Crystallization behavior of poly(lactide)/poly(β-hydroxybutyrate)/talc composites.

The authors thank Dr. Patrice Lefrançois (CNAM) for SEM observations. They are also grateful to Pr. Jack R. Plimmer USDA, Agricultural Research Service, USA for his discussions during this work.The morphology and miscibility of commercial poly(lactide) (PLA)/poly(b-hydroxybutyrate) (PHB, from 5 to 20 wt %) blends prepared by melt extrusion method, were investigated using differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR) observations. The results show that for all the studied blend contents, PLA/PHB blends are immiscible. The effects of PHB and talc on the nonisothermal cold crystallization kinetics of PLA were examined using a differential scanning calorimetry (DSC) at different heating rates. PHB acted as a nucleating agent on PLA and the addition of talc to the blend yielded further improve-ment, since significant increase in the enthalpy peak was observed for samples containing 10 wt % PHB and talc (from 0.5 to 5 phr). The crystallization kinetics were then examined using the Avrami–Jeziorny and Liu–Mo approach. The simultaneous presence of PHB and talc induced a decrease of the crystallization half time. The evolution of activation energies determined with Kissinger’s equation suggests that blending with PHB and incorporating talc promote nonisothermal cold crystallization of PLA. The synergistic nucleating effect of PHB and talc was also observed on isothermal crystallization of PLA from the melt

Space-time adaptive array processing for cancellation of GPS jamming

Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (leaf 68).by Tri T. Phuong.S.B.and M.Eng

BMF CP70: Exploring the climate change-related factors constraining stakeholders’ willingness to protect the ocean

The current study is conducted to examine the following research questions: - Do perceptions that mitigate climate change risk (e.g., developing technology to help address climate change) reduce stakeholders’ willingness to protect the ocean? - Do perceptions of the costs associated with combating climate change (e.g., the belief that responding to climate change will harm economies and societies that are already actively addressing the issue) reduce stakeholders’ willingness to protect the ocean? The findings from this study are expected to provide insights into how perceptions of climate change mitigation and cost beliefs influence stakeholders’ willingness to protect the ocean. This information can inform targeted strategies for policymakers and conservationists to enhance support for marine protection and build the eco-surplus culture in the face of climate change challenges

The Effects of Technology-Assisted Listening Practice on Moodle on English-Majored Freshmen’s Motivation for Learning Listening at a University in The Mekong Delta

Purpose: This study was to investigate the effects of technology-assisted listening practice on MOODLE on English-majored freshmen's motivation for learning English listening at a university in the Mekong Delta. Approach/Methodology/Design: Two groups of sixty-four mixed-gender freshmen majoring in English language studies participated in this quasi-experimental study. To collect data, a pre-questionnaire, a post-questionnaire, and interviews were employed. Findings: The findings indicated that technology-assisted listening practice on MOODLE improved English-majored freshmen's listening motivation in specific areas for learning listening; however, this was a variance development. Practical Implications: This study was aimed to help language teachers and students benefit from technology-assisted listening teaching and learning. Originality/value: This study innovates by applying the MOODLE system to increase students’ listening motivation at a university in the Mekong Delta

Viết tiếp giấc mơ nửa triệu

Đêm ngày 28-7-2023, bài NS đã lăn qua mốc 40 vạn lượt đọc, chính xác là hết ngày 28-7, đạt mốc mới 401066 lượt đọc duy nhất tính theo IP [1]. Đây là cách tính lượt đọc rất khắt khe, vì từ một địa chỉ IP, có cả trăm người đọc thì vẫn chỉ được tính là 1 mà thôi

Biomolecular evaluation of three contrasting rice cultivars (Oryza sativa L.) in salt stress response at seedling stage.

Salt contamination of soils due to climate change faces a severe environmental issue that affects crop production today. However, the response mechanism in plants to salt stress is not fully understood. The present study investigated molecular and biochemical changes under salt stress in rice seedlings of three rice cultivars, i.e., AGPPS114 (salt-tolerant), OM6967 (moderately tolerance), VD20 (salt-sensitive). Increasing salt concentration leads to a reduction in shoot/root length but different levels among the cultivars. In contrast, reactive oxygen species (ROS) accumulation and lipid peroxidation increased progressively with increasing salt concentration and time course treatment. However, at 250 ?M of NaCl, these parameters were more adversely affected in VD20 than AGPPS114 and OM6967. Using ICP showed that Na+ accumulation in rice root increased gradually with increasing NaCl concentrations in all cultivars under salt treatment but was low in salt-sensitive cultivar VD20 compared to other cultivars. Antioxidant enzyme activity analysis indicated catalase (CAT) and superoxide dismutase (SOD) were induced during salt treatment in all cultivars. The results also showed greater proline and glycine betaine accumulation in the AGPPS114 than OM6976 and VD20. qPCR indicated a significant difference in transcript levels of the Na+-transporter gene OsSOS1, OsNHX1 and OsHKT1s in AGPPS114 and OM6967 cultivars compared to VD20 cultivar. In summary, the active regulation of genes related to Na+ transport at the transcription level and with high glycine betaine and proline accumulation levels may be involved in salt tolerance mechanisms and thus might be useful for selecting tolerant plants

Machine Learning Models for Inferring the Axial Strength in Short Concrete-Filled Steel Tube Columns Infilled with Various Strength Concrete

Concrete-filled steel tube (CFST) columns are used in the construction industry because of their high strength, ductility, stiffness, and fire resistance. This paper developed machine learning techniques for inferring the axial strength in short CFST columns infilled with various strength concrete. Additive Random Forests (ARF) and Artificial Neural Networks (ANNs) models were developed and tested using large experimental data. These data-driven models enable us to infer the axial strength in CFST columns based on the diameter, the tube thickness, the steel yield stress, concrete strength, column length, and diameter/tube thickness. The analytical results showed that the ARF obtained high accuracy with the 6.39% in mean absolute percentage error (MAPE) and 211.31 kN in mean absolute error (MAE). The ARF outperformed significantly the ANNs with an improvement rate at 84.1% in MAPE and 65.4% in MAE. In comparison with the design codes such as EC4 and AISC, the ARF improved the predictive accuracy with 36.9% in MAPE and 22.3% in MAE. The comparison results confirmed that the ARF was the most effective machine learning model among the investigated approaches. As a contribution, this study proposed a machine learning model for accurately inferring the axial strength in short CFST columns

Effect of recycling process in twin screws extruder HAAK on structure and crystallization behavior of polypropylene

Recycling process of polypropylene (PP) in twin screws extruder HAAK at high (195 - 230oC) and low (175-190oC) temperature ranges was studied. IR spectra and solubility of recycled samples show that neither oxidative degradation nor network formation has occurred at recycling conditions. So only degradation of PP molecules to smaller fractions may take place, that contributes to increasing of Melt Flow Index (MFI) of recycled samples. The results show also the stronger effect of recycling temperatures on the structure changes than that of number of recycling times. We can see also the structure changes of recycled PP cause the higher crystallization rate, higher crystalline percentage of spherulite formations with smaller dimensions. It leads to higher crystallization temperatures (3-4oC) but lower melting temperatures (4-5oC) of recycled PP in comparison with virgin PP

Using SiO2 nano-particles for better color uniformity and lumen output in 8500 K conformal and in-cup white LEDs

In the effort of improving the performance of white light LEDs devices (WLEDs), the SiO2 nano-particles were applied and have shown a significant impact on the optical properties. Specifically, the light output of the lighting devices is enhanced when a mixture of SiO2 particles and silicone gel is diffused on the encapsulation layer surface. This enhancement is the result of light scattering from SiO2 that strengthens the emitted blue light at further angles and reduces the color discrepancy. The evidence is that CCT deviation in SiO2-doped structure decline from 1000 K to 420 K in -70° to 70°. In addition, the SiO2 with refractive index in between the phosphor material and outside environment allows light to be emitted outward more effectively. This lighting enhancement of SiO2-doped structure increases the lumen output by 2.25% at 120 mA power source in comparison to structure without SiO2. These experimental outcomes suggest that SiO2 is an effective material to add in WLEDs structure for better lighting efficiency

Investigating climate change-related factors that hinder stakeholders’ willingness to protect ocean

Community and stakeholder support for marine and coastal ecosystem conservation policies is crucial. However, extant multinational studies on climate change-related factors that constrain stakeholders’ willingness to protect the ocean are limited. Therefore, the dataset from 709 marine stakeholders across 42 countries, part of the MaCoBioS project funded by the European Commission, was analyzed using the Bayesian Mindsponge Framework (BMF) method to fill the knowledge gap. The findings reveal that for individuals who think society is doing too much to address climate change, new technologies can solve climate change. Responses to climate change can damage the country’s economy and might not be productive in supporting actions protecting the ocean. Based on the study results, we recommend policymakers raise awareness among individuals engaged in marine and coastal ecosystems about the crucial role of marine protection in combating climate change, taking into account the limitations of technology in solving climate change problems and the inadequacy of current efforts. The findings also provide insights for enhancing the effectiveness of awareness and knowledge-raising campaigns, conservation programs, and eco-surplus culture-building agenda