Simple new correlation for the prediction of equilibrium constant (KP) of Haber reaction covering the industrial conditions

Ammonia is an important industrial chemical, and its production is one of the highest of all inorganic chemicals. It is synthesized, in principal, from nitrogen and hydrogen by Haber process. It was found that the equilibrium constant (K_P) of Haber reaction is strongly pressure dependent. Many correlations were developed in order to rigorously express this (K_P); however, the most reliable expressions involved are inherently complex. This paper illustrates a simple correlation which was developed to express the value of (K_P) of Haber reaction at temperatures from 350 to 600 °C and pressures from 50 to 300 atm, which covers today’s industrial range. In this correlation, K_P is expressed in terms of temperature and pressure of equilibrium mixture which is the direct data measured. The effects of temperature and pressure are not separated allowing K_P to be calculated directly, without iterations; using spreadsheet. Results were compared to that of Gillespie and Beattie method showing very good match. The new simple correlation can be used easily in commercial simulation packages, e.g. Hysys, using its embedded spreadsheet to build reliable ammonia synthesis reactor modeling benefiting from featured analysis methods of these packages.     

Acute Lung Injury in Cholinergic-Deficient Mice Supports Anti-Inflammatory Role of α7 Nicotinic Acetylcholine Receptor

(1) Background: The lung cholinergic pathway is important for controlling pulmonary inflammation in acute lung injury, a condition that is characterized by a sudden onset and intense inflammation. This study investigated changes in the expression levels of nicotinic and muscarinic acetylcholine receptors (nAChR and mAChR) in the lung during acute lung injury. (2) Methods: acute lung injury (ALI) was induced in wild-type and cholinergic-deficient (VAChT-KD^HOM) mice using intratracheal lipopolysaccharide (LPS) instillation with or without concurrent treatment with nicotinic ligands. Bronchoalveolar lavage fluid was collected to evaluate markers of inflammation, and then the lung was removed and processed for isolation of membrane fraction and determination of acetylcholine receptors level using radioligand binding assays. (3) Results: LPS-induced increase in lung inflammatory markers (e.g., neutrophils and IL-1β) was significantly higher in VAChT-KD^HOM than wild-type mice. In contrast, LPS treatment resulted in a significant increase in lung’s α7 nicotinic receptor level in wild-type, but not in VAChT-KD^HOM mice. However, treatment with PNU 282987, a selective α7 nicotinic receptor agonist, restored VAChT-KD^HOM mice’s ability to increase α7 nicotinic receptor levels in response to LPS-induced acute lung injury and reduced lung inflammation. LPS also increased muscarinic receptors level in VAChT-KD^HOM mice, and PNU 282987 treatment reduced this response. (4) Conclusions: Our data indicate that the anti-inflammatory effects of the lung cholinergic system involve an increase in the level of α7 nicotinic receptors. Pharmacological agents that increase the expression or the function of lung α7 nicotinic receptors have potential clinical uses for treating acute lung injury.     

Adaptive cumulative sum charts with the adaptive runs rule

Adaptive cumulative sum (ACUSUM) charts, which adjust the reference value dynamically based on estimated shift size, provide good performance in detecting a range of mean shifts. However, when the range is wide, ACUSUM may not perform well for small shifts over the range. An adaptive runs rule, which is motivated by the concept of supplementary runs rule, is proposed, in order to make control charts more sensitive to small mean shifts. The adaptive runs rule assigns scores to consecutive runs based on the estimated shift size of the mean. The ACUSUM chart is supplemented with the adaptive runs rule to enhance its sensitivity in detecting small mean shifts. The average run length performance of the ACUSUM chart with the adaptive runs rule is compared with those of cumulative sum and variants of adaptive charts including ACUSUM. The experimental results reveal that the ACUSUM chart with the adaptive runs rule achieves superior detection performance over a wide range of mean shifts.     

An integrated building information modelling-based environmental impact assessment framework

The application of Environmental Impact Assessment (EIA) studies faces many challenges, especially in developing countries. This problem was investigated in the existing literature and via a designed questionnaire among local practitioners. The reasons were mainly attributed to the seclusion of the EIA process across the project’s phases, as well as the complexity of the EIA procedures. Hence, the research argues that Building Information Modelling (BIM) applications can be the key to resolve several associated problems to EIA either directly, or indirectly by streamlining Environmental Management System (EMS). Thus, a keyword-based scientometric analysis was used to define parameters and interrelations and establish network analysis for a proposed BIM-based EIA framework. The proposed framework presents scoring schemes to support three types of assessments: the efficiency of applying BIM techniques for an EIA process (Score A), proper integration of BIM techniques for different EIA steps (Score I) and proper integration of BIM techniques across project phases (Score B). It also shows the interplay of points between the three schemes via a Sankey diagram. The proposed framework was applied to compare three major construction projects in a developing country, the case of Egypt to pinpoint areas of drawbacks. The results pinpointed poor application of advanced BIM models to support sustainability analysis for EIA studies. This is in addition to imbalance of applying BIM applications across different project phases, it was notably less pronounced for the operation and maintenance stage as well as end of life scenarios. Also, poor integration of BIM tools could not support decisions related to the mitigation step. Hence, applying 6-dimensional BIM model shall enable developing mitigation measures and shall support design optimization during building operation and end of life phase. This novel approach presents the required level of verification and quality control procedure needed by decision-makers and environmental engineers to perform EIA studies and pave the way for further related research.

Graphical Abstract

     

Performance of MIMO cross‐layer MAC protocol based on antenna selection in ad hoc networks

In this paper, we investigate the performance of a cross‐layer (physical and MAC) design for multiple‐input multiple‐output (MIMO) system that aims at maximizing the throughput of ad hoc networks by selecting the optimum antenna combination. Employing this cross‐layer design is shown to improve the overall network performance relative to the case where no antenna selection (AS) is used. To solve the node blocking problem associated with the IEEE 802.11 medium‐access control (MAC) protocol, the proposed protocol leverage the available degrees of freedom offered by the MIMO system to allow neighboring nodes to simultaneously communicate using the zero‐forcing (ZF) Bell‐labs layered space‐time (BLAST) architecture. Using the cross‐layer design, neighboring nodes share their optimum antenna selection (AS) information through control messages. Given this shared information, nodes set their decisions on the number of selected antennas based on the available spatial channels that guarantees collision‐free transmissions. At the destination node, the ZF receiver is employed to extract the desired user data while treating the data from neighboring users as interference. The performance of the proposed cross‐layer design is examined through simulations, where we show that the network throughput is significantly improved compared to conventional MAC protocols. Copyright © 2010 John Wiley & Sons, Ltd.