Comparative study on some selected species of <i>Ocimum</i>genus on free radical scavenging activity and hepatoprotective activity against CCl4 induced intoxication in rats

In this study, we compared the in vitro antioxidant property among the selected Ocimum species (O. sanctum, O. americanum, O. basilicum and O. gratissimum) and hepatoprotective activities of their extracts against CCl4 induced intoxication. The results suggested that the four species of Ocimum genus showed variability in Phenolic content and in vitro antioxi-dant activity against DPPH, superoxide and hydroxyl radicals in the following manner: O. sanctum > O. americanum > O. basilicum > O. gratissimum respec-tively. Based on serum AST, ALT, ALP and T. Bil levels, the alcoholic extracts of Ocimum species showed a significant dose dependent (250 mg and 500 mg and 750 mg/kg p.o.) and a protective effect against CCl4 induced hepatotoxicity in albino rats. The results further revealed that the potential hepatoprotective activity of Ocimum sanctum among the Ocimum species.

A bibliometric analysis of ecotourism:A safeguard strategy in protected areas

Ecotourism projects are mostly implemented in naturally fragile ecosystems as a savior of nature,culture,and indigenous people.This paper aims to make quantitative study of ecotourism in protected areas by using bibliometric analysis.VOSviewer,a popular bibliometric software,was used to analyze as many as 1182 research articles published from 2002 to 2020.Those articles were collected from the Scopus database.The study measured three distinct types of bibliometric indicators(quantity,quality,and structural indicators)to analyze the published articles scientifically.The analysis uncovers ecotourism research in protected areas as an emerging and predominant field of research with a sound growth in annual publications and citations.Importantly,the majority of ecotourism research articles are published in the United States,the United Kingdom,Australia,South Africa,Canada,and China.Nevertheless,ecotourism as a relevant research theme of is getting due importance in African and Asian countries for two key reasons:(1)wildlife and tribal populations,and(2)uncontaminated ecology and environment of ecotourism sites.Further,the main research themes of articles in the field of ecotourism in protected areas are broadly focused on conservation,visitor management,and community.Our findings reveal that controversial issues surrounding ecotourism and its relationship to protected areas,dominated by human-wildlife conflict,gender,and climate change,are attracting the attention of researchers worldwide.

Toxicity of Pyrifluquinazon against Greenhouse Whitefly on Tomato Produced in Greenhouses

The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is a major pest of tomato, Solanum lycopersicum L. Management in both the field and greenhouse is often based on foliar applications of insecticides. A lack of control along with resistance development requires development of alternatives to currently available insecticides. Pyrifluquinazon is a recently developed insecticide by Nichino/Nihon Nohyaku Co., Japan and is marketed in the US by Nichino America. The insecticide inhibits feeding by aphids, thrips, mealybugs and scale insects resulting in death. Because limited information exists on pyrifluquinazon effectiveness against whiteflies, tests were initiated to establish its toxicity against the greenhouse whitefly on greenhouse produced tomato. Data reported herein indicate that pyrifluquinazon was highly effective against adult greenhouse whiteflies. When adults were transferred to tomato shortly after the application had dried, mortality counts taken after 48 h produced LC50 and LC95 values of 0.2469 and 2.4826 μg·g-1, respectively. Although few adults were observed on tomato foliage 24 h post-exposure, little mortality was observed until the 48 h observation. When adult whiteflies were placed on tomato 3 d after pyrifluquinazon application, the LC50 value was 0.3343 μg·g-1 which did not significantly differ from the 0 h LC50 value. A significant increase in LC50 value was observed when adults were placed on tomato 5 d after pyrifluquinazon application. In a greenhouse efficacy trial, both the recommended pyrifluquinazon rate (46.8 g active ingredient [AI] ha-1) and a reduced rate (11.7 g·AI·ha-1) significantly reduced numbers of whitefly adults when compared to the non-treated control for 10 days. The 46.8 g·AI·ha-1 rate was as effective as the insecticide standard, imidacloprid. Pyrifluquinazon applied to tomato foliage in the greenhouse offers a useful alternative to currently available insecticides for control of greenhouse whitefly. Further, its unique mode of action may represent a new tool in management of insecticide resistance.

Toxicity of newly isolated piperideine alkaloids from the red imported fire ant, Solenopsis invicta Buren, against the green peach aphid, Myzus persicae (Sulzer)

The green peach aphid, Myzuspersicae (Sulzer), is a major insect pest of many agronomic and horticultural crops and is distributed worldwide. Aphid management is often based on application of insecticides. However, the aphid is now resistant to many of these and much interest has recently developed in identification of novel alternative insecticides. Venom isolated from the red imported fire ant, Solenopsisinvicta Buren, is composed of two groups of alkaloids, piperidines and piperideines, and has shown activity against many organisms including fungi, bacteria, mites and several insects. Prior to the study reported herein, no information on the venom’s activity to Myzuspersicae has been reported. Both of the alkaloids were active against M.persicae. The 24 h LC50 values were116.6 and 91.5 ppm for the piperideine and piperidine extracts, respectively. Based on overlap of the 95% fiducial limits the LC50 values for the two alkaloids did not significantly differ. At the high dosages, mortality occurred in as few as four hours and all treated aphids were dead by six hours. Little additional mortality was detected in the 48-hobservation. Both piperideine and piperidine extracts isolated from red imported fire ant venom possess sufficient activity to cause death of green peach aphids and at high dosages, death occurs rapidly. In the search for new replacements to synthetic insecticides, these extracts may offer a novel but potentially successful alternative.

Assessing the effects of surface-bound humic acid on the phototoxicity of anatase and rutile TiO_2 nanoparticles in vitro

In this study,the cytotoxicity of two different crystal phases of TiO2 nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO2 nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO2 nanoparticles（denoted as A/RHA50,A/RHA100,and A/RHA200,respectively）.Results indicate that rutile（LC50（concentration that causes 50%mortality compared the control group）=6.5）was more toxic than anatase（LC50=278.8）under simulated sunlight（SSL）irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC50of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species（ROS）by TiO2 nanoparticles in terms of hydroxyl radicals（OH）and superoxide anions（O2^-）.Data suggested that O2^- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O2^- on rutile,but increased O2^- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase.

ILES for mechanism of ramp-type MVG reducing shock induced flow separation

A high order implicit large eddy simulation (ILES) is carried out to study the mechanism of shock induced flow separation reduction under ramp-type MVG control. The mechanism was originally considered as that MVG can generate streamwise vortices which strongly mix boundary layer and the boundary layer becomes more capable to resist strong adverse pressure gradient caused by shock and to keep the boundary layer attached. However, according to our ILES, a chain of ring-like vortices is generated behind the ramp-type MVG and goes further to interact with the shock. When the ring-like vortices pass through the shock, the shock wave is weakened and altered while the vortex structures are quite stable. The instantaneous simulation shows that the spanwise ring-like vortex, not the streamwise vortex, plays a key role to weaken the shock and reduce the shock-induced separation. Detailed investigation on ring-like vortices and shock interaction will be given in this paper.