321 research outputs found
Toxicity on Dengue Mosquito Vectors Through Myristica fragrans-Synthesized Zinc Oxide Nanorods, and Their Cytotoxic Effects on Liver Cancer Cells (HepG2)
No full textDengue is an arbovirus mainly vectored by Aedes mosquitoes. Its prevention and control depends to effective vector control measures. Cancer causes millions of death every year. Most of the anticancer drugs have high toxicity and low specificity of action, leading to systemic toxicity and severe side effects. Thus, the development of effective tools is a priority. We fabricated zinc oxide nanoparticles using the Myristica fragrans extract as a reducing and stabilizing agent. Nanoparticles were studied using UV–vis spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, zeta potential, dynamic light scattering, energy dispersive X-ray analysis, field emission scanning electron microscopy and transmission electron microscopy. ZnO nanorods were highly effective against A. aegypti young instars, with LC50 ranging from 3.44 (larva I) to 14.63 ppm (pupa). Nanorods showed adult LC50 of 15.004 ppm. ZnO nanorods exhibited dose-dependent cytotoxicity against human hepato-cancer cells (HepG2). After 48 and 24 h of incubation, the IC50 were 20 and 22 μg/ml, respectively. Nanorods triggered the induction of apoptosis. Overall, this study highlights that the possibility to employ M. fragrans-synthesized ZnO nanorods in mosquito control, as well as in the development of novel chemotherapeutic agents with reduced systemic toxicity
Green-synthesized silver nanoparticles using Psychotria nilgiriensis: toxicity against the dengue vector Aedes aegypti (Diptera: Culicidae) and impact on the predatory efficiency of the non-target organism Poecilia sphenops (Cyprinodontiformes: Poeciliidae)
No full textMosquitoes transmit serious diseases to humans and animals, causing millions of deaths every year. Effective insecticides of natural origin for eco-friendly vector control are a priority. In this study, silver nanoparticles (AgNPs) biosynthesized using as cheap Psychotria nilgiriensis leaf extract were tested on larvae and pupae of Aedes aegypti (Diptera: Culicidae). Biophysical characterization was carried out with UV–vis spectrophotometry, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Larvae were exposed to varying concentrations of aqueous extract of synthesized AgNPs for 24 h. The maximum mortality was observed for green-synthesized AgNPs. Moreover, the combined treatment of leaf extract of P. nilgiriensis and AgNPs lowered the plant extract LC50 to 92.87, 115.27, 140.37, 169.30 and 212.55 μg/ml. The effectiveness of green synthesized AgNPs was confirmed against eggs and adults of A. aegypti. Furthermore, we showed that the predatory efficiency of Poecilia sphenops on A. aegypti was not reduced after the exposure at sublethal doses of AgNPs. Predation in the control was 65% (larva I) and 49.62% (larva II). Predation against late-instar larvae was minimal. In AgNPs-treated environment (3 ppm), predation was boosted to 90.25% (larva I) and 76.50% (larva II), respectively. Overall, P. nilgiriensis-synthesized AgNPs could be proposed at ultra-low doses to reduce larval population of dengue vectors enhancing predation rates of P. sphenops
Nyateism vs teism-debatten : En analys av Dinesh D'Souza's argumentation
No full textDuring the last few years the western world has seen an increasing interest in the topic of atheism, with bestselling books by writers like Richard Dawkins, Sam Harris and Christopher Hitchens. The critic of religions that these writers have brought to the table have not gone unmet, with writers like Dinesh D'Souza rushing to the defence of Chrisianity. Taking on the arguments of New York Times bestselling author Dinesh D'Souza in the current debate on the existece of God and the usefullness of religion, I here examine the claim by D'Souza that atheism, in fact, is responsible for the worst mass murders of history. In taking D'Souza's arguments and analyzing them on its own philosophical merits, with methods like the process of elimination and information evaluation (i.e source criticism), I will here show just exactly how persuasive these arguments prove to be. In the following pages we will not only discuss the role of atheism in 20th centuary totalitarianism, but also answer questions like ”Was Hitler an atheist or a theist?”, ”Is atheism responsible for the worst crimes of history?” and ”Are people who believe in God in fact more moral the those who do not?
Determinig the efficacy of mathematical programming approaches for multi-group classification:
No full textManagers have been grappling with the problem of extracting patterns out of the vast database generated by their systems. The advent of powerful information systems in organizations and the consequent agglomeration of vast pool of data since the mid-1980s have created renewed interest in the usefulness of discriminant analysis (DA). Expert systems have come to the aid of managers in their day-to-day decision making with many successful applications in financial planning, sales management, and other areas of business operations (Erenguc and Koehler 1990).
Currently, no comprehensive research study exists that tests the robustness of multi-group classification analysis. Our research aims to bridge the gaps in the existing works and take a step further by extending our study to four-group classification problems. The main purpose of this research is to determine the efficacy of mathematical programming classification models, more specifically, LP methods vis-à-vis statistical approaches such as discriminant analysis (Mahalanobis) and logistic regression, an artificial intelligence (AI) technique such as a neural network, and a non-parametric technique such as k-nearest neighborhood (k-NN) for four-group classification problems. This research also proposes an integrated (hybrid) model that combines a non-parametric classification technique and a LP approach to enhance the overall classification performance. Furthermore, the study extends an existing two-group LP model (Bal et al. 2006) based on the work of (Lam and Moy 1996b) and apply it to four-group classification problems. These models are tested through robust computational experiments under varying data conditions using a financial product example. The characteristics of a real dataset are used to simulate (Monte Carlo method) multiple sample runs for four group classification problems with three continuous independent variables.
The experimental results show that LP approaches in general and the proposed integrated method in particular consistently have lower misclassification rates for most data characteristics. Furthermore, the integrated method utilizes the strengths of both the methods: k-NN and linear programming, thereby considerably improving the classification accuracy.Ph.D.Includes bibliographical references (p. 83-97)by Dinesh R. Pa
Tackling the growing threat of dengue. Phyllanthus niruri-mediated synthesis of silver nanoparticles and their mosquitocidal properties against the dengue vector Aedes aegypti (Diptera: Culicidae)
No full textMosquitoes are vectors of devastating pathogens and parasites, causing millions of deaths every year. Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. Recently, transmission has strongly increased in urban and semiurban areas, becoming a major international public health concern. Aedes aegypti (Diptera: Culicidae) is the primary vector of dengue. The
use of synthetic insecticides to control Aedes mosquitoes lead to high operational costs and adverse nontarget effects. In this scenario, eco-friendly control tools are a priority. We proposed a novel method to synthesize silver nanoparticles using the aqueous leaf extract of Phyllanthus niruri, a cheap and nontoxic material. The UV–vis spectrum of the aqueous medium containing silver nanostructures showed a peak at 420 nm corresponding to the surface plasmon resonance band of nanoparticles. SEM analyses of the synthesized nanoparticles showed a mean size of 30–60 nm. EDX spectrum showed the chemical composition of the synthesized nanoparticles. XRD highlighted that the nanoparticles are crystalline in nature with face-centered cubic geometry. Fourier transform infrared spectroscopy (FTIR) of nanoparticles exhibited prominent peaks 3,327.63, 2,125.87, 1,637.89, 644.35, 597.41, and 554.63 cm−1 . In laboratory assays, the aqueous extract of P. niruri was toxic against larval instars (I–IV) and pupae of A. aegypti. LC50 was 158.24 ppm (I), 183.20 ppm (II), 210.53 ppm (III), 210.53 ppm (IV), and 358.08 ppm (pupae). P. niruri-synthesized nanoparticles were highly effective against A. aegypti, with LC50 of 3.90 ppm (I), 5.01 ppm (II), 6.2 ppm (III), 8.9 ppm (IV), and 13.04 ppm (pupae). In the field, the application of silver nanoparticles (10×LC50) lead to A. aegypti larval reduction of 47.6 %, 76.7 % and 100 %, after 24, 48, and 72 h, while the P. niruri extract lead to 39.9 %, 69.2 % and 100 % of reduction, respectively. In adulticidal experiments, P. niruri extract and nanoparticles showed LC50 and LC90 of 174.14 and 6.68 ppm and 422.29 and 23.58 ppm, respectively. Overall, this study highlights that the possibility to employ P. niruri leaf extract and green-synthesized silver nanoparticles in mosquito control programs is concrete, since both are effective at lower doses if compared to synthetic products currently marketed, thus they could be an advantageous alternative to build newer and safer tools against dengue vectors
Do Chenopodium ambrosioides-Synthesized Silver Nanoparticles Impact Oryzias melastigma Predation Against Aedes albopictus Larvae?
No full textThe green synthesis of nanopesticides has been recently proposed to
improve the efficacy of mosquito control programs. However, limited efforts shed
light on the impact of sub-lethal doses of nanopesticides on behavioral traits of
mosquito biocontrol agents. We described the synthesis of silver nanoparticles
(AgNP) at room temperature using the aqueous extract of Chenopodium ambrosioides,
and their high toxicity against the invasive mosquito Aedes albopictus. LC50
calculated on young instars ranged from 13 ppm (first instar larvae) to 19 ppm
(pupae). LC50 calculated on adults was 14 ppm. The chemical composition of the C.
ambrosioides extract was characterized by GC–MS analysis. The production of
AgNP was confirmed by the surface Plasmon resonance band illustrated in UV–Vis,
FTIR spectroscopy, EDX, XRD, TEM, and Zeta Potential analyses. In the field, a
single treatment of AgNP (10 9 LC50) led to complete elimination of larval populations
within 72 h. Sub-lethal doses of the reducing extract and AgNP magnify
predation rates of Oryzias melastigma fishes against A. albopictus larvae. Overall,
this study highlights the concrete potential of C. ambrosioides-synthesized AgNP to
develop effective and cheap tools to control young instars and adults of the invasive
mosquito A. albopictus
Cymbopogon citratus-synthesized gold nanoparticles boost the predation efficiency of copepod Mesocyclops aspericornis against malaria and dengue mosquitoes
No full textPlant-borne compounds can be employed to synthesize mosquitocidal nanoparticles that are effective at low doses. However, how they affect the activity of mosquito predators in the aquatic environment is unknown. In this study, we synthesized gold nanoparticles (AuN) using the leaf extract of Cymbopogon citratus, which acted as a reducing and capping agent. AuN were characterized by a variety of biophysical methods and sorted for size in order to confirm structural integrity. C. citratus extract and biosynthesized AuN were tested against larvae and pupae of the malaria vector Anopheles stephensi and the dengue vector Aedes aegypti. LC50 of C. citratus extract ranged from 219.32 ppm to 471.36 ppm. LC50 of AuN ranged from 18.80 ppm to 41.52 ppm. In laboratory, the predatory efficiency of the cyclopoid crustacean Mesocyclops aspericornis against A. stephensi larvae was 26.8% (larval) and 17% (larva II), while against A. aegypti was56% (I) and 35.1% (II). Predation against late-instar larvae was minimal. In AuN-contaminated environment,predation efficiency against A. stephensi was 45.6% (I) and 26.7% (II), while against A. aegypti was 77.3% (I) and 51.6% (II). Overall, low doses of AuN may help to boost the control of Anopheles and Aedes larval populations in copepod-based control programs
Mosquitocidal and antibacterial activity of green-synthesized silver nanoparticles from Aloe vera extracts: towards an effective tool against the malaria vector Anopheles stephensi?
No full textMosquitoes represent an important threat for lives of millions of people worldwide, acting as vectors for devastating pathogens, such as malaria, yellow fever, dengue, and West Nile. In addition, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. Here, we investigated the mosquitocidal and antibacterial properties of Aloe vera leaf extract and silver nanoparticles synthesized using A. vera extract. Mosquitocidal properties were assessed in laboratory against larvae (I-IV instar) and pupae of the malaria vector Anopheles stephensi. Green-synthesized silver nanoparticles were tested against An. stephensi also in field conditions. Antibacterial properties of nanoparticles were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. The synthesized silver nanoparticles were characterized by UV–vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In laboratory conditions, the A. vera extract was toxic against An. stephensi larvae and pupae, even at low dosages. LC50 were 48.79 ppm (I instar), 59.09 ppm (II instar), 70.88 ppm (III instar), 83.58 ppm (IV instar), and 152.55 ppm (pupae). Green-synthesized silver nanoparticles were highly toxic against An. stephensi. LC50 were 3.825 ppm (I instar), 4.119 ppm (II instar), 4.982 ppm (III instar), 5.711 ppm (IV instar), and 6.113 ppm (pupae). In field conditions, the application of A. vera-synthesized silver nanoparticles (10 × LC50) leads to An. stephensi larval reduction of 74.5, 86.6, and 97.7 %, after 24, 48, and 72 h, respectively. Nanoparticles also showed antibacterial properties, and the maximum concentration tested (150 mg/L) evoked an inhibition zone wider than 80 mm in all tested bacterium species. This study adds knowledge about the use of green synthesis of nanoparticles in medical entomology and parasitology, allowing us to propose A. vera-synthesized silver nanoparticles as effective candidates to develop newer and safer mosquitocidal control tools
Aristolochia indica green-synthesized silver nanoparticles: A sustainable control tool against the malaria vector Anopheles stephensi?
No full textMalaria is a life-threatening disease caused by parasites transmitted to people and animals through the bites of infected mosquitoes. We biosynthesized silver nanoparticles (AgNP) using Aristolochia indica extract as reducing and stabilizing agent. AgNP were characterized by UV-vis spectroscopy, FTIR, SEM, EDX and XRD. In laboratory, LC50 of A. indica extract against Anopheles stephensi ranged from 262.66 (larvae I) to 565.02ppm (pupae). LC50 of AgNP against A. stephensi ranged from 3.94 (larvae I) to 15.65ppm (pupae). In the field, the application of A. indica extract and AgNP (10×LC50) leads to 100% larval reduction after 72h. In laboratory, 24-h predation efficiency of Diplonychus indicus against A. stephensi larvae was 33% (larvae II) and 57% (larvae III). In AgNP-contaminated environment (1ppm), it was 45.5% (larvae II) and 71.75% (larvae III). Overall, A. indica-synthesized AgNP may be considered as newer and safer control tools against Anopheles vectors
Neem cake as a promising larvicide and adulticide against the rural malaria vector Anopheles culicifacies (Diptera: Culicidae). A HPTLC fingerprinting approach
No full textMosquitoes are insects of huge public health importance, since they act as vectors for important pathogens and parasites. Here, we focused on the possibility of using the neem cake in the fight against mosquito vectors. The neem cake chemical composition significantly changes among producers, as evidenced by our HPTLC (High performance thin layer chromatography) analyses of different marketed products. Neem cake extracts were tested to evaluate the ovicidal, larvicidal and adulticidal activity against the rural malaria vector Anopheles culicifacies. Ovicidal activity of both types of extracts was statistically significant, and 150 ppm completely inhibited egg hatching. LC50 values were extremely low against fourth instar larvae, ranging from 1.321 (NM1) to 1.818 ppm (NA2). Adulticidal activity was also high, with LC50 ranging from 3.015 (NM1) to 3.637 ppm (NM2). This study pointed out the utility of neem cake as a source of eco-friendly mosquitocides in Anopheline vector control programmes
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