scholarly journals Secondary Mineralization of Ferrihydrite Affects Microbial Methanogenesis in Geobacter-Methanosarcina Cocultures

2016 ◽  
Vol 82 (19) ◽  
pp. 5869-5877 ◽  
Author(s):  
Jia Tang ◽  
Li Zhuang ◽  
Jinlian Ma ◽  
Ziyang Tang ◽  
Zhen Yu ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Biogeochemical Cycling ◽  
Methanosarcina Barkeri ◽  
Geobacter Metallireducens ◽  
Methanogenic Activity ◽  
Content Type ◽  
Iron Minerals ◽  
Iron Mineral ◽  
Iron Mineralogy

ABSTRACTThe transformation of ferrihydrite to stable iron oxides over time has important consequences for biogeochemical cycling of many metals and nutrients. The response of methanogenic activity to the presence of iron oxides depends on the type of iron mineral, but the effects of changes in iron mineralogy on methanogenesis have not been characterized. To address these issues, we constructed methanogenic cocultures ofGeobacterandMethanosarcinastrains with different ferrihydrite mineralization pathways. In this system, secondary mineralization products from ferrihydrite are regulated by the presence or absence of phosphate. In cultures producing magnetite as the secondary mineralization product, the rates of methanogenesis from acetate and ethanol increased by 30.2% and 135.3%, respectively, compared with a control lacking ferrihydrite. Biogenic magnetite was proposed to promote direct interspecies electron transfer betweenGeobacterandMethanosarcinain a manner similar to that ofc-type cytochrome and thus facilitate methanogenesis. Vivianite biomineralization from ferrihydrite in the presence of phosphate did not significantly influence the methanogenesis processes. The correlation between magnetite occurrence and facilitated methanogenesis was supported by increased rates of methane production from acetate and ethanol with magnetite supplementation in the defined cocultures. Our data provide a new perspective on the important role of iron biomineralization in biogeochemical cycling of carbon in diverse anaerobic environments.IMPORTANCEIt has been found that microbial methanogenesis is affected by the presence of iron minerals, and their influences on methanogenesis are associated with the mineralogical properties of the iron minerals. However, how changes in iron mineralogy affect microbial methanogenesis has not been characterized. To address this issue, we constructed methanogenic cocultures ofGeobacterandMethanosarcinastrains with different ferrihydrite mineralization pathways. The experimental results led to two contributions, i.e., (i) the transformation of iron minerals might exert an important influence on methanogenesis under anaerobic conditions and (ii) both biogenic and chemical magnetite can accelerate syntrophic ethanol oxidization betweenGeobacter metallireducensandMethanosarcina barkeri. This study sheds new light on the important role of iron biomineralization in the biogeochemical cycling of carbon in diverse anaerobic environments, particularly in iron-rich natural and agricultural wetland soils.

scholarly journals Direct Interspecies Electron Transfer between Geobacter metallireducens and Methanosarcina barkeri

2014 ◽  
Vol 80 (15) ◽  
pp. 4599-4605 ◽  
Author(s):  
Amelia-Elena Rotaru ◽  
Pravin Malla Shrestha ◽  
Fanghua Liu ◽  
Beatrice Markovaite ◽  
Shanshan Chen ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Model Organism ◽  
Methanosarcina Barkeri ◽  
Physical Contact ◽  
Acetate Metabolism ◽  
Geobacter Metallireducens ◽  
Content Type ◽  
Direct Interspecies Electron Transfer ◽  
Interspecies Electron Transfer ◽  
Effective Form

ABSTRACTDirect interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the diversity of methanogens capable of DIET. The ability ofMethanosarcina barkerito participate in DIET was evaluated in coculture withGeobacter metallireducens. Cocultures formed aggregates that shared electrons via DIET during the stoichiometric conversion of ethanol to methane. Cocultures could not be initiated with a pilin-deficientG. metallireducensstrain, suggesting that long-range electron transfer along pili was important for DIET. Amendments of granular activated carbon permitted the pilin-deficientG. metallireducensisolates to share electrons withM. barkeri, demonstrating that this conductive material could substitute for pili in promoting DIET. WhenM. barkeriwas grown in coculture with the H2-producingPelobacter carbinolicus, incapable of DIET,M. barkeriutilized H2as an electron donor but metabolized little of the acetate thatP. carbinolicusproduced. This suggested that H2, but not electrons derived from DIET, inhibited acetate metabolism.P. carbinolicus-M. barkericocultures did not aggregate, demonstrating that, unlike DIET, close physical contact was not necessary for interspecies H2transfer.M. barkeriis the second methanogen found to accept electrons via DIET and the first methanogen known to be capable of using either H2or electrons derived from DIET for CO2reduction. Furthermore,M. barkeriis genetically tractable, making it a model organism for elucidating mechanisms by which methanogens make biological electrical connections with other cells.

Coloured waterborne aluminium pigments prepared by iron oxides encapsulation method using FeSO4 and FeCl3 as iron source

2018 ◽  
Vol 47 (3) ◽  
pp. 216-227 ◽  
Author(s):  
Zhiling Ma ◽  
Yajing Wen ◽  
Chunyan Zhang ◽  
Jing Wang
Keyword(s):  
Iron Oxide ◽  
Iron Oxides ◽  
Anticorrosion Property ◽  
X Ray Diffraction ◽  
Content Type ◽  
Iron Source ◽  
Encapsulation Method ◽  
And Performance ◽  
Practical Implications

Purpose The purpose of this study is to evaluate the role of encapsulation pH and iron source on the anchorage mode and performance of iron oxide-encapsulated aluminium pigments. Design/methodology/approach The coloured waterborne aluminium pigments were prepared at pH 5-7.5 by using FeSO4 and FeCl3 as iron source. The anchorage mode of iron oxides on aluminium was characterized using optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Furthermore, the pigmentary performance was characterized through anticorrosion test and multi-angle spectroscopy. Findings Diaspore and boehmite could form from H2O2 oxidizing aluminium. Both low pH and FeSO4 systems are beneficial for diaspore, inducing green rust anchor on the aluminium to form goethite. Either in FeSO4 or FeCl3 system, slightly high pH is beneficial for the formation of boehmite, which occurred together with ferrihydrite to form denser coating with yellowness and excellent anticorrosion property. At pH above 7, the formation of dendritic iron oxide is detrimental to the anticorrosion property and the glossiness. Research limitations/implications Only FeSO4·7H2O and FeCl3·6H2O as iron sources were explored. Practical implications The investigation results provide theoretical basis to obtain excellent chromatic waterborne aluminium pigments. Originality/value The method for investigation of encapsulation mechanism by surveying the structure of iron oxides on aluminium, which varies with the pH of the system and iron sources, is novel.

Long-term management of patients with multiple brain metastases after shaped beam radiosurgery

2004 ◽  
pp. 406-412
Author(s):  
Paul Okunieff ◽  
Michael C. Schell ◽  
Russell Ruo ◽  
E. Ronald Hale ◽  
Walter G. O'Dell ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Tumor Control ◽  
Content Type ◽  
Negative Results ◽  
Multiple Metastases ◽  
Extracranial Disease ◽  
Successful Control ◽  
The Brain

✓ The role of radiosurgery in the treatment of patients with advanced-stage metastatic disease is currently under debate. Previous randomized studies have not consistently supported the use of radiosurgery to treat patients with numbers of brain metastases. In negative-results studies, however, intracranial tumor control was high but extracranial disease progressed; thus, patient survival was not greatly affected, although neurocognitive function was generally maintained until death. Because the future promises improved systemic (extracranial) therapy, the successful control of brain disease is that much more crucial. Thus, for selected patients with multiple metastases to the brain who remain in good neurological condition, aggressive lesion-targeting radiosurgery should be very useful. Although a major limitation to success of this therapy is the lack of control of extracranial disease in most patients, it is clear that well-designed, aggressive treatment substantially decreases the progression of brain metastases and also improves neurocognitive survival. The authors present the management and a methodology for rational treatment of a patient with breast cancer who has harbored 24 brain metastases during a 3-year period.

scholarly journals Vulnerable adults in police custody

2019 ◽  
Vol 22 (1) ◽  
pp. 5-8
Author(s):  
Ian Cummins
Keyword(s):  
Design Methodology ◽  
Research Literature ◽  
Police Custody ◽  
England And Wales ◽  
Content Type ◽  
Increased Risk ◽  
Vulnerable Adults

Purpose The purpose of this paper is to discuss the recent National Appropriate Adult Network (NAAN) report on the role of the appropriate adult. Design/methodology/approach This paper is based on the NAAN report and a review of relevant policy and research literature. Findings There to Help 2 highlights that there are still significant gaps in the provision of appropriate adult schemes across England and Wales. These gaps potentially place vulnerable adults at increased risk. Originality/value This paper is a review of recent research.

Financial access and economic development: the moderating role of financial consumer protection

2019 ◽  
Vol 15 (4) ◽  
pp. 406-424 ◽  
Author(s):  
Maryam Kriese ◽  
Joshua Yindenaba Abor ◽  
Elikplimi Agbloyor
Keyword(s):  
Economic Development ◽  
World Bank ◽  
Financial Literacy ◽  
Compliance Monitoring ◽  
Financial Access ◽  
Policy Makers ◽  
Content Type ◽  
The World Bank ◽  
Moderating Role

Purpose The purpose of this paper is to examine the moderating role of financial consumer protection (FCP) in the access–development nexus. Design/methodology/approach The study is based on cross-country data on 102 countries surveyed in the World Bank Global Survey on FCP and Financial Literacy (2013). The White heteroscedasticity adjusted regressions and Two-stage least squares regressions (2SLS) are used for the estimation. Findings Interactions between FCP regulations that foster fair treatment, disclosure, dispute resolution and recourse and financial access have positive net effects on economic development. However, there is no sufficient evidence to suggest that interactions between financial access and enforcement and compliance monitoring regulations have a significant effect on economic development. Practical implications First, policy makers should continue with efforts aimed at instituting FCP regimes as part of strategies aimed at broadening access to financial services for enhanced economic development. Second, instituting FCP regimes per se may not be enough. Policy makers need to consider possible intervening factors such as the provision of adequate resources and supervisory authority, for compliance monitoring and enforcement to achieve the expected positive effect on economic development. Originality/value This study extends evidence in the law–finance–growth literature by providing empirical evidence on the effect of legal institution specific to the protection of retail financial consumers on the access–development nexus using a nouvel data set, the World Bank Global survey on FCP and Financial Literacy (2013).

Categorization flexibility and unconventional choices: is life an adventure?

2020 ◽  
Vol 54 (8) ◽  
pp. 1963-1986
Author(s):  
Tilottama G. Chowdhury ◽  
Feisal Murshed
Keyword(s):  
Interactive Effect ◽  
Interactive Effects ◽  
Cognitive Capacity ◽  
Purchase Behavior ◽  
Consumer Decision Making ◽  
Cross Sectional ◽  
Content Type ◽  
Cross Domain ◽  
Multiple Domains

Purpose This paper proposes that categorization flexibility, operationalized as the cognitive capacity that cross-categorizes products in multiple situational categories across multiple domains, might favorably influence a consumer’s evaluation of unconventional options. Design/methodology/approach Experimental research design is used to test the theory. An exploratory study first establishes the effect of categorization flexibility in a non-food domain. Study 1 documents the moderating role of decision domain, showing that the effect works only under low- (vs high-) consequence domain. Studies 2A and 2B further refine the notion by showing that individuals can be primed in a relatively higher categorization flexibility frame of mind. Study 3 demonstrates the interactive effect of categorization flexibility and adventure priming in a high-consequence domain. Study 4 integrates the interactive effects of decisions with low- vs high-consequence, adventure priming and categorization flexibility within a single decision domain of high consequence. Findings Consumers with higher- (vs lower-) categorization flexibility tend to opt for unconventional choices when the decision domain entails low consequences, whereas such a result does not hold under decision domain of high consequences. The categorization flexibility effects in case of low-consequence decision domain holds true even when consumers are primed to be categorization flexible. Furthermore, with additional adventure priming, consumers show an increased preference for unconventional options even under a decision domain with high consequence. Research limitations/implications This study could not examine real purchase behavior as results are based on cross-sectional, behavioral intention data. In addition, it did not examine the underlying reason for presence of cross-domain categorization flexibility index. Practical implications The results suggest that stimuli may be tailored to consumers in ways that increase the salience and the perceived attractiveness of unconventional choices. Further, data reinforce the notion of cross-categorical interrelations among different domains, which could be leveraged by marketers. Originality/value This study represents the first documentation of the potential ways by which unconventional product choice might be a function of individuals’ categorization flexibility level across different types of decision domains. The findings yield implications that are novel to both categorization and consumer decision-making literature.

The path of support-to-sales: mediating role of seller collaborative information exchange in social commerce

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Li Chen ◽  
Fengxia Zhu ◽  
Murali Mantrala
Keyword(s):  
Information Exchange ◽  
Instrumental Support ◽  
Trade Volume ◽  
Social Commerce ◽  
Content Type ◽  
Mediating Role ◽  
The Social ◽  
Source Data ◽  
Negative Effect

Purpose This paper aims to systematically investigate the direct and indirect effects of four types of support – peer instrumental support, peer emotional support, platform business support and platform communication support – on seller trade volume in social commerce. It also aims to uncover the path of support-to-sales of the seller from a platform perspective and provides a more complete picture of the social commerce phenomenon. Design/methodology/approach This paper uses multi-source data including primary survey data and secondary data on trade volume to test the hypotheses. PROCESS mediation model is used to analyze the multi-source data set. Findings This study finds that the positive effects of peer instrumental support, platform business support and platform communication support on seller trade volume are fully mediated by seller collaborative information exchange. Also, peer emotional support has a significant negative effect on seller trade volume and collaborative information exchange can serve as a buffer to mitigate the negative effect. Research limitations/implications The authors provide new insights into what types of support are or are not conducive to improving transaction volume of individual sellers and highlight the mediating role of seller information exchange in this value generation process in social commerce. These findings advance current knowledge of how seller interactions increase value in social commerce. The chosen research setting may limit the generalizability of the findings of this study. Practical implications This paper offers valuable implications for social commerce platforms on how to better serve their sellers to achieve high growth. Specifically, the findings suggest that platforms should encourage instrumental support and information exchange among peer sellers. In addition, platforms should expand seller support from a single-focus on sellers’ business to a dual-focus on both sellers’ business and socialization in social commerce. Originality/value This paper fulfills an identified need to study how sellers can better derive value from the social interactions and how social commerce platforms can effectively influence transactions, support sales and serve as a selling platform.

The effect of psychological empowerment on job burnout and competitive advantage

2020 ◽  
Vol 18 (1) ◽  
pp. 47-71 ◽  
Author(s):  
Ali Safari ◽  
Arash Adelpanah ◽  
Razieh Soleimani ◽  
Parisa Heidari Aqagoli ◽  
Rosa Eidizadeh ◽  
...  
Keyword(s):  
Data Analysis ◽  
Organizational Commitment ◽  
Competitive Advantage ◽  
Indirect Effect ◽  
Psychological Empowerment ◽  
Job Burnout ◽  
Equation Modeling ◽  
Content Type ◽  
Mediating Role

Purpose This study aims at investigating the effect of psychological empowerment on job burnout and competitive advantage with the mediating role of organizational commitment and creativity. Design/methodology/approach The statistical population included all the managers and staffs of Tooka Company in Iran, and for data analysis, 120 completed questionnaires were used. Data analysis was carried out by SPSS 18 and Amos 20 software and structural equation modeling method. To test the mediating relationships, bootstrap method was used. Findings The findings showed that psychological empowerment has a significant direct effect on job burnout and competitive advantage. Also, psychological empowerment has a significant indirect effect on job burnout through the mediating role of organizational commitment. In addition, psychological empowerment has a significant indirect effect on competitive advantage through the mediating role of organizational creativity. Originality/value This study is among the first to investigate the relationship between psychological empowerment, job burnout, competitive advantage, organizational commitment and creativity.

Role of burnout on job level, job satisfaction, and task performance

2017 ◽  
Vol 38 (5) ◽  
pp. 630-645 ◽  
Author(s):  
Won Ho Kim ◽  
Young-An Ra ◽  
Jong Gyu Park ◽  
Bora Kwon
Keyword(s):  
Job Satisfaction ◽  
Task Performance ◽  
Organizational Context ◽  
Content Type ◽  
Job Level ◽  
Mediating Role ◽  
Final Sample ◽  
The Relationship ◽  
And Task

Purpose The purpose of this paper is to examine the mediating role of burnout (i.e. exhaustion, cynicism, professional inefficacy) in the relationship between job level and job satisfaction as well as between job level and task performance. Design/methodology/approach The final sample included 342 Korean workers from selected companies. The authors employed the Hayes (2013) PROCESS tool for analyzing the data. Findings The results showed that all three subscales of burnout (i.e. exhaustion, cynicism, professional inefficacy) mediate the relationship between job level and job satisfaction. However, only two mediators (i.e. cynicism, professional inefficacy) indicated the mediating effects on the association between job level and task performance. Originality/value This research presented the role of burnout on the relationships between job level, job satisfaction, and task performance especially in South Korean organizational context. In addition to role of burnout, findings should prove helpful in improving job satisfaction and task performance. The authors provide implications and limitations of the findings.

scholarly journals Limiting role of resource dependence: an examination of director interlocks, board meetings and family ownership

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vidya Sukumara Panicker ◽  
Rajesh Srinivas Upadhyayula
Keyword(s):  
Board Of Directors ◽  
Resource Dependence ◽  
Family Firms ◽  
Emerging Market ◽  
Resource Provisioning ◽  
Independent Directors ◽  
Family Ownership ◽  
Independent Director ◽  
Content Type

PurposeThis paper attempts to examine the activity and involvement of board of directors in internationalization activities of firms in emerging markets, by evaluating the resource provisioning roles of interlocks provided by board of directors, and the frequency of board meetings. We demonstrate that the effectiveness of board involvement is contingent upon the levels of family ownership in firms since family ownership could impact the firm’s ability to utilize the presence of different types of board members.Design/methodology/approachThe authors test our hypotheses on a sample of listed Indian companies, extracted from the Prowess database published by the Centre for Monitoring Indian Economy (CMIE), a database of the financial performance of Indian companies. On a panel of 3,133 firm years of 605 unique Indian firms with foreign investments, over a time period of 2006–2017, the authors apply different estimation techniques.FindingsThe results demonstrate that both board meeting frequency and director interlocks are instrumental in supporting internationalization activities in emerging market firms. However, family ownership moderates the role of insider and independent interlocks on internationalization investments in different ways; the authors find that interlocks provided by independent directors support internationalization activities in family firms, whereas those provided by insider directors do not. Further, the study also finds that board meetings are less effective in internationalization of family firms.Practical implicationsThe authors conclude that family firms aiming at international diversification require to develop more connected and networked independent directors to enable internationalization in firms. While independent director interlocks enhance the international investments, it is also useful to know that board meetings are ineffective in utilizing the resources in family firms. This points to the possibility that family firms should device mechanisms to integrate family meetings with board meetings so that they can utilize the within-family processes to aid in their internationalization decisions.Originality/valueThe study contributes to resource dependence theory by understanding its limiting role in family firms. Theoretically, it helps delineate the limiting resource provision role of the insider directors vis-à-vis independent directors. The authors argue that the resource provision role of insider director interlocks does not effectively help in internationalization in comparison to independent director interlocks in family-dominated firms. Consequently, the study shows the limiting role of resource provision and utilization by family-owned firms in comparison to non-family-owned firms.

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