Cyanobacteria are phototrophic organisms widely found in most types of natural habitats in the tropical regions of the world. In this study, we isolated and identified cyanobacterial strains from ...paddy soil in Hanoi (Vietnam) and investigated their cytotoxic activities. Five isolated cyanobacterial strains showed distinctive profiles of gene sequences (rRNA 16S and
rbcL
), phylogenetic placements, and morphological characteristics. Based on the polyphasic evaluation, they were classified as
Scytonema bilaspurense
NK13,
Hapalosiphon welwitschii
MD2411,
Aulosira
sp. XN1103,
Desikacharya
sp. NS2000, and
Desmonostoc
sp. NK1813. The cytotoxic screening revealed that the extract of strain
Scytonema bilaspurense
NK13 exhibited potent cytotoxic activities against four human cell lines of HeLa cells, OVCAR-8 cells, HaCaT cells, and HEK-293T cells, with IC
50
values of 3.8, 34.2, 21.6, and 0.6 μg/mL, respectively. This is the first time a well-classified
Scytonema
strain from tropical habitat in Southeast Asia has been recognized as a potential producer of cytotoxic compounds.
In this paper, a design of frequency reconfigurable SIW-cavity-based antenna is introduced with MIMO mechanism for various wireless applications. The antenna exhibits frequency reconfigurability, ...compactness, and low profile thanks to quarter-mode SIW design and integration of the varactor diodes. The prototype can scan the frequency from 2.35 GHz to 2.55 GHz by tuning the voltage applied at varactor. The radiation characteristics show high gain and good patterns across the bandwidth (below -15 dB). Additionally, the MIMO design demonstrates negligible reflection and mutual coupling magnitude while MIMO parameters are satisfied. The good agreement between measured and simulated results validates the suitability of the proposed antenna for various MIMO applications in ISM band.
In this paper, a 2-by-1 MIMO reconfigurable antenna using Quarter Mode Substrate Integrated Waveguide (QMSIW) is introduced for wireless communication application. By combining three antenna ...techniques, the proposed design has a compact size due to QMSIW cavity, operation frequency flexibility by using varactor diodes, and channel capacity improvement from MIMO setup. The antenna is integrated with varactor (MA46H120) to tune its operating frequency from 2.35 to 2.55 GHz (ISM band). The antenna has a high isolation level (below -15 dB), and a peak gain of around 2.3 dBi across the tuning frequency range. The agreement between measured and simulated results shows successful performance and characteristics satisfying various MIMO parameters requirements.
In Class-Incremental Learning (Class-IL), deep neural networks often fail to learn a sequence of classes incrementally due to catastrophic forgetting, a phenomenon arising from the absence of ...exposure to old knowledge. To alleviate this issue, conventional rehearsal methods, such as experience replay, store a limited number of old exemplars and then interleave with the current data for joint learning and rehearsal. However, the networks following this training scheme might not successfully reduce forgetting due to the lack of direct consideration of relations between samples of previously learned and new classes. Drawing inspiration from how humans learn by noticing the similarities and differences between classes, we propose a novel Class-IL framework called Relational Replay (RR). RR learns and recalls relations between images across all classes over time. To ensure these relations remain intrinsic and robust to forgetting, we incorporate causal reasoning to RR, resulting in Causal Relational Replay (CRR). CRR analyzes these relations using a causality perspective, aiming to identify intrinsic relations rooted in the images’ semantic features, serving as the cause of these relations. Our proposed method shows a competitive performance compared to the state-of-the-art rehearsal methods in Class-IL with clear and consistent improvements in the majority of settings on standard benchmark datasets.
•We tackle the problem of catastrophic forgetting in Class-IL.•Our method leverages object relations, inspired by human memory, to prevent forgetting.•We discover spurious relations worsen forgetting, best to focus only on intrinsic ones.•We add a causal learning mechanism to analyze relations and combat spurious factors.•Our algorithm excels in Class-IL, consistently surpassing top rehearsal techniques.
Calcium silicate is produced from a mixture of silica sand powder, lime, paper pulp, and Portland cement hydrothermally steamed at 180 °C for about 16 h. This material is considered environmentally ...friendly and is popular in countries around the world. In this study, quartz sand was replaced with residual waste sludge from water-filtration plants to produce calcium silicate materials. Nowadays, the residual waste sludge from water-filtration plants is an environmental problem that needs to be treated. The results of determining the properties showed that a sample using 10 w/% residual waste sludge gave the best replacement. This sample had a bending strength of 10.95 MPa, a volumetric density of 1.57 g/cm3, and water absorption of 23.67 %. The results of the analysis of the mineral composition (by X-ray diffraction analysis and Fourier-transform infrared spectroscopy) and microstructure (by scanning electron microscopy) showed that all samples formed tobermorite and xonotlite minerals. The tobermorite and the xonotlite are hydro-silicate-calcium minerals characteristic of calcium silicate materials, which are the synthesis products of chemical reactions of SiO2, CaO, and H2O under hydrothermal conditions. Samples using 5–10 w/% of waste residual sludge have even higher mechanical strength than samples without. Therefore, using waste residual sludge from water-filtration plants to replace part of the sand in producing calcium silicate materials can be considered an effective method to treat environmental problems caused by waste residual sludge.
Abstract
Agricultural production in Vietnam annually generates a substantial volume of by-products and waste, with rice husks constituting the predominant fraction. Due to their meager economic ...value, rice husks are typically deemed agricultural waste and are commonly disposed of through incineration or discharge into rivers, contributing significantly to environmental pollution. In this investigation, rice husks were employed as the principal raw material for synthesizing silicon carbide. A blend of rice husks and silica gel in a ratio of 1.4/1 was subjected to sintering in a CO
2
environment within the temperature range of 800 °C–1300 °C for 30 min. The chemical composition of the resultant product post-pyrolysis was ascertained in accordance with the ISO 21068–2:2008 standard. The capacity for SiC formation was further assessed utilizing Fourier transform infrared spectroscopy and x-ray diffraction. The outcomes revealed that the optimal temperature for SiC synthesis was 1200 °C. The composition of the sample post-pyrolysis was determined as 20.4% SiC, 51.2% SiO
2
, and 26.4% C (%wt). The primary phase constituents encompass amorphous carbon, cristobalite,
α
-SiC, and
β
-SiC. Scanning Electron Microscopy/ Energy Dispersive x-ray imaging of the product at 1200 °C exhibited dispersed SiC crystals on a SiO
2
-C substrate. The presence of SiC suggests the potential application of the product as a wear-resistant material.
Titanium slag is a by-product of iron extraction from Ilmenite ore. Titanium slag has a high TiO₂ content, so it is a suitable material for preparing TiO₂. This study investigated the influence of ...the slag particle size on the ability to synthesise TiO₂ by the hydrothermal alkalisation method. Three groups of titanium slag powder with average particle sizes from 18 μm to 108 μm were alkalised with a 10M NaOH solution to separate TiO₂ by the hydrothermal method. The mixing ratio by mass between the slag and the 10M NaOH solution is 1:1.5. The hydrothermal reaction was carried out at 180 °C for 7 hours. The products were analysed for their mineral, chemical, and microstructural properties using X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy-dispersive detector. The results show that the particle size significantly influences the efficiency of the TiO₂ chemical extraction from the titanium slag. The formed TiO₂ is of high purity, and the main mineral composition is anatase. The anatase polymorph of TiO₂ has the potential application as a photocatalyst and an antibacterial material.
