Secondary Vectors Research Articles

Molecular phylogeny of Anopheles nivipes based on mtDNA-COII and mosquito diversity in Cambodia-Laos border

BackgroundFew studies have been conducted to investigate the distribution of mosquito vectors and the population structure of secondary vectors in the border region of Cambodia-Laos. The aim of this work was to study the mosquito diversity and molecular phylogeny of secondary vectors, i.e., Anopheles nivipes in this area.Methods1440 adult mosquitoes were trapped in the Cambodia-Laos border. mtDNA-COII were amplified and sequenced from 53 An. nivipes DNA samples. Together with COII sequences deposited in GenBank, a total of 86 COII sequences were used for examining population variations, genetic differentiation, spatial population structure, population expansion, and gene flow patterns.ResultsThe adult mosquitoes were classified into 5 genera and 27 species in this border region. The predominant genera were Culex (60.07%, 865/1440) and Anopheles (31.25%, 450/1440), and the major Anopheles species were An. nivipes (73.56%, 331/450) and Anopheles maculatus (14.22%, 64/450). Based on sequences analysis of COII, a high level of genetic differentiation was reported in two Northwest India (Cheema and Bathinda, Punjab) and Cambodia-Laos (Siem Pang, Stung treng) populations (FST = 0.97824, 0.97343, P < 0.05), as well as lower gene flow (Nm = 0.01112, 0.01365) in the An. nivipes populations. Phylogenetic analysis and SAMOVA revealed a gene barrier restricting gene flow among three An. nivipes populations. Mantel test suggested a significant correlation between geography and gene distance in all An. nivipes populations (Z = 44,983.1865, r = 0.5575, P = 0.0070). Neutrality test and Mismatch distribution revealed a recent population expansion of An. nivipes in the Cambodia-Laos population.ConclusionsAnopheles nivipes was one of the major Anopheles species in the Cambodia-Laos border. Based on sequences analysis of COII, a genetic barrier between Cambodia-Laos and two Indian populations was found, and a recent population expanding or selecting of An. nivipes occurred in the Cambodia-Laos population, suggesting that COII might be an effective marker for describing the molecular phylogeny of An. nivipes. Further investigation and continuous surveillance of An. nivipes are warranted in this region.

Susceptibility of Aedes albopictus Larvae to the Larvicidal Activity of Three Types of Derris elliptica Extract.

&lt;b&gt;Background and Objective:&lt;/b&gt; The methanol, ethyl acetate and n-hexane extracts of &lt;i&gt;D. elliptica&lt;/i&gt; root have high larvicidal activity against &lt;i&gt;Aedes aegypti&lt;/i&gt; larvae, the primary vector of dengue but have not been understood their potential against &lt;i&gt;Ae. albopictus&lt;/i&gt; larvae, the secondary vector of dengue that also transmits Chikungunya and Zika viruses. This &lt;i&gt;in vitro&lt;/i&gt; study aims to understand the larvicidal activity of the 3 extract types of &lt;i&gt;D. elliptica &lt;/i&gt;root against &lt;i&gt;Ae. albopictus&lt;/i&gt; larvae. &lt;b&gt;Materials and Methods:&lt;/b&gt; The tuba root extract types were obtained from the sequential extraction process with 3 steps of liquid-liquid partition as described in the previous report. Six concentrations were occupied in this experiment ranging of 0.5, 1.0, 2.0, 4.0, 10.0 and 15.0 mg L&lt;sup&gt;1&lt;/sup&gt; each concentration was 5 times replicated and placed in 250 mL plastic cups. As many as 20 of 3rd instar larvae of &lt;i&gt;Ae. albopictus&lt;/i&gt; were subjected in each treatment cup and larval mortality was observed after 24 and 48 hrs of exposure. &lt;b&gt;Results:&lt;/b&gt; Larval mortality rates based on concentration range of 13.75-97.00 and 43,75-100%, 14.00-44.00, 34.00-90.00%, 12.00-47.00 and 28.00-88.00%, with the LC&lt;sub&gt;50&lt;/sub&gt; after 24 and 48 hrs of exposure were 2.925 and 0.414, 16.184, 2.900, 15.789 and 4.380 mg L&lt;sup&gt;1&lt;/sup&gt;, respectively for methanol, ethyl acetate and n-hexane extracts. &lt;b&gt;Conclusion:&lt;/b&gt; The methanol, ethyl acetate and n-hexane extract of tuba root have high larvicidal activity against &lt;i&gt;Ae. albopictus&lt;/i&gt; larvae. Further study on prototype formulation of larvicide and elucidation of the specific phytochemical compounds of the extracts were necessarily conducted.

Comparison of nodal and edge basis functions for the forward modelling of three‐dimensional frequency‐domain wire source electromagnetic data using a potentials formulation

ABSTRACTAn investigation of forward modelling 3‐D wire source electromagnetic data in the frequency domain using nodal and edge finite‐element basis functions is presented. The equations solved are those for the coupled secondary vector–scalar potentials (i.e. magnetic vector potential A and electric scalar potential φ), which give rise to a less ill‐conditioned system of equations to be solved. The effectiveness of these two methods is validated with two 3‐D examples, i.e. multi‐blocks models and topography models, which considered the computation of the A–φ potentials and the electromagnetic fields due to a grounded electric line source by inter‐comparing the numerical solutions computed from each method and by comparing them against the equivalent solutions for the same model computed using other methods. Based on the multiple‐blocks models, we compare the relative contributions of the inductive and galvanic parts to the E‐field for different frequencies. Results show that for the type of source considered in this paper, the galvanic parts dominate for a relatively low frequency (10 Hz), but that for a relatively high frequency (10 kHz), the inductive parts also contribute. The extent to which the Coulomb gauge condition is satisfied when using nodal basis functions for A is also investigated, with results showing that the divergence of the numerically calculated A is almost zero as desired. Based on the topography models, we analyse the electromagnetic response characteristics at different survey planes, with results of this investigation indicating that the electromagnetic responses measured over a plane close to the target will carry more accurate geometry information (such as position, shape and size) of the target, which is expected, and less distortion due to topography compared to those measured at the earth's surface. This suggests that when conducting electromagnetic prospecting in an area with complex topography, it is possible to obtain better anomaly detection affected less by topography if the electromagnetic measurement is carried out underground (such as in a borehole).

Biodiversity and insecticide susceptibility status of major Anopheline fauna in three malariogenically stratified districts of Odisha, India

• Anopheline fauna showed a higher species richness and diversification in Kalahandi district. • An. culicifacies showed resistant to DDT as well as Malathion in all the three districts. • An. annularis showed resistance to Malathion only in Kalahandi district. • Vector diversification and their insecticide resistant status influenced malaria transmission. Understanding the species composition and biodiversity of anopheles mosquito population is a vital part of any malaria control intervention. Similarly, an effective malaria control strategy relies primarily on insecticides. The Anopheline diversity, composition, distribution as well as insectide susceptibility/resistance status were surveyed in three districts of Odisha viz. Kalahandi (southern hyper –endemic district), Bargarh (western meso -endemic district) and Cuttack (sub-coastal hypo-endemic district) which significantly differ from each other according to the malariogenic stratification. Anopheline fauna showed a higher species richness and diversification in Kalahandi followed by Cuttack and Bargarh. An. culicifacies , the most abundant primary vector in Odisha, showed resistant to DDT as well as malathion in all three districts with a higher knockdown time in Kalahandi. Except Bargarh and Cuttack, the vector species also showed resistance to deltamethrin in Kalahandi district. The species found susceptible to deltamethrin in Cuttack while in Bargarh, its response was under ‘verification required’. In contrast, the secondary vector, An. annularis showed resistance to DDT in all three districts and to malathion in only Kalahandi district. In Cuttack and Bargarh district, their response against the insecticide malathion was under verification required. The deltamethrin susceptible populations were detected in Cuttack and Bargarh district where as in Kalahandi they came under verification required category. The current study constitutes an essential step for understanding the dynamics of malaria transmission in relation to vector diversification and their resistant status to various insecticides that can provide guide to intervention policies and programmes in the fight against malaria.

Discrimination of 15 Amazonian Anopheline Mosquito Species by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism.

Precise identification of anopheline species is paramount for incrimination of malaria vectors and implementation of a sustainable control program. Anopheline mosquitoes are routinely identified morphologically, a technique that is time-consuming, needs high level of expertise, and prone to misidentifications especially when considering Amazonian species. The aim of this study was therefore to develop a DNA-based identification technique to supplement traditional morphological identification methods for the discrimination of anopheline mosquitoes collected in French Guiana. The internal transcribed spacer 2 (ITS2) region of ribosomal DNA (rDNA) for anopheline species was amplified by polymerase chain reaction (PCR), and digested with AluI/MspI restriction enzymes. PCR-restriction fragments length polymorphism (RFLP) assay was compared to sequencing of the ITS2 region for validation. Fifteen Anopheles species have shown distinct PCR-RFLP profiles. A concordance of 100% was obtained when identification by PCR-RFLP was compared to sequencing of ITS2. A high throughput, fast, and cost-effective PCR-RFLP assay has been developed for unambiguous discrimination of fifteen anopheline mosquito species from French Guiana including primary and suspected secondary malaria vectors.

Detection of Plasmodium Sporozoites and Blood-Meal Source in a Population of Anopheles Coustani Senso Lato in Kakamega County, Western Kenya

Background Re-emerging of malaria vectors in the highlands of Western Kenya pose a challenge to malaria eradication efforts . Anopheles coustanis.l is a sub-Saharan mosquito species implicated in transmission of malaria in many parts of Africa as a secondary vector. It is zoo-anthropophilic species that has been assumed to be of negligible importance which may not be the case. This study therefore aimed at getting the malaria vectorial system of the study area, has tried to determine the relative abundance of the vectors and a new outdoor malaria vector. Methods A cross sectional study was carried out in April to June, 2020 in Eluche location, Mumias East sub-County, Kakamega County, Kenya. Pyrethrum spray collections (PSC) and Centers for Disease Control (CDC) and prevention light traps were used for sampling mosquitoes. Mosquitoes were collected both indoors; between 0700h and 1100h using PSC and outdoors between 1800h and 0700h using CDC light traps. All mosquitoes were identified morphologically and female Anopheles’ heads and thorax were analyzed using Polymerase Chain Reaction (PCR) for Plasmodium sporozoite detection and blood-meal source identification. Results A total of 376 female Anopheles mosquitoes were collected composed of: An. coustanis.l, 42.55%; An. funestus, 27.66%; An. maculipulpis, 25.00%; An. arabiensis, 4.26% and An. gambiaes.s, 0.53%. Malaria sporozoites were detected in only An. coustani (1.06%). Conclusion There is a possibility of Anopheles coustani mosquito involvement in malaria transmission in Mumias east, Kakamega County.

Temporally consistent predominance and distribution of secondary malaria vectors in the Anopheles community of the upper Zambezi floodplain

Regional optimisation of malaria vector control approaches requires detailed understanding both of the species composition of Anopheles mosquito communities, and how they vary over spatial and temporal scales. Knowledge of vector community dynamics is particularly important in settings where ecohydrological conditions fluctuate seasonally and inter-annually, such as the Barotse floodplain of the upper Zambezi river. DNA barcoding of anopheline larvae sampled in the 2019 wet season revealed the predominance of secondary vector species, with An. coustani comprising > 80% of sampled larvae and distributed ubiquitously across all ecological zones. Extensive larval sampling, plus a smaller survey of adult mosquitoes, identified geographic clusters of primary vectors, but represented only 2% of anopheline larvae. Comparisons with larval surveys in 2017/2018 and a contemporaneous independent 5-year dataset from adult trapping corroborated this paucity of primary vectors across years, and the consistent numerical dominance of An. coustani and other secondary vectors in both dry and wet seasons, despite substantial inter-annual variation in hydrological conditions. This marked temporal consistency of spatial distribution and anopheline community composition presents an opportunity to target predominant secondary vectors outdoors. Larval source management should be considered, alongside prevalent indoor-based approaches, amongst a diversification of vector control approaches to more effectively combat residual malaria transmission.

A note on the insecticide susceptibility status of secondary malaria vector An. annularis in Jharkhand state of India.

An. annularis van der Wulp (1884) is the secondary malaria vector of importance in India. In Jharkhand state it is present in almost all the districts abundantly and transmits malaria. The development of resistance to Dichlorodipheny ltrichloroethane (DDT) in An. annularis was reported from various parts of India. The main objective of this study was to generate information on insecticide susceptibility status of An. annularis to DDT, malathion, deltamethrin and permethrin in different districts of Jharkhand state. Methods; Adult An. annularis female mosquitoes were collected form villages of six tribal districts Simdega (Kurdeg and Simdega CHC), Khunti (Murhu and Khunti CHCs), Gumla (Bharno and Gumla CHCs), West Singhbhum (Chaibasa and Bada Jamda CHCs), Godda (Poraiyahat and Sunderpahari (CHCs) and Sahibganj (Borio and Rajmahal CHCs). Insecticide susceptibility status was determined by using WHO tube test method against prescribed discriminatory dosages of insecticides, DDT - 4.0%, malathion - 5.0%, deltamethrin - 0.05% and permethrin - 0.75%. An. annularis was reported resistant to DDT in six districts, possible resistant to malathion in districts Gumla, Khuntiand Sahibganj and susceptible to deltamehrin (98% to100% mortality) and permethrin (100% mortality). An. annularis, the secondary vector species is associated with the transmission of malaria reported resistant to DDT and susceptible to pyrerthroids deltamethrin and permethrin. In view of large-scale distribution of long-lasting insecticidal nets (LLINs) in all the districts, the response to synthetic pyrethroid needs to be periodically monitored to assess the effectiveness.

Vector Bionomics, Potential Vectors, Susceptibility and Bio-efficacy of LLINs Nets on Anopheles Mosquitoes in Nanyin Village Bunmouk Township Sagaing Region in Myanmar

Nanyin village is a malaria endemic area consisting of Bunmouk Township Sagaing Region in Myanmar. Ohnpinkone and Bwedarkone wards were chosen for measuring vector bionomics, potential vectors, susceptibility and bio-efficacy of long lasting insecticidal nets (LLINs) (due to high prevalence of P. falciparum) in both wards from December 2019 to October 2020. A total of 3236 and 3019 Anopheles mosquitoes consist of 12 species were collected from both Ohnpinkone and Bwedarkone wards. Anopheles barbirostris was found highest number (1088 and 820) followed by An. philippinensis (267 and 605) in both areas. Higher number of Anopheles mosquitoes were collected by Cattle bait catching method followed by Indoor Light traps method. The highest was collected in October in Ohnpinkone and September in Bwedarkone. In Ohnpinkone, the highest was collected in April by outdoor and August in indoor light trap and March by outdoor and June by indoor light traps in Bwedarkone. Higher number of main vectors of An. minimus and An. dirus were collected in Ohnpinkone than Bwedarkone and highest number of An. minimus was collected by cattle bait (77) followed by indoor light method (72) in Ohnpinkone. Only 11and 3 An. dirus were collected, of this 9 and 1 number were collected by indoor light traps method from both wards. One An. minimus from Ohnpinkone was found sporozoite positive (0.47%). Main vector An. minimus was collected highest in April in Ohnpinkone and June in Bwedarkone. Susceptibility status of primary and secondary vectors were found susceptible to Pyrethroid insecticides. Bio-efficacy of all tested LLINs nets were found lower efficacy 20% and 63.33% in both wards. Main vector of An. minimus was collected year round in large number in both areas as well as sporozoite positive and An. dirus was available in both areas. Therefore, both areas are highly malaria risk areas and need to proper treatment and control measure using RIS and supply new LLINs nets or retreatment with deltamethrin to old nets according to WHO guideline to ovoid malaria transmission.

Risk factors and spatial analysis for domiciliary infestation with the Chagas disease vectorTriatoma venosain Colombia

Background:In Colombia, communities living in the Andean region are the most affected by Chagas disease due to the presence of the main vectors, the environmental and risk factors associated with house infestation. Triatoma venosa is classified as a secondary vector that is frequently found in the departments of Boyaca and Cundinamarca, but epidemiological information and its association with risk factors in domestic and peridomestic areas is unknown. The study aimed to evaluate housing and environmental characteristics associated with domestic and peridomestic infestation by T. venosa and a risk map was estimated.Methods:A cross-sectional study was conducted in municipalities of Boyaca and Cundinamarca, Colombia. From March to July 2015, triatomine infestation screening surveys were conducted in 155 households. Multivariate analysis was performed to evaluate associations with the infestation and ecological niche modeling was estimated using environmental variables.Results:No statistical association was found with any of the housing variables in the adjusted multivariate analysis. However, in raw relationship infestation was associated with bushes < 10 m (OR = 3; 95% CI: 1.3–7.3) and higher temperature p value < 0.05. The developed final risk map pointed to 12 municipalities with no previous report of the disease, which should be sampled for the presence of T. venosa.Conclusion:This study highlights the relationship between environmental factors and T. venosa in Colombia and the importance of modeling tools to improve mapping efforts. Additional studies are needed to verify the association with bushes and higher temperatures and to verify infestation in predicted risk area with no previous report of the species

Assessment of Dengue larval indices and breeding habitats in the slums of urban field practice area of Bangalore Medical College- An observational study

Background and Objectives Dengue is one of the major mosquito-borne diseases in India posing a threat to human health. The mosquito Aedes Stegomyia aegypti Linn. and Aedes Stegomyia albopictus Skuse Diptera Culicidae are the primary and secondary vectors of dengue virus respectively. This study is aimed at the assessment of Dengue breeding in slum areas of urban Bengaluru.Methodology In this study an entomological survey was carried out indoors and outdoors to record the actual breeding sites and distribution level of dengue vectors. The survey was conducted in the field practice area of Bangalore Medical College India. A total of 9782 containers with water from 4869 houses were surveyed during the study period.Results The larval indices were calculated in each sector belonging to the field practice area of which sector 2 was the highest which had a house index of 4.9 container index of 2.8 and Breteau index of 5.7.Conclusion The most frequently encountered breeding sites were unused grinding stones flower pots drums barrels rubber tires and cement tanks.nbsp

Electric power metering with its low quality

The issue of electricity metering with low quality is being considered. Special attention is paid to checking the connection metering scheme with low quality of electrical energy. It is shown that a specific circuit design can affect the accuracy of metering of electrical energy in case of poor quality of electrical energy. In distribution networks intended for power supply of industrial enterprises, reactive power is also active. If the consumer has compensating devices, the directions of active and reactive power can be opposite. It is noted that current transformers, selected taking into account the short-circuit current or the characteristics of relay protection, do not provide metering accuracy due to the increased transformation ratio, forcing the installation of an additional set of current transformers or transferring the meters to another point in the network. Thus, the current transformation ratio of the current transformer is somewhat different from the nominal one, and the secondary current vector forms a certain angle with the primary current vector. The voltage error is manifested in a slight decrease in the secondary voltage under load. The angular error is characterized by a certain angle between the vectors of the primary and secondary stress. The value of the errors depends on the load power of the transformer. The maximum allowable voltage drop of the transformer determines the accuracy class. A rated power is set for each accuracy class. Thus, the voltage transformer, depending on the load, can operate in different accuracy classes. Changing the accuracy classes leads to errors in the measurements of metering devices and requires appropriate correction. The article reveals the reasons for the occurrence of such errors, which makes it possible to develop methods and, as a consequence, create devices to prevent the described errors of metering devices.

A different cardiac resynchronization therapy technique might be needed in some patients with nonspecific intraventricular conduction disturbance pattern.

BACKGROUNDCurrent cardiac resynchronization therapy (CRT), devised to eliminate dyssynchrony in left bundle branch block (LBBB), works by pacing the latest activated left ventricular site (LALVS). We hypothesized that patients with nonspecific intraventricular conduction disturbance (NICD) pattern respond less favorably to CRT, because their LALVS is far away from that in LBBB.METHODSBy measuring the amplitude and polarity of secondary ST-segment alterations in two optional frontal and horizontal surface electrocardiogram (ECG) leads and using a software, we determined the resultant 3D spatial secondary ST vector, which is directed 180o away from the LALVS, in 110 patients with LBBB pattern and 77 patients with NICD pattern and heart failure. To validate the ECG method, we also estimated the LALVS by echocardiography using 3D parametric imaging and 2D speckle tracking in 22 LBBB patients and 20 NICD patients. Patients with NICD pattern were subdivided according to their non-overlapping frontal plane resultant secondary ST vector ranges to the NICD-1 subgroup (n = 44) and the NICD-2 subgroup (n = 33). RESULTSBased on the software determined coordinates of the resultant 3D spatial secondary ST vector directed 180o away from the LALVS, the LALVSs were located leftward, posterosuperior in the LBBB group, slightly left, superior in the NICD-1 subgroup, and slightly left, posteroinferior in the NICD-2 subgroup. The LALVS determined by ECG and echocardiography matched in all patients, except two. CONCLUSIONSIn the NICD-2 subgroup, a remote LALVS was found from that in LBBB pattern, which might explain the high non-response rate of the NICD pattern to the current CRT technique.

Endemicity of Dengue with Density Figure and Maya Index in Bengkulu City, Indonesia

BACKGROUND: One of the factors contributing to dengue’s endemicity is the density of the dengue vector, namely, Aedes aegypti as the primary vector and Aedes albopictus as the secondary vector. Bentiring and Kandang Limun villages are high endemic areas of dengue. AIM: This study aimed to determine the relationship between dengue endemicity and density figure (DF) and Maya index (MI) in Bentiring and Kandang Limun villages, Bengkulu city. METHODS: This study used a cross-sectional design. The sampling technique used proportionate stratified sampling. The sampling refers to the guidelines for dengue entomology surveys according to the WHO 1999 criteria. A total of 400 ovitraps were installed, 200 ovitraps inside the house and 200 ovitraps outside the house. RESULTS: The results showed that Bentiring and Kandang Limun villages had a high risk of dengue transmission based on entomological parameters, namely, ovitrap index (OI) 56% and 55% (DF 6), house index (HI) 45% and 44% (DF 6), container index (CI) 23% and 23% (DF 6), and BI 96% and 120% (DF 7 and 8). The areas have a high risk of dengue transmission based on the MI 71% and 76%, respectively. There is a relationship between dengue endemicity and entomological index in Bentiring and Kandang Limun villages, Bengkulu city, with a significance value (p = 0.000) and a powerful correlation (r = 1.000). CONCLUSION: There is a relationship between dengue endemicity and the MI in Bentiring village and Kandang Limun village, Bengkulu city, with a significance value (p = 0.014 and 0.058) and a powerful correlation (r = 0.920 and r = 1.000), respectively. The entomological index and DF are predictors for dengue prevention and control environment to minimize mosquito breeding sites and reduce disease transmission.

Eliminasi Endosimbion Wolbachia sp. pada Nyamuk Aedes albopictus dengan Antibiotik Tetrasiklin

Dengue Hemorrhagic Fever (DHF) is a disease caused by the dengue virus which is transmitted through the bite of the Aedes mosquito. Aedes aegypti, which is known as the primary vector of dengue virus, is naturally not infected by Wolbachia sp. endosymbiont, while Ae. albopictus which is a secondary vector naturally infected with Wolbachia sp. The Wolbachia sp. known to inhibit the transmission of Dengue virus, to study the mechanism, it is necessary to eliminate Wolbachia sp. from Ae. albopictus, then infects the Ae. albopictus with the Dengue virus. The aim of the study was to determine the ability of tetracycline antibiotics to eliminate Wolbachia sp. from the Ae. albopictus mosquito. Ae. albopictus eggs was obtained in the Ciamis area by survey method using ovitrap which was installed outside the house. The Ae. albopictus eggs are then incubated in the laboratory and reared until they become adult mosquitoes. Mosquitoes were treated with sugar feeding which had been given tetracycline 0.25mg/ml every two days alternated with blood feed. Detection of the presence of Wolbachia sp. on mosquitoes carried out in first to third generations by the polymerase chain reaction (PCR) method using Wsp-specific primers. The results showed that the first to third generation mosquitoes were still infected with Wolbachia sp. This shows that the dose of tetracycline antibiotics used has not been able to eliminate Wolbachia sp. from the Ae. albopictus mosquito.

An Effective Decoupling Control with Simple Structure for Induction Motor Drive System Considering Digital Delay

Digital processing poses a considerable time delay on controllers of induction motor (IM) driving system, which degrades the effects of torque/flux decoupling, slows the motor torque response down, or even makes the entire system unstable, especially when operating at a low switching frequency. The existing methods, such as feed-forward and feed-back decoupling methods based on the proportional integral controller (PI), have an intrinsic disadvantage in the compromise between high performance and low switching frequency. Besides, the digital delay cannot be well compensated, which may affect the system loop and bring instability. Conventional complex vector decoupling control based on an accurate IM model employs complicated decoupling loops that may be degraded by digital delay leading to discrete error. This article aims to give an alternative complex vector decoupling solution with a simple structure, intended for optimized decoupling and improving the system dynamic performance throughout the entire operating range. The digital delay-caused impacts, including secondary coupling effect and voltage vector amplitude/phase inaccuracy, are specified. Given this, the digital delay impact is canceled accurately in advance, simplifying the entire decoupling process greatly while achieving uncompromised decoupling performance. The simulation and experimental results prove the effectiveness and feasibility of the proposed decoupling technique.

Characteristics of hydrogen production from steam gasification of plant-originated lignocellulosic biomass and its prospects in Vietnam

Demands for the decline of CO2 emissions resulted in a significant transformation of the energy systems working on carbon sources towards more sustainable, clean, and renewable characteristics. Hydrogen is emerging as a secondary energy vector with ever-increasing importance in the decarbonisation progress. Indeed, hydrogen, a green and renewable energy source, could be produced from steam gasification of plant-originated lignocellulosic biomass. In this current review, key factors affect the hydrogen production yield from steam gasification of plant-originated lignocellulosic biomass, including the design of the gasifier, temperature, pressure, and steam-to-biomass ratio, steam flow rate, moisture and particle size of fed biomass, and catalysts were thoroughly analysed. Moreover, the effects of the abovementioned factors on the reduction of tar formation, which is also a key parameter towards ensuring the trouble-free operation of the reactor, were critically evaluated. More importantly, the separation of produced hydrogen from steam gasification of biomass and challenges over technological, environmental, and economic aspects of biomass gasification were also presented in detail. In addition, this paper is also profiling the prospect of Vietnam in fulfilling its hydrogen economy potential because Vietnam has vast biomass due to its tropical weather and availability of arable land, providing abundant lignocellulosic biomass with 45% of agricultural waste, 30% of firewood, and 25% of other sources. Besides, some primary factors hindering the broad application of biomass for hydrogen production were indicated. Finally, some solutions for implementing the hydrogenization strategy in Vietnam have also been discussed.

Detection of immunogenic protein from salivary gland of Aedes albopictus

BackgroundDengue virus is transmitted by several species of Aedes mosquitoes, with Aedes albopictus as secondary vector. During blood feeding, these vectors inject saliva into the vertebrate hosts. The saliva contains anticoagulant, anti-inflammatory and immunogenic factors. The objective of this research was to detect immunogenic proteins from Ae.albopictus salivary glands reacting with sera of people living in dengue endemic areas. MethodsThe identification of immunogenic proteins of Ae. albopictus salivary gland used one-dimensional gel electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis), and western blot analysis, respectively. To determine the immunogenic nature of the candidate proteins, the antigens from the salivary gland of Ae. albopictus were reacted with sera from healthy persons, dengue hemorrhagic fever (DHF) patients, and neonates, each of the groups comprising 10 samples. ResultsThe protein profiles of Ae. albopictus salivary glands showed 13 bands with molecular weights from 16 kDa up to 97 kDa, i.e. 16, 17, 26, 28, 31, 32, 45, 55, 60, 67, 73, 76, and 97 kDa. According to western blot analysis result, the 31 kDa proteins were recognized in all endemic population sera, both in DHF patients and healthy persons. In contrast, protein bands of 47 and 67 kDa were only recognized by the sera of DHF patients. ConclusionThree immunogenic proteins of 31, 47 and 67 kDa were detected from Ae. albopictus salivary glands. These immunogenic proteins may be developed as candidate biomarkers for bite exposure to Ae. albopictus and as vector-based DHF vaccines.

Development of Various Leishmania (Sauroleishmania) tarentolae Strains in Three Phlebotomus Species.

Leishmania (Sauroleishmania) tarentolae is transmitted by reptile-biting sand flies of the genus Sergentomyia, but the role of Phlebotomus sand flies in circulation of this parasite is unknown. Here, we compared the development of L. (S.) tarentolae strains in three Phlebotomus species: P. papatasi, P. sergenti, and P. perniciosus. Laboratory-bred sand flies were membrane-fed on blood with parasite suspension and dissected on days 1 and 7 post blood meal. Parasites were measured on Giemsa-stained gut smears and five morphological forms were distinguished. In all parasite-vector combinations, promastigotes were found in Malpighian tubules, often in high numbers, which suggests that this tissue is a typical location for L. (S.) tarentolae development in sand flies. All three studied strains colonized the hindgut, but also migrated anteriorly to both parts of the midgut and colonized the stomodeal valve. Significant differences were demonstrated between sand fly species: highest infection rates, high parasite loads, and the most frequent anterior migration with colonization of the stomodeal valve were found in P. perniciosus, while all these parameters were lowest in P. sergenti. In conclusion, the peripylarian type of development was demonstrated for three L. (S.) tarentolae strains in three Phlebotomus sand flies. We suggest paying more attention to Phlebotomus species, particularly P. perniciosus and P. papatasi, as potential secondary vectors of Sauroleishmania.

Entomological survey in two communes with residual malaria transmission in Gia Lai Province in the central highlands of Vietnam

BackgroundIn 2018, the National Malaria Control Programme in Vietnam switched from prioritizing malaria control to elimination. However, with the ongoing elimination programme, there are still areas where residual malaria transmission persists, including the central highlands. This entomological survey was conducted to evaluate Anopheles diversity and host-seeking activity of Anopheles vectors in two communes with very low malaria transmission in Gia Lai Province.MethodsAnopheles species were collected in Ia DReh commune and Ia KDam commune, Gia Lai Province in the central highlands of Vietnam. Collections were conducted using human-baited double net trap, light trap and manual aspiration collections around cattle sheds, in the dry and rainy season. Mosquito specimens were identified morphologically, and members of species complexes were distinguished molecularly. Mosquito night-feeding patterns were investigated during the dry and rainy seasons.ResultsOverall, 18,835 specimens including 19 taxa were collected in Ia KDam and Ia DReh communes. These included the primary malaria vectors, Anopheles dirus and Anopheles minimus, and other secondary vector species. Anopheles dirus was observed to be an anthropophilic species, whereas An. minimus and a number of secondary vectors were observed to be zoophilic. Anopheles vagus was the dominant species, followed by Anopheles sinensis and Anopheles peditaeniatus. The majority of specimens were collected in the rainy season due to the relatively large number of An. vagus, while An. peditaeniatus, An. dirus, Anopheles kochi, Anopheles monstrosus and Anopheles tessellatus were collected in greater numbers during the dry season. The peak of host-seeking activity for An. dirus, An. sinensis, and An. vagus was between 18.00 and 19.00 h.ConclusionThis study provided information on the diversity, seasonal prevalence and behaviour of Anopheles at the study sites. Identifying the diverse mosquito fauna in the central highlands of Vietnam allows species-specific control measures to be implemented by the National Programme to reduce malaria in areas of very low malaria transmission. The peak Anopheles host-seeking activity observed in this study was between 18.00 and 23.00 h, which highlights the need to better characterize Anopheles behaviour in this region of Vietnam to inform on vector control strategies.