Comparing the effectiveness of online and onsite learning in English proficiency classes: Learners’ perspectives

Online education has significantly gained popularity due to new technology and more importantly, the growing impact of the digitalization of the economy. Despite its prominent advantages such as accessibility, affordability and flexibility, the effectiveness of online education is still a constant debate and needs extensive investigations in different research contexts. This study aimed to evaluate the effectiveness of online learning in comparison to traditional learning in the context of English language teaching. This descriptive study was undertaken with learners of English as a foreign language (EFL) in English proficiency preparation classes, employing an online questionnaire together with final scores of proficiency tests. The results revealed that the participants had relatively positive perceptions towards online learning in all four aspects: course content, teachers, learning environment and course supports. The significant finding was that when comparing the final results of the VSTEP exams, the online learners generally were able to perform better than the learners in traditional classrooms, though the difference was not largely remarkable. Online education in the new normal will continue to excel and the effectiveness of this learning mode certainly needs further investigation from different perspectives

Geopolymer recycled aggregate concrete: From experiments to empirical models

Ordinary cement concrete is a popular material with numerous advantages when compared to other construction materials; however, ordinary concrete is also criticized from the public point of view due to the CO2 emission (during the cement manufacture) and the consumption of natural resources (for the aggregates). In the context of sustainable development and circular econ-omy, the recycling of materials and the use of alternative binders which have less environmental impacts than cement are challenges for the construction sector. This paper presents a study on non-conventional concrete using recycled aggregates and alkali-activated binder. The specimens were prepared from low calcium fly ash (FA, an industrial by-product), sodium silicate solution, sodium hydroxide solution, fine aggregate from river sand, and recycled coarse aggregate. First, influences of different factors were investigated: the ratio between alkaline activated solution (AAS) and FA, and the curing temperature and the lignosulfonate superplasticizer. The interfacial transition zone of geopolymer recycled aggregate concrete (GRAC) was evaluated by microscopic analyses. Then, two empirical models, which are the modified versions of Feret’s and De Larrard’s models, respec-tively, for cement concretes, were investigated for the prediction of GRAC compressive strength; the parameters of these models were identified. The results showed the positive behaviour of GRAC investigated and the relevancy of the models proposed

Micromachining of carbon nanofiller reinforced polymern nanocomposites

The modern industry has been observing a growing demand for micromanufacturing of nanocomposites. This is driven by the miniaturisation trend to obtain products with micro features, high accuracy and light weight. From an engineering perspective, a miniaturised system can provide many benefits over its predecessors such as precision operation, mobility, or power consumption. Based on these, many techniques of micro-manufacturing have been applied, and micromilling of nanocomposites has shown a huge potential to be applied in this field due to its high capability in producing high-complexity-3D micro-features in a wide variety of workpiece materials, with high dimensional accuracy. However, micromilling of nanocomposites is deemed to be a complicated process due to the anisotropic, heterogeneous structure and advanced mechanical properties of these materials associated with the size effects in micromachining. Also, applying micromachining of nanocomposites is a principal approach to bridge the knowledge gap between macro and micro/nano cuttings which is identified by the so-called “size effect”. This physical phenomenon exhibits by the association between various factors including cutting edge radius, negative tool rake angle, work-piece material microstructure, and minimum uncut chip thickness (MUCT) (or minimum chip load). These lead to unstable cutting regimes, resulting in corrupted chip formation, tool vibration and subsequently, low machined surface quality as well as high tool wear rate. The enormous potential of applying micromachining of nanocomposites in manufacturing micro-products, as well as the need to fill the knowledge gap of the field of this study, has prompted researchers to uncover the underlying mechanisms and allow appropriate adaption of this technique in industrial applications

Biosynthesis of silver nanoparticles using curcumin against the bovine mastitis bacteria

Bovine mastitis is the most common disease and has greatly affected economies around the world. This study aimed to determine the antibacterial ability of bovine mastitis by curcumin - silver nanoparticles (Cur-AgNPs). The study included experiments on presenting a new process for synthesizing silver nanoparticles using curcumin from fresh turmeric as a reducing agent and stabilizer. UV visible spectroscopy of the samples revealed the localized surface plasmon resonance absorbance of the dispersion of silver nanoparticles at 430 nm. The prepared Cur-AgNPs has a spherical shape with an average size of 30 nm and a size distribution of 15–47 nm. FT-IR (Fourier transform infrared spectroscopy) measurements of the samples showed that silver nanopartilces has been encapsulated well by curcumin. Cur-AgNPs with a concentration of 50-200 μg/mL has very effect to Staphylococcus aureus, Pseudomonas aeruginosa causing bovine mastitis in vitro. The maximum inhibition zone formed was 15 ± 0.85 mm for Staphylococcus aureus and 14 ± 0.56 mm for Pseudomonas aeruginosa. Plant materials mediating for the synthesis of silver nanoparticles have relatively rapid, less expensive, and widespread applications for antimicrobial therapy in the livestock sector

Hybrid electrolyte based on PEO and ionic liquid with in situ produced and dispersed silica for sustainable solid-state battery

This work introduces the synthesis of hybrid polymer electrolytes based on polyethylene oxide (PEO) and electrolyte solution bis(trifluoromethane)sulfonimide lithium salt/ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (LiTFSI/EMIMTFSI) with in situ produced and dispersed silica particles by the sol–gel method. Conventional preparation of solid polymer electrolytes was followed by desolvation of lithium salt in a polymer matrix of PEO, which, in some cases, additionally contains plasticizers. This one-pot synthesis is an alternative route for fabricating a solid polymer electrolyte for solid-state batteries. The presence of TFSI- reduces the crystallinity of the PEO matrix (plasticizing effect), increases the dissociation and solubility of LiTFSI in the PEO matrix because of a highly delocalized charge distribution, and reveals excellent thermal, chemical, and electrochemical stability. Tetraethylorthosilicate (TEOS) was chosen due to the slow reaction rate, with the addition of (3-glycidyoxypropyl)trimethoxysilane (GLYMO), which contributes to the formation of a silica network. FTIR studies confirmed the interactions between the silica, the polymer salt, and EMIMTFSI. Impedance spectroscopy measurements were performed in a wide range of temperatures from 25 to 70 °C. The electrochemical performance was explored by assembling electrolytes in LiCoO2 (LCO), NMC(811), and LiFePO4 (LFP) coin half-cells. The HPEf15 shows a discharge capacity of 143 mA/g for NMC(811) at 0.1 C, 134 mA/g for LCO, and 139 mA/g for LFP half-cells at 0.1 C and 55 °C. The LFP half-cell with a discharge capacity of 135 mA/g at 0.1 C (safety potential range of 2.8 to 3.8) obtained a cyclability of 97.5% at 55 °C after 100 cycles. Such a type of electrolyte with high safety and good electrochemical performance provides a potential approach for developing a safer lithium-ion battery.Ministry of Education, Youth, and Sports of the Czech Research, (CZ.005)Ministry of Education, Youth, and Sport of the Czech Researc

An Improved MobileNet for Disease Detection on Tomato Leaves

Tomatoes are widely grown vegetables, and farmers face challenges in caring for them, particularly regarding plant diseases. The MobileNet architecture is renowned for its simplicity and compatibility with mobile devices. This study introduces MobileNet as a deep learning model to enhance disease detection efficiency in tomato plants. The model is evaluated on a dataset of 2,064 tomato leaf images, encompassing early blight, leaf spot, yellow curl, and healthy leaves. Results demonstrate promising accuracy, exceeding 0.980 for disease classification and 0.975 for distinguishing between diseases and healthy cases. Moreover, the proposed model outperforms existing approaches in terms of accuracy and training time for plant leaf disease detection

Hardware Architectures of Visible Light Communication Transmitter and Receiver for Beacon-based Indoor Positioning Systems

High-speed applications of Visible Light Communications have been presented recently in which response times of photodiode-based VLC receivers are critical points. Typical VLC receiver routines, such as soft-decoding of run-length limited (RLL) codes and FEC codes was purely processed on embedded firmware, and potentially cause bottleneck at the receiver. To speed up the performance of receivers, ASIC-based VLC receiver could be the solution. Unfortunately, recent works on soft-decoding of RLL and FEC have shown that they are bulky and time-consuming computations. This causes hardware implementation of VLC receivers becomes heavy and unrealistic. In this paper, we introduce a compact Polar-code-based VLC receivers. in which flicker mitigation of the system can be guaranteed even without RLL codes. In particular, we utilized the centralized bit-probability distribution of a pre-scrambler and a Polar encoder to create a non-RLL flicker mitigation solution. At the receiver, a 3-bit soft-decision filter was implemented to analyze signals received from the VLC channel to extract log-likelihood ratio (LLR) values and feed them to the Polar decoder. Therefore, the proposed receiver could exploit the soft-decoding of the Polar decoder to improve the error-correction performance of the system. Due to the non-RLL characteristic, the receiver has a preeminent code-rate and a reduced complexity compared with RLL-based receivers. We present the proposed VLC receiver along with a novel very-large-scale integration (VLSI) architecture, and a synthesis of our design using FPGA/ASIC synthesis tools

Geometric effects on mixing performance in a novel passive micromixer with trapezoidal-zigzag channels

A novel passive micromixer, called a trapezoidal-zigzag micromixer (TZM), is reported. A TZM is composed of trapezoidal channels in a zigzag and split–recombine arrangement that enables multiple mixing mechanisms, including splitting–recombining, twisting, transversal flows, vortices, and chaotic advection. The effects of geometric parameters of the TZM on mixing performance are systematically investigated by the Taguchi method and numerical simulations in COMSOL Multiphysics. The number of mixing units, the slope angle of the trapezoidal channel, the height of the constriction element, and the width ratio between the middle-trapezoidal channel and the side-trapezoidal channel are the four parameters under study. The mixing performance of the TZM is investigated at three different Reynolds number (Re) values of 0.5, 5, and 50. The results showed that a TZM with six mixing units, a trapezoidal slope angle of 75°, a constricting height of 100 µm, and a width ratio of 0.5 has the highest mixing efficiency. This optimal TZM has a mixing efficiency greater than 85% for Re values from 0.1 to 80. In particular, for Re  ≤  0.9 and Re  ≥  20, the mixing efficiency of the optimal TZM is greater than 90%. The proposed TZM has a higher mixing efficiency and a smaller footprint than previously reported micromixers