bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR-based analysis of nucleotide π-stacking in a crowded environment: Implications for prebiotic reactions
Authors: Bapat Niraja V. , Paithankar Harshad , Chugh Jeetender , Rajamani Sudha
Published: May 2019

The inherent heterogeneity of the prebiotic milieu is often overlooked when studying nonenzymatic reactions. However, it is important to note that the prebiotic soup of a putative ‘RNA World’ would have been replete with a plethora of molecules resulting from complex chemical syntheses, as well as exogeneous delivery. The presence of such background molecules could lead to pertinent phenomenon such as molecular crowding, which can potentially affect how a reaction would advent in a crowded milieu. In the current study, we have analyzed the effect of crowding on the stacking ability of the RNA monomers, using Nuclear Magnetic Resonance (NMR) spectroscopy. Our findings corroborate that the purine monomers possess better stacking efficiency than pyrimidine based monomers. Significantly, this competence is further enhanced in the presence of a crowding agent. Interestingly, this enhanced stacking could result in higher sequestration of the purine monomers, putting their ready availability for relevant nonenzymatic polymerization and replication reactions into question. Taken together, this study demonstrates the need for systematic biophysical characterization of molecular crowding in the context of prebiotically pertinent processes. Unravelling such phenomena is essential to gather a real understanding of how the transition from abiotic to biotic, would have happened during the origin of life.
Atoh8 acts as a regulator of chondrocyte proliferation and differentiation in endochondral bones
Authors: Schroeder Nadine , Wuelling Manuela , Hoffmann Daniel , Brand-Saberi Beate , Vortkamp Andrea
Published: May 2019

Atonal homolog 8 (Atoh8) is a transcription factor of the basic helix-loop-helix (bHLH) protein family, which is expressed in the cartilaginous elements of endochondral bones. To analyze its function during chondrogenesis we deleted Atoh8 in mice using a chondrocyte- (Atoh8flox/flox;Col2a1-Cre) and a germline- (Atoh8flox/flox;Prx1-Crefemale) specific Cre allele. In both strains, Atoh8 deletion leads to a reduced skeletal size of the axial and appendicular bones, but the stages of phenotypic manifestations differ. While we observed obviously shortened bones inAtoh8flox/flox;Col2a1-Cremice only postnatally, the bones ofAtoh8flox/flox;Prx1-Crefemalemice are characterized by a reduced bone length already at prenatal stages. Detailed histological and molecular investigations revealed reduced zones of proliferating and hypertrophic chondrocytes. In addition, Atoh8 deletion identified Atoh8 as a positive regulator of chondrocyte proliferation. As increased Atoh8 expression is found in the region of prehypertrophic chondrocytes where the expression of Ihh, a main regulator of chondrocyte proliferation and differentiation, is induced, we investigated a potential interaction of Atoh8 function and Ihh signaling. By activating Ihh signaling with Purmorphamine we demonstrate that Atoh8 regulates chondrocyte proliferation in parallel or downstream of Ihh signaling while it acts on the onset of hypertrophy upstream of Ihh likely by modulating Ihh expression levels.
Training effectiveness in an enterprise resource planning system environment
Authors: Arasanmi Chris Niyi
Published: May 2019

Purpose

This study aims to examine the link between supervisor support, transfer motivation and post-training usage of enterprise resource planning (ERP) systems. The study tested the influence of supervisor support and transfer motivation on training transfer in a complex information systems environment. Second, the study tested the mediating effect of transfer motivation in the relationship between supervisor support and training transfer.

Design/methodology/approach

An online survey method was used to collect data from 170 ERP system users, who had previously attended ERP system training. The descriptive analysis was conducted with SPSS version 24, while Hayes Process Macro was used to test the research model and the mediation analysis.

Findings

The findings from this study showed that supervisor support and transfer motivation positively influence training transfer. The additional result also confirmed that transfer motivation mediates the relationship between supervisor support and training transfer.

Research limitations/implications

The study contributes to training theory by specifically analysing the interactions among supervisor support, transfer motivation and training transfer in a complex information system environment. One of the limitations of this study is the cross-sectional design adopted; future studies could improve by using multiple sources of data collection.

Practical implications

The study highlights the importance of social exchanges in an ERP transfer environment.

Originality/value

This paper provides a better understanding of the influences of supervisor support and transfer motivation on the transfer of hard skills in a complex environment.
Exploring the links between talent philosophies and talent management in service organizations
Authors: Pantouvakis Angelos , Karakasnaki Maria
Published: May 2019

Purpose

In line with recent trends in the human resource management literature that address talented employees and their management, the purpose of this paper is to examine the associations between talent philosophies (innate/developable and exclusive/inclusive) and the way talent is identified and assessed in the context of service organisations.

Design/methodology/approach

A structured questionnaire was administered in shipping companies located in Greece and 125 questionnaires suitable for further use were collected. Moreover, the measurement instruments of the constructs under examination were adopted from relevant studies in the literature. Finally, the data were analysed through exploratory factor analysis and multiple regression analysis.

Findings

The findings showed that the different talent philosophies impact upon the way talent is managed (i.e. identified and assessed). Specifically it was found that managers who adopt mainly innate and exclusive talent philosophies tend to rely more on their first impressions in the identification of talent and to focus in a greater extent on their personal judgment rather than standardized procedures in talent assessment.

Originality/value

Despite the increased academic voices on exploring the concepts of talent and talent management in the context of business organisations, the field is still lacking empirical evidence. Therefore, this study contributes to the limited empirical studies on talent issues and provides evidence on the links between the dominant talent philosophies and the way talent is identified and assessed in organisations.
Could the balanced scorecard enhance pharmaceutical organisations’ quality performance?
Authors: Elkanayati Rasha Mahmoud , Shamah Rania
Published: May 2019

Purpose

The purpose of this paper is to investigate the relationship between balanced scorecard (BSC) attributes and quality performance and the possible moderating effect of quality performance on the relationship between BSC and business performance. The positive findings from the multinational pharmaceutical organisations in Egypt may help the national pharmaceutical companies to improve their performance when incorporating the same tool (BSC) in their quality management system.

Design/methodology/approach

This research employs a quantitative approach to conduct a survey, and empirical data were drawn from 28 multinational pharmaceutical organisations in Egypt, 125 correct questionnaires were used for further analysis, and the research model was tested using the structural equation modelling technique by analysis of moment structures software.

Findings

The findings of the empirical research reveal that the BSC attributes significantly and positively relate to quality performance where strategy translated to operations has the strongest relationship, providing feedback/learning and communication have a moderate relationship, whereas alignment relation is negligible in the presence of other attributes. Additionally, BSC attributes have a significant positive relationship with business performance directly and indirectly and quality performance is the moderator. Also, the research suggests that the quality performance has a significant and positive relationship with business performance.

Research limitations/implications

The overall research implication is that the BSC certainly acts as a ground foundation for consolidating the quality management system. The BSC practices presented in this research emphasise that this tool is not just an integration of financial and non-financial metrics that measure performance; rather, it is a performance management system that reinforces the quality system and helps to harmonise the strategy and goals that leads to improvement in the performance levels.

Practical implications

The study shows that BSC practices support the organisational quality/business performances. Therefore, managers must develop and continuously refine their strategies, allocate sufficient resources for achieving targets of strategic measures, in order to achieve superior business performance.

Originality/value

Several studies approached the effect of some of BSC attributes on quality performance; yet, this research considers the association between the four attributes collectively with quality/business performance. Additionally, no previous research has comprehensively studied the moderating effects of quality performance on the relation between BSC and business performance, especially in pharmaceutical companies in Egypt.
Correlating research impact of library and information science journals using citation counts and altmetrics attention
Authors: Ezema Ifeanyi Jonas , Ugwu Cyprian I.
Published: May 2019

Purpose

Since the development of web 2.0, there has been a paradigm shift in methods of knowledge sharing. This has equally impacted on techniques of research evaluation. Many scholars have argued that the social utilization of research is hardly reflected in the traditional methods of research evaluation. The purpose of this paper is to determine the research impact of Library and Information Science (LIS) journals using Web of Science (WoS), Scopus and Google Scholar (GS) and then examine whether there is a correlation between their citations and altmetric attentions.

Design/methodology/approach

This paper is an attempt to contribute to this discussion with focus on the field of LIS. This paper adopted descriptive informatics to analyze LIS journals. The paper extracted citation data from WoS, Scopus and GS, and altmetric attentions from 85 LIS journals indexed by WoS. Further, 18 journals with high altmetric attention were identified, while 9 of these maintained consistent presence in the three databases used.

Findings

Findings show that of these databases, citation data from GS was found to have a high correlation with altmetric attention, while the other two databases maintained moderate correlations with altmetric attention. The paper also found a positive but non-significant correlation between citation scores and altmetric attention in the nine journals that maintained consistent presence in the three databases.

Practical implications

The findings of this paper will be useful to librarians in selection of relevant journals for their libraries and also will assist authors in the choice of publication outlets for their papers particularly when considering journals that have visibility and research impact.

Originality/value

The originality of the paper lies on empirical evidences from the citation and altmetric data extracted from the databases used for the paper.
A standardised flexibility assessment methodology for demand response
Authors: O’Connell Sarah , Reynders Glenn , Seri Federico , Sterling Raymond , Keane Marcus M.
Published: May 2019

Purpose

The purpose of this paper is to standardised four-step flexibility assessment methodology for evaluating the available electrical load reduction or increase a building can provide in response to a signal from an aggregator or grid operator.

Design/methodology/approach

The four steps in the methodology consist of Step 1: systems, loads, storage and generation identification; Step 2: flexibility characterisation; Step 3: scenario modelling; and Step 4: key performance indicator (KPI) label.

Findings

A detailed case study for one building, validated through on-site experiments, verified the feasibility and accuracy of the approach.

Research limitations/implications

The results were benchmarked against available demonstration studies but could benefit from the future development of standardised benchmarks.

Practical implications

The ease of implementation enables building operators to quickly and cost effectively evaluate the flexibility of their building. By clearly defining the flexibility range, the KPI label enables contract negotiation between stakeholders for demand side services. It may also be applicable as a smart readiness indicator.

Social implications

The novel KPI label has the capability to operationalise the concept of building flexibility to a wider spectrum of society, enabling smart grid demand response roll-out to residential and small commercial customers.

Originality/value

This paper fulfils an identified need for an early stage flexibility assessment which explicitly includes source selection that can be implemented in an offline manner without the need for extensive real-time data acquisition, ICT platforms or additional metre and sensor installations.
Central bank independence, elections and fiscal policy in Africa
Authors: Agoba Abel Mawuko , Abor Joshua Yindenaba , Osei Kofi , Sa-Aadu Jarjisu , Amoah Benjamin , Dzeha Gloria Clarissa Odortor
Published: May 2019

Purpose

The purpose of this paper is to primarily investigate the ability of independent central banks (central bank independence (CBI)) to improve fiscal performances in Africa, accounting for election years, and also to examine whether the effectiveness of CBI in improving fiscal performance is enhanced by higher political institutional quality.

Design/methodology/approach

Using recent CBI data from Garriga (2016) on 48 African countries, 90 other developing countries and 40 developed countries over the period 1970–2012, the authors apply a two stage system GMM with Windmeijer (2005) small sample robust correction estimator to examine the impact of CBI and elections on fiscal policy in Africa, other developing countries and developed countries.

Findings

The authors provide evidence that unlike in other developing countries and developed countries, CBI does not significantly improve fiscal performance in Africa. However, the effectiveness of CBI in improving fiscal performance in Africa is enhanced by higher levels of institutional quality. Although elections directly worsen fiscal performance in Africa, institutional quality enhances CBI’s effect on improving fiscal performance in election years across Africa, other developing countries and developed countries.

Practical implications

The findings of the study are significant as they provide insight into the benefits of having strong institutions to complement independent central banks in order to control fiscal indiscipline in election years.

Originality/value

The study is the first among the studies of CBI-fiscal policy nexus, to measure fiscal policy using net central bank claims on government as a percentage of GDP. In addition to the use of fiscal balance, this study also uses cyclically adjusted fiscal balance as a measure of fiscal policy. This is a critical channel through which independent central banks can constrain government spending. It also compares findings in Africa to other developing countries, noting some differences.
Assessing a social responsibility model for sustainable company growth in the Fourth Industrial Revolution
Authors: Park Sung Hyun , Shin Wan Seon , Kim Kwang Jae
Published: May 2019

Purpose

The Fourth Industrial Revolution ( 4th IR) affects the mode of company management. This paper aims to present a revised social responsibility (SR) model as an evaluation tool for corporate social responsibility (CSR) performance for sustainable organizational growth in the era of the 4th IR.

Design/methodology/approach

To develop an SR model that can be used well in the era of the 4th IR, the key references are “ISO 26000: Guidance on Social Responsibility” and the “Global Reporting Initiative (GRI) Guidelines.” For International Organization for Standardization (ISO) 26000 and the GRI guidelines, see the homepages in the References section. On the basis of these guidelines, a new SR model for sustainable development in the 4th IR is developed in this paper.

Findings

For a new SR model in the 4th IR, the concepts of management quality (MQ), quality responsibility (QR), creating shared value (CSV), social value and open data and open quality management are incorporated into the existing ISO 26000 evaluation criteria.

Originality/value

The 4th IR is changing the concepts of both quality management (QM) and SR. To the best of the authors’ knowledge, the new concept of SR has yet to be discussed extensively. In this paper, a new SR model is suggested to reflect the characteristics of the 4th IR.
Setting the foundation for democratization
Authors: Khodary Yasmin
Published: May 2019

Purpose

The purpose of this paper is to investigate the quality of a political science program in an Egyptian private university through assessing three particular dimensions: knowledge of political science core facts and theories; reading comprehension skills; and critical thinking (CT).

Design/methodology/approach

A case study research approach was used. The study relies also on a quantitative methodology. Quantitative data were collected from students in the second and fourth years of political science to assess their knowledge of core political science facts and theories, reading comprehension and CT through the online California Critical Thinking Skills Test.

Findings

Unlike the results of core knowledge and reading comprehension, positive results were found with regard to students’ CT. The levels of students’ CT increased from 0 percent in Year 2 to 18 percent in Year 4. Variables such as the school GPA, non-Egyptian high school degree and not meeting professors during office hours were found statistically significant to higher levels of CT.

Research limitations/implications

One limitation of the study was the relatively small samples’ size. However, while the samples might look small on the surface, they represent, in reality, between 49 and 59 percent of the students enrolled in Years 2 and 4.

Practical implications

Despite its pilot nature, this study provides some insight into the quality of private political science education in Egypt through assessing the degree it contributes to political science students’ knowledge, reading comprehension and CT and through investigating the most statistically significant variables.

Originality/value

Whilst several studies have investigated the quality of higher education programs, very limited literature attempted to assess the quality of political science education, in particular.
Linking motivation and alliance to perceived ambidexterity outcomes at the individual level in academia
Authors: Teye Emmanuel Tetteh , Abosi Beatrice Ayerakwa , Tetteh Alexander Narh , Ntim Seth Yeboah , Teye Abraham , Aseidua-Ayeh Offeibea Love , Dubi Sophia Agyeiwaa
Published: May 2019

Purpose

Previous research has considered human motivation as a determinant of inquisitiveness, learning and innovation. However, how student’s motivation affects both exploitative/exploratory research outcomes has not yet been sufficiently addressed. The purpose of this paper is to examine self-determination theory (SDT) as a conceptual tool to understand post-graduate student’s academic motivation and how it affects two types of ambidextrous outcomes (exploitative and exploratory), and thus posit relational capital as an important mediator in the motivation–innovation process.

Design/methodology/approach

The authors draw conclusions using 331 valid post-graduate foreign scholars data collected via online survey in three Chinese Universities and conduct data analysis using the structural equation modeling technique (AMOS).

Findings

Results indicate that: academic motivation and perceived collaboration capability both has a significant effect on exploitation behavior; there was no significant relationship between academic motivation and tendency to collaborate with actors within their networks; collaboration capability and exploitation behavior mediate the relationship between academic motivation and exploration behavior; and further a complementary link was found to exist between exploitation behavior and exploration behavior in students attempt to be ambidextrous.

Originality/value

The authors advance innovation research by expanding SDT to include relational perspective as an antecedent of ambidexterity (exploration/exploitation behaviors) and provide new insights into current understanding of research engagement in higher education settings. The authors highlight some implications for educational agencies seeking to promote the emergence of psychological and relational conditions to enhance novelty in post-graduate internationalized education.
Four design principles for learner dashboards that support student agency and empowerment
Authors: Bennett Liz , Folley Sue
Published: May 2019

Purpose

The purpose of this paper is to take a student-centred perspective to understanding the range of ways that students respond to receiving information about their learning behaviours presented on a dashboard. It identifies four principles to inform the design of dashboards which support learner agency and empowerment, features which Prinsloo and Slade (2016) suggest are central to ethical adoption of learning analytics.

Design/methodology/approach

The study involved semi-structured interviews with 24 final-year undergraduates to explore the students’ response to receiving dashboards that showed the students’ achievement and other learning behaviours.

Findings

The paper identifies four principles that should be used when designing and adopting learner dashboards to support student agency and empowerment.

Research limitations/implications

The study was based on a small sample of undergraduate students from the final year from one academic school. The data are based on students’ self-reporting.

Practical implications

The paper suggests that these four principles are guiding tenets for the design and implementation of learner dashboards in higher education. The four principles are: designs that are customisable by students; foregrounds students sense making; enables students to identify actionable insights; and dashboards are embedded into educational processes.

Originality/value

The paper’s originality is that it illuminates student-centred principles of learner dashboard design and adoption.
Money attitudes survey of business students in Kazakhstan, Kyrgyzstan and Uzbekistan
Authors: Tynaliev Urmatbek M. , Erdener Carolyn
Published: May 2019

Purpose

The purpose of this study is to analyze the money attitudes among students at English-language business schools in the transitioning Central Asian nations of the former USSR, namely, Kazakhstan, Kyrgyzstan and Uzbekistan.

Design/methodology/approach

The survey was carried out in 2017, using previously established measures of Love of Money survey questionnaire. Over 300 undergraduate students in English-language business degree programs in Kazakhstan, Kyrgyzstan and Uzbekistan participated in the survey. A few hypotheses were tested using three-way MANOVA to test the influence of three factors (country, gender and student years). In addition, post hoc analysis, and one- and two-way ANOVA methods were used for multiple comparisons.

Findings

The results showed evidence of increasing convergence among students who are farther along in the program. Some statistically significant differences were also found, mainly in regard to gender differences in money attitudes across countries and student levels. The results of statistical analysis suggest a need for further research on attitudes and values related to money in the modern nation states of Central Asia.

Originality/value

This study is one of first attempts to study the values and attitudes regarding money among the first generation of business students who were born and grew up after their respective countries gained independence. The findings imply the development of a relatively homogeneous labor pool for business organizations across regions that are characterized by increasing differentiation among countries within the region.
Transformative gamification services for social behavior brand equity: a hierarchical model
Authors: Tanouri Afshin , Mulcahy Rory , Russell-Bennett Rebekah
Published: May 2019

Purpose

The purpose of this paper is twofold: first, to test a hierarchical model with interrelationships between social support, value and brand equity to examine the effect of a transformative gamification service on users’ well-being behaviors; and second, to demonstrate the usefulness of brand equity to measure social behavior brands encouraged via transformative gamification services.

Design/methodology/approach

Data were collected (n=351) via users of a transformative gamification service delivered via mobile in Iran. Structural equation modeling was used to test the model.

Findings

The results revealed that the hierarchical model had a superior fit to the data over rival models measuring constructs at lower orders. The results also reveal that value mediates the relationship between social support and brand equity for social behavior.

Originality/value

This is the first study to hierarchically test a model for transformative gamification services. Furthermore, it begins to shed light on the antecedents of value created within transformative gamification services, which to date have not been thoroughly explored. Finally, the study demonstrates brand equity is applicable beyond commercial campaigns and services and can be used to measure social (well-being) behaviors.
A multi-stakeholders view of the barriers of social sustainability in healthcare supply chains
Authors: Hussain Matloub , Khan Mehmood , Ajmal Mian , Sheikh Karim Sajjad , Ahamat Amiruddin
Published: May 2019

Purpose

The purpose of this paper is to develop a framework for the identification, categorization and prioritization of social sustainability barriers in health-care supply chains.

Design/methodology/approach

An exploratory survey tool is used to identify barriers that are relevant to a health-care supply chain. The identified barriers are grouped into five main categories and experts’ opinions were applied to validate the content. Finally, an analytical hierarchical process (AHP) is used to prioritize the main categories and sub-categories of the barriers.

Findings

The exploratory phase identified 34 barriers that are relevant to a health-care supply chain. These barriers were grouped into the following categories: poor infrastructure, organizational culture, poor coordination, stakeholder disparity, and uncertainty. Organizational culture and poor coordination were assigned the highest priority through the AHP. Overall, lack of management support, lack of commitment and lack of coordination were found to be the top relevant barriers to a health-care supply chain.

Research limitations/implications

This study only explored and prioritized the barriers of social sustainability. Future research should explore the impact of the identified barriers on the overall performance of the hospital supply chain.

Practical implications

The findings of this study may be of value to the local health-care industry in achieving their objectives by overcoming social sustainability barriers, which would in turn facilitate the implementation of social sustainability programs that can positively contribute to the overall supply chain performance.

Social implications

Social sustainability has grown in importance as a pressurizing issue to push supply chain managers to assess their social impacts on the communities. This is especially important in service supply chains such as health care, where human element is a part of every stage.

Originality/value

Despite practitioners’ and academics’ growing emphasis on the social dimension of sustainability, the categorization and prioritization of social sustainability practices across health-care supply chains and general service care supply chains have not been addressed. This study aims to cover this gap by contributing to both the academic literature and the practical health-care environment.
Progress towards sustainable urban water management in Ghana
Authors: Egan Matthew , Agyemang Gloria
Published: May 2019

Purpose

In recent decades, governments in developing countries have experienced relentless pressure from key supranational finance providers (particularly the World Bank) to focus on the achievement of financial efficiency. This pressure persists despite evidence that basic institutions necessary for sustainable infrastructure and competitive commercial arrangements are often not present. This paper aims to examine the steering of urban water management in Ghana as it progressed through a first failed public-private partnership in this sector (from 2005 to 2011), and beyond to 2017. Throughout this 12-year period, the authors consider progress and barriers to the achievement of steering for sustainable development.

Design/methodology/approach

Publicly available documentation is examined through the lens of steering for sustainable development (Voßet al., 2007) to consider the challenges of urban water management between 2005 and 2017.

Findings

Progress towards a more sustainable approach to urban water management was achieved through greater democratic governance, public accountability and public engagement. This acted as a counter foil to power and affected improvements of knowledge and clarity of related goals. Effective sustainable management continued to be challenged, however, by on-going World Bank pressure to focus on financial efficiency.

Practical implications

The provision of a sustainable water supply continues to be a significant challenge for many developing countries, including Ghana. This study provides insights into how progress beyond crippling financial dependency might begin to be achieved.

Social implications

Safe and sustainable water supply is critical for both the health and economic progress of citizens in developing countries such as Ghana. This study provides insight into the value of drawing from a broad range of stakeholders in seeking viable pathways towards those goals.

Originality/value

While water management challenges for developing countries have been significantly researched, particularly in the context of private financing arrangements, little empirical insight is provided into how governments can move forward with sustainable progress beyond the failure of such arrangements. Water management in Ghana beyond 2011 provides that unique context.
Numerical and experimental study of the combustion phenomenon when the compression ignition is fuelled with mineral diesel
Authors: Venkatesan Hariram , J. Godwin John , Sivamani Seralathan , T. Micha Premkumar
Published: May 2019

Purpose

The purpose this experimentation is to study the combustion characteristics of compression ignition engine fuelled with mineral diesel. The reason behind the numerical simulation is to validate the experimental results of the combustion characteristics.

Design/methodology/approach

The numerical analysis was carried out in this study using MATLAB Simulink, and the zero dimensional combustion model was applied to predict the combustion parameters such as in cylinder pressure, pressure rise rate and rate of heat release.

Findings

Incorporating the dynamic combustion duration with respect to variable engine load in the zero dimensional combustion model using MATLAB Simulink reduced the variation of experimental and numerical outputs between 5.5 and 6 per cent in this analysis.

Research limitations/implications

Validation of the experimental analysis is very limited. Investigations were performed using zero dimensional combustion model, which is the very appropriate for analysing the combustion characteristics.

Originality/value

Existing studies assumed that the combustion duration period as invariant in their numerical analysis, but with the real time scenario occurring in CI engine, that is not the case. In this analysis, mass fraction burnt considering the dynamic combustion duration was incorporated in the heat transfer model to reduce the error variation between experimental and numerical studies.
Effect of Shale Reservoir Characteristics on Shale Oil Movability in the Lower Third Member of the Shahejie Formation, Zhanhua Sag
Authors: NING Chuanxiang , MA Zhongliang , JIANG Zhenxue , SU Siyuan , LI Tingwei , ZHENG Lunju , WANG Guozhen , LI Fengxun
Published: May 2019

To reveal the effect of shale reservoir characteristics on the movability of shale oil and its action mechanism in the lower third member of the Shahejie Formation (Es3l), samples with different features were selected and analyzed using N2 adsorption, high‐pressure mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), high‐speed centrifugation, and displacement image techniques. The results show that shale pore structure characteristics control shale oil movability directly. Movable oil saturation has a positive relationship with pore volume for radius > 2 μm, as larger pores often have higher movable oil saturation, indicating that movable oil is present in relatively larger pores. The main reasons for this are as follows. The relatively smaller pores often have oil‐wetting properties because of organic matter, which has an unfavorable effect on the flow of oil, while the relatively larger pores are often wetted by water, which is helpful to shale oil movability. The rich surface provided by the relatively smaller pores is beneficial to the adsorption of immovable oil. Meanwhile, the relatively larger pores create significant pore volume for movable oil. Moreover, the larger pores often have good pore connectivity. Pores and fractures are interconnected to form a complex fracture network, which provides a good permeability channel for shale oil flow. The smaller pores are mostly distributed separately; thus, they are not conducive to the flow of shale oil. The mineral composition and fabric macroscopically affect the movability of shale oil. Calcite plays an active role in shale oil movability by increasing the brittleness of shale and is more likely to form micro‐cracks under the same stress background. Clay does not utilize shale oil flow because of its large specific surface area and its block effect. The bedding structure increases the large‐scale storage space and improves the connectivity of pores at different scales, which is conducive to the movability of shale oil.
Pore Size Distribution of a Tight Sandstone Reservoir and its Effect on Micro Pore‐throat Structure: A Case Study of the Chang 7 Member of the Xin'anbian Block, Ordos Basin, China
Authors: LI Peng , JIA Chengzao , JIN Zhijun , LIU Quanyou , BI He , ZHENG Min , WU Songtao , HUANG Zhenkai
Published: May 2019

Pore distribution and micro pore‐throat structure characteristics are significant for tight oil reservoir evaluation, but their relationship remains unclear. This paper selects the tight sandstone reservoir of the Chang 7 member of the Xin'anbian Block in the Ordos Basin as the research object and analyzes the pore size distribution and micro pore‐throat structure using field emission scanning electron microscopy (FE‐SEM), high‐pressure mercury injection (HPMI), high‐pressure mercury injection, and nuclear magnetic resonance (NMR) analyses. The study finds that: (1) Based on the pore size distribution, the tight sandstone reservoir is characterized by three main patterns with different peak amplitudes. The former peak corresponds to the nanopore scale, and the latter peak corresponds to the micropore scale. Then, the tight sandstone reservoir is categorized into three types: type 1 reservoir contains more nanopores with a nanopore‐to‐micropore volume ratio of 82:18; type 2 reservoir has a nanopore‐to‐micropore volume ratio of 47:53; and type 3 reservoir contains more micropores with a nanopore‐to‐micropore volume ratio of 35:65. (2) Affected by the pore size distribution, the throat radius distributions of different reservoir types are notably offset. The type 1 reservoir throat radius distribution curve is weakly unimodal, with a relatively dispersed distribution and peak ranging from 0.01 μm to 0.025 μm. The type 2 reservoir's throat radius distribution curve is single‐peaked with a wide distribution range and peak from 0.1 μm to 0.25 μm. The type 3 reservoir's throat radius distribution curve is single‐peaked with a relatively narrow distribution and peak from 0.1 μm to 0.25 μm. With increasing micropore volume, pore‐throat structure characteristics gradually improve. (3) The correlation between micropore permeability and porosity exceeds that of nanopores, indicating that the development of micropores notably influences the seepage capacity. In the type 1 reservoir, only the mean radius and effective porosity have suitable correlations with the nanopore and micropore porosities. The pore‐throat structure parameters of the type 2 and 3 reservoirs have reasonable correlations with the nanopore and micropore porosities, indicating that the development of these types of reservoirs is affected by the pore size distribution. This study is of great significance for evaluating lacustrine tight sandstone reservoirs in China. The research results can provide guidance for evaluating tight sandstone reservoirs in other regions based on pore size distribution.
Diatom Response to Global Warming in Douhu Lake, Southeast China
Authors: LI Jingjing , WANG Luo , CAO Qi , RIOUAL Patrick , LEI Guoliang , CAI Binggui , ZHANG Jiaoyang , ZOU Yafei , YAN Yao , WAN Xiaoqiao , XIAO Jule
Published: May 2019

A large number of lacustrine sedimentary records indicate that global warming is the main factor leading to significant changes in diatom communities in lakes of the northern hemisphere. However, due to the intensification of human activities since 1850, some scholars have emphasized that the increasing lake trophic level may be the main reason for the changes in diatom communities. The debate is ongoing. In order to avoid falling into the complex relationship between diatom changes and the seasonal cycle that characterizes lakes in mid and high latitudes, we chose a lake located at a low latitude, where the relationship between diatoms and temperature is not indirect but direct. The diatom record spans the past ca. 100 years and reveals that the abundance of Aulacoseira granulata increased from 1900 until 1985, replacing the previously dominant Aulacoseira ambigua. These changes are in agreement with the increasing trend in global temperature. Since 1985, the percentages of the small‐celled Discostella stelligera and the benthic diatom Navicula heimansioides have increased, while Aulacoseira granulata has decreased. This latest shift is caused by further global warming. We conclude that warming is the main factor leading to changing diatom communities in Douhu Lake.
Study of Fractal Characteristics of the Cementation Index in Shale Gas
Authors: LIU Hongqi , LIU Shiqiong , LUO Xingping , SUN Yangsha , TIAN Jie , LIANG Lixi , LIU Xiangjun
Published: May 2019

The description of pores and fracture structures is a consistently important issue and certainly a difficult problem, especially for shale or tight rocks. However, the exploitation of so‐called unconventional energy, such as shale methane and tight‐oil, has become more and more dependent on an understanding of the inner structure of these unconventional reservoirs. The inner structure of porous rocks is very difficult to describe quantitatively using normal mathematics, but fractal geometry, which is a powerful mathematical tool for describing irregularly‐shaped objects, can be applied to these rocks. To some degree, the cementation index and tortuosity can be used to describe the complexity of these structures. The cementation index can be acquired through electro‐lithology experiments, but, until now, tortuosity could not be quantitatively depicted. This research used the well‐logging curves of a gas shale formation to reflect the characteristics of the rock formations, and the changes in the curves to indicate the changes of the rock matrix, the pores, the connections among the pores, the permeability, and the fluid type. The curves that are affected most by the rock lithology, such as gamma ray, acoustic logging, and deep resistivity curves, can provide significant information about the micro‐ or nanostructure of the rocks. If the rock structures have fractal characteristics, the logging curves will also have fractal properties. Based on the definition of a fractal dimension and the Hausdorff dimension, this paper presents a new methodology for calculating the fractal dimensions of logging curves. This paper also reveals the deep meaning of the rock cementation index, m, through the Hausdorff dimension, and provides a new equation to calculate this parameter through the resistivity and porosity of the formation. Although it represents a very important relationship between the saturation of hydrocarbons with pores and resistivity, the Archie formula was not available for shale and tight rock. The major reason for this was an incorrect understanding of the cementation index, and the calculation of saturation used a single m value from the bottom to the top of the well. Unfortunately, this processing method is clearly inappropriate for the intensely heterogeneous material that is shale and tight rock. This paper proposes a method of calculating m through well‐logging curves based on a fractal geometry that can change with different lithologies, so that it would have more agreement with in situ scenarios than traditional methods.
Radial Permeability Measurements for Shale Using Variable Pressure Gradients
Authors: FAN Kunkun , SUN Renyuan , ELSWORTH Derek , DONG Mingzhe , LI Yajun , YIN Congbin , LI Yanchao , CHEN Zhongwei , WANG Chunguang
Published: May 2019

Shale gas is becoming an important component of the global energy supply, with permeability a critical controlling factor for long‐term gas production. Obvious deviation may exist between helium permeability determined using small pressure gradient (SPG) methods and methane permeability obtained under actual field production with variable pressure gradients (VPG). In order to more accurately evaluate the matrix permeability of shale, a VPG method using real gas (rather than He) is established to render permeability measurements that are more representative of reservoir conditions and hence response. Dynamic methane production experiments were performed to measure permeability using the annular space in the shale cores. For each production stage, boundary pressure is maintained at a constant and the gas production with time is measured on the basis of volume change history in the measuring pump. A mathematical model explicitly accommodating gas desorption uses pseudo‐pressure and pseudo‐time to accommodate the effects of variations in pressure‐dependent PVT parameters. Analytical and semi‐analytical solutions to the model are obtained and discussed. These provide a convenient approach to estimate radial permeability in the core by nonlinear fitting to match the semi‐analytical solution with the recorded gas production data. Results indicate that the radial permeability of the shale determined using methane is in the range of 1×10−6 – 1×10−5 mD and decreases with a decrease in average pore pressure. This is contrary to the observed change in permeability estimated using helium. Bedding geometry has a significant influence on shale permeability with permeability in parallel bedding orientation larger than that in perpendicular bedding orientation. The superiority of the VPG method is confirmed by comparing permeability test results obtained from both VPG and SPG methods. Although several assumptions are used, the results obtained from the VPG method with reservoir gas are much closer to reality and may be directly used for actual gas production evaluation and prediction, through accommodating realistic pressure dependent impacts.
Minimally invasive rehabilitation of the worn dentition: a case report utilising adhesive additive techniques and digital technologies
Authors: Mak A , Chio A
Published: May 2019

The management of the worn dentition presents an increasing challenge that is encountered more frequently in daily dental practice. The consequences of tooth wear tend to be multifactorial and while they may initially only involve the loss of surface enamel it can progressively lead to significant destruction of the dentition. This paper discusses the management of a tooth wear case where a significant amount of tooth structure has been lost from both the anterior and posterior teeth. Protocols for assessment, treatment planning and restorative management of the tooth wear case are presented demonstrating the use of adhesive additive techniques and digital technologies to achieve functional and aesthetic rehabilitation of the dentition.
Diverse clinical and histopathologic features of cutaneous post‐transplant lymphoproliferative disorders: A presentation of two cases
Authors: Roberts Sammie J , McNally Brandon , Rosser Julie A , Willard Nicholas , Golitz Loren , Wisell Joshua
Published: May 2019

Heterogeneous lymphoproliferative disorders occurring in the post‐transplant setting are considered together as post‐transplant lymphoproliferative disorders and can rarely present as primary cutaneous lesions. These disorders are often Epstein–Barr virus‐driven and in some cases need only be treated with reduction in immune suppressive medications. We present two cases of monomorphic post‐transplant lymphoproliferative disorder, a plasmablastic lymphoma and a diffuse large B‐cell lymphoma, and summarise common reported clinical and histopathological features.