Preparation and Characterization of Kenaf Cellulosepolyethylene Glycol- Polyethylene Biocomposites

The possibility of using cellulose as natural fiber for the production of bicomposites was investigated in this study that included two stages. The first stage involved the extraction of cellulose from the cell walls of kenaf (Hibiscus cannabinus L.), an annual herbaceous crop with many environmental advantages and good mechanical properties. It was done from the bast part of the crop by chemical treatments. Then, mixture of different weights of low density polyethylene (LDPE) and high density polyethylene (HDPE), as a matrix, with the obtained cellulose, and polyethylene glycol (PEG) were blended in order to produce a biocomposite material suitable for food packaging. For the second stage, the characterization of LDPE- and HDPE-kenaf cellulose biocomposites was performed in order to develop the optimal blends with optimized thermo-mechanical properties and propensity to environmental degradation. Therefore, the mechanical properties including tensile strength, flexural and unnotched Izod Impact tests were performed using Instron Universal Testing Machine and Izod Impact Tester, respectively. Thermal properties, biodegradability and water absorption of biocomposites were investigated as well. In addition, a scanning electron microscope (SEM) was used to observe the surface morphology of the tensile fracture surface of the samples before and after biodegradation test. The results showed that the mechanical properties of the LDPE and HDPEcellulose composites decreased slightly as the cellulose content increased from 0 to 50 wt % in the biocomposite formulation. It is interesting to note that in all treatments, the mechanical behavior of biocomposites retained in an acceptable level of strength except of HDPE composites with 50% cellulose. In general, there is a good homogeneity between samples with PEG that help to find reasonable and acceptable properties. These findings were confirmed by the SEM study. Thermal analysis of composites is necessary for determining their end use. Therefore, thermal properties of biocomposites were obtained by a thermogravimetry analysis (TGA) and a differential scanning calorimetry (DSC). Addition of cellulose fillers improves the thermal resistance of these biocomposites. The results also showed that PEG has positive role in thermal behavior of composites. This finding gives a good indication that the addition of kenaf cellulose into the body of LDPE and HDPE was capable to increase their thermal degradation properties. Biodegradability of these biocomposites was performed based on soil burial test to investigate their degradation during 120 days. The findings illustrated that there is a clear trend of degradation during burial time. The degradability increased as cellulose content was raised in the composite’s formulation. Finally, water absorption was done for biocomposites. The results showed that water absorption value for both composites was higher than those of LDPE and HDPE polymers. Addition of PEG to the formulations reduced the water absorption of the composites. Generally, it seems that the results of this research may lead to a development of a new type of biocomposites using kenaf cellulose as a natural fiber that can be used to replace plastics for food packaging in the near future

The Timing of Discrepant Interruptions and its Influence on Team Performance

Discrepant interruptions are inevitable in today’s highly dynamic and turbulent environment. Organizations need to handle discrepant interruptions effectively in order to survive. Since organizations mostly rely on teams to do task and achieve goals, teams are required to deal with the discrepant interruptions and modify their plans and strategies to address the interruptions. A team’s approach in handling discrepant interruptions has a significant effect on team effectiveness and accordingly affects the organization’s performance. In addition, team development literature suggests that project teams working on a creative task under a deadline engage in task transition during their allotted time (Gersick, 1988, 1989; Waller, Zellmer-Bruhn, & Giambatista, 2002). This dissertation focuses on the timing of the discrepant interruptions with regards to task transition. More specifically, I aim to explore how the relative timing of a discrepant interruption affects how a team works under a deadline. Building on the literature, I hypothesize that teams facing discrepant interruptions after their task transition would perceive the interruption as a hindrance to their performance, and thus have lower team coordination and performance. In contrast teams who face the discrepant interruptions before their task transition would perceive the interruption as a challenge, and thus have higher team coordination and performance. To test these hypothesis, I conduct an experiment in which teams of three work on a creative task for 40 minutes. Their goal is to create an audio commercial for an existing airline. All teams face the same discrepant interruption at 20 minutes into the task. I measure their appraisal of the discrepant interruption and team coordination using a questionnaire and code their video for the time lapse of their task transition. My analysis shows no support for any of the hypotheses except for the positive association between team coordination and team performance. As next step, I present some exploratory analysis on my data and identify a number of interesting findings. I find that teams working on a creative task under deadline go through their task transitions at different times within their allotted time. Teams that have their first task transition before a discrepant interruption have higher performance than others. Moreover, in this setting, teams have lower performance if they make their transition too early or too late. Observing team coordination, I find that team coordination positively affects team performance given the context I created. Finally, exploring team members’ pacing style, I find that, for teams delaying their task transition until after a discrepant interruption, having a deadline action style increases team performance

A Collaboration-Mediated Exploration of Nonnative L2 Teachers’ Cognition of Language Teaching Methodology

The present study sought to investigate nonnative L2 teachers’ cognition of teaching methodology based on their collaborative talks. Participants were 12 nonnative EFL teachers categorized into three collaborative discussion groups by their teaching experience. Collaborative discussions were aimed at exploring the participants’ cognition of language teaching methodology, including the criteria for the evaluation of teaching methodology, classroom activities, teaching language skills and sub-skills, teachers’ roles, and learners’ roles in general and communicative language teaching (CLT) in particular. Analysis of the data indicated that the teachers participating in each discussion group held largely similar cognition about most of the issues in teaching methodology and CLT. In addition, there were similarities between the High-experience and Mid-experience groups regarding their cognition of the advantages of CLT, teachers’ roles, and learners’ roles. The results of this study can help teacher educators design more effective teacher education courses and in-service programs to enhance EFL teachers’ cognition of teaching methodology

Association of diverse bacterial communities in human bile samples with biliary tract disorders: a survey using culture and polymerase chain reaction-denaturing gradient gel electrophoresis methods

Bacterial infection is considered a predisposing factor for disorders of the biliary tract. This study aimed to determine the diversity of bacterial communities in bile samples and their involvement in the occurrence of biliary tract diseases. A total of 102 bile samples were collected during endoscopic retrograde cholangiopancreatography (ERCP). Characterization of bacteria was done using culture and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) methods. Antimicrobial susceptibility of the isolates was determined based on the Clinical and Laboratory Standards Institute (CLSI) guidelines and identity of the nucleotide sequences of differentiated bands from the DGGE gels was determined based on GenBank data. In total, 41.2 (42/102) of the patients showed bacterial infection in their bile samples. This infection was detected in 21 (4/19), 45.4 (5/11), 53.5 (15/28), and 54.5 (24/44) of patients with common bile duct stone, microlithiasis, malignancy, and gallbladder stone, respectively. Escherichia coli showed a significant association with gallstones. Polymicrobial infection was detected in 48 of the patients. While results of the culture method established coexistence of biofilm-forming bacteria (Pseudomonas aeruginosa, E. coli, Klebsiella pneumoniae, Enterococcus spp., and Acinetobacter spp.) in different combinations, the presence of Capnocytophaga spp., Lactococcus spp., Bacillus spp., Staphylococcus haemolyticus, Enterobacter or Citrobacter spp., Morganella spp., Salmonella spp., and Helicobacter pylori was also characterized in these samples by the PCR-DGGE method. Multidrug resistance phenotypes (87.5 ) and resistance to third- and fourth-generation cephalosporins and quinolones were common in these strains, which could evolve through their selection by bile components. Ability for biofilm formation seems to be a need for polymicrobial infection in this organ. © 2016 Springer-Verlag Berlin Heidelber

Teachers’ classroom interactional competence: Scale development and validation

Interactional competence has recently gained considerable attention in language education. As an aspect of this competence, classroom interactional competence has been in the limelight since Walsh’s (2006) delineation of this concept. However, there is no survey tool to measure teachers’ classroom interactional competence. To bridge this gap, the present study describes the development and validation of a teachers’ classroom interactional competence (TCIC) scale. An outline of the relevant literature related to classroom interactional competence is provided, along with the process of scale development and validation. An exploratory factor analysis of the data from a large sample of language teachers (N = 564) resulted in a 46-item scale that constituted nine factors, namely visual organizers, sociocultural interaction, questioning, interactional patterns, repair, language modification, turn taking, managerial interaction, and rhetorical script. The implications of the scale for the measurement and, in turn, the enhancement of teachers’ classroom interactional competence are discussed

Thermal properties of high density polyethylene-kenaf cellulose composites.

Biocomposites of high density polyethylene (HDPE) and kenaf cellulose (KC) with polyethylene glycol (PEG) have been prepared by melt blending and compression moulding. The optimum temperature and reaction period for blending KC with HDPE were 145 C and 12 minutes with rotation speed of 30 rpm, respectively. The effects of composition on the thermal properties of HDPE-KC biocomposites were investigated using TGA and DSC. Each sample of HDPE-KC biocomposites was subjected to heating programs between 35-600 C for TGA, and the DSC analysis was determined under heating cycles of 25-600 C. The results from TGA and DSC indicated that by increasing the KC content, the thermal stability was slightly improved. The melting temperature for all the composites was less than the melting point of KC (148.70 C), and almost the same as that of HDPE (130.38 C). Therefore no significant change in the melting temperature resulted from adding KC to the HDPE matrix. However, HDPE's presence surrounding the KC fibres, prevented water from reaching the cellulose fibre particles, thus reducing the water content in the composite; hence a significant advantage of forming KC composites with hydrophobic HDPE is that it helps to make the cellulose hydrophobic instead of hydrophilic

Emergence and Influence of Expertise in Group Decision Making: A Judgmental Task

This thesis investigates the emergence and influence of expertise in group decision making while performing a judgmental task. Previous studies focused on intellective tasks or compared the group performance with the performance of the best individual in the group. In this study, performance feedbacks are provided to groups to help group members compare the individual performances and identify the expert. Laboratory experiments were conducted in which the task was to select a proverb that Canadians would like the most from the list of four proverbs from countries other than Canada. The four proverbs for each question were guaranteed to have equal selection probability based on the pretest survey. 18 four-person cooperative groups were asked to perform the task for eight iterations each. One member in each group was selected randomly to be the expert. Groups received performance feedbacks that reinforced the expert at the end of each iteration. The amount of information conveyed to each group regarding the expertise level of each group member was measured with a novel application of information analysis that captures the expert's gradual emergence. Experiment results supported the hypotheses of this study that (1) group members recognize the expert when working on a judgmental task with performance feedback and (2) while performing a judgmental task, the expert has more influence on the group decision making compared to others

Scaffolding Comprehension and Recall Gaps: Effects of Paratextual Advance Organizers

Although filling the gap in reading comprehension gained momentum with the rise of the top-down approach, Vygotsky’ concept of scaffolding and the dual code  theory provided a strong support for the use of paratext to enhance comprehension. Scaffolding is dependent on other-regulation, one type of which is object-regulation. From this vantage-point, various types of paratext can function as sources of object-regulation to scaffold the interaction between the reader and the text. Hence, the purpose of this study was to explore the effect of three types of paratext (the picture, preface, and title) on the reading comprehension and recall of less proficient and more proficient EFL learners. The control groups in the two proficiency levels read a text with no paratext, whereas participants in the experimental groups read the same text accompanied by the three types of scaffolding paratext. Both groups were also given a recall test which required the recall of propositions from the original texts. The results showed the beneficial effect of paratext on reading comprehension among the more proficient experimental group. As to reading recall, neither less proficient nor more proficient group succeeded in manifesting better recall than the control groups. These findings have two implications. First, there is proficiency “short-circuit” for the scaffolding effect of paratext on reading comprehension. Second, short-circuit has a task-bound nature. As the results of this study show, the proficiency ceiling needed to move beyond the short-circuit effect of comprehension is different from that of recall because recall is a comparatively more demanding task