Mechanical properties and dissipation energy of carbon black/rubber composites:

The effects of carbon black on the properties of rubber composites were studied in order to explore their value in producing low rolling resistance truck tires. Carbon black with different grades, N330 (coarser grade of 26–30 nm) and N220 (finer grade of 20–25 nm), was used as a reinforcing agent of natural rubber. The effects of different ratios of carbon black N330 at 40, 45, 50 and 55 parts per hundred rubber (phr) and N220 at 30, 35, 40 and 50 phr were investigated. Rubber composites with N220 had greater rubber/carbon black interaction than those with N330. The Mooney viscosity of rubber composite increased when the carbon black ratio increased. After vulcanisation of rubber, the samples were characterised by dynamic mechanical analysis, tensile strength and heat build-up. The results showed that the strength of rubber composites increased with increasing carbon black ratios. Interestingly, at the same bound rubber level, rubber composites with N220 presented lower dissipation energy, heat build-up and better mechanical properties than those with N330. This study indicated that reinforcement with an optimum amount of carbon black N220 would improve several desirable characteristics of rubber composites when used in low rolling resistance truck tires

Replenishment planning and control in supply chain management

Bibliography: p. 247-253This research aims to gam insights into the effects of the supply chain factors on performance when using alternative replenishment strategies. The objectives include the development of guidelines to select appropriate strategies and to improve the performance when given a particular strategy. A simulation test bed has been developed to support this research. As well, a methodology based on the statistical analysis of inventory and delivery performance tradeoffs has been developed. This methodology allows main and interaction effects to be evaluated so that material and information flow behaviour can better be understood. The first experiments compare three replenishment strategies, namely Distribution Requirements Planning (DRP), Reorder Point (ROP), and KANBAN, within distribution channels with no capacity constraints. The supply chain factors studied include: supply I chain configuration, demand pattern, lot size, demand uncertainty and transit time uncertainty. A second study extends the research by analyzing the effects of capacity constraints, scrap and assembly processes within a network involving supply, manufacturing and distribution stages. Finally, a study to explore time-phased replenishment strategies (e.g. DRP/MRP) more fully is undertaken. In particular, the effectiveness of safety stock versus safety lead time to protect against variability and uncertainty under capacity constraints is examined. The results from scenarios without capacity constraints show that DRP is the most robust strategy, followed by ROP and KANBAN. Under seasonal demand, DRP always dominates. KANBAN yields inferior performance, especially under seasonal demand. The relative performances are not generally affected much by capacity constraints, scrap and assembly process. The exception is that under some level demand conditions, KANBAN can provide superior performance due to more consistent material flow to capacity-constrained resources. In time-phased strategies with capacity constraints, high demand uncertainty, seasonal demand, and use of some lot-sizing rules can increase replenishment times and induce supply timing uncertainty. The use of safety lead time is found preferable when supply timing uncertainty dominates demand uncertainty. Key Words: Supply Chain Management, Distribution Requirements Planning (DRP), Materials Requirements Planning (MRP), Reorder Point, KANBAN, Simulation

Extracted sericin from silk waste for film formation

Sericin is the second main component in cocoons, which are removed in the silk reeling process of the raw silk industry and in the silk waste degumming of the spun silk industry. The main amino acid of sericin, serine, exhibits a skin moisturing and antiwrinkle action, which is interesting to use for film formation in this study. The extraction conditions of sericin from two silk wastes, pieced cocoon and inferior knubbs were studied to find the optimum extraction conditions. Boiling water extraction was considered based on the response surface methodology (RSM) in order to identify the important factors for the sericin extraction. The two factors considered were time and temperature. Both factors were needed to be independent parameters in the predicted equation in order to improve the model fit with R2 = 0.84. The components ofextracted sericin were 18.24% serine, 9.83% aspatate, and 5.51% glycine with a molecular weight of 132 kDa. Film formationfrom extracted sericin was carried out to find the optimum conditions. Extracted sericin could not form a stand-alonefilm. Therefore, polysaccharide polymers, such as glucomannan, were incorporated with glycerol to form a flexible film.Sericin-based films were characterized for its properties in terms of solubility and permeability before application. It wasfound that sericin-based films showed a film flexibility and solubility without an increasing film water vapor permeability

การวิเคราะห์คำถามในหนังสือเรียนวิทยาศาสตร์ ระดับชั้นมัธยมศึกษาตอนต้น (AN ANALYSIS OF QUESTIONS IN JUNIOR HIGH SCHOOL SCIENCE TEXTBOOKS)

การวิจัยครั้งนี้มีวัตถุประสงค์เพื่อวิเคราะห์รูปแบบของคำถามในหนังสือเรียนวิทยาศาสตร์ ระดับมัธยมศึกษาตอนต้น โดยใช้วิธีการศึกษาจากเอกสาร ผู้วิจัยรวบรวมข้อมูลจากหนังสือเรียนวิทยาศาสตร์ ระดับมัธยมศึกษาตอนต้น ในประเทศไทยที่มีการพิมพ์เป็นภาษาไทยโดยสำนักพิมพ์เอกชน จำนวน 3 เล่ม วิเคราะห์บริบทและประเภทของคำถามโดยใช้แบบวิเคราะห์คำถามในหนังสือเรียนวิชาวิทยาศาสตร์ นำบริบทและประเภทของคำถามมาจัดกลุ่มแล้วหาค่าความถี่แล้วจึงวิเคราะห์หารูปแบบของคำถามที่ปรากฏในหนังสือเรียนวิทยาศาสตร์ ระดับมัธยมศึกษาตอนต้น ผลการวิจัยพบว่า คำถามในหนังสือเรียนวิทยาศาสตร์ ระดับมัธยมศึกษาตอนต้นมีทั้งหมด 1306 คำถาม โดยเป็นคำถามจากหนังสือเล่มที่ 1 จำนวน 477 คำถาม (8 หน่วยการเรียนรู้) หนังสือเล่มที่ 2 จำนวน 470 คำถาม (9 หน่วยการเรียนรู้) และหนังสือเล่มที่ 3 จำนวน 359 คำถาม (7 หน่วยการเรียนรู้) ซึ่งคำถามในหนังสือเรียนวิทยาศาสตร์มี 3 รูปแบบ คือ รูปแบบ 1 เป็นคำถามที่หาคำตอบโดยใช้ความรู้เดิมของผู้เรียน ร้อยละ 19.49 รูปแบบ 2 เป็นคำถามที่หาคำตอบจากการปฏิบัติกิจกรรม ร้อยละ 39.28 และรูปแบบ 3 เป็นคำถามที่หาคำตอบจากข้อมูลหรือสถานการณ์ที่กำหนดให้ ร้อยละ 41.23 โดยคำถามส่วนใหญ่ในรูปแบบ 1 และ 2 เป็นคำถามประเภทความรู้-ความจำ แต่คำถามส่วนใหญ่ในรูปแบบ 3 เป็นคำถามประเภทความเข้าใจ ส่วนคำถามประเภทการนำไปใช้ และการประเมินค่ามีจำนวนน้อย จึงควรเพิ่มคำถามทั้งสองประเภทนี้ให้มีจำนวนมากขึ้นเพื่อส่งเสริมการเรียนรู้และพัฒนากระบวนการคิดของผู้เรียนคำสำคัญ: รูปแบบคำถาม หนังสือเรียนวิทยาศาสตร์ การวิเคราะห์หนังสือเรียนThis research aimed to analyze questioning patterns in junior high school science textbooks. The study method was based on documentary analysis in which the researcher collected data from three junior high school science textbooks in Thailand. They were printed in Thai and published by private publishers. The instrument used for questioning analysis is a question pattern analysis of science textbooks. Context and question types were applied to classify and find out the frequency of questions. After that, the question patterns were finally analyzed. The result of study indicated that the total number of questions were 1306. There were questions from the first book to totaling 477(8 lessons), the second book 470 (9 lessons) and the third book 359 questions (7 lessons). There were three question patterns. Pattern 1; 19.49 percent of the questions were probing student’s prior knowledge. Question pattern 2; 39.28 percent of the questions were focused on asking students to do practical tasks, and pattern 3; 41.23 percent of the questions were situation analysis questions. Question patterns 1 and 2 mainly focused on knowledge but question pattern 3 focused on comprehension questions. Only few questions were application and evaluation questions. To promote leaning and thinking process of students, application and evaluation questions should be increased.Keywords: Question patterns, Science textbooks, Textbooks analysi

Comparison of sodium dithionite and glucose as a reducing agent for natural indigo dyeing on cotton fabrics

A traditional reducing agent in an indigo dyeing process with cotton fabrics is sodium dithionite (Na2S2O4) which is environmentally unfavorable because the resulting by-products cause various problems to the disposal wastewaters. In this research, glucose was used as a possible replacement of Na2S2O4 in indigo dyeing. The comparison of reduction power of Na2S2O4 and glucose for natural indigo dyeing on cotton fabrics based on reduction potential was analyzed. The optimum reduction temperature for natural indigo dye of both reducing agents was at 70°C. The reduction time did not have a significant effect on the reduction potential under the condition studied. Na2S2O4 could give higher color strength than glucose. However, wash fastness of the fabric samples from a glucose reduction was slightly better than Na2S2O4 ones. Hence, glucose virtually has a potential to be used as a green reducing agent in natural indigo dyeing

Comparison of sodium dithionite and glucose as a reducing agent for natural indigo dyeing on cotton fabrics

A traditional reducing agent in an indigo dyeing process with cotton fabrics is sodium dithionite (Na2S2O4) which is environmentally unfavorable because the resulting by-products cause various problems to the disposal wastewaters. In this research, glucose was used as a possible replacement of Na2S2O4 in indigo dyeing. The comparison of reduction power of Na2S2O4 and glucose for natural indigo dyeing on cotton fabrics based on reduction potential was analyzed. The optimum reduction temperature for natural indigo dye of both reducing agents was at 70°C. The reduction time did not have a significant effect on the reduction potential under the condition studied. Na2S2O4 could give higher color strength than glucose. However, wash fastness of the fabric samples from a glucose reduction was slightly better than Na2S2O4 ones. Hence, glucose virtually has a potential to be used as a green reducing agent in natural indigo dyeing