210 research outputs found
Effects of Cardiolipin on Membrane Morphology: A Langmuir Monolayer Study
AbstractCardiolipin (CL) is a complex phospholipid that is specifically found in mitochondria. Owing to the association of the CL levels with mitochondrial physiopathology such as in Parkinson’s disease, we study the molecular effect of CL on membrane organization using model Langmuir monolayer, fluorescence microscopy, and x-ray reflectivity. We find that the liquid-expanded phase in membranes increases with increasing CL concentration, indicating an increase in the elasticity of the mixed membrane. The Gibbs excess free energy of mixing indicates that the binary monolayer composed of CL and DPPC is most thermodynamically stable at ΦCL = 10 mol %, and the stability is enhanced when the surface pressure is increased. Additionally, when ΦCL is small, the expansion of the membrane with increasing CL content was slower at higher surface pressure. These abnormal results are indicative of a folding structure being present before a collapsing structure, which was confirmed by using fluorescence microscopy and was characterized by using x-ray reflectivity with the electron density profile along the membrane’s surface normal
Optimal power generation for wind-hydro-thermal system using meta-heuristic algorithms
In this paper, Cuckoo search algorithm (CSA) is suggested for determining optimal operation parameters of the combined wind turbine and hydrothermal system (CWHTS) in order to minimize total fuel cost of all operating thermal power plants while all constraints of plants and system are exactly satisfied. In addition to CSA, Particle swarm optimization (PSO), PSO with constriction factor and inertia weight factor (FCIWPSO) and Social Ski-Driver (SSD) are also implemented for comparisons. The CWHTS is optimally scheduled over twenty-four one-hour interval and total cost of producing power energy is employed for comparison. Via numerical results and graphical results, it indicates CSA can reach much better results than other ones in terms of lower total cost, higher success rate and faster search process. Consequently, the conclusion is confirmed that CSA is a very efficient method for the problem of determining optimal operation parameters of CWHTS
Benefits of triple-layer remote phosphor structure in improving color quality and luminous flux of white LED
Remote phosphor structure has higher luminous efficiency comparing to that of both conformal phosphor and in-cup phosphor structures. However, it is hard to control the color quality of remote phosphor structure, and this issue has become one of the most researchable objectives to many researchers in recent years. Up to now, there are two remote phosphor structures applied to improve the color quality, including dual-layer phosphor configuration and triple-layer phosphor configuration. The purpose of this research is to select one of those configurations to have multi-chip white LEDs (WLEDs) achieved the highest color rendering index (CRI), color quality scale (CQS), luminous efficacy (LE), and color uniformity. In this research, WLEDs with two correlated color temperatures (CCT) of 6600K and 7700K were applied. The obtained results showed that triple-layer phosphor configuration is more outstanding in CRI, CQS, and LE. Moreover, the color deviation has been significantly reduced, which means the color uniformity has been enhanced with the application of triple-layer phosphor configuration. These results can be proven by scattering properties of phosphor layers based on Mie theory. Thus, the researched results have become a reliable and valuable reference for manufacturing higher-quality WLEDs
Molecular cloning gene and nucleotide sequence of the gene encoding an endo-1,4-β-glucanase from Bacillus sp VLSH08 strain applying to biomass hydrolysis: Research article
Bacillus sp VLSH08 screened from sea wetland in Nam Dinh province produces an extracellular endo-1,4-beta-glucanase. According to the results of the classified Kit API 50/CHB as well as sequence of 1500 bp fragment coding for 16S rRNA gene of the Bacillus sp VLSH 08 strain showed that the taxonomical characteristics between the strain VLSH 08 and Bacillus amyloliquefaciene JN999857 are similar of 98%. Culture supernatant of this strain showed optimal cellulase activity at pH 5.8 and 60 Celsius degree and that was enhanced 2.03 times in the presence of 5 mM Co2+. Moreover, the gene encoding endo-1,4-beta-glucanase from this strain was cloned in Escherichia coli using pCR2.1 vector. The entire gene for the enzyme contained a 1500-bp single open reading frame encoding 500 amino acids, including a 29-amino acid signal peptide. The amino acid sequence of this enzyme is very close to that of an EG of Bacillus subtilis (EU022560.1) and an EG of Bacillus amyloliquefaciene (EU022559.1) which all belong to the cellulase family E2. A cocktail of enzyme containing this endo-1,4-beta-glucanase used for biomass hydrolysis indicated that the cellulose conversion attained to 72.76% cellulose after 48 hours.Chủng vi khuẩn Bacillus sp VLSH08 được tuyển chọn từ tập hợp chủng vi khuẩn phân lập ở vùng ngập mặn tỉnh Nam Định có khả năng sinh tổng hợp enzyme endo-1,4-beta-glucanase ngoại bào. Kết quả phân loại chủng vi khuẩn Bacillus sp VLSH08 bằng Kit hóa sinh API 50/CHB cũng như trình tự gen mã hóa 16S rRNA cho thấy độ tương đồng của chủng Bacillus sp VLSH08 và chủng Bacillus amyloliquefaciene JN999857 đạt 98%. Dịch lên men của chủng được sử dụng làm nguồn
enzyme thô để nghiên cứu hoạt độ tối ưu của enzyme ở pH 5,8 và nhiệt đô 60oC. Hoạt tính enzyme tăng 2,03 lần khi có mặt 5 mM ion Co2+. Đồng thời, gen mã hóa cho enzyme endo-1,4-betaglucanase cũng được tách dòng trong tế bào Escherichia coli sử dụng vector pCR 2.1. Gen mã hóa cho enzyme này có chiều dài 1500 bp, mã hóa cho 500 axit amin, bao gồm 29 axit amin của chuỗi peptid tín hiệu. So sánh cho thấy trình tự gen endo-1,4-beta-glucanase của chủng Bacillus sp VLSH08 có độ tương đồng cao với enzyme này của chủng Bacillus subtilis (EU022560.1) và của chủng Bacillus amyloliquefaciene (EU022559.1). Tất cả các enzyme nhóm này đều thuộc họ cellulase E2. Enzyme của chủng này cũng đã được phối trộn với các enzyme khác tạo thành cocktail để thủy phân sinh khối cho kết quả cellulose bị thủy phân 72,76% sau 48 giờ
ANALYSIS OF THE POPULARITY OF VOCABULARY USED WHEN PERFORMING SPEAKING ACTIVITIES IN THE CLASS OF FIRST-YEAR ENGLISH LANGUAGE STUDENTS IN THE DIRECTION OF DISCOURSE ANALYSIS
Vocabulary learning is extremely important when learning a foreign language. Fluency in a language depends on vocabulary and its use in specific situations. Speaking well is using vocabulary flexibly and speaking fluently. Researching the popularity of vocabulary is analyzing the prevalence of vocabulary used by linguistics students in communication from discourse analysis. This is a topic the research team is working on. This project will help the researchers learn about common vocabulary that students often use to communicate outside or in the classroom. Thereby understanding whether the vocabulary that students use is diverse, rich, and for the right purpose or not. This study will help students have a more comprehensive view of the ways to use words in communication. In addition, it also helps students improve their communication vocabulary, helps in exams and can be useful for later work. In this study, the research team will investigate the students' ability to use spoken vocabulary, i.e., frequency and extent of vocabulary usage. Article visualizations
Microstructure, microhardness and thermal expansion of CNT/Al composites prepared by flake powder metallurgy
Carbon nanotube/aluminum (CNT/Al) composites are prepared by a combination of flake powder metallurgy and hot-isostatic-pressing. The specimens are investigated by several techniques including Raman spectroscopy, optical microscopy, scanning- and transmission electron microscopy. The composites show a layered-microstructure with a stacking of CNT/Al flakes with a CNT-rich layer between two flakes. The individual Al grains forming the flakes are about 500 nm in size. The CNTs are well dispersed within a flake and they bridge the micro-cracks. The results reveal that the coefficient of thermal expansion (CTE) decreases markedly upon the increase in carbon content, reaching 15.4 x 10-6 K-1 for the specimen with a carbon content of 2.0 wt% (2.9 vol%), i.e. a 30% decrease compared to the CTE of pure Al. This could arise from the layered-microstructure resulting from the utilization of Al flakes as opposed to rounded particles
EFL STUDENT’S PROBLEMS WITH PARAGRAPH WRITING AT TAY DO UNIVERSITY, VIETNAM
This paper studied problems in EFL students’ paragraph writing. The research participants were first-year students of English in Tay Do University (TDU). To achieve the desired aims of the current study, the researcher combined both qualitative and quantitative methods, using questionnaires, interviews, and observations as the main instruments. The researcher used the package of social sciences (SPSS) for analysis. Research results showed that the freshmen at TDU often encountered problems in writing paragraphs. These accounted for grammatical structures, vocabulary, and coherence. Basing on the research results, students could recognize their difficulties when writing and find some new ways to overcome them. It is suggested that teachers should find and update some new teaching methods so as to develop students’ paragraph writing skills.
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