Top PDF Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign

Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign

Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign

Hallquist, M., Wenger, J. C., Baltensperger, U., Rudich, Y., Simpson, D., Claeys, M., Dom- men, J., Donahue, N. M., George, C., Goldstein, A. H., Hamilton, J. F., Herrmann, H., Hoff- mann, T., Iinuma, Y., Jang, M., Jenkin, M. E., Jimenez, J. L., Kiendler-Scharr, A., Maen- haut, W., McFiggans, G., Mentel, Th. F., Monod, A., Pr ´ev ˆot, A. S. H., Seinfeld, J. H., Sur- ratt, J. D., Szmigielski, R., and Wildt, J.: The formation, properties and impact of sec-

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Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign

Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign

Wiedensohler, A., Birmili, W., Nowak, A., Sonntag, A., Weinhold, K., Merkel, M., Wehner, B., Tuch, T., Pfeifer, S., Fiebig, M., Fj¨araa, A. M., Asmi, E., Sellegri, K., Depuy, R., Venzac, H., Vil- lani, P., Laj, P., Aalto, P., Ogren, J. A., Swietlicki, E., Williams, P., Roldin, P., Quincey, P., H¨uglin, C., Fierz-Schmidhauser, R., Gysel, M., Weingartner, E., Riccobono, F., Santos, S., Gr¨uning, C., Faloon, K., Beddows, D., Harrison, R., Monahan, C., Jen- nings, S. G., O’Dowd, C. D., Marinoni, A., Horn, H.-G., Keck, L., Jiang, J., Scheckman, J., McMurry, P. H., Deng, Z., Zhao, C. S., Moerman, M., Henzing, B., de Leeuw, G., L¨oschau, G., and Bastian, S.: Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high qual- ity long-term observations of atmospheric particle number size distributions, Atmos. Meas. Tech., 5, 657-685, doi:10.5194/amt- 5-657-2012, 2012.
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Biomass-burning impact on CCN number, hygroscopicity and cloud formation  during summertime in the eastern Mediterranean

Biomass-burning impact on CCN number, hygroscopicity and cloud formation during summertime in the eastern Mediterranean

Abstract. This study investigates the concentration, cloud condensation nuclei (CCN) activity and hygroscopic proper- ties of particles influenced by biomass burning in the eastern Mediterranean and their impacts on cloud droplet formation. Air masses sampled were subject to a range of atmospheric processing (several hours up to 3 days). Values of the hy- groscopicity parameter, κ, were derived from CCN measure- ments and a Hygroscopic Tandem Differential Mobility An- alyzer (HTDMA). An Aerosol Chemical Speciation Monitor (ACSM) was also used to determine the chemical composi- tion and mass concentration of non-refractory components of the submicron aerosol fraction. During fire events, the in- creased organic content (and lower inorganic fraction) of the aerosol decreases the values of κ, for all particle sizes. Par- ticle sizes smaller than 80 nm exhibited considerable chemi- cal dispersion (where hygroscopicity varied up to 100 % for particles of same size); larger particles, however, exhibited considerably less dispersion owing to the effects of conden- sational growth and cloud processing. ACSM measurements indicate that the bulk composition reflects the hygroscopic- ity and chemical nature of the largest particles (having a di- ameter of ∼ 100 nm at dry conditions) sampled. Based on
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Particle hygroscopicity and its link to chemical composition in the urban atmosphere of Beijing, China, during summertime

Particle hygroscopicity and its link to chemical composition in the urban atmosphere of Beijing, China, during summertime

Another key product of AMS measurements is the oxi- dation level and chemical information of organic aerosols. Compared to inorganic species, which exhibit a well- characterized hygroscopic behavior, knowledge on the in- fluence of the water uptake of the organic aerosols remains limited (Kanakidou et al., 2005; Hallquist et al., 2009). The hygroscopicity of organic material varies with its oxidation state (Jimenez et al., 2009), which may be highly variable in the real atmosphere, depending on the history of an air mass. Such variation may present a significant challenge when predicting hygroscopicity, assuming a constant hygro- scopic growth factor of the organic aerosol fraction at a given relative humidity, as has usually been done in closure studies. More recently, some studies have been performed to inves- tigate the relationship between particle hygroscopicity and chemical composition in both field measurements and labo- ratory experiments (Massoli et al., 2010; Wong et al., 2011; Lambe et al., 2011; Rickards et al., 2013; Moore et al., 2012a, b; Suda et al., 2014; Paramonov et al., 2013; Levin et al., 2012). These works specially focused on parametriz- ing the empirical correlations between the atomic oxy- gen : carbon (O : C) ratio and organic hygroscopicity pa- rameter (κ) derived from either hygroscopic growth factor (e.g., Wu et al., 2013; Rickards et al., 2013) or cloud conden- sation nuclei (CCN) activity (e.g., Mei et al., 2013; Wong et al., 2011; Lambe et al., 2011; Chang et al., 2010). Typically, a linear parametrization of the correlation between κ and O:C was presented. Rickards et al. (2013) recently summarized the literature data and pointed out that the systematic vari- ability in parametrizations between organic κ and the O : C ratio determined from the different studies remains large. A recent work done by Suda et al. (2014) tested the influence of the number and location of molecular functional groups on the hygroscopicity of organic aerosols and may improve our understanding the mechanisms of the hygroscopicity of organics.
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Relating hygroscopicity and optical properties to chemical composition and structure of secondary organic aerosol particles generated from the ozonolysis of α-pinene

Relating hygroscopicity and optical properties to chemical composition and structure of secondary organic aerosol particles generated from the ozonolysis of α-pinene

smaller than the sensitivity of the H-TDMA. (2) Other fac- tors, other than the bulk O : C, can control the water uptake of SOA. Recently, Alfarra et al. (2014) reported a positive correlation between hygroscopicity of particles and their de- gree of oxidation for SOA produced from the photooxidation of α-pinene, β-caryophyllene, linalool and myrcene, but not for limonene SOA. They suggested that other factors such as solubility, surface tension, molecular weight, density and particle phase are likely to be playing important roles in con- trolling GF values. We observed that the O : C of the parti- cle surface was lower than the bulk O : C and remained con- stant over time (see Sect. 3.4.1). This structure would affect the heterogeneous chemistry of the particle and avoid the water absorption on particles. Broekhuizen et al. (2004) ob- served that the oxidation of oleic acid by low concentration of ozone, shown to produce oxygenated products (Moise and Rudich, 2002), did not increase the particle CCN activity. Katrib et al. (2004) demonstrated that hydrophobic products were formed at the surface of oleic acid particles after ozone exposure that prevented water adsorption on particles. McIn- tire et al. (2010) exposed particles formed from ozonolysis of surface-bound alkenes to ozone and observed formation of polar groups buried inside a hydrophobic shell. This is also consistent with Moussa et al. (2009) who observed that the uptake of water does not increase after the oxidation of surface-bound alkenes. A core–shell structure could explain the low O : C of the surface α-pinene–O 3 SOA obtained in
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Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

As noted above and shown in Fig. 10a (inserts) during hy- dration cycles in the 60–96 % RH range, the water uptake is followed by a water release (negative peaks) despite grow- ing RH. These observations can be explained by the com- plex morphology of the particles. Most likely at intermedi- ate RHs due to partial dissolution, the different species be- come more mobile, which leads to compaction (restructur- ing) of the particles and release of excess water. The fact that in the second hydration cycle the water loss effect is reproducible (inserts in Fig. 10c) suggests that re-dried par- ticles retained their irregular microstructure even at a dry- ing rate as low as ∼ 0.4 % RH min −1 . The reproducibility of the irregular particle microstructure in subsequent hydration– dehydration cycles is in agreement with the earlier results of Zardini et al. (2008), who investigated laboratory-generated mixed AS–adipic acid particles by the electrodynamic bal- ance (EDB) technique, and with recent STXM-NEXAFS re- sults for Amazonian aerosol samples obtained by Pöhlker et al. (2014).
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Chemical composition, antibacterial and antioxidant profile of essential oil from Murraya koenigii (L.) leaves

Chemical composition, antibacterial and antioxidant profile of essential oil from Murraya koenigii (L.) leaves

Ocimene and α-terpinene are the main components with such capacity. The presence of major compounds in M. koenigii is not reported from elsewhere, completely differs from those reported by Raina et al. (2002), Walde et al. (2005) and Chowdhury et al. (2008). The undiluted essential oil exhibited strong antibacterial activity when tested with microorganisms. In comparison with the antibiotics as positive control they are expressing the remarkable activities on Proteus mirabilis compared in Amoxicillin (10mg/disc), Staphylococcus aureus compared in Gentamicin (10mg/disc), Corynebacterium pseudotuberculosis compared in Gentamicin (10mg/disc), Klebsiella pneumonia compared in Gentamicin (10mg/disc), Pseudomonas aeruginosa compared in Clarithromycin (15mg/disc), Enterobacter aerogenes compared in Gentamicin (10mg/disc) and the moderate level zone of inhibition observed against in Salmonella enterica compared in Gentamicin (10mg/disc), Streptococcus pyogenes compared in Penicillin (10mg/disc). Based on this finding, it can be concluded that the essential oil of M. koenigii have the bioactive potential and it will be the prominent antibiotic therapy for tested microbes. This oil may be studied for any bioactive properties for therapeutic uses and also may serve as a useful source of flavors and fragrances. Murraya koenigii essential oil manifested greater antiradical activity with respect to OH• in comparison with DPPH radicals, attested by the respective IC 50 values. The inhibitory capacity of
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Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

Figure 6. STXM images and elemental maps of representative particles in the coarse mode range with some smaller accumulation mode particles. The particles shown here represent a volume equivalent diameter range of 0.6–1.9 µm. (a and b) carbon pre- and post-edge im- ages, (c) carbon elemental map, (d) nitrogen map, (e) oxygen map, and (f) overlay of C (green), N (blue), and O (red) maps. Axes in (a–e) display image dimensions in µm. Optical density (color code) is displayed for individual maps. Red boxes and labels in (b) highlight internally mixed particles with ammoniated sulfate and variable amounts of organics.
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Total OH reactivity measurements using a new fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

Total OH reactivity measurements using a new fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

Abstract. The primary and most important oxidant in the at- mosphere is the hydroxyl radical (OH). Currently OH sinks, particularly gas phase reactions, are poorly constrained. One way to characterize the overall sink of OH is to measure directly the ambient loss rate of OH, the total OH reac- tivity. To date, direct measurements of total OH reactivity have been either performed using a Laser-Induced Fluores- cence (LIF) system (“pump-and-probe” or “flow reactor”) or the Comparative Reactivity Method (CRM) with a Proton- Transfer-Reaction Mass Spectrometer (PTR-MS). Both tech- niques require large, complex and expensive detection sys- tems. This study presents a feasibility assessment for CRM total OH reactivity measurements using a new detector, a Gas Chromatographic Photoionization Detector (GC-PID). Such a system is smaller, more portable, less power consuming and less expensive than other total OH reactivity measure- ment techniques.
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Braz. J. Pharm. Sci.  vol.52 número4

Braz. J. Pharm. Sci. vol.52 número4

Antioxidants are a unique class of substances that are able to protect the biomolecules from oxidative damage caused by endogenous free radicals such as superoxide and hydroxyl radicals produced during various metabolic processes (Nimse, Pal, 2015; Lobo et al., 2010; Sisein, 2014). These free radicals may lead to protein denaturation, lipid per-oxidation, DNA lesions and inally diseased conditions if not captured efectively (Kabel, 2014; Valko et al., 2007). The antioxidants perform their action by trapping the free radicals, reducing the metal ions and preventing the initiation of free radical chain, hydrogen abstraction and peroxide decomposition (Nimse, Pal, 2015). A large number of natural compounds such as ascorbic acid, tocopherols, phenolic acids, lavonoids, anthocyanins, proanthocyanidins and other phytochemical compounds present in food materials have been reported to possess antioxidant properties due to the presence of hydrogen donating groups in their chemical structures (Goufo, Trindade, 2014; Shahidi, 2000). Foods rich in
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Global distribution of the effective aerosol hygroscopicity parameter for CCN activation

Global distribution of the effective aerosol hygroscopicity parameter for CCN activation

about 10% lower and the standard deviation is a factor of two higher than the estimate of Andreae and Rosenfeld (2008). Note, however, that the standard deviations calculated and reported in this study include both spatial and temporal variability unless noted otherwise (see Sect. 3.5.), whereas the observations reviewed by Andreae and Rosenfeld (2008) were mostly short-term measurements providing only lim- ited information about temporal variability. Considering that the two approaches used to estimate the average continental and marine κ values (Andreae and Rosenfeld, 2008, and ours) are completely different and independent, we find the overall agreement between the two studies quite good. In view of the limited observational database, we suggest that the model-derived standard deviation may be a more realistic estimator for the variability of κ in continental aerosols.
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Phytochemical analysis and antifungal activity of selected seaweeds from Okha coast, Gujarat, India

Phytochemical analysis and antifungal activity of selected seaweeds from Okha coast, Gujarat, India

The study evaluated the activity of different species of seaweeds from the Okha coast against pathogenic fungus. As for the tests with pathogenic fungus, the extracts showed differences in their activity depending on the solvent used in the extraction. The brown seaweeds show high antifungal activity as compare to red and green algae. The chloroform and ethanol extract of S. tenerrimum and T. ornate showed highest antifungal activity against tested pathogenic organism than other seaweeds whereas S. cinereum, and Cladophora sp. shown moderate activity against tested pathogens. The acetone extract of seaweeds showed minimum activity against both organisms. In the present study, the species of Phaeophyta showed the strongest activities against fungi, which was in agreement with the findings of Padmakumar and Ayyakkannu [41] . The brown seaweeds contain high amount of flavanoid and phenolic compound could be the reason for antifungal activity, Cowan et al. [42] , further confirmed the greater amounts of phenolic compound in brown algae in the present investigation.
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Examining the major contributors of ozone pollution in a rural area of the Yangtze River Delta region during harvest season

Examining the major contributors of ozone pollution in a rural area of the Yangtze River Delta region during harvest season

Pan, X. L., Kanaya, Y., Wang, Z. F., Komazaki, Y., Taketani, F., Aki- moto, H., and Pochanart, P.: Variations of carbonaceous aerosols from open crop residue burning with transport and its implication to estimate their lifetimes, Atmos. Environ., 74, 301–310, 2013. Ran, L., Zhao, C., Geng, F., Tie, X., Tang, X., Peng, L., Zhou, G., Yu, Q., Xu, J., and Guenther, A.: Ozone photochemical pro- duction in urban Shanghai, China: Analysis based on ground level observations, J. Geophys. Res.-Atmos., 114, D15301, doi:10.1029/2008JD010752, 2009.

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Impact of mixing state and hygroscopicity on CCN activity of biomass burning aerosol in Amazonia

Impact of mixing state and hygroscopicity on CCN activity of biomass burning aerosol in Amazonia

On the other hand, several observational biomass burning studies conducted in the Amazon region reported rather sim- ilar number size distributions for biomass burning aerosols within the boundary layer (Andreae et al., 2004; Artaxo et al., 2013; Brito et al., 2014; Reid et al., 1998; Rissler et al., 2004, 2006). In terms of hygroscopicity, these smoke par- ticles have been found to be externally mixed (Rissler et al., 2004, 2006). Their population effective hygroscopicity pa- rameter, converted from the original data using expressions suggested by Gunthe et al. (2009), ranged between 0.05 and 0.13 (Rissler et al., 2004, 2006); these compare well with observed values for biomass burning aerosols but are rather on the lower side of the range of values reported elsewhere. Reported values of the hygroscopicity parameter for freshly emitted smoke particles in biomass burning laboratory exper- iments reached values up to 0.6, although a significant num- ber of data indicated values between 0.02 and 0.2, with wood species and smoldering fires producing the less hygroscopic particles (Carrico et al., 2010; Dusek et al., 2011; Engelhart et al., 2012; Petters et al., 2009). An average hygroscopicity parameter of 0.21 was obtained for a 4-day biomass burning episode near Guangzhou, China, using airborne data (Rose et al., 2010). The hygroscopicity parameter obtained from CCN airborne measurements for boreal fires biomass burn- ing aerosols in Canada was 0.18 for both recently emitted and aged aerosols, while the values estimated assuming an aver- age chemical composition were, on average, 0.11 for fresh aerosol particles and 0.24 for aged ones, both within the level of variability in the value estimated from CCN measurements (Lathem et al., 2013). A recent study of the hygroscopicity of recently emitted and aged smoke particles reported rang- ing between 0.05 and 0.1 for the same parameter in Thailand (Hsiao et al., 2016).
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Cerâmica  vol.60 número356 v60n356a14

Cerâmica vol.60 número356 v60n356a14

TDF combines scrap tires, which are continuously fed to the kiln, and whole tires, which are fed to the kiln in regular intervals of ca. 30 s each. For this particular study, the current fuel composition was changed, in order to assess the effect of the fuel on the chemical and mineralogical composition of the clinker. Fuel compositions during clinker sampling were: (A) pet coke + coal + scrap waste tires + whole waste tires, which is the current fuel used in the plant; (B) pet coke + coal + scrap waste tires; (C) pet coke + coal. Capital letters A, B and C are used throughout this paper to indicate fuel composition. For each fuel composition, ive samples of clinker (5 kg each) were collected in the lifter to the silo, one sample per hour; each clinker sample is composed by the ive sub-samples, that were checked for their compositional homogeneity and mechanically mixed. Clinker sampling started two hours after changing the fuel composition, for the system to reach equilibrium and avoid major oscillations
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CCN predictions using simplified assumptions of organic aerosol composition and mixing state: a synthesis from six different locations

CCN predictions using simplified assumptions of organic aerosol composition and mixing state: a synthesis from six different locations

small OMF under all assumptions (as also reflected in Table 2). As organic fractions increase above ∼50% (MEX, CBG, HSC), it is evident that CCN number concentra- tions are increasingly underestimated if insoluble organics (EM-I or IM-I) are assumed (Fig. 3a and c), but reasonably well predicted for the EM-S and IM-S assumptions. This is in agreement with the study by Wang et al. (2008) who found that the best closure for

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Antimicrobial activity of berries and leaves essential oils of Macedonian Juniperus foetidissima Willd. (Cupressaceae)

Antimicrobial activity of berries and leaves essential oils of Macedonian Juniperus foetidissima Willd. (Cupressaceae)

Хемискиот состав и антимикробната активност се испитувани кај етеричното масло од иглички и од бобинки од Juniperus foetidissima Willd. (Cupressaceae) кој расте на територија на Р. Македонија. Со GC/FID/MS анализа се идентификувани 93 компоненти кои сочинуваат од 89,7 до 96,5% од маслото. Доминантни компоненти во етеричното масло од бобинки се a-пинен (19,2%), лимонен (24,9%) и цедрол (23,1%), следени со пониска застапеност на b -фунебрен, trans-кариофилен, гермакрен D и d-кадинен. Составот на етеричното масло од иглички варира во зависност од локалитетот на собирање на растителниот материјал. Според тоа, примероците што потекнуваат од југоисточна Македонија содржат етерично масло со доминантни a-пинен (67,6%) и лимонен (10,0%), од централна Македонија лимонен (17,9-27,1%) и цедрол (28,8-33,9%), додека примероците од југозападна Македонија содржат етерично масло со доминантни терпинен-4-ол (19,1%), cis-тујон (8,3%), гермакрен D (11,0%) and d-кадинен (6,3%). Антимикробната активност на етеричните масла е испитувана со агар дифузиона и со агар дилуциона метода кон 16 бактериски изолати на Грам позитивни и Грам негативни бактерии и еден изолат на габата Candida albicans. Етеричните масла од иглички покажаа подобра антимикробна активност кон Staphylococcus aureus, Streptococcus pyogenes и Haemophilus inluenzae (МИК = 125 ml/ml) и умерена активност кон Campylobacter jejuni (МИК > 500 ml/ ml). Останатите испитувани бактерии и Candida albicans покажаа резистентност кон антимикробната активност на етерични масла од J. foetidissima.
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Horário de coleta sobre o teor e a composição química do óleo essencial das folhas de goiabeira Elizabeth Aparecida Josefi da SilvaI Vanessa Paula da SilvaI Cassia Cristina Fernandes AlvesI José Milton AlvesI Edson Luiz SouchieI Luiz Cláudio de Almeida Ba

Horário de coleta sobre o teor e a composição química do óleo essencial das folhas de goiabeira Elizabeth Aparecida Josefi da SilvaI Vanessa Paula da SilvaI Cassia Cristina Fernandes AlvesI José Milton AlvesI Edson Luiz SouchieI Luiz Cláudio de Almeida Ba

be a native Mexican plant, but has spread throughout South America, Europe, Africa, and Asia (SHAH et al., 2011). Because it adapts to different climate conditions, it grows in all tropical and subtropical regions of the world; however, it is widespread in Brazil (GUTIÉRREZ et al., 2008; ROZANE, 2009). Studies characterizing the essential oil derived from guava leaves have shown the presence of 1,8-cineol, d-limonene, and α-pinene, important compounds with potential use as an insecticide (LIMA et al., 2009). Flavonoids, which possess strong antibacterial activity, have also been detected in guava extract (GUTIÉRREZ et al., 2008). Guava is widely used in folk medicine, and data published in the literature showed that extracts obtained from its leaves possess hepatoprotective, anti- inflammatory, antioxidant, antinociceptive, antidiabetic, and other properties (BEATRIZ, et al., 2012). Guava is also used for the treatment of diarrhea and dysentery due to its antispasmodic and antimicrobial properties, which have supported its long-standing use in traditional medicine (BEATRIZ, et al., 2012).
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Néji GHARSALLAH1 , Adel KADRI 1,5

Néji GHARSALLAH1 , Adel KADRI 1,5

DPPH–ABTS, DPPH–FRAP and FRAP–ABTS were 0.74, 0.99 and 0.74, respectively. These results implied that the antioxidants in these extracts were capable of reducing oxidants (ferric ions) and scavenging free radicals (DPPH and ABTS).These strong correlations further confirmed the strong antioxidant potential of phenolic compounds. The differences in the antioxidant properties of the different fruit juice extracts could presumably be attributed to the differences in phenolic and flavonoid compositions, which exhibited several biological effects (Canas et al., 2008). Also the concentration of polyphenols may be influenced by the extent of fruit’s maturity (Kondakova et al., 2009). The variations of TPC in the present analysis of freeze-dried extracts of E. elaterium fruit juices among different locations could be explained by the influence of different parameters such as temperature and different prevalent environmental factors (Wang & Zheng, 2001; Miguel et al., 2014).
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Cold and transition season cloud condensation nuclei measurements in western Colorado

Cold and transition season cloud condensation nuclei measurements in western Colorado

stacks included 5 altitudes, the lowest between 250–500 m above ground level (a.g.l.) and increasing about 500 m on each leg with some variation. Flight plan #2 was used during northerly wind events. It differed mainly in the location of the southern stack, which was moved north to Nucla to sample flow into the San Juan Mountains better in this regime. The north to south transects were similar in both flight plans. These were

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