Trends in socioeconomic inequalities in full vaccination coverage among vietnamese children aged 12–23 months, 2000–2014: Evidence for mitigating disparities in vaccination
- Vo, Hoang, Huynh, Le-Thai, Anh, Hao, Do, Dang-An, Nguyen, Huy
- Authors: Vo, Hoang , Huynh, Le-Thai , Anh, Hao , Do, Dang-An , Nguyen, Huy
- Date: 2019
- Type: Text , Journal article
- Relation: Vaccines Vol. 7, no. 4 (2019), p.
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- Description: There has been no report on the situation of socioeconomic inequalities in the full vaccination coverage among Vietnamese children. This study aims to assess the trends and changes in the socioeconomic inequalities in the full vaccination coverage among Vietnamese children aged 12–23 months from 2000 to 2014. Data were drawn from Multiple Indicator Cluster Surveys (2000, 2006, 2011, and 2014). Concentration index (CCI) and concentration curve (CC) were applied to quantify the degree of the socioeconomic inequalities in full immunization coverage. The prevalence of children fully receiving recommended vaccines was significantly improved during 2000–2014, yet, was still not being covered. The total CCI of full vaccination coverage gradually decreased from 2000 to 2014 (CCI: from 0.241 to 0.009). The CC increasingly became close to the equality line through the survey period, indicating the increasingly narrow gap in child full immunization amongst the poor and the rich. Vietnam witnessed a sharp decrease in socioeconomic inequality in the full vaccination coverage for over a decade. The next policies towards children from vulnerable populations (ethnic minority groups, living in rural areas, and having a mother with low education) belonging to lower socioeconomic groups may mitigate socioeconomic inequalities in full vaccination coverage. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Huy Nguyen” is provided in this record**
- Authors: Vo, Hoang , Huynh, Le-Thai , Anh, Hao , Do, Dang-An , Nguyen, Huy
- Date: 2019
- Type: Text , Journal article
- Relation: Vaccines Vol. 7, no. 4 (2019), p.
- Full Text:
- Reviewed:
- Description: There has been no report on the situation of socioeconomic inequalities in the full vaccination coverage among Vietnamese children. This study aims to assess the trends and changes in the socioeconomic inequalities in the full vaccination coverage among Vietnamese children aged 12–23 months from 2000 to 2014. Data were drawn from Multiple Indicator Cluster Surveys (2000, 2006, 2011, and 2014). Concentration index (CCI) and concentration curve (CC) were applied to quantify the degree of the socioeconomic inequalities in full immunization coverage. The prevalence of children fully receiving recommended vaccines was significantly improved during 2000–2014, yet, was still not being covered. The total CCI of full vaccination coverage gradually decreased from 2000 to 2014 (CCI: from 0.241 to 0.009). The CC increasingly became close to the equality line through the survey period, indicating the increasingly narrow gap in child full immunization amongst the poor and the rich. Vietnam witnessed a sharp decrease in socioeconomic inequality in the full vaccination coverage for over a decade. The next policies towards children from vulnerable populations (ethnic minority groups, living in rural areas, and having a mother with low education) belonging to lower socioeconomic groups may mitigate socioeconomic inequalities in full vaccination coverage. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Huy Nguyen” is provided in this record**
The effect of sub-concussive impacts during a rugby tackling drill on brain function
- McNabb, Colm, Reha, Tahere, Georgieva, Julia, Jacques, Angela, Netto, Kevin, Lavender, Andrew
- Authors: McNabb, Colm , Reha, Tahere , Georgieva, Julia , Jacques, Angela , Netto, Kevin , Lavender, Andrew
- Date: 2020
- Type: Text , Journal article
- Relation: Brain Sciences Vol. 10, no. 12 (2020), p. 1-12
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- Description: Concussion is known to detrimentally affect brain health. Rugby tackles commonly occur with high collision force between tackler and ball carrier, and low impact head contact is not uncommon. Cognitive deficits following a bout of soccer ball heading has been attributed to the impact and termed sub-concussion. Although soccer ball heading studies provide evidence for acute effects of sub-concussion, it is unknown whether this phenomenon occurs following rugby tackles. This study investigates the acute effects of rugby tackles on brain function and balance in rugby players. Twenty-six volunteers were assigned to either the ball carrier (9), tackler (9) or control (8) group. Controls performed running without the tackle. Outcome measures included corticomotor function using transcranial magnetic brain stimulation (TMS) and balance was assessed by a series of tasks performed on a NeuroCom Balance Master before and immediately after a tackle training drill. Following the tackling bout, the cortical silent period (cSP) increased for the tacklers with no change for ball carrier and control groups, and no differences between groups for balance measures were observed. Lengthening of cSP observed in the tacklers following the bout has been reported in studies of concussion and may indicate long term detrimental effects. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: McNabb, Colm , Reha, Tahere , Georgieva, Julia , Jacques, Angela , Netto, Kevin , Lavender, Andrew
- Date: 2020
- Type: Text , Journal article
- Relation: Brain Sciences Vol. 10, no. 12 (2020), p. 1-12
- Full Text:
- Reviewed:
- Description: Concussion is known to detrimentally affect brain health. Rugby tackles commonly occur with high collision force between tackler and ball carrier, and low impact head contact is not uncommon. Cognitive deficits following a bout of soccer ball heading has been attributed to the impact and termed sub-concussion. Although soccer ball heading studies provide evidence for acute effects of sub-concussion, it is unknown whether this phenomenon occurs following rugby tackles. This study investigates the acute effects of rugby tackles on brain function and balance in rugby players. Twenty-six volunteers were assigned to either the ball carrier (9), tackler (9) or control (8) group. Controls performed running without the tackle. Outcome measures included corticomotor function using transcranial magnetic brain stimulation (TMS) and balance was assessed by a series of tasks performed on a NeuroCom Balance Master before and immediately after a tackle training drill. Following the tackling bout, the cortical silent period (cSP) increased for the tacklers with no change for ball carrier and control groups, and no differences between groups for balance measures were observed. Lengthening of cSP observed in the tacklers following the bout has been reported in studies of concussion and may indicate long term detrimental effects. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Cyberattacks detection in iot-based smart city applications using machine learning techniques
- Rashid, Md Mamunur, Kamruzzaman, Joarder, Hassan, Mohammad, Imam, Tassadduq, Gordon, Steven
- Authors: Rashid, Md Mamunur , Kamruzzaman, Joarder , Hassan, Mohammad , Imam, Tassadduq , Gordon, Steven
- Date: 2020
- Type: Text , Journal article
- Relation: International Journal of Environmental Research and Public Health Vol. 17, no. 24 (2020), p. 1-21
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- Description: In recent years, the widespread deployment of the Internet of Things (IoT) applications has contributed to the development of smart cities. A smart city utilizes IoT-enabled technologies, communications and applications to maximize operational efficiency and enhance both the service providers’ quality of services and people’s wellbeing and quality of life. With the growth of smart city networks, however, comes the increased risk of cybersecurity threats and attacks. IoT devices within a smart city network are connected to sensors linked to large cloud servers and are exposed to malicious attacks and threats. Thus, it is important to devise approaches to prevent such attacks and protect IoT devices from failure. In this paper, we explore an attack and anomaly detection technique based on machine learning algorithms (LR, SVM, DT, RF, ANN and KNN) to defend against and mitigate IoT cybersecurity threats in a smart city. Contrary to existing works that have focused on single classifiers, we also explore ensemble methods such as bagging, boosting and stacking to enhance the performance of the detection system. Additionally, we consider an integration of feature selection, cross-validation and multi-class classification for the discussed domain, which has not been well considered in the existing literature. Experimental results with the recent attack dataset demonstrate that the proposed technique can effectively identify cyberattacks and the stacking ensemble model outperforms comparable models in terms of accuracy, precision, recall and F1-Score, implying the promise of stacking in this domain. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Rashid, Md Mamunur , Kamruzzaman, Joarder , Hassan, Mohammad , Imam, Tassadduq , Gordon, Steven
- Date: 2020
- Type: Text , Journal article
- Relation: International Journal of Environmental Research and Public Health Vol. 17, no. 24 (2020), p. 1-21
- Full Text:
- Reviewed:
- Description: In recent years, the widespread deployment of the Internet of Things (IoT) applications has contributed to the development of smart cities. A smart city utilizes IoT-enabled technologies, communications and applications to maximize operational efficiency and enhance both the service providers’ quality of services and people’s wellbeing and quality of life. With the growth of smart city networks, however, comes the increased risk of cybersecurity threats and attacks. IoT devices within a smart city network are connected to sensors linked to large cloud servers and are exposed to malicious attacks and threats. Thus, it is important to devise approaches to prevent such attacks and protect IoT devices from failure. In this paper, we explore an attack and anomaly detection technique based on machine learning algorithms (LR, SVM, DT, RF, ANN and KNN) to defend against and mitigate IoT cybersecurity threats in a smart city. Contrary to existing works that have focused on single classifiers, we also explore ensemble methods such as bagging, boosting and stacking to enhance the performance of the detection system. Additionally, we consider an integration of feature selection, cross-validation and multi-class classification for the discussed domain, which has not been well considered in the existing literature. Experimental results with the recent attack dataset demonstrate that the proposed technique can effectively identify cyberattacks and the stacking ensemble model outperforms comparable models in terms of accuracy, precision, recall and F1-Score, implying the promise of stacking in this domain. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Evidence for cryptic diversity in the “pan-antarctic” springtail friesea antarctica and the description of two new species
- Carapelli, Antonio, Greenslade, Penelope, Nardi, Francesco, Leo, Chiara, Convey, Peter, Frati, Francesco, Fanciulli, Paolo
- Authors: Carapelli, Antonio , Greenslade, Penelope , Nardi, Francesco , Leo, Chiara , Convey, Peter , Frati, Francesco , Fanciulli, Paolo
- Date: 2020
- Type: Text , Journal article
- Relation: Insects Vol. 11, no. 3 (2020), p.
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- Description: The invertebrate terrestrial fauna of Antarctica is being investigated with increasing interest to discover how life interacts with the extreme polar environment and how millions of years of evolution have shaped their biodiversity. Classical taxonomic approaches, complemented by molecular tools, are improving our understanding of the systematic relationships of some species, changing the nomenclature of taxa and challenging the taxonomic status of others. The springtail Friesea grisea has previously been described as the only species with a “pan-Antarctic” distribution. However, recent genetic comparisons have pointed to another scenario. The latest morphological study has confined F. grisea to the sub-Antarctic island of South Georgia, from which it was originally described, and resurrected F. antarctica as a congeneric species occurring on the continental mainland. Molecular data demonstrate that populations of this taxon, ostensibly occurring across Maritime and Continental Antarctica, as well as on some offshore islands, are evolutionarily isolated and divergent and cannot be included within a single species. The present study, combining morphological with molecular data, attempts to validate this hypothesis and challenges the taxonomic status of F. antarctica, suggesting that two additional new species, described here as Friesea gretae sp. nov. and Friesea propria sp. nov., are present in Continental Antarctica. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Carapelli, Antonio , Greenslade, Penelope , Nardi, Francesco , Leo, Chiara , Convey, Peter , Frati, Francesco , Fanciulli, Paolo
- Date: 2020
- Type: Text , Journal article
- Relation: Insects Vol. 11, no. 3 (2020), p.
- Full Text:
- Reviewed:
- Description: The invertebrate terrestrial fauna of Antarctica is being investigated with increasing interest to discover how life interacts with the extreme polar environment and how millions of years of evolution have shaped their biodiversity. Classical taxonomic approaches, complemented by molecular tools, are improving our understanding of the systematic relationships of some species, changing the nomenclature of taxa and challenging the taxonomic status of others. The springtail Friesea grisea has previously been described as the only species with a “pan-Antarctic” distribution. However, recent genetic comparisons have pointed to another scenario. The latest morphological study has confined F. grisea to the sub-Antarctic island of South Georgia, from which it was originally described, and resurrected F. antarctica as a congeneric species occurring on the continental mainland. Molecular data demonstrate that populations of this taxon, ostensibly occurring across Maritime and Continental Antarctica, as well as on some offshore islands, are evolutionarily isolated and divergent and cannot be included within a single species. The present study, combining morphological with molecular data, attempts to validate this hypothesis and challenges the taxonomic status of F. antarctica, suggesting that two additional new species, described here as Friesea gretae sp. nov. and Friesea propria sp. nov., are present in Continental Antarctica. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Value-based caching in information-centric wireless body area networks
- Al-Turjman, Fadi, Imran, Muhammad, Vasilakos, Athanasios
- Authors: Al-Turjman, Fadi , Imran, Muhammad , Vasilakos, Athanasios
- Date: 2017
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 17, no. 1 (2017), p.
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- Description: We propose a resilient cache replacement approach based on a Value of sensed Information (VoI) policy. To resolve and fetch content when the origin is not available due to isolated in-network nodes (fragmentation) and harsh operational conditions, we exploit a content caching approach. Our approach depends on four functional parameters in sensory Wireless Body Area Networks (WBANs). These four parameters are: age of data based on periodic request, popularity of on-demand requests, communication interference cost, and the duration for which the sensor node is required to operate in active mode to capture the sensed readings. These parameters are considered together to assign a value to the cached data to retain the most valuable information in the cache for prolonged time periods. The higher the value, the longer the duration for which the data will be retained in the cache. This caching strategy provides significant availability for most valuable and difficult to retrieve data in the WBANs. Extensive simulations are performed to compare the proposed scheme against other significant caching schemes in the literature while varying critical aspects in WBANs (e.g., data popularity, cache size, publisher load, connectivity-degree, and severe probabilities of node failures). These simulation results indicate that the proposed VoI-based approach is a valid tool for the retrieval of cached content in disruptive and challenging scenarios, such as the one experienced in WBANs, since it allows the retrieval of content for a long period even while experiencing severe in-network node failures. © 2017 by the authors; licensee MDPI, Basel, Switzerland.
- Authors: Al-Turjman, Fadi , Imran, Muhammad , Vasilakos, Athanasios
- Date: 2017
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 17, no. 1 (2017), p.
- Full Text:
- Reviewed:
- Description: We propose a resilient cache replacement approach based on a Value of sensed Information (VoI) policy. To resolve and fetch content when the origin is not available due to isolated in-network nodes (fragmentation) and harsh operational conditions, we exploit a content caching approach. Our approach depends on four functional parameters in sensory Wireless Body Area Networks (WBANs). These four parameters are: age of data based on periodic request, popularity of on-demand requests, communication interference cost, and the duration for which the sensor node is required to operate in active mode to capture the sensed readings. These parameters are considered together to assign a value to the cached data to retain the most valuable information in the cache for prolonged time periods. The higher the value, the longer the duration for which the data will be retained in the cache. This caching strategy provides significant availability for most valuable and difficult to retrieve data in the WBANs. Extensive simulations are performed to compare the proposed scheme against other significant caching schemes in the literature while varying critical aspects in WBANs (e.g., data popularity, cache size, publisher load, connectivity-degree, and severe probabilities of node failures). These simulation results indicate that the proposed VoI-based approach is a valid tool for the retrieval of cached content in disruptive and challenging scenarios, such as the one experienced in WBANs, since it allows the retrieval of content for a long period even while experiencing severe in-network node failures. © 2017 by the authors; licensee MDPI, Basel, Switzerland.
On connectivity of wireless sensor networks with directional antennas
- Wang, Qiu, Dai, Hong-Ning, Zheng, Zibin, Imran, Muhammad, Vasilakos, Athanasios
- Authors: Wang, Qiu , Dai, Hong-Ning , Zheng, Zibin , Imran, Muhammad , Vasilakos, Athanasios
- Date: 2017
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 17, no. 1 (2017), p.
- Full Text:
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- Description: In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models. © 2017 by the authors; licensee MDPI, Basel, Switzerland.
- Authors: Wang, Qiu , Dai, Hong-Ning , Zheng, Zibin , Imran, Muhammad , Vasilakos, Athanasios
- Date: 2017
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 17, no. 1 (2017), p.
- Full Text:
- Reviewed:
- Description: In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models. © 2017 by the authors; licensee MDPI, Basel, Switzerland.
A quantitative risk assessment model involving frequency and threat degree under line-of-business services for infrastructure of emerging sensor networks
- Jing, Xu, Hu, Hanwen, Yang, Huijun, Au, Man, Li, Shuqin, Xiong, Naixue, Imran, Muhammad, Vasilakos, Athanasios
- Authors: Jing, Xu , Hu, Hanwen , Yang, Huijun , Au, Man , Li, Shuqin , Xiong, Naixue , Imran, Muhammad , Vasilakos, Athanasios
- Date: 2017
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 17, no. 3 (2017), p.
- Full Text:
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- Description: The prospect of Line-of-Business Services (LoBSs) for infrastructure of Emerging Sensor Networks (ESNs) is exciting. Access control remains a top challenge in this scenario as the service provider’s server contains a lot of valuable resources. LoBSs’ users are very diverse as they may come from a wide range of locations with vastly different characteristics. Cost of joining could be low and in many cases, intruders are eligible users conducting malicious actions. As a result, user access should be adjusted dynamically. Assessing LoBSs’ risk dynamically based on both frequency and threat degree of malicious operations is therefore necessary. In this paper, we proposed a Quantitative Risk Assessment Model (QRAM) involving frequency and threat degree based on value at risk. To quantify the threat degree as an elementary intrusion effort, we amend the influence coefficient of risk indexes in the network security situation assessment model. To quantify threat frequency as intrusion trace effort, we make use of multiple behavior information fusion. Under the influence of intrusion trace, we adapt the historical simulation method of value at risk to dynamically access LoBSs’ risk. Simulation based on existing data is used to select appropriate parameters for QRAM. Our simulation results show that the duration influence on elementary intrusion effort is reasonable when the normalized parameter is 1000. Likewise, the time window of intrusion trace and the weight between objective risk and subjective risk can be set to 10 s and 0.5, respectively. While our focus is to develop QRAM for assessing the risk of LoBSs for infrastructure of ESNs dynamically involving frequency and threat degree, we believe it is also appropriate for other scenarios in cloud computing. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Jing, Xu , Hu, Hanwen , Yang, Huijun , Au, Man , Li, Shuqin , Xiong, Naixue , Imran, Muhammad , Vasilakos, Athanasios
- Date: 2017
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 17, no. 3 (2017), p.
- Full Text:
- Reviewed:
- Description: The prospect of Line-of-Business Services (LoBSs) for infrastructure of Emerging Sensor Networks (ESNs) is exciting. Access control remains a top challenge in this scenario as the service provider’s server contains a lot of valuable resources. LoBSs’ users are very diverse as they may come from a wide range of locations with vastly different characteristics. Cost of joining could be low and in many cases, intruders are eligible users conducting malicious actions. As a result, user access should be adjusted dynamically. Assessing LoBSs’ risk dynamically based on both frequency and threat degree of malicious operations is therefore necessary. In this paper, we proposed a Quantitative Risk Assessment Model (QRAM) involving frequency and threat degree based on value at risk. To quantify the threat degree as an elementary intrusion effort, we amend the influence coefficient of risk indexes in the network security situation assessment model. To quantify threat frequency as intrusion trace effort, we make use of multiple behavior information fusion. Under the influence of intrusion trace, we adapt the historical simulation method of value at risk to dynamically access LoBSs’ risk. Simulation based on existing data is used to select appropriate parameters for QRAM. Our simulation results show that the duration influence on elementary intrusion effort is reasonable when the normalized parameter is 1000. Likewise, the time window of intrusion trace and the weight between objective risk and subjective risk can be set to 10 s and 0.5, respectively. While our focus is to develop QRAM for assessing the risk of LoBSs for infrastructure of ESNs dynamically involving frequency and threat degree, we believe it is also appropriate for other scenarios in cloud computing. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.
Secure authentication for remote patient monitoring withwireless medical sensor networks
- Hayajneh, Taier, Mohd, Bassam, Imran, Muhammad, Almashaqbeh, Ghada, Vasilakos, Athanasios
- Authors: Hayajneh, Taier , Mohd, Bassam , Imran, Muhammad , Almashaqbeh, Ghada , Vasilakos, Athanasios
- Date: 2016
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 16, no. 4 (2016), p.
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- Description: There is broad consensus that remote health monitoring will benefit all stakeholders in the healthcare system and that it has the potential to save billions of dollars. Among the major concerns that are preventing the patients from widely adopting this technology are data privacy and security. Wireless Medical Sensor Networks (MSNs) are the building blocks for remote health monitoring systems. This paper helps to identify the most challenging security issues in the existing authentication protocols for remote patient monitoring and presents a lightweight public-key-based authentication protocol for MSNs. In MSNs, the nodes are classified into sensors that report measurements about the human body and actuators that receive commands from the medical staff and perform actions. Authenticating these commands is a critical security issue, as any alteration may lead to serious consequences. The proposed protocol is based on the Rabin authentication algorithm, which is modified in this paper to improve its signature signing process, making it suitable for delay-sensitive MSN applications. To prove the efficiency of the Rabin algorithm, we implemented the algorithm with different hardware settings using Tmote Sky motes and also programmed the algorithm on an FPGA to evaluate its design and performance. Furthermore, the proposed protocol is implemented and tested using the MIRACL (Multiprecision Integer and Rational Arithmetic C/C++) library. The results show that secure, direct, instant and authenticated commands can be delivered from the medical staff to the MSN nodes. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
- Authors: Hayajneh, Taier , Mohd, Bassam , Imran, Muhammad , Almashaqbeh, Ghada , Vasilakos, Athanasios
- Date: 2016
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 16, no. 4 (2016), p.
- Full Text:
- Reviewed:
- Description: There is broad consensus that remote health monitoring will benefit all stakeholders in the healthcare system and that it has the potential to save billions of dollars. Among the major concerns that are preventing the patients from widely adopting this technology are data privacy and security. Wireless Medical Sensor Networks (MSNs) are the building blocks for remote health monitoring systems. This paper helps to identify the most challenging security issues in the existing authentication protocols for remote patient monitoring and presents a lightweight public-key-based authentication protocol for MSNs. In MSNs, the nodes are classified into sensors that report measurements about the human body and actuators that receive commands from the medical staff and perform actions. Authenticating these commands is a critical security issue, as any alteration may lead to serious consequences. The proposed protocol is based on the Rabin authentication algorithm, which is modified in this paper to improve its signature signing process, making it suitable for delay-sensitive MSN applications. To prove the efficiency of the Rabin algorithm, we implemented the algorithm with different hardware settings using Tmote Sky motes and also programmed the algorithm on an FPGA to evaluate its design and performance. Furthermore, the proposed protocol is implemented and tested using the MIRACL (Multiprecision Integer and Rational Arithmetic C/C++) library. The results show that secure, direct, instant and authenticated commands can be delivered from the medical staff to the MSN nodes. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
Mobile crowd sensing for traffic prediction in internet of vehicles
- Wan, Jiafu, Liu, Jianqi, Shao, Zehui, Vasilakos, Athanasios, Imran, Muhammad, Zhou, Keliang
- Authors: Wan, Jiafu , Liu, Jianqi , Shao, Zehui , Vasilakos, Athanasios , Imran, Muhammad , Zhou, Keliang
- Date: 2016
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 16, no. 1 (2016), p.
- Full Text:
- Reviewed:
- Description: The advances in wireless communication techniques, mobile cloud computing, automotive and intelligent terminal technology are driving the evolution of vehicle ad hoc networks into the Internet of Vehicles (IoV) paradigm. This leads to a change in the vehicle routing problem from a calculation based on static data towards real-time traffic prediction. In this paper, we first address the taxonomy of cloud-assisted IoV from the viewpoint of the service relationship between cloud computing and IoV. Then, we review the traditional traffic prediction approached used by both Vehicle to Infrastructure (V2I) and Vehicle to Vehicle (V2V) communications. On this basis, we propose a mobile crowd sensing technology to support the creation of dynamic route choices for drivers wishing to avoid congestion. Experiments were carried out to verify the proposed approaches. Finally, we discuss the outlook of reliable traffic prediction. © 2016 by the authors, licensee MDPI, Basel, Switzerland.
- Authors: Wan, Jiafu , Liu, Jianqi , Shao, Zehui , Vasilakos, Athanasios , Imran, Muhammad , Zhou, Keliang
- Date: 2016
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 16, no. 1 (2016), p.
- Full Text:
- Reviewed:
- Description: The advances in wireless communication techniques, mobile cloud computing, automotive and intelligent terminal technology are driving the evolution of vehicle ad hoc networks into the Internet of Vehicles (IoV) paradigm. This leads to a change in the vehicle routing problem from a calculation based on static data towards real-time traffic prediction. In this paper, we first address the taxonomy of cloud-assisted IoV from the viewpoint of the service relationship between cloud computing and IoV. Then, we review the traditional traffic prediction approached used by both Vehicle to Infrastructure (V2I) and Vehicle to Vehicle (V2V) communications. On this basis, we propose a mobile crowd sensing technology to support the creation of dynamic route choices for drivers wishing to avoid congestion. Experiments were carried out to verify the proposed approaches. Finally, we discuss the outlook of reliable traffic prediction. © 2016 by the authors, licensee MDPI, Basel, Switzerland.
Efficient data gathering in 3D linear underwater wireless sensor networks using sink mobility
- Akbar, Mariam, Javaid, Nadeem, Khan, Ayesha, Imran, Muhammad, Shoaib, Muhammad, Vasilakos, Athanasios
- Authors: Akbar, Mariam , Javaid, Nadeem , Khan, Ayesha , Imran, Muhammad , Shoaib, Muhammad , Vasilakos, Athanasios
- Date: 2016
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 16, no. 3 (2016), p.
- Full Text:
- Reviewed:
- Description: Due to the unpleasant and unpredictable underwater environment, designing an energy-efficient routing protocol for underwater wireless sensor networks (UWSNs) demands more accuracy and extra computations. In the proposed scheme, we introduce a mobile sink (MS), i.e., an autonomous underwater vehicle (AUV), and also courier nodes (CNs), to minimize the energy consumption of nodes. MS and CNs stop at specific stops for data gathering; later on, CNs forward the received data to the MS for further transmission. By the mobility of CNs and MS, the overall energy consumption of nodes is minimized. We perform simulations to investigate the performance of the proposed scheme and compare it to preexisting techniques. Simulation results are compared in terms of network lifetime, throughput, path loss, transmission loss and packet drop ratio. The results show that the proposed technique performs better in terms of network lifetime, throughput, path loss and scalability. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
- Authors: Akbar, Mariam , Javaid, Nadeem , Khan, Ayesha , Imran, Muhammad , Shoaib, Muhammad , Vasilakos, Athanasios
- Date: 2016
- Type: Text , Journal article
- Relation: Sensors (Switzerland) Vol. 16, no. 3 (2016), p.
- Full Text:
- Reviewed:
- Description: Due to the unpleasant and unpredictable underwater environment, designing an energy-efficient routing protocol for underwater wireless sensor networks (UWSNs) demands more accuracy and extra computations. In the proposed scheme, we introduce a mobile sink (MS), i.e., an autonomous underwater vehicle (AUV), and also courier nodes (CNs), to minimize the energy consumption of nodes. MS and CNs stop at specific stops for data gathering; later on, CNs forward the received data to the MS for further transmission. By the mobility of CNs and MS, the overall energy consumption of nodes is minimized. We perform simulations to investigate the performance of the proposed scheme and compare it to preexisting techniques. Simulation results are compared in terms of network lifetime, throughput, path loss, transmission loss and packet drop ratio. The results show that the proposed technique performs better in terms of network lifetime, throughput, path loss and scalability. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
Algorithm development for the non-destructive testing of structural damage
- Noori Hoshyar, Azadeh, Rashidi, Maria, Liyanapathirana, Ranjith, Samali, Bijan
- Authors: Noori Hoshyar, Azadeh , Rashidi, Maria , Liyanapathirana, Ranjith , Samali, Bijan
- Date: 2019
- Type: Text , Journal article
- Relation: Applied sciences Vol. 9, no. 14 (2019), p. 2810
- Full Text:
- Reviewed:
- Description: Monitoring of structures to identify types of damages that occur under loading is essential in practical applications of civil infrastructure. In this paper, we detect and visualize damage based on several non-destructive testing (NDT) methods. A machine learning (ML) approach based on the Support Vector Machine (SVM) method is developed to prevent misdirection of the event interpretation of what is happening in the material. The objective is to identify cracks in the early stages, to reduce the risk of failure in structures. Theoretical and experimental analyses are derived by computing the performance indicators on the smart aggregate (SA)-based sensor data for concrete and reinforced-concrete (RC) beams. Validity assessment of the proposed indices was addressed through a comparative analysis with traditional SVM. The developed ML algorithms are shown to recognize cracks with a higher accuracy than the traditional SVM. Additionally, we propose different algorithms for microwave- or millimeter-wave imaging of steel plates, composite materials, and metal plates, to identify and visualize cracks. The proposed algorithm for steel plates is based on the gradient magnitude in four directions of an image, and is followed by the edge detection technique. Three algorithms were proposed for each of composite materials and metal plates, and are based on 2D fast Fourier transform (FFT) and hybrid fuzzy c-mean techniques, respectively. The proposed algorithms were able to recognize and visualize the cracking incurred in the structure more efficiently than the traditional techniques. The reported results are expected to be beneficial for NDT-based applications, particularly in civil engineering.
- Authors: Noori Hoshyar, Azadeh , Rashidi, Maria , Liyanapathirana, Ranjith , Samali, Bijan
- Date: 2019
- Type: Text , Journal article
- Relation: Applied sciences Vol. 9, no. 14 (2019), p. 2810
- Full Text:
- Reviewed:
- Description: Monitoring of structures to identify types of damages that occur under loading is essential in practical applications of civil infrastructure. In this paper, we detect and visualize damage based on several non-destructive testing (NDT) methods. A machine learning (ML) approach based on the Support Vector Machine (SVM) method is developed to prevent misdirection of the event interpretation of what is happening in the material. The objective is to identify cracks in the early stages, to reduce the risk of failure in structures. Theoretical and experimental analyses are derived by computing the performance indicators on the smart aggregate (SA)-based sensor data for concrete and reinforced-concrete (RC) beams. Validity assessment of the proposed indices was addressed through a comparative analysis with traditional SVM. The developed ML algorithms are shown to recognize cracks with a higher accuracy than the traditional SVM. Additionally, we propose different algorithms for microwave- or millimeter-wave imaging of steel plates, composite materials, and metal plates, to identify and visualize cracks. The proposed algorithm for steel plates is based on the gradient magnitude in four directions of an image, and is followed by the edge detection technique. Three algorithms were proposed for each of composite materials and metal plates, and are based on 2D fast Fourier transform (FFT) and hybrid fuzzy c-mean techniques, respectively. The proposed algorithms were able to recognize and visualize the cracking incurred in the structure more efficiently than the traditional techniques. The reported results are expected to be beneficial for NDT-based applications, particularly in civil engineering.
A comparative study on the role of polyvinylpyrrolidone molecular weight on the functionalization of various carbon nanotubes and their composites
- Namasivayam, Muthuraman, Andersson, Mats, Shapter, Joseph
- Authors: Namasivayam, Muthuraman , Andersson, Mats , Shapter, Joseph
- Date: 2021
- Type: Text , Journal article
- Relation: Polymers Vol. 13, no. 15 (2021), p.
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- Description: Polyvinylidene fluoride (PVDF) nanocomposites filled with polyvinylpyrrolidone (PVP) wrapped carbon nanotubes were prepared via a solution casting technique. The effect of the molecular weight (polymer chain length) of the PVP on the ability to wrap different nanotube structures and its impact towards nanotube dispersibility in the polymer matrix was explored. The study was conducted with PVP of four different molecular weights and nanotubes of three different structures. The composites that exhibit an effective nanotube dispersion lead to a nanotube network that facilitates improved thermal, electrical, and mechanical properties. It was observed that nanotubes of different structures exhibit stable dispersions in the polymer matrix though PVP functionalization of different molecular weights, but the key is achieving an effective nanotube dispersion at low PVP concentrations. This is observed in MWNT and AP-SWNT based composites with PVP of low molecular weight, leading to a thermal conductivity enhancement of 147% and 53%, respectively, while for P3-SWNT based composites, PVP of high molecular weight yields an enhancement of 25% in thermal conductivity compared to the non-functionalized CNT-PVDF composite. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Namasivayam, Muthuraman , Andersson, Mats , Shapter, Joseph
- Date: 2021
- Type: Text , Journal article
- Relation: Polymers Vol. 13, no. 15 (2021), p.
- Full Text:
- Reviewed:
- Description: Polyvinylidene fluoride (PVDF) nanocomposites filled with polyvinylpyrrolidone (PVP) wrapped carbon nanotubes were prepared via a solution casting technique. The effect of the molecular weight (polymer chain length) of the PVP on the ability to wrap different nanotube structures and its impact towards nanotube dispersibility in the polymer matrix was explored. The study was conducted with PVP of four different molecular weights and nanotubes of three different structures. The composites that exhibit an effective nanotube dispersion lead to a nanotube network that facilitates improved thermal, electrical, and mechanical properties. It was observed that nanotubes of different structures exhibit stable dispersions in the polymer matrix though PVP functionalization of different molecular weights, but the key is achieving an effective nanotube dispersion at low PVP concentrations. This is observed in MWNT and AP-SWNT based composites with PVP of low molecular weight, leading to a thermal conductivity enhancement of 147% and 53%, respectively, while for P3-SWNT based composites, PVP of high molecular weight yields an enhancement of 25% in thermal conductivity compared to the non-functionalized CNT-PVDF composite. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- Filipović, Vilim, Defterdarović, Jasmina, Krevh, Vedran, Filipović, Lana, Ondrašek, Gabrijel, Kranjčec, Filip, Magdić, Ivan, Rubinić, Vedran, Stipičević, Sanja, Mustać, Ivan, Bubalo Kovačić, Marina, He, Hailong, Haghverdi, Amir, Gerke, Horst
- Authors: Filipović, Vilim , Defterdarović, Jasmina , Krevh, Vedran , Filipović, Lana , Ondrašek, Gabrijel , Kranjčec, Filip , Magdić, Ivan , Rubinić, Vedran , Stipičević, Sanja , Mustać, Ivan , Bubalo Kovačić, Marina , He, Hailong , Haghverdi, Amir , Gerke, Horst
- Date: 2021
- Type: Text , Journal article
- Relation: Agronomy (Basel) Vol. 12, no. 1 (2021), p. 33
- Full Text: false
- Reviewed:
- Description: Erosion has been reported as one of the top degradation processes that negatively affect agricultural soils. The study objective was to identify hydropedological factors controlling soil water dynamics in erosion-affected hillslope vineyard soils. The hydropedological study was conducted at identically-managed Jastrebarsko (location I), and Jazbina (II) and (III) sites with Stagnosol soils. Soil Hydraulic Properties (SHP) were estimated on intact soil cores using Evaporation and WP4C methodssoil hydraulic functions were fitted using HYPROP-FIT software. For Apg and Bg/Btg horizons, uni- and bimodal soil hydraulic models could be well fitted to data although, the bimodal model performed better in particular cases where data indicated non-uniform pore size distribution. With these SHP estimations, a one-year (2020) water flow scenario was simulated using HYDRUS-1D to compare water balance results obtained with uni- and bimodal hydraulic functions. Simulation results revealed relatively similar flux distribution at each hillslope position between the water balance components infiltration, surface runoff, and drainage. However, at the bottom profile at Jastrebarsko, bimodality of the hydraulic functions led to increased drainage. Soil water storage was reduced, and the vertical movement increased due to modified soil water retention curve shapes. Adequate parameterization of SHP is required to capture the hydropedological response of heterogenous erosion-affected soil systems.
Short-term impact of tillage on soil and the hydrological response within a Fig (Ficus Carica) orchard in Croatia
- Telak, Leon, Pereira, Paulo, Ferreira, Carla, Filipovic, Vilim, Filipovic, Lana, Bogunovic, Igor
- Authors: Telak, Leon , Pereira, Paulo , Ferreira, Carla , Filipovic, Vilim , Filipovic, Lana , Bogunovic, Igor
- Date: 2020
- Type: Journal article
- Relation: Water (Basel) Vol. 12, no. 11 (2020), p. 3295
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- Description: Tillage is well known to have impacts on soil properties and hydrological responses. This work aims to study the short-term impacts of tillage (0–3 months) on soil and hydrological responses in fig orchards located in Croatia. Understanding the soil hydrological response in the study area is crucial for soil management due to frequent autumn floods. The hydrological response was investigated using rainfall simulation experiments (58 mm h−1, for 30 min, over 0.785 m2 plots). The results show that the bulk density was significantly higher 3 months after tillage than at 0 and 1 months. The water holding capacity and amount of soil organic matter decreased with time. The water runoff and phosphorous loss (P loss) increased over time. The sediment concentration (SC) was significantly higher 3 months after tillage than in the previous monitoring periods, while sediment loss (SL) and carbon loss (C loss) were significantly lower 0 months after tillage than 3 months after tillage. Overall, there was an increase in soil erodibility with time (high SC, SL, C loss, and P loss), attributed to the precipitation patterns that increase the soil water content and therefore the hydrological response. Therefore, sustainable agricultural practices are needed to avoid sediment translocation and to mitigate floods and land degradation.
- Authors: Telak, Leon , Pereira, Paulo , Ferreira, Carla , Filipovic, Vilim , Filipovic, Lana , Bogunovic, Igor
- Date: 2020
- Type: Journal article
- Relation: Water (Basel) Vol. 12, no. 11 (2020), p. 3295
- Full Text:
- Reviewed:
- Description: Tillage is well known to have impacts on soil properties and hydrological responses. This work aims to study the short-term impacts of tillage (0–3 months) on soil and hydrological responses in fig orchards located in Croatia. Understanding the soil hydrological response in the study area is crucial for soil management due to frequent autumn floods. The hydrological response was investigated using rainfall simulation experiments (58 mm h−1, for 30 min, over 0.785 m2 plots). The results show that the bulk density was significantly higher 3 months after tillage than at 0 and 1 months. The water holding capacity and amount of soil organic matter decreased with time. The water runoff and phosphorous loss (P loss) increased over time. The sediment concentration (SC) was significantly higher 3 months after tillage than in the previous monitoring periods, while sediment loss (SL) and carbon loss (C loss) were significantly lower 0 months after tillage than 3 months after tillage. Overall, there was an increase in soil erodibility with time (high SC, SL, C loss, and P loss), attributed to the precipitation patterns that increase the soil water content and therefore the hydrological response. Therefore, sustainable agricultural practices are needed to avoid sediment translocation and to mitigate floods and land degradation.
Reclamation of salt-affected land: A review
- Shaygan, Mandana, Baumgartl, Thomas
- Authors: Shaygan, Mandana , Baumgartl, Thomas
- Date: 2022
- Type: Text , Journal article
- Relation: Soil systems Vol. 6, no. 3 (2022), p. 61
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- Description: Reclamation of salt-affected soil has been identified by the FAO as being critical to meet the needs to increase agricultural productivity. This paper reviews commonly used reclamation methods for salt-affected soils, and provides critical identifiers for an effective reclamation practice of salt-affected soil. There are widely used methods to reduce salinity and sodicity of salt-affected soils, including salt leaching, addition of amendments, revegetation using halophytes and salt scrapping. Not all reclamation techniques are suitable for salt-affected land. The reclamation strategy must be tailored to the site, and based on understanding the soil, plant and climate interactions. On some occasions, a combination of techniques may be required for reclamation. This can include salt scrapping to remove salts from the surface soil, the addition of physical amendments to improve soil pore systems and enhance salt leaching, followed by amelioration of soil by chemical amendments to preserve soil physical conditions, and then halophyte establishment to expand the desalinization zone. This study reveals that soil hydro-geochemical models are effective predictive tools to ascertain the best reclamation practice tailored to salt-affected land. However, models need to be calibrated and validated to the conditions of the land before being applied as a tool to combat soil salinity.
- Authors: Shaygan, Mandana , Baumgartl, Thomas
- Date: 2022
- Type: Text , Journal article
- Relation: Soil systems Vol. 6, no. 3 (2022), p. 61
- Full Text:
- Reviewed:
- Description: Reclamation of salt-affected soil has been identified by the FAO as being critical to meet the needs to increase agricultural productivity. This paper reviews commonly used reclamation methods for salt-affected soils, and provides critical identifiers for an effective reclamation practice of salt-affected soil. There are widely used methods to reduce salinity and sodicity of salt-affected soils, including salt leaching, addition of amendments, revegetation using halophytes and salt scrapping. Not all reclamation techniques are suitable for salt-affected land. The reclamation strategy must be tailored to the site, and based on understanding the soil, plant and climate interactions. On some occasions, a combination of techniques may be required for reclamation. This can include salt scrapping to remove salts from the surface soil, the addition of physical amendments to improve soil pore systems and enhance salt leaching, followed by amelioration of soil by chemical amendments to preserve soil physical conditions, and then halophyte establishment to expand the desalinization zone. This study reveals that soil hydro-geochemical models are effective predictive tools to ascertain the best reclamation practice tailored to salt-affected land. However, models need to be calibrated and validated to the conditions of the land before being applied as a tool to combat soil salinity.
A Method for the design of concrete with combined steel and basalt fiber
- Dvorkin, Leonid, Bordiuzhenko, Oleh, Tekle, Biruk, Ribakov, Yuri
- Authors: Dvorkin, Leonid , Bordiuzhenko, Oleh , Tekle, Biruk , Ribakov, Yuri
- Date: 2021
- Type: Text , Journal article
- Relation: Applied sciences Vol. 11, no. 19 (2021), p. 8850
- Full Text:
- Reviewed:
- Description: Combining different fiber types may improve the mechanical properties of fiber reinforced concrete. The present study is focused on investigating hybrid fiber reinforced concrete (HFRC) with steel and basalt fiber. Mechanical properties of fiber reinforced fine-grained concrete are investigated. The results demonstrate that using optimal steel and basalt fiber reinforcement ratios avoids concrete mixtures’ segregation and improves their homogeneity. Concrete with hybrid steel and basalt fiber reinforcement has higher strength. Effective methodology for proper design of HFRC compositions was proposed. It is based on the mathematical experiments planning method. The proposed method enables optimal mix proportioning of high-strength fine-grained concrete with hybrid steel and basalt fiber reinforcement.
- Authors: Dvorkin, Leonid , Bordiuzhenko, Oleh , Tekle, Biruk , Ribakov, Yuri
- Date: 2021
- Type: Text , Journal article
- Relation: Applied sciences Vol. 11, no. 19 (2021), p. 8850
- Full Text:
- Reviewed:
- Description: Combining different fiber types may improve the mechanical properties of fiber reinforced concrete. The present study is focused on investigating hybrid fiber reinforced concrete (HFRC) with steel and basalt fiber. Mechanical properties of fiber reinforced fine-grained concrete are investigated. The results demonstrate that using optimal steel and basalt fiber reinforcement ratios avoids concrete mixtures’ segregation and improves their homogeneity. Concrete with hybrid steel and basalt fiber reinforcement has higher strength. Effective methodology for proper design of HFRC compositions was proposed. It is based on the mathematical experiments planning method. The proposed method enables optimal mix proportioning of high-strength fine-grained concrete with hybrid steel and basalt fiber reinforcement.
Growth and element uptake by salt-sensitive crops under combined nacl and cd stresses
- Ondrasek, Gabrijel, Rengel, Zed, Maurović, Nada, Kondres, Nada, Filipović, Vilim, Savić, Radovan, Blagojević, Boško, Tanaskovik, Vjekoslav, Gergichevich, Cristian, Romić, Davor
- Authors: Ondrasek, Gabrijel , Rengel, Zed , Maurović, Nada , Kondres, Nada , Filipović, Vilim , Savić, Radovan , Blagojević, Boško , Tanaskovik, Vjekoslav , Gergichevich, Cristian , Romić, Davor
- Date: 2021
- Type: Text , Journal article
- Relation: Plants (Basel) Vol. 10, no. 6 (2021), p. 1202
- Full Text: false
- Reviewed:
- Description: To test an assumption that organic soil can ameliorate nutritional disorders associated with metal and salinity stresses, we exposed salt-sensitive strawberry and lettuce to four salinity (0–60 mM NaCl) and three contamination (0.3–5 mg Cd/kg) rates in peat (pHH2O = 5.5). The results showed that, even at 20 mM NaCl, salinity stress exerted a dominant effect on rhizosphere biogeochemistry and physiological processes, inducing leaf-edge burns, chlorosis/necrosis, reducing vegetative growth in crops at ≥40 mM, NaCl mortality was induced in strawberry. Signifiacntly decreased K/Na, Ca/Na and Mg/Na concentration ratios with raising salinity were confirmed in all tissues. The combined CdxNaCl stresses (vs. control) increased leaf Cd accumulation (up to 42-fold in lettuce and 23-fold in strawberry), whereas NaCl salinity increased the accumulation of Zn (>1.5-fold) and Cu (up to 1.2-fold) in leaves. Lettuce accumulated the toxic Cd concentration (up to 12.6 mg/kg) in leaves, suggesting the strong root-to-shoot transport of Cd. In strawberry Cd, concentration was similar (and sub-toxic) in fruits and leaves, 2.28 and 1.86 mg/kg, respectively, suggesting lower Cd root-to-shoot translocation, and similar Cd mobility in the xylem and phloem. Additionally, the accumulation of Cd in strawberry fruits was exacerbated at high NaCl exposure (60 mM) compared with lower NaCl concentrations. Thus, in salinized, slightly acidic and organically rich rhizosphere, pronounced organo- and/or chloro-complexation likely shifted metal biogeochemistry toward increased mobility and phytoavailability (with metal adsorption restricted due to Na+ oversaturation of the caton exchange complex in the substrate), confirming the importance of quality water and soils in avoiding abiotic stresses and producing non-contaminated food.
Microplastics in terrestrial ecosystems: A scientometric analysis
- He, Donghui, Bristow, Keith, Filipović, Vilim, Lv, Jialong, He, Hailong
- Authors: He, Donghui , Bristow, Keith , Filipović, Vilim , Lv, Jialong , He, Hailong
- Date: 2020
- Type: Text , Journal article
- Relation: Sustainability Vol. 12, no. 20 (2020), p. 8739
- Full Text: false
- Reviewed:
- Description: Microplastics, as an emerging contaminant, have been shown to threaten the sustainability of ecosystems, and there is also concern about human exposure, as microplastic particles tend to bioaccumulate and biomagnify through the food chain. While microplastics in marine environments have been extensively studied, research on microplastics in terrestrial ecosystems is just starting to gain momentum. In this paper, we used scientometric analysis to understand the current status of microplastic research in terrestrial systems. The global scientific literature on microplastics in terrestrial ecosystems, based on data from the Web of Science between 1986 and 2020, was explored with the VOSviewer scientometric software. Co-occurrence visualization maps and citation analysis were used to identify the relationship among keywords, authors, organizations, countries, and journals focusing on the issues of terrestrial microplastics. The results show that research on microplastics in terrestrial systems just started in the past few years but is increasing rapidly. Science of the Total Environment ranks first among the journals publishing papers on terrestrial microplastics. In addition, we also highlighted the desire to establish standards/protocols for extracting and quantifying microplastics in soils. Future studies are recommended to fill the knowledge gaps on the abundance, distribution, ecological and economic effects, and toxicity of microplastics.
Rheology of alkali-activated blended binder mixtures
- Tekle, Biruk, Hertwig, Ludwig, Holschemacher, Klaus
- Authors: Tekle, Biruk , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2021
- Type: Text , Journal article
- Relation: Materials Vol. 14, no. 18 (2021), p. 5405
- Full Text: false
- Reviewed:
- Description: Alkali-activated cement (AAC) is an alternative cement that has been increasingly studied over the past decades mainly because of its environmental benefits. However, most studies are on heat-cured AACs and are focused on mechanical properties. There is a lack of research on the fresh properties of ambient-cured AAC systems. This study investigates the rheological properties of ambient-temperature-cured alkali-activated blended binder mixtures activated with sodium silicate and sodium hydroxide solutions. The influence of binder amount, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water content to total solid (from the binding materials) ratio (TW/TS) on the rheological properties are investigated. The effect of borax as an admixture and silica fume as a replacement for fly ash is also investigated. The results showed that both the yield stress and plastic viscosity are mainly affected by the binder content and TW/TS ratio decreasing with the increase of each parameter. The yield stress increased with the increase of the SS/SH ratio. Borax significantly reduced the yield stress, while silica fume’s effect was dependent on its dosage.
Setting time and strength monitoring of alkali-activated cement mixtures by ultrasonic testing
- Tekle, Biruk, Hertwig, Ludwig, Holschemacher, Klaus
- Authors: Tekle, Biruk , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2021
- Type: Text , Journal article
- Relation: Materials Vol. 14, no. 8 (2021), p. 1889
- Full Text:
- Reviewed:
- Description: Alkali-activated cement (AAC) is a promising binder that replaces ordinary Portland cement (OPC). In this study, the development of setting time and strength of AAC mixes were studied using ultrasonic testing method. The test results were compared with traditional Vicat setting time and compressive and flexural strengths. The findings showed that setting times and strengths have a strong correlation with ultrasonic velocity curve. The initial setting time corresponds well with the ultrasonic velocity curve's dormant period, and the final setting time with the time it takes to reach the velocity curve's maximum acceleration. Both setting times also showed a correlation with the value of the maximum acceleration. An exponential relation was found between the ultrasonic velocity and the compressive and flexural strengths. The effect of binder content, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water to total solid binder ratio (TW/TS) on the strength and setting time are also studied using Taguchi method of experimental design. AS/B ratio showed a significant influence on the setting time of AAC while TW/TS ratio showed only a minor effect. The ultrasonic velocities were able to capture the effect of the different parameters similar to the compressive strength. The velocity decreased mainly with the increase of TW/TS ratio and binder content, while AS/B and SS/SH ratios showed a lower influence.
- Authors: Tekle, Biruk , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2021
- Type: Text , Journal article
- Relation: Materials Vol. 14, no. 8 (2021), p. 1889
- Full Text:
- Reviewed:
- Description: Alkali-activated cement (AAC) is a promising binder that replaces ordinary Portland cement (OPC). In this study, the development of setting time and strength of AAC mixes were studied using ultrasonic testing method. The test results were compared with traditional Vicat setting time and compressive and flexural strengths. The findings showed that setting times and strengths have a strong correlation with ultrasonic velocity curve. The initial setting time corresponds well with the ultrasonic velocity curve's dormant period, and the final setting time with the time it takes to reach the velocity curve's maximum acceleration. Both setting times also showed a correlation with the value of the maximum acceleration. An exponential relation was found between the ultrasonic velocity and the compressive and flexural strengths. The effect of binder content, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water to total solid binder ratio (TW/TS) on the strength and setting time are also studied using Taguchi method of experimental design. AS/B ratio showed a significant influence on the setting time of AAC while TW/TS ratio showed only a minor effect. The ultrasonic velocities were able to capture the effect of the different parameters similar to the compressive strength. The velocity decreased mainly with the increase of TW/TS ratio and binder content, while AS/B and SS/SH ratios showed a lower influence.