bluuebunny/crossref_metadata_2025 huggingface dataset:
Thyroid Hormone Indices in Computer Workers with Emphasis on the Role of Zinc Supplementation
Authors: Amin Ahmed Ibrahim , Hegazy Noha Mohamed , Ibrahim Khadiga Salah , Mahdy-Abdallah Heba , Hammouda Hamdy A. A. , Shaban Eman Essam
Published: March 2016

AIM: This study aimed to investigate the effects of computer monitor-emitted radiation on thyroid hormones and the possible protective role of zinc supplementation.MATERIAL AND METHODS: The study included three groups. The first group (group B) consisted of 42 computer workers. This group was given Zinc supplementation in the form of one tablet daily for eight weeks. The second group (group A) comprised the same 42 computer workers after zinc supplementation. A group of 63 subjects whose job does not entail computer use was recruited as a control Group (Group C). All participants filled a questionnaire including detailed medical and occupational histories. They were subjected to full clinical examination. Thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and zinc levels were measured in all participants. RESULTS: TSH, FT3, FT4 and zinc concentrations were decreased significantly in group B relative to group C. In group A, all tested parameters were improved when compared with group B. The obtained results revealed that radiation emitted from computers led to changes in TSH and thyroid hormones (FT3 and FT4) in the workers. CONCLUSION: Improvement after supplementation suggests that zinc can ameliorate hazards of such radiation on thyroid hormone indices.
Hypercalcemia as a Cause of Kidney Failure: Case Report
Authors: Stojceva-Taneva Olivera , Taneva Borjanka , Selim Gjulsen
Published: March 2016

BACKGROUND: Hypercalcemia is a common manifestation in clinical practice and occurs as a result of primary hyperparathyroidism, malignancy, milk-alkali syndrome, hyper or hypothyroidism, sarcoidosis and other known and unknown causes. Patients with milk-alkali syndrome typically are presented with renal failure, hypercalcemia, and metabolic alkalosis caused by the ingestion of calcium and absorbable alkali. This syndrome is caused by high intake of milk and sodium bicarbonate.CASE PRESENTATION: We present a 28-year old male admitted to hospital with a one-month history of nausea, vomiting, epigastric pain, increased blood pressure and worsening of renal function with hypercalcemia. His serum PTH level was almost undetectable; he had mild alkalosis, renal failure with eGFR of 42 ml/min, anemia, hypertension and abnormal ECG with shortened QT interval and ST elevation in V1-V4. He had a positive medical history for calcium-containing antacids intake and after ruling out primary hyperparathyroidism, malignancy, multiple myelomas, sarcoidosis, and thyroid dysfunction, it seemed plausible to diagnose him as having the milk-alkali syndrome.CONCLUSION: Although milk-alkali syndrome currently may be more probably a result of calcium and vitamin D intake in postmenopausal women, or in elderly men with reduced kidney function taking calcium-containing medications, one should not exclude the possibility of its appearance in younger patients taking calcium-containing medications and consider it a serious condition taking into account its possibility of inducing renal insufficiency.
Utilisation and trade of edible grasshoppers in the western region of the state of Morelos, Mexico
Authors: Pino Moreno J.M. , García Flores A. , Barreto Sánchez S.D. , Martínez Luque E.O.
Published: March 2016

This article presents a taxonomic analysis of the grasshoppers utilised as food sources in several municipalities of the state of Morelos, Mexico; three families, four genera, and ten species were documented. The representative genus,Sphenarium, consists of seven different species. Various aspects regarding the host plants and collection and trade of these organisms are discussed. In addition, the importance of these organisms as a renewable natural food resource for rural communities in the state of Morelos is discussed.
The career of Dr J. Ramos-Elorduy Blásquez
Authors: Pino Moreno J.M.
Published: March 2016

Dr Julieta Ramos-Elorduy retired in 2015 after a long career that covered different topics, but she is best known for her outstanding contributions to the use of insects as food and feed. This paper presents an outline of her career including a thematic analysis of her different academic activities, which include professional activities, fields of specialty, academic honours, published scientific articles, chapters in internationally and nationally published books, published books, full articles published in the proceedings of international and national congresses, papers presented in international and national congresses, experience in innovation and technological description, copyrights and patents, teaching experience, thesis direction, academic staff that has developed under her tuition, evaluation of scientific papers for diverse institutions, consultancy, lectures, and their participation in newspapers magazines, television and radio. Finally the importance and impact of her contributions in the field of entomology, ethnoentomology, cultural entomology and especially in the anthropoentomophagy in Mexico and other countries is discussed.
Benefits and Limitations of Using Decision-Analytic Tools to Assess Uncertainty and Prioritize Landscape Conservation Cooperative Information Needs
Authors: van der Burg Max Post , Thomas Catherine Cullinane , Holcombe Tracy , Nelson Richard D.
Published: March 2016

The Landscape Conservation Cooperatives (LCCs) are a network of partnerships throughout North America that are tasked with integrating science and management to support more effective delivery of conservation at a landscape scale. To achieve this integration, some LCCs have adopted the approach of providing their partners with better scientific information in an effort to facilitate more efficient and coordinated conservation decisions. Taking this approach has led many LCCs to begin funding research to provide the information for improved decision making. To ensure that funding goes to research projects with the highest likelihood of leading to more integrated broad-scale conservation, some LCCs have also developed approaches for prioritizing which information needs will be of most benefit to their partnerships. We describe two case studies in which decision-analytic tools were used to quantitatively assess the relative importance of information for decisions made by partners in the Plains and Prairie Potholes LCC. The results of the case studies point toward a few valuable lessons in terms of using these tools with LCCs. Decision-analytic tools tend to help shift focus away from research-oriented discussions and toward discussions about how information is used in making better decisions. However, many technical experts do not have enough knowledge about decision-making contexts to fully inform the latter type of discussion. When assessed in the right decision context, however, decision analyses can point out where uncertainties actually affect optimal decisions and where they do not. This helps technical experts understand that not all research is valuable in improving decision making. Perhaps most important, our results suggest that decision-analytic tools may be more useful for LCCs as a way of developing integrated objectives for coordinating partner decisions across the landscape, rather than simply ranking research priorities.
The Case of ISO 9000 Quality Management System Certification in a Faculty of a Turkish Public University
Authors: Eryılmaz Mehmet Eymen , Erdur Duygu Acar , Bektaş Olcay , Kara Esen , Aydoğan Ebru
Published: March 2016

It is clear that ISO 9000 Quality Management System and Total Quality Management have an extensive literature. However, it is observed that the literature principally focuses on implementation consequences of them. In this study, ISO 9000 Quality Management System certification process in a faculty of a Turkish public university is taken into consideration. However, the study focuses on not only consequences of taking this certification but also its' triggers and processes. To examine these triggers, processes and consequences, data collection methods of the study were semi-structured interviews and unstructured participative observation. In addition, extensive amount of document was used to make triangulation.
Bridging Theory and Practice
Authors: Cendon Eva
Published: March 2016

This chapter focuses on reflective learning in higher education as central point of reference in answering to the social demands and the ongoing changes in modern societies. Empirical basis is a two and a half year study with a group of students in different master's programs at a University for Professional Studies and interviews with teachers who are teaching in master's programs of professional studies. The chapter presents a concept of reflective learning that values the students' practice and expertise as professionals and provides ways to further develop and transform this practice into new contexts. Hence, the productive linkage between academic ways of knowing and professional ways of knowing and the development of students as reflective practitioners are central elements.
Teaching Entrepreneurship
Authors: Gámez Gutiérrez Jorge Alberto , Garzón Baquero Jossie Esteban
Published: March 2016

Capitalism has promoted and requires the growing knowledge of entrepreneurs, creative people who have the ability to solve problems in the form of innovation. The types of enterprises they create can be social, public and private. By creating an enterprising company new products and new production methods can be introduced, new markets are open, new sources of raw materials and inputs are developed and new market structures in an industry are created. Entrepreneurship can be taught, the question is how to do it. Teaching entrepreneurship should go beyond the business plan. It proposes a form that overcomes the mistakes found by the author in two research studies in 2008 and 2014 in the programs of management in Bogotá.
Subspace Clustering of DNA Microarray Data
Authors: Tchagang Alain B. , Famili Fazel , Pan Youlian
Published: March 2016

Identification of biological significant subspace clusters (biclusters and triclusters) of genes from microarray experimental data is a very daunting task that emerged, especially with the development of high throughput technologies. Several methods and applications of subspace clustering (biclustering and triclustering) in DNA microarray data analysis have been developed in recent years. Various computational and evaluation methods based on diverse principles were introduced to identify new similarities among genes. This review discusses and compares these methods, highlights their mathematical principles, and provides insight into the applications to solve biological problems.
Decision Support for Mental Health
Authors: Kalina Jan , Zvárová Jana
Published: March 2016

Decision support systems represent an important tool offering assistance with the decision making process in a variety of applications. This paper starts with recalling the basic principles and structure of decision support systems in medicine from a general perspective. Their effect in terms of both potential and limitations for finding the diagnosis, prognosis and therapy are overviewed from the points of view of health care effectiveness and patient safety. The authors are particularly interested in the specialty field of psychiatry. They discuss its specific challenges and analyze the slower penetration of telemedicine tools to psychiatry compared to other clinical fields. Finally, they claim that the development of decision support systems play a key role in the development of the concept of information-based medicine in general as well as to the particular context of information-based psychiatry.
A Research Approach to Detect Unreliable Information in Online Professional Social Networks
Authors: Jing Nan , Li Mengdi , Zhang Su
Published: March 2016

Professional social network gives companies a platform to post hiring information and locate professional talents. However, the professional network has a great number of users who generate huge amount of information every day, which makes it difficult for the hiring company to distinguish reliability of users' information and evaluate their professional abilities. In this context, this article bases on LinkedIn Mobile as the online professional social network and proposes a research approach to effectively identify unreliable information and evaluate users' abilities. First, the authors look for relevant social network profiles for a cross-site check. Second, on a single professional social networking they site, the authors check the similarity between the user's background and his connections' backgrounds, to detect any possible unreliable information. Third, they propose an algorithm to rank the trustfulness of users' recommendations based on a PageRank algorithm that was traditionally to evaluate the importance of web pages.
A Novel OpenFlow-Based DDoS Flooding Attack Detection and Response Mechanism in Software-Defined Networking
Authors: Wang Rui , Zhang Zhiyong , Ju Lei , Jia Zhiping
Published: March 2016

Software-Defined Networking (SDN) and OpenFlow have brought a promising architecture for the future networks. However, there are still a lot of security challenges to SDN. To protect SDN from the Distributed denial-of-service (DDoS) flooding attack, this paper extends the flow entry counters and adds a mark action of OpenFlow, then proposes an entropy-based distributed attack detection model, a novel IP traceback and source filtering response mechanism in SDN with OpenFlow-based Deterministic Packet Marking. It achieves detecting the attack at the destination and filtering the malicious traffic at the source and can be easily implemented in SDN controller program, software or programmable switch, such as Open vSwitch and NetFPGA. The experimental results show that this scheme can detect the attack quickly, achieve a high detection accuracy with a low false positive rate, shield the victim from attack traffic and also avoid the attacker consuming resource and bandwidth on the intermediate links.
Authentication in Ubiquitous Networking
Authors: Almuhaideb Abdullah Mohammed , Srinivasan Bala
Published: March 2016

Mobile authentication is an essential service to ensure the security of engaging parties in a ubiquitous wireless network environment. Several solutions have been proposed mainly based on both centralised and distributed authentication models to allow ubiquitous mobile access authentication; however, limitations still exist in these approaches, namely flexibility, security and performance issues and vulnerabilities. These shortcomings are influenced by the resource limitations of both wireless networks and the mobile devices together with inter-technology and inter-provider challenges. In this paper, the authors reviewed the major techniques in the field of ubiquitous mobile access authentication, which has attracted many researchers in the past decade. After investigating existing mobile authentication models and approaches, the common challenges are summarised to serve as the solution key requirements. The identified key solution requirements allow analysing and evaluating mobile authentication approaches.
The Relationship between B2B E-Procurement Solutions and the Purchasing Portfolio
Authors: Truong Dothang
Published: March 2016

Business-to-business e-procurement has attracted special attention from the academia and industry. However, e-procurement platforms are not homogenous and the use of e-procurement solutions for a specific purchasing situation has not been adequately addressed. The purpose of this research is to examine the relationship between e-procurement types and the purchasing portfolio. A large scaled survey was conducted to collect data from purchasing organizations in different industries. The results showed significant differences in purchasing situations across three types of e-procurement.
Evaluating Critical Success Factors Model of Knowledge Management
Authors: Sedighi Mohammadbashir , van Splunter Sander , Zand Fardad , Brazier Frances
Published: March 2016

Knowledge management is a critical issue in today's business world. Knowledge is considered to be one of the most strategic resources of a firm and sources of competitive advantage. This paper identifies and ranks Critical Success Factors (CSFs) for implementation of knowledge management in the Iranian Energy Sector. Using the Analytic hierarchy process (AHP) method the relative quantitative weights of 8 of the major CSFs for implementation of knowledge management are identified, based on analyses with KM designers in the Iranian energy sector. The outcomes of the research designate that the critical success factors in the order of importance are: corporate culture, human and financial resources, strategy and leadership, structures and procedures, meso environmental factors, knowledge management process, macro environmental factors, technology and infrastructure.
Maximizing Power Saving for VoIP over WiMAX Systems
Authors: Emara Tamer Z.
Published: March 2016

The voice-over-Internet protocol (VoIP) service is expected to be widely supported in wireless mobile networks. Mobile Broadband Wireless networks VoIP service to users with high mobility requirements, connecting via portable devices which rely on the use of batteries by necessity. Energy consumption significantly affects mobile subscriber stations in wireless broadband access networks. Efficient energy saving is an important and challenging issue because all mobile stations are powered by limited battery lifetimes. Therefore, the authors propose an adaptive mechanism suitable for VoIP service with silence suppression. The proposed mechanism was examined with a computer simulation. The simulation results demonstrate that the proposed mechanism reduces energy consumption.
Throughput-Delay Evaluation of a Hybrid-MAC Protocol for M2M Communications
Authors: Verma Pawan Kumar , Verma Rajesh , Prakash Arun , Tripathi Rajeev
Published: March 2016

This paper proposes a robust hybrid-MAC protocol for direct communication among M2M devices with gateway coordination. The proposed protocol combines the benefits of both contention-based and reservation-based MAC schemes. The authors assume that the contention and reservation portion of M2M devices is a frame structure, which is comprised of two sections: Contention Interval (CI) and Transmission Interval (TI). The CI is based on p-persistent CSMA mechanism, which allows M2M devices to compete for the transmission slots with equal priorities. After contention, only those devices, which have won time-slots, are allowed to transmit data packets during TI. In the authors' proposed MAC scheme, the TI is basically a TDMA frame and each M2M device is 802.11 enabled. Each M2M transmitter device and its corresponding one-hop distant receiver communicate using IEEE 802.11 DCF protocol within each TDMA slot to overcome the limitations of TDMA mechanism. The simulation results demonstrate the effectiveness of the proposed hybrid-MAC protocol.
Managing the Commonplace
Authors: Chaudron Gerald
Published: March 2016

When libraries undertake emergency planning, it is likely that the risks such planning attempts to address are at the catastrophic level. In the case of water-related emergencies, the literature about disaster planning focuses on 100-year floods or hurricanes rather than the more common events of burst pipes or leaky roofs. This article uses two case studies to examine the impact of small water incursions on the libraries concerned, how those libraries managed the emergencies, and what lessons were learned which will inform their planning for future incidents. The case studies show that while both incidents were water-related, they are quite different in terms of source, size, impact, recovery time, and frequency. Libraries should be planning for the small emergencies first, and then scaling up their preparation to account for the larger, less frequent events, rather than the reverse. More libraries may be persuaded to do such planning if they are preparing for a probable scenario rather than one which may only be a possibility.
Libraries to the Rescue
Authors: Mabe Michael R.
Published: March 2016

Emergency management professionals over the years have realized that preplanning and coordination is essential when mounting an effective reaction to a natural disaster. During Hurricane Katrina, professionals learned that preplanning and preparation must include a plan for responding to the unexpected. Chesterfield County, VA learned this lesson in 2011 during Hurricane Irene when unexpected events required adjusting the plan. The amount of damage caused by Irene was minimal compared to Katrina but the impact of responding to unexpected needs was just as compelling. During Irene and other natural disasters that followed the Chesterfield County Public (CCPL) became a key component in meeting unexpected needs mass care and communications. CCPL can now serve as an information hub, double as a daytime relief shelter and participate in mass feeding if necessary during emergency situations. Selected library branches are also be used as overnight relief shelters when the activation of a standard sized shelter facility is not warranted.
VIRTUAL OFFICE
Authors: Aragon Maria Victoria de la Fuente , Ros-McDonnell Lorenzo
Published: March 2016

The integration of functions in business networks requires a high level of integration of the information processes. Based on file transfers, these networks respond to the requirements of collaborative processes. There is an effective need for a strategy of integration among the members of the network. In the ICT era, the collaborative company needs to reach and maintain agility in the dynamics of their collaborative processes. Within the frame of a collaborative network, the development of a web platform permits the growth of an area that integrates collaborative processes, in which several companies participate, each supplying their own data. The Fruit-and-Vegetable Collaborative Network studied in this paper is formed by producers, processers, packaging companies, marketers, transporters, and distributors. It has been developed via a web platform (Virtual Office), which allows the network to carry out processes in a collaborative way, and helps the network in its process of confidence-building and in the interactions among its members.
Evaluation of User Acceptance of Virtual Environments and Interfaces for Communication in Virtual Teams
Authors: Cruz-Cunha Maria Manuela , Putnik Goran D. , Gonçalves Patrícia , Gonçalves Joaquim
Published: March 2016

Several studies have highlighted the relevance of face-to-face communication, suggesting that computer-mediated communication can lead to decreases in group effectiveness and reduce satisfaction levels in terms of trust and comfort of its users. Supported by an experiment where the emotional or affective aspects of communication were tested, this paper validates the thesis that, from the users' perspective, there is no opposition to the acceptance of virtual environments and interfaces for communication, and that these environments are able to cope with the reconfiguration dynamics requirements of virtual teams or client-server relations in a virtual enterprise operation. For the thesis validation, the authors experimented with two architectures, the Direct Communication Architecture (DCA) and the Virtual Communication Architecture (VCA) and found that the VCA could represent a “natural” environment to cope with the new generation of organizational environments and teams, characterised by intense reconfiguration dynamics.
Case-Based Planning with User Preferences for Web Service Composition
Authors: Hachemi Yamina , Benslimane Sidi Mohamed
Published: March 2016

Web services composition has emerged as a solution to answer the requester's requirements. However, the selection of an appropriate Web service has become a difficult task due to the number of Web services present on the Web and mostly they offer similar functionalities. User preferences are a key factor that can be used to rank candidate services and retain only the best ones. To improve the process of web service composition the authors propose a Case-Based Planning (CBP) approach based on preferences which uses successful experiences in past to solve similar problems at present or/and in the future. How to make a choice base on non-functional factors becomes a problem that need to be solved. This paper, argues that the selection should be considered in a global manner based on the user's preferences. The authors present a framework that deals with web service composition based on user preferences and CBP method. Results obtained offer more than a solution to the user and taking both functional and non-functional requirements.
Process Batch Offloading Method for Mobile-Cloud Computing Platform
Authors: Thakur Pawan Kumar , Verma Amandeep
Published: March 2016

Mobile cloud applications transfers the computational power and data storage outside the mobile device and into the mobile cloud, getting mobile computing and mobile applications to not handheld devices users but a wider choice of mobile subscribers. Process offloading is the technique in which some part of the application is transferred into the mobile cloud for execution. Many applications like GPS, face recognition, video editing etc. consumes more battery of the mobile devices. By offloading the power hunger part to the cloud is one of the approach to elongate the battery lifetime of mobile devices. The major goal of the proposed model is to combine the similar processes into single batch and offload the batch into cloud rather than offloading a single process into cloud. A MPCEPGM (Multilevel Process Cost Evaluation with Process Group Merging) algorithm is proposed for application partitioning and offloading to the cloud. MPCEPGM will predict the overall execution cost of the whole batch or process tree as single entity. This will help the mobile offloading procedure to organize the processes according to their delivery time. Proposed model is energy efficient to deliver the data effectively to the mobile cloud. The performance of the proposed system is assessed on the basis of total execution time and communication cost using Matlab simulations.
Secure Computation on Cloud Storage
Authors: Gupta Daya Sagar , Biswas G. P.
Published: March 2016

This paper describes a way by which computation on cloud storage is securely possible. A user stores their secret (encrypted) files on cloud storage and later on, retrieves an addition of their original files, however, the cloud system cannot decrypt the stored encrypted files by own. In this paper, the authors use the homomorphic property to securely compute the addition of the files. The implementation of their proposed protocol is based on the computation on the basic properties of elliptic curves and bilinear mapping. The security of proposed encryption technique depends on the hardness of elliptic curve operations.
The Effects of Social Capital on Firm Substantive and Symbolic Performance
Authors: Liu Hefu , Ke Weiling , Wei Kwok Kee , Lu Yaobin
Published: March 2016

This study examines the effects of social capital in the context of e-business and investigates how each of the three dimensions of social capital (structural, relational and cognitive) differentially influences a firm's substantive and symbolic performance. The study explores how structural capital and cognitive capital indirectly affect firm performance through relational capital. The research model is generally supported by data collected from a survey of 205 firms in China. The results suggest that structural and relational capital positively influence substantive and symbolic performance, respectively. However, cognitive capital does not have significant effects on substantive performance, though it positively affects symbolic performance. Also, the study found that structural capital and relational capital have stronger effects on substantive performance than symbolic performance. In contrast, cognitive capital has stronger effects on symbolic performance than substantive performance. Further, both structural capital and cognitive capital positively affect relational capital.
Social Media and Value Creation
Authors: Boughzala Imed
Published: March 2016

Organizations increasingly rely on corporate social networks and online communities, under what is called today Enterprise 2.0, to enhance socialization and favor information/knowledge sharing, collaboration and value creation among coworkers. Researchers and practitioners to date have mostly assumed that people from this generation Y, because of their massive use of social media in the private arena, would be willing to accept and use them more easily and quickly in corporate environment. However, to the best of our knowledge, there is no empirical work which has been reported on this issue confirming this assumption.
Firing and Contact Resistivity of Ag2O-Aided Pb-Free Silver Paste for Crystalline Silicon Solar Cells
Authors: Jiao Ruo Bing , Wu Tao , Zhang Bo Ping , Li Liang Liang
Published: March 2016

The silver pastes containing Ag2O powder, Ag powder, α-terpineol, ethyl-cellulose and Pb-free glass were synthesized for crystalline silicon (c-Si) solar cells. It was found that α-terpineol assisted the decomposition of Ag2O powder and effectively lowered the decomposition temperature of Ag2O. Ag nanoparticles were produced during the decomposition of Ag2O, which helped to reduce the sintering temperature of the silver pastes. The Ag2O-aided silver pastes were fired on polycrystalline silicon solar cells at various temperatures, and large plate-shaped Ag crystallites appeared at the interfaces between the sintered pastes and the emitter, which ensured a good electrical contact. The contact resistivity of Ag2O-aided silver paste with an optimal ratio of Ag2O to Ag was lower than that of the paste with pure Ag powder. The lowest contact resistivity of Ag2O-aided Pb-free silver pastes sintered at 800°C was 0.029 Ω⋅cm2, which was close to that of commercial silver paste that contained Pb-based glass (0.026 Ω⋅cm2). The experimental data demonstrated that the addition of Ag2O reduced the contact resistance and promoted the sintering of Pb-free silver pastes, and Ag2O-aided Pb-free silver paste could be a promising candidate used for front-contact electrode of c-Si solar cells.
Facile Synthesis of Co3O4/Nitrogen-Doped Graphene Composite with Enhanced Electrochemical Performance
Authors: Tan Hui Yun , Ren Zhao Yu
Published: March 2016

Co3O4 nanoflakes/N-doped graphene (NG) was synthesized through a facile two-step synthesis route. The phase composition and morphology of the products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). It has been found that introduction of NG has effects on the morphology of Co3O4 and leads to a well distribution of Co3O4 nanoflakes. The electrochemical properties of as-synthesized materials were measured by cyclic voltammetry (CV), galvanostatic charge/discharge tests and electrochemical impedance spectroscopy (EIS). The composite presents an enhanced supercapacitor performance than the pristine Co3O4 nanoflakes, mainly due to the strong synergistic effect of the NG and Co3O4.
Thermoelectric Enhancement of Polyaniline Grafting from Graphene Oxide
Authors: Wang Xiao Yang , Miao Lei , Liu Cheng Yan , Gao Jie , Chen Yu
Published: March 2016

In this study, a PANI covalently grafted GO (GO-PANI) was obtained through amide reaction and a PANI covered GO (GO/PANI) was prepared via in-situ polymerization. The better thermoelectric properties were achieved in GO-PANI compared with GO/PANI under the same situation, i.e., the equal mass ratio of GO and PANI as well as the oxidative degree of polymerization reaction. Furthermore, polyaniline grafted from the reduced graphene [R(GO-PANI)] was prepared by reducing the above GO-PANI using hydrazine hydrate and the improved power factor as high as 3.6 × 10-8 W m-1 K-2 was attained at 341 K.
Thermoelectric Properties of Mn Doped Cu12-xMnxSb4S13 Tetrahedrites
Authors: Wang Ju Yi , Li Xiao Ya , Bao Ye Feng
Published: March 2016

In this study, Mn doped Cu12-xMnxSb4S13(x=0, 0.5, 1.0, and 2.0) tetrahedrite samples were prepared by melting and annealing followed by hot press sintering. Powder X-ray diffraction and scanning electron microscopy and electron energy dispersive spectroscopy analysis were performed for the samples, and the thermoelectric transport properties of samples were characterized. The experimental results showed that the synthetic tetrahedrites were consisted of principal Cu12Sb4S13 phase and a small amount of secondary Cu3SbS4 and CuSbS2. The electrical conductivity of the tetrahedrites decreased with increasing the Mn doping amount. Contrary to the electrical conductivity, the Seebeck coefficient of the tetrahedrites increased with increasing Mn doping amount. The thermal conductivity decreased with increasing Mn doping amount due to the suppression of the carrier contribution, as well as due to the substitution effect of Mn on the Cu site. For the Mn doped Cu12-xMnxSb4S13 compounds with x=0.5, 1.0, and 2.0, the ZT values decreased with the increase of Mn doping amount, a maximum ZT=0.89 was obtained for the Mn doped compound with x=0.5.
Band Structures and Transport Properties of Half-Heusler Compounds NbMSb (M = Fe, Ru)
Authors: Fang Teng , Zheng Shu Qi , Chen Hong , Zhang Peng
Published: March 2016

The band structures and transport properties of Half-Heusler compounds NbFeSb and NbRuSb were studied using ab initio calculations and the Boltzmann transport equation with constant scattering time approximation (CSTA). Both compounds were identified as good p-type thermoelectric materials because of the combination of heavy and light bands in the valence band maximum (VBM). The Seebeck coefficients for NbRuSb were lower than that for NbFeSb; while the electrical conductivities for NbRuSb were little higher than that for NbFeSb. Consequently, the power factors in the p-type regimes for both compounds were similar at a given temperature. NbFeSb and NbRuSb could be efficient materials for thermoelectric generators based on the results in the present investigation.
Synthesis of BiVO4/Bi2VO5.5 Heterogeneous Nanostructures with Enhanced Visible Light Photocatalytic Activity
Authors: Wang Jian Min , Cao Feng , Lv Xin , Li Song , Cai Jia Jia , Qin Gao Wu
Published: March 2016

BiVO4/Bi2VO5.5 heterogeneous nanostructures with enhanced visible light photocatalytic activity were successfully prepared by a facile one-pot solvothermal method, where diethylene glycol (DEG) was used as the solvent. The as-prepared products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS) and UV-Vis absorption spectroscopy. The results revealed that the molar ratio of Bi3+ to VO43- played an important role in the formation of crystal and morphology. These BiVO4/Bi2VO5.5 heterogeneous nanostructures exhibited higher visible-light-driven photocatalytic efficiency compared to the pure BiVO4 and Bi2VO5.5. For the methyl orange (MO) degradation efficiency of BiVO4/Bi2VO5.5 heterogeneous nanostructures under visible light irradiation, about 95% of MO was degraded within 40min, which is much higher than pure BiVO4 and Bi2VO5.5. The enhancement of photocatalytic activity can attribute to the promoted light absorption capability and the separation efficiency of photo-generated electron-hole pairs.
Synthesis and Electrochemical Performance of Polypyrrole-Coated Sulfur/Multi-Walled Carbon Nanotube Composite Cathode Materials for Lithium/Sulfur Batteries
Authors: Wei Ya Qiong , Li Yue , Bakenova Zagipa , Yin Fu Xing , Li Hai Peng , Zhang Yong Guang , Bakenov Zhumabay
Published: March 2016

In situ chemical oxidation polymerization of pyrrole on the surface of sulfur/multi-walled carbon nanotube particle was carried out to synthesize a novel polypyrrole coated sulfur/multi-walled carbon nanotube (PPy@S/MWCNT) composite. The sulfur/multi-walled carbon nanotube composite (S/MWCNT) was prepared by a facile quasi-emulsion template method in an oil/water system. The ternary PPy@S/MWCNT composite was characterized by elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements. In the composite, polypyrrole works as a conducting matrix as well as a coating agent, confining the active materials within the electrode, while the MWCNT creates a highly conductive and mechanically flexible framework, hence enhancing the electronic conductivity and the rate capability of the material. This ternary composite exhibits stable cyclability, retaining a discharge capacity of 612 mAh g-1 at 0.1 C after 100 cycles. Furthermore, up to 1.5 C rate, the ternary composite still delivered a highly reversible discharge capacity of 463 mAh g-1.
Polyethylene Glycol/Expanded Vermiculite Shape-Stabilized Composite Phase Change Materials for Thermal Energy Storage
Authors: Deng Yong , Li Jin Hong , Qian Ting Ting , Guan Wei Min , Wang Xiang
Published: March 2016

Polyethylene glycol (PEG)/ expanded vermiculite (EVMT) shape-stabilized composite phase change material (ss-CPCM) was prepared by a facile vacuum impregnation method. The maximum mass percentage for PEG retained in ss-CPCM was 75.1 wt.% due to specific non-uniform flat layers pore structure of EVMT. The scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) analysis results indicated that the melted PEG was adsorbed on the surface and completely dispersed into the pores of EVMT and no chemical changes took place during the heating and cooling processes. X-ray diffraction (XRD) results showed that the crystal structure of PEG was not destroyed after impregnation whereas the crystallization process of PEG was greatly restrained. Differential scanning calorimetry (DSC) results indicated that ss-CPCM melted at 57.61°C with a latent heat of 103.1 J/g and solidified at 33.19°C with a latent heat of 88.29 J/g. In addition, the thermal conductivity of ss-CPCM reached 0.418W/m K. The ss-CPCM can be considered as promising candidate materials for building applications due to their suitable phase change temperature, large latent heat and excellent chemical compatibility.
Effect of Silane Coupling Agent Surface Modified Layered Double Hydroxides on Properties of Bitumen
Authors: Zhang Can Lin , Yu Jian Ying , Sun Yu Bin , Feng Kai
Published: March 2016

Layered double hydroxides (LDHs) surface modified by silane coupling agent KH550 were prepared to modify bitumen, the surface modified LDHs (KH550-LDHs) were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD). The effect of KH550-LDHs and LDHs on physical and anti-ageing properties of bitumen was evaluated by means of physical test. The results of FTIR showed that KH550 had successfully grafts onto the surface of LDHs, and XRD result showed that KH550 had little effect on the crystal structure of LDHs. The storage stability test showed that KH550-LDHs dispersed better homogeneously and existed more stable than LDHs in bitumen. The physical properties tests indicated that high and low temperature properties of bitumen were improved compared with LDHs. After UV aging with the addition of KH550-LDHs, the increase rate of softening point slowed remarkably, the reduction rate of ductility declined evidently compared with LDHs. Aging indices (softening point increment and ductility retention rate) show that KH550-LDHs exhibited better improvement than LDHs in UV aging resistance of bitumen, implying more effective modification of KH550-LDHs which is due to the enhanced compatibility between KH550-LDHs and bitumen.
Research of Influences on Second Interface Cementation Performance in Well Cementation of Adding Metakaolin into Drilling Fluid
Authors: Mei Yu Kun , Li Ming , Liu Lu , Zhou Biao , Guo Xiao Yang
Published: March 2016

It is difficult for conventional drilling fluid filter cake to form integration cementation with cement sheath, which causing weak cementation of the second interface. Therefore the following researches on improving the second interface cementation strength were carried out based on alkali activation mechanism of metakaolin. Cementation strength between metakaolin drilling fluid filter cake and cement sheath has been observed; the mechanism has been analyzed through SEM, XRD and FT-IR; engineering application performance of metakaolin drilling fluid has been studied; and circulation time of the technology has been researched. The results of the experiments showed that: 1) adding metakaolin into drilling fluid was helpful to improve the second interface cementing performance; 2) calcium hydroxide produced by cement hydration inspired metakaolin to generate C-S-H gel and realized overall cementation of filter cake and cement sheath; 3) through select particle size of metakaolin matched with other solids in drilling fluid, drilling fluid performance index could meet requirements of engineering application; 4) and for best results, the circulation time of metakaolin drilling fluid should be more than 40 minutes. The results prove that metakaolin drilling fluid can improve the second interface cementation performance, showing feasibility on flied using and practical values on improving wellbore integrity.
Nonisothermal and Isothermal Degradation Kinetics of Thermotropic Liquid Crystal Copolyesters Containing BPA and BPAF Units
Authors: Wei Peng , Huang Shuo Han , Wang Yi Min
Published: March 2016

The thermotropic liquid crystal copolyester P-BPA2.5 and P-BPAF2.5 with low melting temperature and high glass transition temperature were obtained by introducing 2.5mol% bisphenol A (BPA), bisphenol AF (BPAF) and terephthalic acid (TA) receptively into the molecular chain of poly (oxybenzoate-co-oxynaphthoate). The isothermal and nonisothermal degradation behavior of the two copolyesters P-BPA2.5 and P-BPAF2.5 were studied by thermo-gravimetry analysis (TGA) under nitrogen atmosphere. The degradation kinetics of the copolyesters under dynamic and isothermal heating conditions was evaluated byKissinger-Akahira-Sunose (KAS) and iso-conversional methodrespectively. Results showed that the activation energy (E) values followed the order P-BPAF2.5>P-BPA2.5 under dynamic heating atmosphere. However, the P-BPA2.5 showed a better thermal stability as compared with P-BPAF2.5 under isothermal heating conditions. The differences of degradation mechanism between the two copolyesters may be a reason for this phenomenon, which was discussed in detail in the text.
Effect of Pre-Added Cristobalite Content on the Properties of Silica-Based Ceramic Cores
Authors: Niu Shu Xin , Tang Ding Zhong , Liu Xiao Guang , Yao Jian Sheng , Li Xin , Wang Li Li , Gu Guo Hong , Yang Yin Ping , Yang Xiao Wei
Published: March 2016

In this study, cristobalite was used as the addition to prepare silica based ceramic cores, and then the effect of cristobalite content on the mechanical and chemical properties was investigated. The increasing of pre-added cristobalite content resulted in more crystallized cristobalite in the sintered samples and the variation of the linear shrinkage and mechanical properties. When pre-added cristobalite content was 6.0 wt%, the shrinkage of ceramic core was 0.42%, the creep at 1540°C for 30 min was 0.10 mm, and the flexural strength at room temperature and at 1550°C were 25.2 MPa and 28.7 MPa, respectively, which meets the need of ceramic cores of hollow turbine blades.
Preparation of NiO Nanosheets by Hydrothermal Method and its Electrochemical Capacitive Properties
Authors: Wang Zhong Yang , Fan Run Hua , Li Qian Qian , Qian Lei
Published: March 2016

The precursor Ni (OH)2 was synthesized by a simple hydrothermal method with NiSO4•6H2O and (CH2)6N4 as reactants. Both concentrations of reactants are 0.02 M, 0.04 M, 0.06 M, 0.08 M for experiment contrast, and then NiO was gained after calcination at 400°C. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The electrochemical capacitive characterization was performed using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrical impedance spectroscopy (EIS) measurements in a 6mol/L KOH aqueous solution electrolyte. The result shows that with the increase of concentrations of reactants, nanosheets stack together and turn into thick slices. CV curves have obvious redox peak, the GCD curves are nonlinear and EIS curves of high frequency area are semicircle. From electrochemical analysis, the capacitance type is pseudocapacitance. And a maximal specific capacitance value when two reactants concentration both are 0.08 M which the specific capacitance decreases from 97 F/g (at a current density of 0.3A/g) to 56 F/g (at a current density of 1 A/g).
Effect of Sm3+ Concentration on the Vibrational and Luminescent Properties of LaPO4
Authors: Zhang Zhong Ju , Zheng Xu Dong , Shi Zhi Cheng , Wang Xin
Published: March 2016

Lanthanum orthophosphate (LaPO4) is a useful host for doping rare earth ions with high quantum efficiencies. In the present investigation the monoclinic LaPO4 and LaPO4:Sm3+ were synthesized via hydrothermal route. SEM, XRD, FTIR and Raman spectroscopy as well as the luminescence spectroscopy were utilized to character the samples of the Sm3+-doped LaPO4. The results indicated that the lattice parameters decreased linearly with Sm3+ concentration, and general linear hypsochromic shifts regarding Sm3+ concentration were observed in infrared spectroscopic wavenumbers and Raman band positions. The emission spectra showed that Sm3+ ions were in more non-centrosymmetric environment when Sm3+ concentration increased.
Effect of Sintering Temperature on Porous Structures and Mechanical Properties of Ti-39Nb-6Zr Alloys
Authors: Shao Ye , Song Xiao Yun , Ye Wen Jun , Hui Song Xiao , Yu Yang , Liu Rui , Li Cheng Lin
Published: March 2016

Titanium and its alloys have been widely used as implants replacing hard human tissues in biomedical fields. To improve the stability of implants in the surrounding bone tissues, the materials with porous structures were fabricated. In this paper powder metallurgy technique was employed to fabricate porous Ti-39Zr-6Nb (wt.%) alloys. The porous structures and mechanical properties of the porous alloys were examined by scanning electron microscopy (SEM) and compressive tests. The results showed that with increasing the sintering temperature the porosity of the alloys decreased and the compressive strength and the elastic modulus increased. The porosity of the alloys was in the range from 20.8% to 23.2%, and the pore sizes mostly centered in 10~30μm. The compressive strength and the elastic modulus were in the range from 110.4 to 292.4MPa and 4.7 to 12.4GPa respectively, which was close to human bone.