High Gain Flat-Panel mmWave Antenna Array.

In the realm of mmWave communication and connectivity, integrating chips and antennas into a cohesive system is paramount. Given this, planar antenna arrays have become indispensable. In this article, we introduce a novel antenna array tailored for mmWave applications, characterized by its high directivity. Distinctively, this new array employs a flat-panel radiator, ensuring an augmented gain without necessitating additional superstrate layers. To validate its potency, a 4 × 4 flat-panel array with dimensions of 3.74 λ0 × 3.74 λ0 × 0.106 λ0 at 28 GHz including a ground plane was designed and tested for n257 band. The standalone array element exhibited a bandwidth of 20.6%, centered at 28.5 GHz. Furthermore, a 1 × 16 mmWave feed network was designed and amalgamated with the array elements to assess the comprehensive antenna performance. The measured peak gain of 21.3 dBi at 28.5 GHz was observed with the measured half power beamwidth of 15° while the gain variation within the operation band was less than 3 dB.

Dual-Polarized Multi-Channel 24 GHz Radar Sensor Antenna for High Channel-to-Channel Isolation.

This article presents a dual-polarized, high gain multi-beam and high T/Rx channel-to-channel isolation antenna module for 24 GHz sensor applications. The proposed antenna is configured to support 2-Tx and 2-Rx channels with a pair of vertically polarized (VP) radiation pattern and a pair of horizontally polarized (HP) radiation pattern. Further, each linearly polarized T/Rx antenna is configured by 2 × 4 array with a multi-layer integrated feed network, resulting in four sets of 2 × 4 array antennas fabricated within a single printed circuit board (PCB). Since multiple RF channels must be ensured with minimal interference, high antenna-to-antenna, including Tx-to-Tx, Rx-to-Rx, and Tx-to-Rx port isolations in the proposed antenna are achieved by multi-layered feed network and four sets of T-shaped magnetic walls. To verify the performance of the proposed structure, a 2-Tx and 2-Rx antenna module was fabricated at 24 GHz. The fabricated antenna showed a measured maximum 10-dB impedance bandwidth of 3.9% with a maximum measured gain of 11.7 dBi, considering both Tx and Rx. Further, the measured channel-to-channel isolations were always better than 35.6 dB at 24 GHz.

mmWave High Gain Planar H-Shaped Shorted Ring Antenna Array.

A new design approach for a mmWave high gain planar antenna is presented. The proposed method can increase antenna directivity with a minimally enlarged radiation patch while the operation frequency is still matched at a higher target frequency. The fundamental structure of the proposed antenna is configured by a H-shaped and slot-loaded patch with a shorting pin symmetrically located across a signal excitation port. Further, to match the operation frequency with the frequency for the highest achievable gain, a vertically stacked matching conductor was inserted along the signal feed path between the radiation patch and the ground layer. The proposed single antenna showed the simulated directivity of 9.46 dBi while the conventional patch with a same dielectric had 8.07 dBi. To verify practical performance, a 2 × 2 array antenna was fabricated at 28 GHz and showed the measured gain of 12.5 dBi including the array feed loss.

Revisiting Information Detection and Energy Harvesting: A Power Splitting-Based Approach.

Wireless sensors are becoming essential in machine-type communications and Internet of Things. As the key performance metrics, the spectral efficiency as well as the energy efficiency have been considered while determining the effectiveness of sensor networks. In this paper, we present several power-splitting solutions to maximize the average harvested energy under a rate constraint when both the information and power are transmitted through the same wireless channel to a sensor (i.e., a receiver). More specifically, we first designed the optimal dynamic power-splitting policy, which decides the optimal fractional power of the received signal used for energy harvesting at the receiver. As effective solutions, we proposed two types of single-threshold-based power-splitting policies, namely, Policies I and II, which decide to switch between energy harvesting and information decoding by comparing the received signal power with some given thresholds. Additionally, we performed asymptotic analysis for a large number of packets along with practical statistics-based policies. Consequently, we demonstrated the effectiveness of the proposed power-splitting solutions in terms of the rate-energy trade-off.

Determination of antibacterial activity and minimum inhibitory concentration of larval extract of fly via resazurin-based turbidometric assay.

BACKGROUND: Antimicrobial resistance is currently a major global issue. As the rate of emergence of antimicrobial resistance has superseded the rate of discovery and introduction of new effective drugs, the medical arsenal now is experiencing shortage of effective drugs to combat diseases, particularly against diseases caused by the dreadful multidrug-resistant strains, such as the methicillin-resistant Staphylococcus aureus (MRSA). The ability of fly larvae to thrive in septic habitats has prompted us to determine the antibacterial activity and minimum inhibitory concentrations (MICs) of larval extract of flies, namely Lucilia cuprina, Sarcophaga peregrina and Musca domestica against 4 pathogenic bacteria [Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa and Escherichia coli] via a simple and sensitive antibacterial assay, resazurin-based turbidometric (TB) assay as well as to demonstrate the preliminary chemical profile of larval extracts using gas chromatography-mass spectrophotometry (GC-MS). RESULTS: The resazurin-based TB assay demonstrated that the L. cuprina larval extract was inhibitory against all tested bacteria, whilst the larval extract of S. peregrina and M. domestica were only inhibitory against the MRSA, with a MIC of 100 mg ml-1. Subsequent sub-culture of aliquots revealed that the larval extract of L. cuprina was bactericidal against MRSA whilst the larval extracts of S. peregrina and M. domestica were bacteriostatic against MRSA. The GC-MS analysis had quantitatively identified 20 organic compounds (fatty acids or their derivatives, aromatic acid esters, glycosides and phenol) from the larval extract of L. cuprina; and 5 fatty acid derivatives with known antimicrobial activities from S. peregrina and M. domestica. CONCLUSION: The resazurin-based turbidometric assay is a simple, reliable and feasible screening assay which evidently demonstrated the antibacterial activity of all fly larval extracts, primarily against the MRSA. The larval extract of L. cuprina exerted a broad spectrum antibacterial activity against all tested bacteria. The present study revealed probable development and use of novel and effective natural disinfectant(s) and antibacterial agent(s) from flies and efforts to screen more fly species for antibacterial activity using resazurin-based TB assay should be undertaken for initial screening for subsequent discovery and isolation of potential novel antimicrobial substances, particularly against the multi-drug resistant strains.

Evaluation of Insect Growth Regulators Against Field-Collected Aedes aegypti and Aedes albopictus (Diptera: Culicidae) from Malaysia.

Susceptibility status of Aedes aegypti (L.) and Aedes albopictus Skuse larvae obtained from 12 states in Malaysia were evaluated against five insect growth regulators (IGRs), namely, pyriproxyfen, methoprene, diflubenzuron, cyromazine, and novaluron under laboratory conditions. Field populations of Ae. aegypti exhibited moderate resistance toward methoprene and low resistance toward pyriproxyfen, with resistance ratios of 12.7 and 1.4, respectively, but susceptibility to diflubenzuron, cyromazine, and novaluron. On the other hand, field populations of Ae. albopictus exhibited low resistance against diflubenzuron and novaluron, with resistance ratio of 2.1 and 1.0, respectively, but susceptibility to other tested IGRs. Our study concluded that the tested IGRs provide promising results and can be used to control field population of Ae. aegypti and Ae. albopictus, especially cyromazine. The use of IGR should be considered as an alternative when larvae develop resistance to conventional insecticides.

Association of physical activity with blood pressure and blood glucose among Malaysian adults: a population-based study.

BACKGROUND: The health-enhancing benefits of physical activity (PA) on hypertension and diabetes have been well documented for decades. This study aimed to determine the association of PA with systolic and diastolic blood pressure as well as blood glucose in the Malaysian adult population. METHODS: Data were extracted from the 2011 National Health and Morbidity Survey (NHMS), a nationally representative, cross-sectional study. A two-stage stratified sampling method was used to select a representative sample of 18,231 Malaysian adults aged 18 years and above. The PA levels of the respondents were categorised as low, moderate or high according to the International Physical Activity Questionnaire (IPAQ)-short form. Blood pressure and fasting blood glucose levels were measured using a digital blood pressure-measuring device and finger-prick test, respectively. RESULTS: Systolic blood pressure (SBP) level was positively associated with PA level (p = 0.02) whilst no significant association was noted between PA level and diastolic blood pressure (DBP). In contrast, respondents with low (adjusted coefficient = 0.17) or moderate (adjusted coefficient = 0.03) level of PA had significantly higher blood glucose level as compared to those who were highly active (p = 0.04). CONCLUSIONS: A significant negative association was observed between PA level and blood glucose only. Future studies should employ an objective measurement in estimating PA level in order to elucidate the actual relationship between PA, hypertension and diabetes for the development of effective interventions to combat the increasing burden of premature-mortality and cardiovascular disease-related morbidity in Malaysia.

The cry toxin operon of Clostridium bifermentans subsp. malaysia is highly toxic to Aedes Larval Mosquitoes.

The management and control of mosquito vectors of human disease currently rely primarily on chemical insecticides. However, larvicidal treatments can be effective, and if based on biological insecticides, they can also ameliorate the risk posed to human health by chemical insecticides. The aerobic bacteria Bacillus thuringiensis and Lysinibacillus sphaericus have been used for vector control for a number of decades. But a more cost-effective use would be an anaerobic bacterium because of the ease with which these can be cultured. More recently, the anaerobic bacterium Clostridium bifermentans subsp. malaysia has been reported to have high mosquitocidal activity, and a number of proteins were identified as potentially mosquitocidal. However, the cloned proteins showed no mosquitocidal activity. We show here that four toxins encoded by the Cry operon, Cry16A, Cry17A, Cbm17.1, and Cbm17.2, are all required for toxicity, and these toxins collectively show remarkable selectivity for Aedes rather than Anopheles mosquitoes, even though C. bifermentans subsp. malaysia is more toxic to Anopheles. Hence, toxins that target Anopheles are different from those expressed by the Cry operon.

First report on adulticide susceptibility status of Aedes albopictus, Culex quinquefasciatus, and Culex vishnui from a pig farm in Tanjung Sepat, Selangor, Malaysia.

The present study aims to investigate the susceptibility status of Aedes albopictus, Culex quinquefasciatus, and Cx. vishnui collected from a pig farm in Tanjung Sepat, Selangor, toward 11 insecticides representing the classes of organochlorines, carbamates, organophosphates, and pyrethroids. The results of a World Health Organization adult mosquito bioassay revealed that Ae. albopictus, Cx. quinquefasciatus, and Cx. vishnui exhibited different susceptibility toward various insecticides. Overall, pyrethroids were able to induce rapid knockdown for all test mosquito species. The pyrethroids lambdacyhalothrin and etofenprox were able to cause high mortality (> 80%) of all 3 species. The findings of the present study will benefit local authorities in selecting appropriate dosage of insecticides to be used in mosquito control in this area.

Spatial Distribution and Long-Term Persistence of Wolbachia-Infected Aedes aegypti in the Mentari Court, Malaysia.

Dengue is endemic in Malaysia, and vector control strategies are vital to reduce dengue transmission. The Wolbachia strain wAlbB carried by both sexes of Ae. aegypti was released in Mentari Court, a high-rise residential site, in October 2017 and stopped after 20 weeks. Wolbachia frequencies are still being monitored at multiple traps across this site, providing an opportunity to examine the spatiotemporal distribution of Wolbachia and mosquito density with respect to year, residential block, and floor, using spatial interpolation in ArcGIS, GLMs, and contingency analyses. In just 12 weeks, Wolbachia-infected mosquitoes were established right across the Mentari Court site with an overall infection frequency of >90%. To date, the Wolbachia frequency of Ae. aegypti has remained high in all areas across the site despite releases finishing four years ago. Nevertheless, the Wolbachia invaded more rapidly in some residential blocks than others, and also showed a relatively higher frequency on the eighth floor. The Ae. aegypti index tended to differ somewhat between residential blocks, whilst the Ae. albopictus index was relatively higher at the top and bottom floors of buildings. In Mentari Court, only a short release period was required to infiltrate Wolbachia completely and stably into the natural population. The results inform future releases in comparable sites in a dengue control programme.

Nationwide distribution of Culex mosquitoes and associated habitat characteristics at residential areas in Malaysia.

A standardized larval dipping method was used to determine the infestation rates of Culex and other species of mosquitoes in stagnant water at 20 residential areas. This study also examined the associations between Culex distribution and various habitat characteristics across all states in Malaysia. Identification of 7,848 specimens yielded 6 species dominated by Culex quinquefasciatus (82.74%), followed by Cx. vishui (14.39%), Cx. gelidus (2.70%), Lutzia fuscanus (0.11%), Armigeres subalbatus (0.05%), and Anopheles separatus (0.01%). The Culex larvae occurred in stagnant water with pH ranging from 6.4 to 8.2; conductivity, 139.7 to 6635.2 micros/cm; salinity, 0.07 to 3.64 ppt; total dissolved solids, 0.09 to 4.27g/liter; and dissolved oxygen, 5.11 to 8.11 mg/liter. The mean number of Culex larvae was positively correlated with pH, conductivity, salinity, and total dissolved solids. In contrast, the elevation and dissolved oxygen were found negatively correlated with mean number of Culex larvae. This study documented baseline information on the habitat characteristics of Culex species for the 1st time at different residential areas in Malaysia. The findings of this study will be a timely reminder to local authorities that effective control measures should be monitored regularly in order to reduce the nuisance of these mosquitoes and the risks of disease transmission.

Molecular identification of blow flies recovered from human cadavers during crime scene investigations in Malaysia.

Forensic entomology applies knowledge about insects associated with decedent in crime scene investigation. It is possible to calculate a minimum postmortem interval (PMI) by determining the age and species of the oldest blow fly larvae feeding on decedent. This study was conducted in Malaysia to identify maggot specimens collected during crime scene investigations. The usefulness of the molecular and morphological approach in species identifications was evaluated in 10 morphologically identified blow fly larvae sampled from 10 different crime scenes in Malaysia. The molecular identification method involved the sequencing of a total length of 2.2 kilo base pairs encompassing the 'barcode' fragments of the mitochondrial cytochrome oxidase I (COI), cytochrome oxidase II (COII) and t-RNA leucine genes. Phylogenetic analyses confirmed the presence of Chrysomya megacephala, Chrysomya rufifacies and Chrysomya nigripes. In addition, one unidentified blow fly species was found based on phylogenetic tree analysis.

Hirudotherapy in Wound Healing.

Leeches are hermaphrodite, bloodsucking parasitic worms usually found in places with fresh water. Leech therapy existed 3000 years, and it is being used at a different scope. Several species of leeches have been used in medicine, and the most common species used is Hirudo medicinalis. Leeches suck the excess blood, reduce the swelling in the tissues, and promote healing by allowing fresh oxygenated blood to reach the area until normal circulation can be restored. Pain relief from leech therapy is rapid, effective, and long-lasting in many conditions. The aim of this study was to evaluate the efficacy and duration of healing utilizing sterile medicinal leeches, Hirudinaria manillensis, in the management of pain and wound healing. Leech was taken out from its sterile tube by using a pair of non-tooth sterile plastic forceps and gloved hands. Each leech was left in place for as long as it was feeding. Leeches were removed only after they became detached from the patient. The specimen jars containing the used leeches were sealed in either a biohazard bag or in a small yellow clinical waste bin liner securely fastened with a cable tie. The leech was killed by using 70% alcohol prior to disposal into a yellow hazard bin, which undergoes incineration. All 3 patients had improvements in their condition, especially in terms of reduction in the pain and improvement in their sense of balance. All the wounds healed well. Therefore, leech therapy is effective in reducing pain and increasing perfusion to allow the wounds to heal quickly. However, a more robust trial is needed to show significance as the sample size is small.

Maggot Debridement Therapy in Malaysia.

Maggot therapy, also known as maggot debridement therapy, larval therapy, biodebridement, or biosurgery, is a type of biotherapy involving the intentional application of live, disinfected fly larvae or maggots into the nonhealing wound of a human or animal to debride the necrotic wound, reduce bacterial contamination of the wound as well as enhance the formation of healthy granulation tissue and stimulate healing in nonhealing wounds. In addition, van der Plas et al reported that the use of the medicinal larvae as natural remover of necrotic and infected tissue had prevented amputation in 11 selected patients. In Malaysia, Aaron et al had demonstrated prevention of amputation in 25 patients.

Adulticide Resistance Status of Aedes albopictus (Diptera: Culicidae) in Sarawak State, Malaysia.

Resistance status of Aedes albopictus (Skuse) from 13 districts in Sarawak State, Malaysia, was evaluated against four major classes of adulticides, namely organochlorine, organophosphate, carbamate, and pyrethroid. Adult bioassays were performed according to the World Health Organization (WHO) standard protocols to assess knockdown and mortality rates of Ae. albopictus. Among the tested pyrethroids, only cyfluthrin was able to exhibit complete knockdown. On the other hand, different susceptibility and resistance patterns were observed in other adulticides. As for mortality rates, the mosquitoes were susceptible to cyfluthrin and dieldrin but exhibited various susceptibilities to other tested adulticides. Cross-resistance was discovered within and between tested insecticide classes. Significant correlations were found within pyrethroid and carbamate classes (i.e., bendiocab and propoxur, P = 0.036; etofenprox and permethrin, P = 0.000; deltamethrin and lambda-cyhalothrin, P = 0.822; deltamethrin and permethrin, P = 0.042). Additionally, insecticides belonging to different groups were also found significantly correlated (i.e., malathion and deltamethin, P = 0.019; malathion and bendiocarb, P = 0.008; malathion and propoxur, P = 0.007; and bendiocarb and deltamethrin, P = 0.031). In conclusion, cyfluthrin was effective for Aedes albopictus control in Sarawak State and these data may assist local authorities to improve future vector control operations.

Insecticide resistance in dengue vectors from hotspots in Selangor, Malaysia.

BACKGROUND: In Malaysia, dengue remains a top priority disease and usage of insecticides is the main method for dengue vector control. Limited baseline insecticide resistance data in dengue hotspots has prompted us to conduct this study. The present study reports the use of a map on the insecticide susceptibility status of Aedes aegypti and Aedes albopictus to provide a quick visualization and overview of the distribution of insecticide resistance. METHOD AND RESULTS: The insecticide resistance status of Aedes populations collected from 24 dengue hotspot areas from the period of December 2018 until June 2019 was proactively monitored using the World Health Organization standard protocol for adult and larval susceptibility testing was conducted, together with elucidation of the mechanisms involved in observed resistance. For resistance monitoring, susceptibility to three adulticides (permethrin, deltamethrin, and malathion) was tested, as well as susceptibility to the larvicide, temephos. Data showed significant resistance to both deltamethrin and permethrin (pyrethroid insecticides), and to malathion (organophosphate insecticide) in all sampled Aedes aegypti populations, while variable resistance patterns were found in the sampled Aedes albopictus populations. Temephos resistance was observed when larvae were tested using the diagnostic dosage of 0.012mg/L but not at the operational dosage of 1mg/L for both species. CONCLUSION: The present study highlights evidence of a potential threat to the effectiveness of insecticides currently used in dengue vector control, and the urgent requirement for insecticide resistance management to be integrated into the National Dengue Control Program.

Entomological Surveillance Associated with Human Zika Cases in Miri Sarawak, Malaysia.

Two confirmed human cases of Zika virus (ZIKV) were reported in the district of Miri, Sarawak, in 2016. Following that, a mosquito-based ZIKV surveillance study was conducted within 200-m radius from the case houses. Mosquito surveillance was conducted using five different methods, that is, biogents sentinel mosquito (BG) sentinel trap, modified sticky ovitrap, resting catch, larval surveillance, and conventional ovitrap. A total of 527 and 390 mosquito samples were obtained from the case houses in two localities, namely, Kampung Lopeng and Taman Shang Ri La, Miri, Sarawak, respectively. All mosquitoes collected were identified, which consisted of 11 species. Aedes albopictus, both the adult and larval stages, was the dominant species. Resting catch method obtained the highest number of adult mosquitoes (67%), whereas ovitrap showed the highest catch for larval mosquitoes (84%). Zika virus was detected in both adults and larvae of Ae. albopictus together with adults of Culex gelidus, and Culex quinquefasciatus using the real-time reverse transcriptase polymerase chain reaction (PCR) technique. It was noteworthy that Ae. albopictus positive with ZIKV were caught and obtained from four types of collection method. By contrast, Cx. gelidus and Culex quinquefasciatus adults collected from sticky ovitraps were also found positive with ZIKV. This study reveals vital information regarding the potential vectors of ZIKV and the possibility of transovarian transmission of the virus in Malaysia. These findings will be essentials for vector control program managers to devise preparedness and contingency plans of prevention and control of the arboviral disease.

Semi-field evaluation of the bio-efficacy of two different deltamethrin formulations against Aedes species in an outdoor residual spraying study.

In recent decades, dengue incidence has trended upward worldwide causing urgent needs for new or modified vector control methods. We modified the existing indoor residual spraying (IRS) method by applying insecticide on the outer walls of building structures in an outdoor residual spraying (ORS) study. A semi-field study was conducted to investigate the bio-efficacy of two different deltamethrin formulations: K-Othrine® Polyzone, new polymer-enhanced deltamethrin formulated as a suspension concentrate (SC-PE), and K-Othrine® WG 250, traditional deltamethrin formulated as water dispersible granule (WG). The residual bio-efficacy of deltamethrin SC-PE was compared to deltamethrin WG on finished cement surfaces applied to the outer walls at the Institute for Medical Research (IMR), Malaysia. Standard WHO cone wall bioassays were adapted to evaluate the effective duration of action of these deltamethrin formulations against susceptible laboratory-reared and wild, free-flying Aedes aegypti and Ae. albopictus. Analyses of bioassay results showed that deltamethrin SC-PE 30 mg/m2 has improved longevity in comparison to deltamethrin WG 30 mg/m2. Deltamethrin SC-PE 30 mg/m2 was effective until week 17 (producing > 80% mortality), surpassing deltamethrin WG 30 mg/m2 which only lasted until week 10. This was supported by post-hoc test analyses which demonstrated that deltamethrin SC-PE 30 mg/m2 produced the highest mean of mortality in laboratory-reared Aedes species and the wild Ae. albopictus. However, the effective duration of action of deltamethrin SC-PE (17 weeks) was less than the recommended period by WHO (6 months) but was reasonable given that the spraying was undertaken outdoor. This preliminary data could be of use for the deployment of locally adapted ORS operation in controlling dengue.

Vertical Infestation Profile of Aedes in Selected Urban High-Rise Residences in Malaysia.

Dengue is placing huge burdens on the Malaysian healthcare system as well as the economy. With the expansion in the number of high-rise residential buildings, particularly in the urban centers, the flight range and behavior of Aedes mosquitoes may be altered in this habitat type. In this study, we aimed to expand the understanding of the vertical distribution and dispersal of Aedes in nine selected high-rise residences in Kuala Lumpur, Selangor, and Johor using ovitraps as the sampling method. We discovered that Ae. aegypti is the predominant species in all study sites. Both Ae. aegypti and Ae. albopictus are most abundant within the first three levels and could be found up to level 21 (approximately 61.1-63.0 m). Pearson correlation analyses exhibited negative correlations in eight out of nine study sites between the ovitrap indexes (OIs) within each floor level, suggesting that Aedes density decreased as the building level increased. Our findings provide information to the public health authorities on 'hot spot' floors for effective suppression of dengue transmission.

Wide-Angle Scanning Phased Array Antenna using High Gain Pattern Reconfigurable Antenna Elements.

This paper presents a wide-angle scanning phased array antenna using high gain pattern reconfigurable antenna (PRA) elements. Using PRA elements is an attractive solution for wide-angle scanning phased array antennas because the scanning range can be divided into several subspaces. To achieve the desired scanning performance, some characteristics of the PRA element such as the number of switching modes, tilt angle, and maximum half-power beamwidth (HPBW) are required. We analyzed the required characteristics of the PRA element according to the target scanning range and element spacing, and presented a PRA element design guideline for phased array antennas. In accordance with the guideline, the scanning range was set as ±70° and a high gain PRA element with three reconfigurable patterns was used to compose an 8x1 array antenna with 0.9 λ0 spacing. After analyzing whether the active element patterns meet the guideline, the array antenna was fabricated and measured to demonstrate the scanning performance. The fabricated array can scan its beam from -70° to 70° by dividing the scanning range into three subspaces. It shows that even if the array antenna has large element spacing, the desired scanning performance can be obtained using the elements designed under the guideline.