scholarly journals Volcanic Lakes in Africa: The VOLADA_Africa 2.0 Database, and Implications for Volcanic Hazard

2021 ◽  
Vol 9 ◽  
Author(s):  
Dmitri Rouwet ◽  
Karoly Németh ◽  
Giancarlo Tamburello ◽  
Sergio Calabrese ◽  
Issa
Keyword(s):  
Volcanic Hazard ◽  
Hydrothermal Systems ◽  
Future Research ◽  
Special Focus ◽  
Volcanic Lake ◽  
Crater Lakes ◽  
Volcanic Lakes ◽  
Open Access Database ◽  
Lake Nyos ◽  
Physical And Chemical

Volcanic lakes pose specific hazards inherent to the presence of water: phreatic and phreatomagmatic eruptions, lahars, limnic gas bursts and dispersion of brines in the hydrological network. Here we introduce the updated, interactive and open-access database for African volcanic lakes, country by country. The previous database VOLADA (VOlcanic LAke DAta Base, Rouwet et al., Journal of Volcanology and Geothermal Research, 2014, 272, 78–97) reported 96 volcanic lakes for Africa. This number is now revised and established at 220, converting VOLADA_Africa 2.0 in the most comprehensive resource for African volcanic lakes: 81 in Uganda, 37 in Kenya, 33 in Cameroon, 28 in Madagascar, 19 in Ethiopia, 6 in Tanzania, 2 in Rwanda, 2 in Sudan, 2 in D.R. Congo, 1 in Libya, and 9 on the minor islands around Africa. We present the current state-of-the-art of arguably all the African volcanic lakes that the global experts and regional research teams are aware of, and provide hints for future research directions, with a special focus on the volcanic hazard assessment. All lakes in the updated database are classified for their genetic origin and their physical and chemical characteristics, and level of study. The predominant rift-related volcanism in Africa favors basaltic eruptive products, leading to volcanoes with highly permeable edifices, and hence less-developed hydrothermal systems. Basal aquifers accumulate under large volcanoes and in rift depressions providing a potential scenario for phreatomagmatic volcanism. This hypothesis, based on a morphometric analysis and volcanological research from literature, conveys the predominance of maar lakes in large monogenetic fields in Africa (e.g. Uganda, Cameroon, Ethiopia), and the absence of peak-activity crater lakes, generally found at polygenetic arc-volcanoes. Considering the large number of maar lakes in Africa (172), within similar geotectonic settings and meteoric conditions as in Cameroon, it is somewhat surprising that “only” from Lake Monoun and Lake Nyos fatal CO2 bursts have been recorded. Explaining why other maars did not experience limnic gas bursts is a question that can only be answered by enhancing insights into physical limnology and fluid geochemistry of the so far poorly studied lakes. From a hazard perspective, there is an urgent need to tackle this task as a community.

scholarly journals Geochemistry of Water and Gas Emissions From Cuicocha and Quilotoa Volcanic Lakes, Ecuador

2021 ◽  
Vol 9 ◽  
Author(s):  
G. V. Melián ◽  
T. Toulkeridis ◽  
N. M. Pérez ◽  
P. A. Hernández ◽  
L. Somoza ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Potential Hazard ◽  
Vertical Profiles ◽  
Volcanic Lake ◽  
Gas Emissions ◽  
Crater Lakes ◽  
Volcanic Lakes ◽  
The World ◽  
Water Stratification ◽  
Potential Risks

There are hundreds of volcanic lakes around the world that represent an important hazard due to the potential occurrence of phreatomagmatic or limnic eruptions. Variations in geochemical and geophysical parameters could help to identify potential risks for these events. Cuicocha and Quilota volcanic lakes, located at the North Andean Volcanic Zone of Ecuador, are geologically young, with gas emissions manifested mainly as CO2 via bubbling gases. Both lakes present a limited monitoring record. Therefore, volcanic monitoring is a priority task due to the potential hazard they represent by the possibility of water stratification and CO2 accumulation. During 2012-2018 period, geochemical investigation based mainly on diffuse CO2 surveys and analyzing the chemical and isotopic composition of bubbling gases has been carried out at Cuicocha and Quilotoa lakes. Additionally, vertical profiles of water columns were conducted in both lakes to investigate the possibility of water stratification and CO2 accumulation in the lakes. A bathymetric study was also carried out in Quilotoa in 2017, giving further information about the degasification processes and the morphology of the lake bottom. The computed diffuse CO2 output for Cuicocha volcanic lake (3.95 km2) showed a range from 53 to 652 t d−1 for the period 2006–2018, with a maximum value in 2012, coinciding with a maximum of the 3He/4He ratio measured at the bubbling gases and an increase in the seismic activity with an episode of long-period seismicity recorded in 2011–2012. For Quilotoa volcanic lake (3.50 km2) diffuse CO2 output was estimated between 141 and 536 t d−1 for the period 2014–2018. The chemical and isotopic data show that Cuicocha has a chemical composition typical of worldwide superficial shallow waters and aquifers, while Quilotoa shows a chemical composition typical of crater lakes in active volcanic systems. The distribution of the dissolved gas composition along the vertical profiles shows the existence of different water masses in both lakes, with an increase in the concentration of dissolved gases with depth. The carbon isotopic signature indicates an endogenous origin of the CO2, with a greater contribution in the stratification zone in both lakes. This study shows methods applicable to other volcanic lakes of the world to monitor their activity and potential risks.

Electrochemical polymerization for two-dimensional conjugated polymers

2018 ◽  
Vol 6 (40) ◽  
pp. 10672-10686 ◽  
Author(s):  
Qing Zhang ◽  
Huanli Dong ◽  
Wenping Hu
Keyword(s):  
Conjugated Polymers ◽  
Electrochemical Polymerization ◽  
Research Progress ◽  
Future Research ◽  
Special Focus ◽  
Two Dimensional ◽  
Research Directions ◽  
Potential Applications ◽  
Future Research Directions ◽  
Recent Research Progress

This article places special focus on the recent research progress of the EP method in synthesizing CPs. In particular, their potential applications as 2D CPs are summarized, with a basic introduction of the EP method, its use in synthesizing CPs as well as the promising applications of the obtained CPs in different fields. Discussions of current challenges in this field and future research directions are also given.

Some physical and chemical features of two upland crater lakes in tropical north-eastern Australia

1999 ◽  
Vol 50 (2) ◽  
pp. 159 ◽  
Author(s):  
D. Walker
Keyword(s):  
Thermal Stability ◽  
Meteorological Data ◽  
Euphotic Zone ◽  
Open Water ◽  
Crater Lakes ◽  
Ground Temperatures ◽  
Eastern Australia ◽  
North Eastern ◽  
Physical And Chemical ◽  
Continuous Deposition

Lakes Barrine and Eacham, ~1.0 and 0.5 km2 area, 67 and 63 m depth respectively, lie at ~740 m a.s.l., ~17°S in north-eastern Australia. Seasonal changes in their volumes modelled from meteorological data correspond well with observations at Eacham. Temperature profiles through 6 years show summer stratification with a metalimnion at 20–30 m; in winter, near isothermy is usually attained. At Barrine, thermal stability varies between winter and summer (<500 and >4000 g-cm cm-2 respectively). Mixing is related to low ground temperatures during periods of generally low thermal stability; exceptionally it penetrates to >60 m. Oxygen saturation decreases from the surface to ~20% at the base of the euphotic zone (15–21 m) but oxygen is carried lower by mixing after which anoxia commonly rises to ~40 m. At Barrine, Fe-reducing redox (<200 mV) usually occurs below 50 m, but during mixing this boundary falls to within 1 m of the mud–water interface. The Barrine solution is dilute (total dissolved solids 55–58 mg L-1), and that of Eacham is more so. A concentrated monimolimnion has developed in the lowermost 2–3 m at Barrine but not at Eacham. Sedimentation at the middle of each lake results from the continuous deposition of open-water products punctuated by the redistribution of coarser detritus from the ‘shallows’ at times of deep mixing. The resultant laminations are preserved only at Barrine, protected by the chemical stability of the monimolimnion.

scholarly journals Response to BNT162b2 mRNA COVID-19 vaccine among healthcare workers in Italy: a 3-month follow-up

2021 ◽  
Author(s):  
Domenico Ponticelli ◽  
Fabiana Madotto ◽  
Sara Conti ◽  
Ippazio C. Antonazzo ◽  
Andrea Vitale ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Future Research ◽  
Nasopharyngeal Swab ◽  
Special Focus ◽  
Rt Pcr ◽  
Vaccine Response ◽  
Serology Testing ◽  
Effectiveness Data

AbstractThis study investigated the response to BNT162b2 mRNA COVID-19 vaccine among healthcare workers (HCWs) in an Italian teaching hospital. 444 participants were surveyed with either multiple RT-PCR assays for detection of SARS-CoV-2 nucleic acid in nasopharyngeal swabs or serology testing for the research of virus-specific immunoglobulins. Adverse events following immunization (AEFI) were reported. Two weeks after the first dose anti-SARS-CoV-2 antibodies exceeded reactivity cut-off in 82.5% the participants. Four HCWs tested positive at nasopharyngeal swab after 3 months. More than three-quarters reported AEFIs. Our findings offer an insight regarding the vaccine response after 3 months from its administration, with a special focus on effectiveness data, as well as the type and number of AEFIs complained by HCW recipients. The presented study may serve as reference for future research which will be necessary to explore the long-term safety of this vaccine, especially in population at high risk for infection, such as HCWs.

scholarly journals Gossip and Reputation in Adolescent Networks

2019 ◽  
pp. 358-379 ◽  
Author(s):  
Dorottya Kisfalusi ◽  
Károly Takács ◽  
Judit Pál
Keyword(s):  
Social Network ◽  
Secondary School ◽  
Peer Relations ◽  
School Context ◽  
Future Research ◽  
Special Focus ◽  
Network Methods ◽  
Good Reputation ◽  
Practical Implications

Adolescence is an important age of development when collective norms emerge, social exclusion often takes place, and competition for reputation is relatively intense. Negative gossip is used with increasing intentionality to interfere in these processes. At the same time, being the object of negative gossip undermines chances to obtain good reputation. This chapter reviews the role of gossiping in the formation of informal status relations of adolescents. It provides an overview of theoretical explanations and empirical findings on how reputation and gossip are related with a special focus on the school context. It presents recent methodological advancements of social network methods used for analyzing the complex interrelated dynamics of gossip, reputation, and peer relations among adolescents. As an illustration, the chapter shows that malicious gossip leads to disdain while disdain induces malicious gossip in a longitudinal analysis of Hungarian secondary school classes. Finally, it discusses the theoretical and practical implications of our illustrative analysis and formulate suggestions for future research.

Investigation of the effects of silicone emulsions having different particle sizes on knitted fabrics depending on the type of yarn

2017 ◽  
Vol 29 (3) ◽  
pp. 394-416 ◽  
Author(s):  
Burcu Sancar Besen ◽  
Onur Balci
Keyword(s):  
Future Research ◽  
Particle Sizes ◽  
Knitted Fabrics ◽  
Content Type ◽  
Bursting Strength ◽  
Chemical Structures ◽  
Strength And Stiffness ◽  
Ring Open ◽  
Working Parameters ◽  
Physical And Chemical

Purpose The purpose of this paper is to investigate the effects of silicone-based softeners, which were developed with different particle sizes (nano, micro, and macro) and chemical structures, on the performance of 100 percent cotton fabrics knitted with different type of yarn (ring, open-end, and compact). Design/methodology/approach In the study, the silicone emulsions having expected particle sizes were produced at laboratory conditions. The produced silicone emulsions were applied to knitted fabrics with both padding and exhaust methods at different concentrations. Some characterization tests (particle size and zeta potential) were applied to the silicone emulsions before the applications. After the applications, CIELab values, whiteness and color fastness, hyrophility, abrasion, pilling, bursting strength, and stiffness performances of the samples were tested. The changes of the investigated properties were also examined via ANOVA. Findings According to the results, it was found that the silicone applications caused the CIELab values, whiteness degree, hyrophility, pilling, bursting strength and stiffness performance of the fabrics to change depending on the particle sizes of the emulsions, the yarn type of the fabrics, the application type, and the concentration of the silicone emulsions. When the ANOVA results were examined, it was seen that the types of the yarn and the silicone emulsions were the most effective working parameters on the results. Research limitations/implications Because no additives were added to the produced silicone emulsions, in the future research, they can be developed with the use of some additives. Thus, it can resolve some of the disadvantages of the silicone emulsions on the textiles. Practical implications While applying the silicone softeners to the knitted fabrics, the type of the yarn and the particle sizes of the emulsions must be determined according to each other, in order to obtain enough handle performance without causing negative change on the other important properties of the knitted fabrics. Originality/value When the studies regarding silicone softeners were investigated, it was found that there were no studies about the effect of the silicone softeners having different particle sizes on the physical and chemical structures of the knitted fabrics depending on the type of yarn and some working parameters such as concentration and type of the application.

Advanced Joining Techniques in European Shipbuilding

2004 ◽  
Vol 20 (03) ◽  
pp. 200-210 ◽  
Author(s):  
Frank Roland ◽  
Luciano Manzon ◽  
Pentti Kujala ◽  
Markus Brede ◽  
Jan Weitzenbock
Keyword(s):  
Adhesive Bonding ◽  
High Strength ◽  
Industrial Applications ◽  
Future Research ◽  
Special Focus ◽  
Open Problems ◽  
Ongoing Research ◽  
Mechanical Joining ◽  
Laser Hybrid Welding ◽  
The Impact

Joining processes are an important key factor for the competitiveness of European shipbuilders. They not only represent a significant portion of the total man hour consumption in hull production and outfitting, but due to heat distortions they also have a significant impact on nonproductive work operations, such as straightening and fitting. Those operations can interfere with on-board outfitting and increase lead time and construction cost. In addition to their contribution to shipyard productivity, joining techniques have a significant impact on material properties and thus on product performance and quality. Those factors become increasingly important for complex structures using comparatively thin and high-strength materials. Considering the importance of efficient joining, European shipbuilders in the past decade have invested significant efforts to develop new joining techniques, such as laser welding, adhesive bonding, and mechanical joining. Based on research results, practical industrial applications have been developed recently. After reviewing the impact of joining processes on competitiveness, the article will summarize a number of past and ongoing research projects with special focus on design methods, process and equipment development, fatigue strength of joints, quality assurance, and approval. It will then present a number of recent applications of new joining techniques in European shipyards. Finally, open problems and future research needs will be briefly discussed. The article is based on a joint effort of leading European experts and will focus on laser and laser hybrid welding, adhesive bonding, and mechanical joining

Investigating Diachronic Variation and Change in New Varieties of English

2019 ◽  
pp. 24-36
Author(s):  
Rita Calabrese
Keyword(s):  
Future Research ◽  
Special Focus ◽  
Specific Information ◽  
Indian English ◽  
Language Standardization ◽  
New Varieties ◽  
Methodological Procedures ◽  
Language Universals ◽  
Verb Particle Constructions ◽  
Over Time

This contribution focuses on processes of language feature convergence which gradually lead to linguistic stabilization over time, whereby specific attention will be given to the process of Englishization in the South-Asian area. The chapter outlines some basic concepts pertaining language universals, contact, and change, as well as descriptive approaches to world varieties of English by referring to the feature classification proposed by Meshtrie and Bhatt. Then, as an explanatory case, it presents the results of a study of verb-particle constructions in a well-established variety of English (i.e., Indian English) obtained by sampling data from sources varying in time, genre, and register with a special focus on the methodological procedures and the analysis tools adopted to extract specific information from the data. Finally, the implications of those findings for future research on the process of language standardization in new varieties of English will be further explored.

scholarly journals Physical and Chemical Modifications of Plant Fibres for Reinforcement in Cementitious Composites

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
R. Ahmad ◽  
R. Hamid ◽  
S. A. Osman
Keyword(s):  
Mechanical Properties ◽  
Interfacial Adhesion ◽  
Moisture Absorption ◽  
Surface Modifications ◽  
Future Research ◽  
Cementitious Composites ◽  
Chemical Surface ◽  
Plant Fibre ◽  
Physical And Chemical ◽  
Fibre Matrix

This paper highlights the physical and chemical surface modifications of plant fibre (PF) for attaining suitable properties as reinforcements in cementitious composites. Untreated PF faces insufficient adhesion between the fibres and matrix due to high levels of moisture absorption and poor wettability. These conditions accelerate degradation of the fibre in the composite. It is also essential to reduce the risk of hydrophilic PF conditions with surface modification, to enhance the mechanical properties of the fibres. Fibres that undergo chemical and physical modifications had been proven to exhibit improved fibre-matrix interfacial adhesion in the composite and contribute to better composite mechanical properties. This paper also gives some recommendations for future research on chemical and physical modifications of PF.

scholarly journals Identifying Potential Leakage Zones in an Irrigation Supply Channel by Mapping Soil Properties Using Electromagnetic Induction, Inversion Modelling and a Support Vector Machine

Soil Systems ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 25
Author(s):  
Ehsan Zare ◽  
Nan Li ◽  
Tibet Khongnawang ◽  
Mohammad Farzamian ◽  
John Triantafilis
Keyword(s):  
Electrical Conductivity ◽  
Support Vector Machine ◽  
Chemical Properties ◽  
Exchange Capacity ◽  
Future Research ◽  
Support Vector ◽  
Stream Channels ◽  
Supply Channel ◽  
Physical And Chemical ◽  
And Chemical Properties

The clay alluvial plains of Namoi Valley have been intensively developed for irrigation. A condition of a license is water needs to be stored on the farm. However, the clay plain was developed from prior stream channels characterised by sandy clay loam textures that are permeable. Cheap methods of soil physical and chemical characterisations are required to map the supply channels used to move water on farms. Herein, we collect apparent electrical conductivity (ECa) from a DUALEM-421 along a 4-km section of a supply channel. We invert ECa to generate electromagnetic conductivity images (EMCI) using EM4Soil software and evaluate two-dimensional models of estimates of true electrical conductivity (σ—mS m−1) against physical (i.e., clay and sand—%) and chemical properties (i.e., electrical conductivity of saturated soil paste extract (ECe—dS m−1) and the cation exchange capacity (CEC, cmol(+) kg−1). Using a support vector machine (SVM), we predict these properties from the σ and depth. Leave-one-site-out cross-validation shows strong 1:1 agreement (Lin’s) between the σ and clay (0.85), sand (0.81), ECe (0.86) and CEC (0.83). Our interpretation of predicted properties suggests the approach can identify leakage areas (i.e., prior stream channels). We suggest that, with this calibration, the approach can be used to predict soil physical and chemical properties beneath supply channels across the rest of the valley. Future research should also explore whether similar calibrations can be developed to enable characterisations in other cotton-growing areas of Australia.

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