Removal of Pb(II) from aqueous solutions by using clinoptilolite and bentonite as adsorbents

In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remove Pb(II) from aqueous solutions has been investigated in batch reactors with a maximum contact time of 120 min. Adsorption tests of Pb(II) were carried out using a solution concentration of 1,036 ppm at initial pH = 4, and solid to liquid ratio of 2 g/100 mL. The effects of agitation speed (0, 100, 200, 500 rpm), temperature (28°C, 45°C, 60°C) and particle size (2.5–5.0 mm, dust) of the minerals were examined. The effect of acidity of the aqueous solution was also examined. Bentonite was found to be more effective for the removal of Pb(II) than clinoptilolite, under the experimental conditions used. The removal of Pb(II) using bentonite reached 100% at ambient temperature and mild agitation (100 rpm), while it was approximately 90% at 60°C without agitation. On the other hand, the highest removal level reached by clinoptilolite was 55%. Clinoptilolite dust is found to be more efficient than granular clinoptilolite. Agitation and temperature affected the uptake of Pb(II), especially in the case of granular clinoptilolite (2.5–5.0 mm). Finally, it can be seen that acidity of the aqueous solution influences the removal of lead by the minerals. The adsorption of lead increases with an increase in pH of the solution from 1 to 4.     

Evaluating e-government: learning from the experiences of two UK local authorities

Abstract. Part of the remit of public sector management includes planning and reflecting on capital expenditure on new technology. With this in mind, the role that information systems play in supporting improvements in e-government service delivery to stakeholder groups continues to attract much attention. The authors of this paper seek to define the scope and role that information systems evaluation plays within the public sector. In particular, the authors assess whether public sector organizations might benefit from the use of established ex-ante evaluation techniques, when applied to analyse the impact of e-government information systems. Following a comprehensive review of the normative literature, an initial conceptual framework for public sector information systems evaluation is proposed, which is then empirically explored within two local government authorities. The conceptual framework is then revised by using the structured case approach, which is dependent on an iterative research cycle where triangulated data are elicited. This then supports the emergence of new concepts during each research cycle that leads to the view that information systems evaluation in the public sector is a process of experiential and subjective judgement, which is grounded in opinion and world views. This leads the authors to challenge the appropriateness of traditional modes of investment appraisal when applied in the public sector. The finalized framework embraces investment decisions, evaluation methods, culture and structure, as well as post hoc evaluation. It emphasizes the importance of situated, interpretive user assessments in evaluating e-government investments.     

S‐N curve for riveted details in corrosive environment and its application to a bridge

A formula for stress‐life curve is proposed to predict the fatigue life of riveted bridges located in corrosive environments. The corrosive environment‐dependent parameters of the S‐N curve are determined based on the corrosion fatigue testing results of different types of steel specimens in air, fresh water, and seawater. Eurocode detail category 71 and UK WI‐rivet detail category represent the fatigue strength of riveted members. The proposed S‐N curve formula is compared with full‐scale fatigue test results of riveted joints, plate girders, and truss girders, which were tested in a corrosive environment. Thus, the validity of the formula is confirmed. The formula does not require any material parameter other than the code‐given fatigue curve of riveted details. The fatigue life of a riveted railway bridge is estimated by using the proposed formula, and the results are compared with conventional approaches. The applicability and significance of the proposed curve are confirmed.     

The Athens–Corinth highway and railway crossing a tectonically active area in Greece

The paper discusses the appraisal, in terms of geological risk, of the new Athens–Corinth highway and railway projects in the area of Kakia Skala, which exhibits strong characteristics of neotectonic activity. After detailed mapping of the faults and the evaluation of their future behavior based on geological criteria, a seismic displacement of up to 0.5 m along the fault line was considered possible. Modifications were made to the initial alignment so that the engineering structures, particularly bridges, were located away from the main active fault. In places where such changes were not possible, for technical or economic reasons, the construction of over-bored tunnels was recommended.      

Environmental effects in a karstic aquifer due to seepage from an in-river reservoir

The paper estimates the anticipated changes in the seepage conditions towards the karstic aquifer, the recharge of the aquifer from the combined rainfall, seepage and exploitation as well as the potential alteration in the quality of the aquifer due to the creation of a nearby reservoir. It is shown that despite the somewhat increased seepage of polluted river water towards the aquifer, the quality of the groundwater in the karstic aquifer is not expected to degrade appreciably. However, since the water of the aquifer is used for the supply of neighbouring communities, it is proposed that in the areas where the thickness of the intervening semi-permeable alluvia is small, artificial sealing is installed using either compacted clay or plastic membranes.     

Using intelligent clustering techniques to classify the energy performance of school buildings

The present paper deals with the energy performance, energy classification and rating and the global environmental quality of school buildings. A new energy classification technique based on intelligent clustering methodologies is proposed. Energy rating of school buildings provides specific information on their energy consumption and efficiency relative to the other buildings of similar nature and permits a better planning of interventions to improve its energy performance. The overall work reported in the present paper, is carried out in three phases. During the first phase energy consumption data have been collected through energy surveys performed in 320 schools in Greece. In the second phase an innovative energy rating scheme based on fuzzy clustering techniques has been developed, while in the third phase, 10 schools have been selected and detailed measurements of their energy efficiency and performance as well as of the global environmental quality have been performed using a specific experimental protocol. The proposed energy rating method has been applied while the main environmental and energy problems have been identified. The potential for energy and environmental improvements has been assessed.     

Effects on TCP of routing strategies in satellite constellations

A broadband satellite network uses a constellation of a number of similar satellites to provide wireless networking services to the Earth. A number of these constellation networks are under development. This article introduces the types of satellite constellation networks, and examines how overall performance of TCP communications carried across such a network can be affected by the choice of routing strategies used within the network. Constellations utilizing direct intersatellite links are capable of using multiple paths between satellites simultaneously as a strategy to spread network load. This allows more general routing strategies than shortest-path routing, but we show these strategies to be detrimental to the performance of individual TCP connections     

A management and control architecture for providing IPdifferentiated services in MPLS-based networks

As the Internet evolves toward the global multiservice network of the future, a key consideration is support for services with guaranteed quality of service. The proposed differentiated services framework is seen as the key technology to achieve this. DiffServ currently concentrates on control/data plane mechanisms to support QoS, but also recognizes the need for management plane aspects through the bandwidth broker. In this article we propose a model and architectural framework for supporting DiffServ-based end-to-end QoS in the Internet, assuming underlying MPLS-based explicit routed paths. The proposed integrated management and control architecture will allow providers to offer both quantitative and qualitative services while optimizing the use of underlying network resources     

Technology interoperation in ATM networks: the REFORM system

This article addresses the applicability and interoperation of standards and emerging technologies for the operation and management of ATM networks. The issue is tackled from a practical perspective based on experiences gained through the design, realization, and experimentation of a system developed by the ACTS AC208 REFORM project. Assuming an ATM-based network infrastructure offering a range of services with distinct QoS guarantees, the REFORM system encompasses the required functions for ensuring cost-effective network survivability and availability; fast-responding reliable fault detection and self-healing mechanisms, distributed dynamic routing functions with inherent load balancing capabilities, efficient VP layer design, and dynamic network reconfiguration functions. A number of standards and emerging technologies were used for designing and realizing the wide spectrum of functionality incorporated within the REFORM system, including ITU-T OAM 1.610 and Q.2931, ATM Forum UNI 3.0 and PNNI v. 1, OMG CORBA and Component Model, TINA NRA and ISO/OSI, and ITU-T TMN. Based on the experience gained, the article discusses and draws conclusions on the applicability, coexistence, and interoperation of the adopted technologies. It is shown that these technologies can coexist, through careful design, to the benefit of network design and operation     

Intact Type I Interferon Receptor Signaling Prevents Hepatocellular Necrosis but Not Encephalitis in a Dose-Dependent Manner in Rift Valley Fever Virus Infected Mice

Rift Valley fever (RVF) is a zoonotic and emerging disease, caused by the RVF virus (RVFV). In ruminants, it leads to “abortion storms” and enhanced mortality rates in young animals, whereas in humans it can cause symptoms like severe hemorrhagic fever or encephalitis. The role of the innate and adaptive immune response in disease initiation and progression is still poorly defined. The present study used the attenuated RVFV strain clone 13 to investigate viral spread, tissue tropism, and histopathological lesions after intranasal infection in C57BL/6 wild type (WT) and type I interferon (IFN-I) receptor I knockout (IFNAR^−/−) mice. In WT mice, 10⁴ PFU RVFV (high dose) resulted in a fatal encephalitis, but no hepatitis 7–11 days post infection (dpi), whereas 10³ PFU RVFV (low dose) did not cause clinical disease or significant histopathological lesions in liver and the central nervous system (CNS). In contrast, IFNAR^−/− mice infected with 10³ PFU RVFV developed hepatocellular necrosis resulting in death at 2–5 dpi and lacked encephalitis. These results show that IFNAR signaling prevents systemic spread of the attenuated RVFV strain clone 13, but not the dissemination to the CNS and subsequent fatal disease. Consequently, neurotropic viruses may be able to evade antiviral IFN-I signaling pathways by using the transneuronal instead of the hematogenous route.