A novel green antenna phase-shift system with data acquisition boards

A novel green phase shifter system is proposed in this research. The system is developed by a combination of reconfigurable beam steering antennas and data acquisition (DAQ) boards. A combination of two reconfigurable beam steering antennas, located side-by-side, forms a spatial configuration structure with a fabricated ‘green’ element plank of rice husk placed in between. The concept of a spatial configuration technique has been ‘mutated’ by shifting the structure of spiral feed line and aperture slots of first beam steering antenna by as much as 45 ◦ . The PIN diode switches connected to the DAQ boards enable the intelligent capability of the spatial antennas. The activation of certain degree radiation patterns of either the first beam steering antenna or the second beam steering antenna depends on the memory of the DAQ boards — Beam Manager. When an intruder comes from the cardinal angles of 0◦/ 360◦, 90◦, 180◦, or 270◦, its range and angles’ location will be automatically detected by the first antenna through the output ports of the 1st DAQ: P1.0, P1.1, P1.2, and P1.3. The second antenna is then activated by the output ports of the 2nd DAQ: P2.0 up to P2.3, to adaptively maneuver the beam towards four different ordinal directions of 45◦, 135◦, 225◦, and 315◦

Design and mechanical analysis of a 3D-printed biodegradable biomimetic micro air vehicle wing

The biomimetic micro air vehicles (BMAV) are unmanned, micro-scaled aircraft that are bio-inspired from flying organisms to achieve the lift and thrust by flapping their wings. There are still many technological challenges involved with designing the BMAV. One of these is designing the ultra-lightweight materials and structures for the wings that have enough mechanical strength to withstand continuous flapping at high frequencies. Insects achieve this by having chitin-based, wing frame structures that encompass a thin, film membrane. The main objectives of this study are to design a biodegradable BMAV wing (inspired from the dragonfly) and analyze its mechanical properties. The dragonfly-like wing frame structure was bio-mimicked and fabricated using a 3D printer. A chitosan nanocomposite film membrane was applied to the BMAV wing frames through casting method. Its mechanical performance was analyzed using universal testing machine (UTM). This analysis indicates that the tensile strength and Young's modulus of the wing with a membrane is nearly double that of the wing without a membrane, which allow higher wing beat frequencies and deflections that in turn enable a greater lifting performance

Isolation of anticancer and anti-trypanosome secondary metabolites from the endophytic fungus Aspergillus flocculus via bioactivity guided isolation and MS based metabolomics

This study aims to identify bioactive anticancer and anti-trypanosome secondary metabolites from the fermentation culture of Aspergillus flocculus endophyte assisted by modern metabolomics technologies. The endophyte was isolated from the stem of the medicinal plant Markhamia platycalyx and identified using phylogenetics. Principle component analysis was employed to screen for the optimum growth endophyte culturing conditions and revealing that the 30-days rice culture (RC-30d) provided the highest levels of the bioactive agents. To pinpoint for active chemicals in endophyte crude extracts and successive fractions, a new application of molecular interaction network is implemented to correlate the chemical and biological profiles of the anti-trypanosome active fractions to highlight the metabolites mediating for bioactivity prior to purification trials. Multivariate data analysis (MVDA), with the aid of dereplication studies, efficiently annotated the putatively active anticancer molecules. The small-scale RC-30d fungal culture was purified using high-throughput chromatographic techniques to yield compound 1, a novel polyketide molecule though inactive. Whereas, active fractions revealed from the bioactivity guided fractionation of medium scale RC-30d culture were further purified to yield 7 metabolites, 5 of which namely cis-4-hydroxymellein, 5-hydroxymellein, diorcinol, botryoisocoumarin A and mellein, inhibited the growth of chronic myelogenous leukemia cell line K562 at 30 μM. 3-Hydroxymellein and diorcinol exhibited a respective inhibition of 56% and 97% to the sleeping sickness causing parasite Trypanosoma brucei brucei. More interestingly, the anti-trypanosomal activity of A. flocculus extract appeared to be mediated by the synergistic effect of the active steroidal compounds i.e. ergosterol peroxide, ergosterol and campesterol. The isolated structures were elucidated by using 1D, 2D NMR and HR-ESIMS

Mechanical characterization of 3/2 fibre metal laminate materials

Development of lightweight materials onto vehicle bodies, especially in the automotive sector is seen as one of the best alternative solutions in order to reduce fuel consumption and decrease harmful emissions produced by the emission. Reducing in weight of a vehicle can improve fuel efficiency with no prejudice to safety strength requirements. Fibre metal laminate (FML) is hybrid composite structure based on thin sheet of metal alloys and plies of fibre reinforced polymeric materials which offer the ability of superior mechanical properties such as lightweight, high fatigue growth resistance and high strength and stiffness. Multi-material auto bodies will allow optimal material selection in structural components for higher performance and lower cost. This study aims to fabricate and investigate the failure behaviour of a 3/2 layer fibre metal laminate subjected to the quasi-static indentation test. The FML is constructed from aluminium 2024-T3 and layered with composite materials CFRP, GFRP and SRPP. The crosshead speed test analysis ran in different parameters on 1 mm/min, 5 mm/min, 10 mm/min and 50 mm/min, respectively in quasi-static indentation test. The experimental performances of each specimen were compared to predict the behaviour and performance of the FML composite. The test indicates that varying crosshead speeds have influenced the affected region of the FML, causing debonding on the laminate as a result of continued loading

Effects on hybridization of interlayer composites and self-reinforced polypropylene

In recent years, there has been increasing attention to develop a high-strength, lightweight composite as a potential substitution for conventional materials in various sectors, whereby most studies have focused on the mechanical performances of fibre-reinforced plastic (FRP) such as carbon, glass and aramid. In contrast, the hybrid composites are less common, though are viewed to have substantial potential in terms of flexibility and capability to merge the benefits of different composites. In this study, five composite designs consisting of several types of woven fibres and self-reinforced polypropylene (SRPP) sheets have been fabricated using the hand lay-up procedure. Several designs are arranged based on the interlayer hybridization mode. The static mechanical properties of the composite designs were examined through the standard tensile and three-point flexural tests. The outcomes attained from the experimental works revealed that carbon fibre-reinforced plastic (CFRP) produced the best tensile characteristics. The CFRP structure displayed 46% higher tensile strength and a 33% greater elastic modulus compared to the CAFRP specimen. Meanwhile, hybrid carbon/aramid fibre-reinforced plastic (CAFRP) pointedly enhanced flexural properties in comparison with single type and other hybrid composites, whereby CAFRP structure outperformed the CFRP structure, exhibiting superior results with variations of 50% and 19% in flexural strength and modulus, respectively. Though the inclusion of SRPP layers in-between the hybrid setup exhibited a decrease in both tensile and flexural strength, but improved the total strain level. The evidence from this study suggests that FRP composites indicate structures of high strength and stiffness but low elongation, whereas SRPP-based composites improve toughness but reduce stiffness characteristics

A systematic review of maternal dietary intake and its association with childhood stunting

The first 1,000 days of a child’s life is a critical period of development in preventing childhood stunting. Despite various intervention programs, the global prevalence remains high. Maternal nutrition during pregnancy and exclusive breastfeeding plays an important role in infant development; thus, a systematic review of the relationship between maternal dietary intake and childhood stunting was conducted. The Web of Science, Scopus, PubMed, and Google Scholar electronic databases were used. Articles related to maternal nutrition and supplement intake with children's anthropometry data were included. Eleven studies met the inclusion criteria and seven were included after quality assessment. The studies were reviewed thematically as the statistical analysis was not possible due to data heterogeneity. The Appraisal Tool for Cross-Sectional Studies (AXIS) and Critical Appraisal Skills Program tools were used to assess the quality of the included studies. The findings demonstrated that pregnant women need to eat a diverse diet with the inclusion of at least five food groups to fulfill the nutritional requirement. Daily protein intake between 0.8 and 1.1g/kg body weight is recommended for positive birth weight and height outcomes. Supplementation of vitamin A, vitamin C, iron, zinc, vitamin D, and calcium, was also shown to improve pregnancy outcomes. However, future studies should consider confounding factors such as hygiene level and clean water availability to determine the transparent effect of nutrition on childhood stunting. More longitudinal studies are required to ascertain the relationship between maternal dietary intake and childhood stunting, especially in Malaysi

Genotoxic effect induced by hydrogen peroxide in human hepatoma cells using comet assay

Background: Hydrogen peroxide is a common reactive oxygen intermediate generated by variousforms of oxidative stress. Aims: The aim of this study was to investigate the DNA damage capacity ofH2O2 in HepG2 cells. Methods: Cells were treated with H2O2 at concentrations of 25 μM or 50 μM for5 min, 30 min, 40 min, 1 h or 24 h in parallel. The extent of DNA damage was assessed by the cometassay. Results: Compared to the control, DNA damage by 25 μM and 50 μM H2O2 increasedsignificantly with increasing incubation time up to 1 h, but it was not increased at 24 h. Conclusions:Our Findings confirm that H2O2 is a typical DNA damage inducing agent and thus is a good modelsystem to study the effects of oxidative stress. DNA damage in HepG2 cells increased significantlywith H2O2 concentration and time of incubation but later decreased likely due to DNA repairmechanisms and antioxidant enzyme

A reconfigurable Ultra Wide Band (UWB) compact tree-design antenna system

A novel compact tree-design antenna (NCTA) with the ability of reconfigurable ultra-wideband (UWB) of 3.1 GHz to 10.6 GHz to five multi-narrowband applications is proposed. This antenna has a novel radiating element design that consists of seven small circles (7- filter) surrounding a central circle. Moreover, the NCTA incorporates the 7-filter that functioned as filter into the antenna design. The compact 38 mm×38 mm antenna integrates three PIN diode switches, which are connected to a single National Instrument Data Acquisition (NI-DAQ) Board. The DAQ itself is controlled (ON/OFF state) by a virtual instrument known as “Lab VIEW Interface Software”. The activation of specific PIN diode switches in the configuration that is controlled by the DAQ then, in turn, determines the frequency agility. The presented antenna is capable of performing up to five multibands. The operating frequencies are as follows; band 1 (2.72– 11.8 GHz), band 2 (2.4–4 GHz, 5.3–11.6 GHz), band 3 (2.7–6.5 GHz, 7.1–11.6 GHz), band 4 (2.7–4.4 GHz, 5.2–6.5 GHz, 7.1–11.7 GHz) and band 5 (2.6–3.5 GHz, 4.8–7.0 GHz, 7.4 GHz–11.5 GHz). Furthermore, the antenna has a gain of up to 6 dBi which is considered better than that of conventional antenna. The proposed antenna produces a proficient divisive radiation pattern at 4 and 6 GHz. The experimental results exhibit the success of the antenna performance. It is competent as future candidate for cognitive radio and military applications