heat transfer and thermodynamic properties. In addition to an understanding and knowledge of the thermodynamic properties of refrigerants, it is essential to understand the tribological properties of refrigerants within the context of sustainable development. Tribo-performance of refrigerants applied in refrigeration, air-conditioning and energy systems directly influences the durability, reliability and cost effectiveness of the system. HFE-7000 has considerable potential for engineering applications in green energy and low carbon technologies. In this research, a detailed investigation has been performed to assess friction and wear performance of HFE-7000 (HFE-347mcc3). HFE-7000 has been employed as lubricants. Experimental results indicate the formation of tribo-films on the topmost surfaces. Energy-Dispersive X-ray Spectroscopic (EDS) and X-ray Photoelectron Spectroscopic (XPS) analyses on the tested samples revealed significant presence of oxygenated and fluorinated anti-wear tribo-films. These oxygen and fluorine containing tribo-layers prevent metal to metal contact and contribute to the reduction of friction and wea

Rural road management in Botswana

This paper discusses the management of rural roads in Chobe in Botswana, which are mainly tertiary and access roads. These roads are low-volume roads and mostly gravelled. It was observed that the maintenance management of these roads was based on engineering judgement through visual inspection all over the country, without having any economic or technical analysis. Therefore, a comprehensive pavement management system for rural roads' maintenance is needed in Chobe and also in all the council areas of Botswana, which would consist of data collection, database, use of the Highway Development and Management Model to undertake efficient decision making project preparation, funding, implementation and feedback. A partial implementation of pavement management system in Chobe has been highlighted in this paper. The present analysis reveals that total demand for the road network in Chobe was 41·29 million pula, the backlog was 34·86 million pula and the first-year backlog demand was 20·63 million pula. Furthermore, the analysis found the long-term periodic maintenance strategy for the network at 6·43 million pula when there is no backlog. This huge backlog indicates that roads are not being maintained appropriately. The paper also estimates current road asset value in Chobe at 55·48 million pula. Finally, the paper recommends several solutions for the efficient preservation of road assets in Botswana

Backward and Forward Inference in Interacting Independent-Cascade Processes: A Scalable and Convergent Message-Passing Approach

We study the problems of estimating the past and future evolutions of two diffusion processes that spread concurrently on a network. Specifically, given a known network $G=(V, \overrightarrow{E})$ and a (possibly noisy) snapshot $\mathcal{O}_n$ of its state taken at (a possibly unknown) time $W$, we wish to determine the posterior distributions of the initial state of the network and the infection times of its nodes. These distributions are useful in finding source nodes of epidemics and rumors -- $\textit{backward inference}$ -- , and estimating the spread of a fixed set of source nodes -- $\textit{forward inference}$. To model the interaction between the two processes, we study an extension of the independent-cascade (IC) model where, when a node gets infected with either process, its susceptibility to the other one changes. First, we derive the exact joint probability of the initial state of the network and the observation-snapshot $\mathcal{O}_n$. Then, using the machinery of factor-graphs, factor-graph transformations, and the generalized distributive-law, we derive a Belief-Propagation (BP) based algorithm that is scalable to large networks and can converge on graphs of arbitrary topology (at a likely expense in approximation accuracy)

Engineered nanoparticles for removal of pollutants from wastewater: Current status and future prospects of nanotechnology for remediation strategies

Significant aspects of the world\u27s water scenario, primarily associated with global population growth and climate change, necessitate new technology implementation to ensure a supply of drinking water and prevent global water contamination. In light of this, the incorporation of state-of-the-art nanotechnology in conventional process engineering opens new paths for improved wastewater treatment technologies. Nano-based materials techniques, such as disinfection, desalination, sensing and monitoring, photocatalysis, membrane process, adsorption, biological treatment, coagulation/precipitation, and oxidation are discussed in this overview of current breakthroughs in nanotechnologies for removal of pollutants from wastewater. The benefits of these nano-based materials for wastewater treatment approaches, as well as the technical challenges are discussed in this review. The current state of commercialization, as well as future research opportunities in nano-based materials and technologies are highlighted. Additionally, the anticipated scientific breakthroughs, the constraints of nanotechnology for desalination processes, such as rules and regulations, and potential health risks are addressed. The regulation of nanoengineered materials and technologies used in wastewater treatment is being addressed in both Europe and United States of America

Emerging contaminants of high concern for the environment: Current trends and future research

Wastewater is contaminated water that must be treated before it may be transferred into other rivers and lakes in order to prevent further groundwater pollution. Over the last decade, research has been conducted on a wide variety of contaminants, but the emerging contaminants are those caused primarily by micropollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, and toxins, as well as industrially-related synthetic dyes and dye-containing hazardous pollutants. Most emerging pollutants did not have established guidelines, but even at low concentrations they could have harmful effects on humans and aquatic organisms. In order to combat the above ecological threats, huge efforts have been done with a view to boosting the effectiveness of remediation procedures or developing new techniques for the detection, quantification and efficiency of the samples. The increase of interest in biotechnology and environmental engineering gives an opportunity for the development of more innovative ways to water treatment remediation. The purpose of this article is to provide an overview of emerging sources of contaminants, detection technologies, and treatment strategies. The goal of this review is to evaluate adsorption as a method for treating emerging pollutants, as well as sophisticated and cost-effective approaches for treating emerging contaminants

Islamic Monetary Economics: Insights from the Literature

This chapter reviews critical early literature of Islamic monetary economics. The prohibition of Riba has imposed challenges on Islamic economists to come up with the viable alternatives to achieve Islamic monetary policy goals. Our extensive review of theoretical and empirical literature indicates that equity based profit- and loss-sharing instruments have been proposed for conducting open market operations in an interest-free economy. Theoretically, the central bank can achieve desired goals by controlling money supply and profit-sharing ratios. The findings from empirical literature suggest that money demand tend to be more stable in an interest-free economy. Whether monetary transmission works through Islamic banking channel is controversial, but the literature is growing. These findings are not surprising as majority Muslim countries lack sustainable and equitable economic growth. Moreover, these countries suffer from higher inflation and unemployment with little or no monetary freedom due to fixed exchange rate regime, shallow financial markets and strict capital control

Sustainable green nanoadsorbents for remediation of pharmaceuticals from water and wastewater: A critical review

In the last three decades, pharmaceutical research has increased tremendously to offer safe and healthy life. However, the high consumption of these harmful drugs has risen devastating impact on ecosystems. Therefore, it is worldwide paramount concern to effectively clean pharmaceuticals contaminated water streams to ensure safer environment and healthier life. Nanotechnology enables to produce new, high-technical material, such as membranes, adsorbent, nano-catalysts, functional surfaces, coverages and reagents for more effective water and wastewater cleanup processes. Nevertheless, nano-sorbent materials are regarded the most appropriate treatment technology for water and wastewater because of their facile application and a large number of adsorbents. Several conventional techniques have been operational for domestic wastewater treatment but are inefficient for pharmaceuticals removal. Alternatively, adsorption techniques have played a pivotal role in water and wastewater treatment for a long, but their rise in attraction is proportional with the continuous emergence of new micropollutants in the aquatic environment and new discoveries of sustainable and low-cost adsorbents. Recently, advancements in adsorption technique for wastewater treatment through nanoadsorbents has greatly increased due to its low production cost, sustainability, better physicochemical properties and high removal performance for pharmaceuticals. Herein, this review critically evaluates the performance of sustainable green nanoadsorbent for the remediation of pharmaceutical pollutants from water. The influential sorption parameters and interaction mechanism are also discussed. Moreover, the future prospects of nanoadsorbents for the remediation of pharmaceuticals are also presented

Integrated multi-band WSS: from design to performance evaluation

Modern day optical communications require ever-increasing bandwidths and capacity, in order to keep up with the growth of traffic and resource-intensive applications. This increase in network capacity can be achieved through the use of the residual capacity of current-day infrastructure, although this requires switching and routing devices capable of wide-band operation in multiple transmission windows. In this work, we describe the design principle, architecture, and performance simulation of a photonic integrated circuit (PIC) based multi-band WSS, which is envisioned to operate on the S+C+L windows. While the architecture is scalable to an arbitrary channel and port count, we showcase a 24-channel implementation deployed on the 400ZR standard, providing both the penalty evaluation through DSP simulations, as well as a footprint evaluation based on the components design

Cooking with elaborate recipes can reduce the formation of mutagenic heterocyclic amines and promote comutagenic amines

Heterocyclic amines (HCAs) are foodborne carcinogens which formation is highly dependent on cooking conditions. HCAs have been commonly quantified in food items prepared with simple procedures. This approach is suitable for elucidating HCAs’ formation, but it reflects partially the contamination in consumed food. In the current investigation, the generation of HCAs has been investigated in fried beef items prepared with elaborated cooking recipes, and their occurrence has been compared with control beef fried without the addition of other ingredients than oil. The food recipes that included a variety of food ingredients had lower yields of mutagenic HCAs (≥ 47% reduction, with individual HCA levels ranging between 0.01 and 2.22 ng/g) with respect to the control beef. In contrast, the co-mutagens norharman and harman were formed generally at greater levels (up to 3 times the contamination in the control fried beef) in the items prepared including greater variety of ingredients

Recent technologies for nutrient removal and recovery from wastewaters: A review

Water scarcity and its pollution has become a concern in recent times. The disposal of nutrient-rich (nitrogen and phosphorous) wastewater is also one of the main cause of water pollution through eutrophication, reduced dissolved oxygen that poses threat to aquatic ecosystems. As a result, nutrient removal has become a mandate apart from the removal of organics. However, the removal of nutrients from sewage is a challenging task. Conversely, conventional biological treatment processes provide little relief in nutrient removal. The treated effluents from conventional biological processes do not achieve the stringent nutrient removal disposal standard limits and become primary cause of pollution in the receiving water bodies. This has stressed upon the need for eco-friendly, low-energy and cost-efficient nutrient removal treatment technologies. Various biological treatment combinations or variants are in use for the efficient removal of nutrients. The biological processes in itself or in combination with chemical processes are preferred over technologies based solely on physico-chemical processes for its treatment performance at lower cost. This review summarizes the existing treatment processes and their possible up-gradation with the aim to accomplish the marked effluent standards for the nutrients. The concept of conventional systems and advanced systems for nutrients (nitrogen and phosphorous) removal which are already developed or under development are deeply discussed. Further, the challenges of each treatment systems are abridged. Finally, the possible suggestions for the modification/retrofitting of existing treatment systems for achieving stringent disposal standards are pointed out