Comparison of the reaction of polar mesosphere winter echoes and polar mesosphere summer echoes to high-frequency heating in terms of modulated characteristics

In this work,for the first time,we have analyzed and compared the responses of polar mesosphere winter echoes(PMWE)and their summer counterpart,polar mesosphere summer echoes(PMSE),to high-frequency(HF)heating in terms of modulated characteristics(i.e.,backscatter intensity reduction,recovery,and overshoot).Both PMWE and PMSE observations were from the same site(Tromsφ,Norway;69.6°N,19.2°E)and radar(EISCAT[European Incoherent Scatter Scientific Association]very high frequency,224 MHz).The heating patterns of both PMWE and PMSE were found to be similar;however,PMSE was more greatly affected by HF heating.Polar mesosphere summer echoes showed recovery and overshoot more frequently than did PMWE.In addition,the mean recovery and overshoot of PMSE were greater than those of PMWE.The associated electron temperature enhancement was estimated for both PMWE and PMSE and showed that,compared with PMWE,the electron temperature enhancement was more significant in PMSE.The strong heating effects on PMSE may be due to the considerable increase in electron temperature.

PMSE dependence on frequency observed simultaneously with VHF and UHF radars in the presence of precipitation

Using PMSE （polar mesosphere summer echoes） observations in combination with particle flux measurements obtained with detectors onboard the Geostationary Operational Environmental Satellite （GOES） a special condition is shown for the occurrence of rare observed UHF PMSE. When electron flux observed from GOES satellites show a decrease, then after being in the presence of precipitation UHF PMSE occurs. The heating effect on PMSE is small when the UHF electron density is enhanced at 90 km due to particle precipitation. We analyzed and compared the frequency dependence of PMSE under the condition of high energy particle precipitation in July of 2004 and 2007 at well separated frequencies （224 and 930 MHz） at the same site, height, and time. The frequency index varies with height and time. At different heights, the maximum as well as the minimum value of volume reflectivity at VHF is greater than that at UHF with 2 to 3 orders of magnitude. A new qualitative method for the analysis of dust distribution is used by analyzing the relationship between volume reflectivity and frequency index. In agreement with the results of the model it is shown that dust particles of smaller size generally did not occur at the edges, instead they occurred in the middle PMSE regions.

On the radar frequency dependence of polar mesosphere summer echoes

Polar mesosphere summer echoes(PMSEs)are very strong radar echoes in the polar mesopause in local summer.Here we present the frequency dependence of the volume reflectivity and the effect of energetic particle precipitation on modulated PMSEs by using PMSEs observations carried out by European Incoherent SCATter(EISCAT)heating equipment simultaneously with very high frequency(VHF)radar and ultra high frequency(UHF)radar on 12 July 2007.According to the experimental observations,the PMSEs occurrence rate at VHF was much higher than that at UHF,and the altitude of the PMSEs maximum observed at VHF was higher than that at UHF.Overlapping regions were observed by VHF radar between high energetic particle precipitation and the PMSEs.In addition,highfrequency heating had a very limited impact on PMSEs when the UHF electron density was enhanced because of energetic particle precipitation.In addition,an updated qualitative method was used to study the relationship between volume reflectivity and frequency.The volume reflectivity was found to be inversely proportional to the fourth power of radar frequency.The theoretical and experimental results provide a definitive data foundation for further analysis and investigation of the physical mechanism of PMSEs.

In vivo sedative and muscle relaxants activity of Diospyros lotus L

Objective: To evaluate the sedative effect of Diospyros lotus L(D. lotus) extract in mice using the open field and Rota rod tests.Methods: For the sedative and muscle relaxants activities of extract/fractions of the plant, invivo open field and phenobarbitone-induced sleeping time were used, while the Roda rod test was employed in animals for the assessment of muscle relaxant activity.Results: Results from this investigation revealed that the extracts of D. lotus have exhibited significant sedative effect in mice(45.98%) at 100 mg/kg i.p. When the extract was partitioned with different solvents, the n-hexane fraction was inactive whereas the chloroform fraction was the most active with 82.67% sedative effect at 50 and 100 mg/kg i.p. On the other hand,the ethyl acetate and n-butanol fractions displayed significant sedative effects(55.65% and40.87%, respectively) at 100 mg/kg i.p. Among the tested extract/fractions, only chloroform and ethyl acetate fractions showed significant(P < 0.05) muscle relaxant activity in the Rota rod test.Conclusions: In short, our study provided scientific background to the traditional uses of D.lotus as sedative.

Investigation of PMSE echoes characteristics using the discontinuous EISCAT UHF observation and its relation with space environment

The observations of Polar Mesosphere Summer Echoes (PMSE) were carried out using the sporadic data of EISCAT UHF radar during the summer season from 2004 to 2015. There were 25 h of PMSE echoes with EISCAT UHF radar. PMSE echoes were mostly observed only during the early morning and fore-noon time. Moreover, the PMSE echoes are positively correlated with Lymanα radiation, but the correlation is non-significant. The occurrence of PMSE echoes in the early morning and fore-noon time and there positive correlation with Lymanαradiation suggests that solar radiations might be one important factor for PMSE echoes in this study. Very weak positive, but statistically non-significant correlation is found between PMSE occurrence rate and the local geomagneticK-indices. It is found that there is a matching between the variation in the occurrence rate of PMSE and noctilucent clouds (NLC) up to some extent and they are positively correlated. This positive correlation might support the earlier proposed idea about the role of ice particle size in producing PMSE echoes at higher frequencies.

Numerical Analysis of Artificial Electron Heating Effects on Polar Mesospheric Winter Echoes

In this paper,an analytical model is used to analyze the modulated polar mesospheric winter echoes(PMWE).The winter parameters were introduced to simulate the effects of different parameters during the artificial electron heating of PMWE.The important role of the charged dust particle in the creation of PMWE is confirmed again.It is found that during the heating of PMWE,the increases of the dust size,dust charge,electron temperature,initial electron density,and ion-neutral collision frequency cause the increase of the electron density irregularity,and hence the PMWE strength.However,with increasing the dust density,the electron density irregularity and the PMWE strength decrease.

In vitro biological screening of the stem of Desmodium elegans

Objective:To explore the medicinal importance of the stem of Desmodium elegans,methanolic extract,and its different solvent fractions were evaluated for brine shrimp lethality,insecticidal and phytotoxicity,antifungal,and antibacterial activities.Methods:The methanolic extract and its solvent fractions were tested for cytotoxic,phytotoxic,insecticidal,antifungal,and antibacterial effects using our previous published protocols.Results:The methanolic,DCM,ethyl acetate and n-butanol fractions exhibited insecticidal effect against Callosobruchus analis and Rhyzopertha dominie.The methanolic extract,n-hexane,DCM ethyl acetate and n-butanol showed 75,85,85,65 and 5%phytotoxicity at the tested concentration of 500μg/ml.respectively.The solvent fractions(DCM and ethyl acetate)were effective against F.solani(10%and 20%,inhibition respectively).All the tested samples were devoid of cytotoxic and antibacterial effects.Conclusions:It was concluded diat diis plant can be practiced for control of weeds and insects.

POM analysis and computational interactions of 8-hydroxydiospyrin inside active site of protein tyrosine phosphatase 1B

Proteintyrosine phosphatase 1B(PTP1B)inhibitionis consideredas a potentialtherapeuticfor the treatmentof cancer,type2 diabetes,andobesity.Inour presentwork,weinvestigatedtheanti-diabeticpotentialof8-hydroxydiospyrin(8-HDN)from D.lotus against the PTP1B enzyme.It showed significant inhibitory activity of PTP1B with an IC 50 value of 18.37±0.02μM.A detailed molecular docking study was carried out to analyze the binding orientation,binding energy,and mechanism of inhibition.A comparative investigation of 8-HDN in the catalytic,as well as the allosteric site of PTP1B,was performed.Binding energy data showed that compound 8-HDN is more selective for the allosteric site and hence avoids the problems associated with catalytic site inhibition.The inhibition mechanism of 8-HDN can be further investigated as an active lead compound against PTP1B by using in vitro and in vivo models.

Reversal of multidrug resistance and antitumor promoting activity of 3-oxo-6β-hydroxy-β-amyrin isolated from Pistacia integerrima

The bioactive triterpenoid 3-oxo-6-β-hydroxy-β-amyrin(1)has been isolated from multiple plant sources.In this study,chloroform fraction of Pistacia integerrima extract was processed for the isolation of the compound.The compound identity was confirmed by advanced spectroscopy technique.X-ray crystallography was applied for molecular structure confirmation.In addition,compound 1 was screen for its activity on reversal of MDR(multidrug resistance)mediated by P-gp(P-glycoprotein).This was accomplished by using rhodamine123 exclusion on multidrug-resistant human ABCB1 gene transfected mouse T-lymphoma cell line.Outcomes revealed that MDR reversing effect was comparable to verapamil as positive control in vitro.Treatment of TPA-induced tumor promotion with 3-oxo-6β-hydroxy-β-amyrin led to reduction in the applied anti-tumor promotion experiment.The chemo-preventive effect of 3-oxo-6β-hydroxy-β-amyrin was comparable to curcumin as positive control based on the reduction of immediate early tumor antigen expression.Molecular docking by applying Autodock Vina 1 and i-GEMDOCK v 2.1 tools indicated that compound 1 gives good docking results,as determined by their fitness score and specificity.Moreover,results showed that compound 1 isolated from Pistacia integerrima precisely attached to a region where co-crystallized ligand for receptor previously existed.Our findings may explain the use of Pistacia integerrima plant extracts as an anticancer agent in folk medicine.

Exploring the occurrence rate of PMSE-Es by Digisonde at Tromsø

Polar mesosphere summer echoes(PMSE)are observed simultaneously with Digisonde and EISCAT VHF radar.The phenomenon of irregular Es layers is called PMSE-like or PMSE-Es(Polar Mesosphere Summer Echoes-Es)and has some relationship with real PMSE.In this paper,the characteristics of irregular Es layers at 80–100 km were observed by Digisonde at Tromsøduring 2003–2014 are statistically analyzed with ionograms.The diurnal,day-to-day and year-to-year variations and discrepancies of occurrence rate between PMSE and PMSE-Es are compared with the statistical results observed by Esrange MST radar(ESRAD),and the reasons are discussed.The results show that the trends in the occurrence rate of PMSE-Es are similar to the trends in the occurrence rate of PMSE,but there are some notable differences.The occurrence rate of PMSE-Es is much lower than the occurrence rate of PMSE.The minimum value of PMSE-Es appears 1–2 hours earlier than the minimum value of the PMSE occurrence rate,while PMSE-Es appear earlier than PMSE in the year.In addition,there is a significant positive correlation between the annual average occurrence rates of PMSE and PMSE-Es.PMSEEs is a relatively important occurrence in the polar mesopause.Analysis of its characteristics can provide new ideas and methods for studying the formation mechanism of PMSE.

Effect of ions on conductivity and permittivity in the Polar Mesosphere Summer Echoes region

For the first time,the effect of ions on complex conductivity and permittivity of dusty plasma at Polar Mesosphere Summer Echoes(PMSE)altitude is analyzed.Because of ions higher mass and smaller thermal velocity,generally,their effects are not considered in the study of electromagnetic properties of dusty plasmas.In this study,we modified the equations of conductivity and permittivity by adding the effect of ions.In the PMSE altitude region between 80 and 90 km,a local reduction in electron density(i.e.,an electron biteout),is produced by electron absorption onto dust particles.The bite-out condition contains high dust density and smaller electron density.From simulation results in comparatively strong bite-out conditions,we found that the ion effects on conductivity become significant with smaller dust size,lower electron temperature,and lower neutral density.For comparatively weak bite-out conditions,the ion effects on conductivity become significant with larger dust size,higher electron temperature,and higher neutral density.On the other hand,for different dust sizes,electron temperatures and neutral density,the ion effects on complex permittivity become significant only in very strong bite-out conditions.Based on these simulation results,we conclude that,in the absence of electron bite-out conditions,the effect of ions on complex conductivity and permittivity is not significant and can be ignored.However,during bite-out conditions,the effect of ions becomes significant and cannot be ignored because it significantly changes the conductivity and permittivity of dusty plasmas.

Characteristic analysis of layered PMSEs measured with different elevation angles at VHF based on an experimental case

Polar Mesosphere Summer Echoes(PMSEs)are very strong radar echoes observed at altitudes near the polar summer mesopause.One of the essential properties of these radar echoes is that they can give useful diagnostic information about the physics of the scattering process.In this paper,the related characteristics of PMSEs measured with the European Incoherent SCATter Very High Frequency(EISCAT VHF)224 MHz radar on 13–15 July 2010 are studied at different elevation angles from 78°to 90°.It is found that the PMSEs peak power and strongest PMSEs average power occur at the same elevation angles.Also interesting is that the strongest PMSEs occur at off-vertical angles when a PMSEs has a layered(multilayer)structure.And reflection may have more significant effects on PMSEs when there are double or multilayer PMSEs.Possible explanations regarding these observations are discussed.

Influence of Ni/Mn ratio on magnetostructural transformation and magnetocaloric effect in Ni48-xCo2Mn38+xSn12(x=0,1.0,1.5,2.0,and 2.5)ferromagnetic shape memory alloys

An investigation on the magnetostructural transformation and magnetocaloric properties of Ni48-xCo2Mn38＋xSn12（x = 0, 1.0, 1.5, 2.0, and 2.5） ferromagnetic shape memory alloys is carried out. With the partial replacement of Ni by Mn in the Ni_（48）Co2Mn38Sn12 alloy, the electron concentration decreases. As a result, the martensitic transformation temperature is decreased into the temperature window between the Curie-temperatures of austenite and martensite. Thus, the samples with x = 1.5 and 2.0 exhibit the magnetostructural transformation between the weak-magnetization martensite and ferromagnetic austenite at room temperature. The structural transformation can be induced not only by the temperature,but also by the magnetic field. Accompanied by the magnetic-field-induced magnetostructural transformation, a considerable magnetocaloric effect is observed. With the increase of x, the maximum entropy change decreases, but the effective magnetic cooling capacity increases.

Bioassay-guided isolation of novel and selective urease inhibitors from Diospyros lotus

Two new dimeric naphthoquinones, 5′,8′-dihydroxy-6,6′-dimethyl-7,3′-binaphthyl-1,4,1′,4′-tetraone(1; Di-naphthodiospyrol D) and 5′,8′-dihydroxy-5,8-dimethoxy-6,6′-dimethyl-7,3′-binaphthyl-1,4,1′,4′-tetraone(2; Di-naphthodiospyrol E), along with known naphthoquinones diospyrin(3) and 8-hydroxy diospyrin(4) were isolated from the chloroform fraction of extract of Diospyros lotus roots. Their structures were elucidated by advanced spectroscopic analyses, including HSQC, HMBC, NOESY, and J-resolved NMR experiments. The fractions and compounds 1-4 were evaluated for urease activity and phosphodiesterase-Ⅰ, carbonic anhydrase-Ⅱ and α-chymotrypsin enzyme inhibitory activities. Compounds 1 and 2 and their corresponding fractions showed significant and selective inhibitory effects on urease activities. The IC_(50) values of 1 and 2 were 260.4 ± 6.37 and 381.4 ± 4.80 μmol·L-1, respectively, using thiourea(IC_(50) = 21 ± 0.11 μmol·L^(-1)) as the standard inhibitor. This was the first report demonstrating that the naphthoquinones class showed urease inhibition.

Sedative and antinociceptive activities of two new sesquiterpenes isolated from Ricinus communis

Two new sesquiterpenes, trivially named ricinusoids A(1) and ricinusoids B(2), were isolated from ethyl acetate fraction of Ricinus communis. The structures of new compounds were elucidated by detailed spectroscopic techniques, including 1 D-and 2 D-NMR, UV, IR spectroscopy, and mass spectrometry. The compounds(1-2) were also assessed for in-vivo sedative and analgesic like effects in open field and acetic acid induced writhing tests respectively at 5, 10, and 20 mg·kg^(–1) i.p. Pretreatment of both test compounds caused significant(P ≤ 0.05) reduction in locomotive activity like sedative agents and abdominal constrictions like analgesics. Both compounds(1-2) possessed marked sedative and antinociceptive effects in animal models.

Scandix pecten-veneris L.的植物素、生物学潜力及酶抑制活性研究（英文）

目的:本研究旨在测定Scandix pecten-veneris L.的植物素和评价其生物学潜力。方法:测定S.pecten-veneris提取物中植物素的含量,包括生物碱、黄酮、多酚和单宁。使用2,2-二苯基-1-苦肼基(DPPH)测定抗氧化活性;同时通过铁还原/抗氧化能力(FRAP)测定还原能力;使用琼脂扩散测定法评价对七种细菌和四种真菌菌株的抗微生物活性。同时,对脲酶、磷酸二酯酶-Ⅰ和过氧化氢酶-Ⅱ进行酶抑制研究。结论:沙门氏菌显示出适度的抗自由基活性;羟基自由基的潜能降至初始值的20%左右。S.pectenveneris多种提取物的抗氧化活性与总酚含量呈线性相关。S.pecten-veneris叶对金黄色葡萄球菌表现出最高的抑制活性;对白色念珠菌表现出到最高的抗真菌活性。植物提取物对脲酶的活性最有效;对磷酸二酯酶-Ⅰ和碳酸酐酶-Ⅱ显示出中等活性。结果表明,S.pecten-veneris具有良好的药用潜力,可用于治疗一些特定的疾病。

Three new anthraquinone derivatives isolated from Symplocos racemosa and their antibiofilm activity

Three new alkyl substituted anthraquinone derivatives, trivially named as symploquinones A-C(Compounds 1-3) were isolated from Symplocos racemosa. The structures of these compounds were determined on the basis of extensive spectroscopic analyses(UV, IR, Mass, ~1 H-and ^(13)C-NMR, and two-dimensional(2D) NMR techniques). The resulting data were also compared with the reported literature. These compounds were then subjected to antibacterial or antibiofilm testing. Compounds 1 and 3 exhibited good antibacterial activity in the concentration range of 160-83 μg·m L^(-1) against Streptococcus mutans, methicillin resistant Staphylococcus aureus and Proteus mirabilis. Both compounds were further screened for anti-biofilm activity, which revealed promising activities at sub-MIC concentrations. None of the compounds were found to be active against Klebsiella pneumoniae.