Exploratory Investigation of Bacteroides fragilis Transcriptional Response during In vitro Exposure to Subinhibitory Concentration of Metronidazole

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de Freitas, Michele C. R.; Resende, Juliana A.; Ferreira-Machado, Alessandra B.; Saji, Guadalupe D. R. Q.; de Vasconcelos, Ana T. R.; da Silva, Vânia L.; Nicolás, Marisa F.; Diniz, Cláudio G.

2016-01-01

Bacteroides fragilis, member from commensal gut microbiota, is an important pathogen associated to endogenous infections and metronidazole remains a valuable antibiotic for the treatment of these infections, although bacterial resistance is widely reported. Considering the need of a better understanding on the global mechanisms by which B. fragilis survive upon metronidazole exposure, we performed a RNA-seq transcriptomic approach with validation of gene expression results by qPCR. Bacteria strains were selected after in vitro subcultures with subinhibitory concentration (SIC) of the drug. From a wild type B. fragilis ATCC 43859 four derivative strains were selected: first and fourth subcultures under metronidazole exposure and first and fourth subcultures after drug removal. According to global gene expression analysis, 2,146 protein coding genes were identified, of which a total of 1,618 (77%) were assigned to a Gene Ontology term (GO), indicating that most known cellular functions were taken. Among these 2,146 protein coding genes, 377 were shared among all strains, suggesting that they are critical for B. fragilis survival. In order to identify distinct expression patterns, we also performed a K-means clustering analysis set to 15 groups. This analysis allowed us to detect the major activated or repressed genes encoding for enzymes which act in several metabolic pathways involved in metronidazole response such as drug activation, defense mechanisms against superoxide ions, high expression level of multidrug efflux pumps, and DNA repair. The strains collected after metronidazole removal were functionally more similar to those cultured under drug pressure, reinforcing that drug-exposure lead to drastic persistent changes in the B. fragilis gene expression patterns. These results may help to elucidate B. fragilis response during metronidazole exposure, mainly at SIC, contributing with information about bacterial survival strategies under stress conditions in their

Influence of subinhibitory-concentration (sub-MIC Cefetoxime on biofilm formation. SEM study of ESBL-producing Salmonella typhi

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Rahul Narasanna, Manjunath Chavadi, Ajaykumar Oli

2017-06-01

Full Text Available Objectives: In the present study, we have analyzed ESBL-producing S. typhi’s capability in forming a significant amount of biofilm on plastic and glass surface, and the influence of cefetoxime on biofilm development at subinhibitory (Sub-MIC concentration. Methods: Nine strains of cefetoxime-mediated ESBL-producing S. typhi were used in the study. S. typhi formed biofilm on plastic and glass materials; it was demonstrated using micro titre plate (MTP and standard test tube methods. Comparative study of the influence of cefetoxime on biofilm formation in its MIC (128 µg/ml and at sub-MIC (64 µg/ml was demonstrated by microtitre plate method. The biofilm production was observed in SEM images, statistical analysis (ANOVA showed significant increase in cell surface and volume due to the influence of Cefetoxime. Results: Of the nine selected isolates, two S. typhi strains, namely BST 51 and BST 130, produced relatively strong biofilm in the presence of cefetoxime at sub-MIC level (64 µg/ml, comparatively weak biofilm formation at MIC level (128 µg/ml. Typical morphological changes were observed in cefetoxime-resistant strains, S. typhi BST 51 and BST 130, in comparison to cefetoxime-sensitive strain S. typhi BST 63 used as a control. We found an increase in surface and volume of a cell in response to cefetoxime and statistical data (ANOVA proved that resistant strains were significantly different from control strains. Conclusion: The above study clearly shows that cefetoxime at sub-MIC level efficiently induces biofilm formation and promotes changes in morphology of the cell. J Microbiol Infect Dis 2017; 7(2: 67-75

Effects of subinhibitory concentrations of antimicrobial agents on Escherichia coli O157:H7 Shiga toxin release and role of the SOS response.

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Nassar, Farah J; Rahal, Elias A; Sabra, Ahmad; Matar, Ghassan M

2013-09-01

Treatment of Escherichia coli O157:H7 by certain antimicrobial agents often exacerbates the patient's condition by increasing either the release of preformed Shiga toxins (Stx) upon cell lysis or their production through the SOS response-triggered induction of Stx-producing prophages. Recommended subinhibitory concentrations (sub-MICs) of azithromycin (AZI), gentamicin (GEN), imipenem (IMI), and rifampicin (RIF) were evaluated in comparison to norfloxacin (NOR), an SOS-inducer, to assess the role of the SOS response in Stx release. Relative expression of recA (SOS-inducer), Q (late antitermination gene of Stx-producing prophage), stx1, and stx2 genes was assessed at two sub-MICs of the antimicrobials for two different strains of E. coli O157:H7 using reverse transcription-real-time polymerase chain reaction. Both strains at the two sub-MICs were also subjected to Western blotting for LexA protein expression and to reverse passive latex agglutination for Stx detection. For both strains at both sub-MICs, NOR and AZI caused SOS-induced Stx production (high recA, Q, and stx2 gene expression and high Stx2 production), so they should be avoided in E. coli O157:H7 treatment; however, sub-MICs of RIF and IMI induced Stx2 production in an SOS-independent manner except for one strain at the first twofold dilution below MIC of RIF where Stx2 production decreased. Moreover, GEN caused somewhat increased Stx2 production due to its mode of action rather than any effect on gene expression. The choice of antimicrobial therapy should rely on the antimicrobial mode of action, its concentration, and on the nature of the strain.

Cefditoren and ceftriaxone enhance complement-mediated immunity in the presence of specific antibodies against antibiotic-resistant pneumococcal strains.

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Elisa Ramos-Sevillano

Full Text Available BACKGROUND: Specific antibodies mediate humoral and cellular protection against invading pathogens such as Streptococcus pneumoniae by activating complement mediated immunity, promoting phagocytosis and stimulating bacterial clearance. The emergence of pneumococcal strains with high levels of antibiotic resistance is of great concern worldwide and a serious threat for public health. METHODOLOGY/PRINCIPAL FINDINGS: Flow cytometry was used to determine whether complement-mediated immunity against three antibiotic-resistant S. pneumoniae clinical isolates is enhanced in the presence of sub-inhibitory concentrations of cefditoren and ceftriaxone. The binding of acute phase proteins such as C-reactive protein and serum amyloid P component, and of complement component C1q, to pneumococci was enhanced in the presence of serum plus either of these antibiotics. Both antibiotics therefore trigger the activation of the classical complement pathway against S. pneumoniae. C3b deposition was also increased in the presence of specific anti-pneumococcal antibodies and sub-inhibitory concentrations of cefditoren and ceftriaxone confirming that the presence of these antibiotics enhances complement-mediated immunity to S. pneumoniae. CONCLUSIONS/SIGNIFICANCE: Using cefditoren and ceftriaxone to promote the binding of acute phase proteins and C1q to pneumococci, and to increase C3b deposition, when anti-pneumococcal antibodies are present, might help reduce the impact of antibiotic resistance in S. pneumoniae infections.

Effects of subtherapeutic concentrations of antimicrobials on gene acquisition events in Yersinia, Proteus, Shigella, and Salmonella recipient organisms in isolated ligated intestinal loops of swine.

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Brewer, Matt T; Xiong, Nalee; Anderson, Kristi L; Carlson, Steve A

2013-08-01

To assess antimicrobial resistance and transfer of virulence genes facilitated by subtherapeutic concentrations of antimicrobials in swine intestines. 20 anesthetized pigs experimentally inoculated with donor and recipient bacteria. 4 recipient pathogenic bacteria (Salmonella enterica serotype Typhimurium, Yersinia enterocolitica, Shigella flexneri, or Proteus mirabilis) were incubated with donor bacteria in the presence of subinhibitory concentrations of 1 of 16 antimicrobials in isolated ligated intestinal loops in swine. Donor Escherichia coli contained transferrable antimicrobial resistance or virulence genes. After coincubations, intestinal contents were removed and assessed for pathogens that acquired new antimicrobial resistance or virulence genes following exposure to the subtherapeutic concentrations of antimicrobials. 3 antimicrobials (apramycin, lincomycin, and neomycin) enhanced transfer of an antimicrobial resistance plasmid from commensal E coli organisms to Yersinia and Proteus organisms, whereas 7 antimicrobials (florfenicol, hygromycin, penicillin G, roxarsone, sulfamethazine, tetracycline, and tylosin) exacerbated transfer of an integron (Salmonella genomic island 1) from Salmonella organisms to Yersinia organisms. Sulfamethazine induced the transfer of Salmonella pathogenicity island 1 from pathogenic to nonpathogenic Salmonella organisms. Six antimicrobials (bacitracin, carbadox, erythromycin, sulfathiazole, tiamulin, and virginiamycin) did not mediate any transfer events. Sulfamethazine was the only antimicrobial implicated in 2 types of transfer events. 10 of 16 antimicrobials at subinhibitory or subtherapeutic concentrations augmented specific antimicrobial resistance or transfer of virulence genes into pathogenic bacteria in isolated intestinal loops in swine. Use of subtherapeutic antimicrobials in animal feed may be associated with unwanted collateral effects.

Effects of Subinhibitory Concentrations of Ceftaroline on Methicillin-Resistant Staphylococcus aureus (MRSA Biofilms.

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María Lázaro-Díez

Full Text Available Ceftaroline (CPT is a novel cephalosporin with in vitro activity against Staphylococcus aureus. Ceftaroline exhibits a level of binding affinity for PBPs in S. aureus including PBP2a of methicillin-resistant S. aureus (MRSA. The aims of this study were to investigate the morphological, physiological and molecular responses of MRSA clinical strains and MRSA biofilms to sub-MICs (1/4 and 1/16 MIC of ceftaroline by using transmission, scanning and confocal microscopy. We have also used quantitative Real-Time PCR to study the effect of sub-MICs of ceftaroline on the expression of the staphylococcal icaA, agrA, sarA and sasF genes in MRSA biofilms. In one set of experiments, ceftaroline was able to inhibit biofilm formation in all strains tested at MIC, however, a strain dependent behavior in presence of sub-MICs of ceftaroline was shown. In a second set of experiments, destruction of preformed biofilms by addition of ceftaroline was evaluated. Ceftaroline was able to inhibit biofilm formation at MIC in all strains tested but not at the sub-MICs. Destruction of preformed biofilms was strain dependent because the biofilm formed by a matrix-producing strain was resistant to a challenge with ceftaroline at MIC, whereas in other strains the biofilm was sensitive. At sub-MICs, the impact of ceftaroline on expression of virulence genes was strain-dependent at 1/4 MIC and no correlation between ceftaroline-enhanced biofilm formation and gene regulation was established at 1/16 MIC. Our findings suggest that sub-MICs of ceftaroline enhance bacterial attachment and biofilm formation by some, but not all, MRSA strains and, therefore, stress the importance of maintaining effective bactericidal concentrations of ceftaroline to fight biofilm-MRSA related infections.

The in vitro synergistic inhibitory effect of human amniotic fluid and gentamicin on growth of Escherichia coli.

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Miglioli, P A; Schoffel, U; Gianfranceschi, L

1996-01-01

The activity of serum and its synergistic effect with many antibiotics against bacteria are well known. Few reports are available on similar phenomena produced by human amniotic fluid (HAF). Thus we investigated the antibacterial activity of HAF and the presence of a synergistic effect with gentamicin (GM) against Escherichia coli strains. Antimicrobial activity was evaluated as a delay of the growth curve, using a turbidimetric method. E. coli ATCC 10798 and E. coli SC 12155 were employed as test micro-organisms in nutrient broth, and GM was used at a subinhibitory concentration. HAF exerted antibacterial activity and, cooperating with GM at subinhibitory concentration, enhanced its antibiotic activity against E. coli. The presence of Schlievert's glycoprotein in HAF could explain these results.

Subinhibitory concentrations of cell wall synthesis inhibitors promote biofilm formation of Enterococcus faecalis

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Yu, Wen; Hallinen, Kelsey; Wood, Kevin

Enterococcus faecalis are commonly associated with hospital acquired infections, because they readily form biofilms on instruments and medical devices. Biofilms are inherently more resistant to killing by antibiotics compared to planktonic bacteria, in part because of their heterogeneous spatial structure. Surprisingly, however, subminimal inhibitory concentrations (sub-MICs) of some antibiotics can actually promote biofilm formation. Unfortunately, much is still unknown about how low drug doses affect the composition and spatial structure of the biofilm. In this work, we investigate the effects of sub-MICs of ampicillin on the formation of E. faecalis biofilms. First, we quantified biofilm mass using crystal violet staining in polystyrene microtiter plates. We found that total biofilm mass is increased over a narrow range of ampicillin concentrations before ultimately declining at higher concentrations. Second, we show that sub-MICs of ampicillin can increase mass of E. faecalis biofilms while simultaneously increasing extracellular DNA/RNA and changing total number of viable cells under confocal microscopy. Further, we use RNA-seq to identify genes differentially expressed under sub-MICs of ampicillin. Finally, we show a mathematical model to explain this phenomenon. This work was funded by The Hartwell Foundation Individual Biomedical Research Award and NSF CAREER 1553208 to KBW.

β-lactam antibiotics promote bacterial mutagenesis via an RpoS-mediated reduction in replication fidelity

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Gutierrez, A.; Laureti, L.; Crussard, S.; Abida, H.; Rodríguez-Rojas, A.; Blázquez, J.; Baharoglu, Z.; Mazel, D.; Darfeuille, F.; Vogel, J.; Matic, I.

2013-01-01

Regardless of their targets and modes of action, subinhibitory concentrations of antibiotics can have an impact on cell physiology and trigger a large variety of cellular responses in different bacterial species. Subinhibitory concentrations of β-lactam antibiotics cause reactive oxygen species production and induce PolIV-dependent mutagenesis in Escherichia coli. Here we show that subinhibitory concentrations of β-lactam antibiotics induce the RpoS regulon. RpoS-regulon induction is required for PolIV-dependent mutagenesis because it diminishes the control of DNA-replication fidelity by depleting MutS in E. coli, Vibrio cholerae and Pseudomonas aeruginosa. We also show that in E. coli, the reduction in mismatch-repair activity is mediated by SdsR, the RpoS-controlled small RNA. In summary, we show that mutagenesis induced by subinhibitory concentrations of antibiotics is a genetically controlled process. Because this mutagenesis can generate mutations conferring antibiotic resistance, it should be taken into consideration for the development of more efficient antimicrobial therapeutic strategies. PMID:23511474

Evolution of antibiotic resistance in biofilm and planktonic P. aeruginosa populations exposed to sub-inhibitory levels of ciprofloxacin

DEFF Research Database (Denmark)

Ahmed, Marwa N.; Porse, Andreas; Sommer, Morten Otto Alexander

2018-01-01

in planktonic cultures and are less studied in biofilms. We experimentally evolved P. aeruginosa PAO1 colony-biofilms and stationary-phase planktonic cultures for seven passages in the presence of sub-inhibitory levels (0.1 mg/L) of ciprofloxacin (CIP) and performed a genotypic (whole bacterial population......The opportunistic Gram-negative pathogen Pseudomonas aeruginosa, known for its intrinsic and acquired antibiotic resistance, has a notorious ability to form biofilms, which often facilitate chronic infections. The evolutionary paths to antibiotic resistance have mainly been investigated......-dependent adaptations. A general trend towards a reduction in type IV-pili dependent motility (twitching) in CIP-evolved populations, and towards loss of virulence associated traits in the populations evolved in the absence of antibiotic, was observed. In conclusion, our data indicate that biofilms facilitate...

and their biological role

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Agnieszka Zabłotni

2014-08-01

Full Text Available Nowadays antibiotics are broadly used not only for treatment of bacterial infections but also in nonmedical applications. For many years they have been added as livestock and poultry growth supplements, and they are applied similarly in fish farming. In basically unchanged form they may get into the natural environment and remain there for a long time. Excessive use of antibiotics leads to widespread of antibiotic resistance among clinical and environmental bacterial strains. Subinhibitory concentrations of antibiotics, which do not inhibit growth of bacteria, are often found in soil, water or even in the tissue of different organisms. Such low concentrations affect many bacterial genes through changes in their transcription level and increase of the mutation rate, and as a consequence lead to many bacterial adaptations to environmental stresses. There is also evidence that subinhibitory concentrations of antibiotics induce transfer of mobile genetic elements through horizontal gene transfer pathways, and therefore enhance antibiotic resistance, also among environmental strains. The analyzed data suggest the necessity of restriction and regular monitoring of antibiotics, which may be considered as environmental pollutants.

Enhancement of PM2.5 Concentrations by Aerosol-Meteorology Interactions Over China

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Zhang, Xin; Zhang, Qiang; Hong, Chaopeng; Zheng, Yixuan; Geng, Guannan; Tong, Dan; Zhang, Yuxuan; Zhang, Xiaoye

2018-01-01

Aerosol-meteorology interactions can change surface aerosol concentrations via different mechanisms such as altering radiation budget or cloud microphysics. However, few studies investigated the impacts of different mechanisms on temporal and spatial distribution of PM2.5 concentrations over China. Here we used the fully coupled Weather Research and Forecasting model with online chemistry (WRF-Chem) to quantify the enhancement of PM2.5 concentrations by aerosol-meteorology feedback in China in 2014 for different seasons and separate the relative impacts of aerosol radiation interactions (ARIs) and aerosol-cloud interactions (ACIs). We found that ARIs and ACIs could increase population-weighted annual mean PM2.5 concentration over China by 4.0 μg/m3 and 1.6 μg/m3, respectively. We found that ARIs play a dominant role in aerosol-meteorology interactions in winter, while the enhancement of PM2.5 concentration by ARIs and ACIs is comparable in other three seasons. ARIs reduced the wintertime monthly mean wind speed and planetary boundary layer (PBL) height by up to 0.1 m/s and 160 m, respectively, but increased the relative humidity by up to 4%, leading to accumulation of pollutants within PBL. Also, ARIs reduced dry deposition velocity of aerosols by up to 20%, resulting in an increase in PM2.5 lifetime and concentrations. ARIs can increase wintertime monthly mean surface PM2.5 concentration by a maximum of 30 μg/m3 in Sichuan Basin. ACIs can also increase PM2.5 concentration with more significant impacts in wet seasons via reduced wet scavenging and enhanced in-cloud chemistry. Dominant processes in PM2.5 enhancement are also clarified in different seasons. Results show that physical process is more important than chemical processes in winter in ARIs, while chemical process of secondary inorganic aerosols production may be crucial in wet seasons via ACIs.

Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.

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Telma Blanca Lombardo Bedran

Full Text Available Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.

Alterations in growth and branching of Neurospora crassa caused by sub-inhibitory concentrations of antifungal agents Alteraciones de crecimiento y ramificación en Neurospora crassa provocadas por concentraciones subinhibitorias de agentes antimicóticos

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R. C. Pereira

2009-03-01

Full Text Available Six antifungal agents at subinhibitory concentrations were used for investigating their ability to affect the growth and branching in Neurospora crassa. Among the antifungals herein used, the azole agent ketoconazole at 0.5 μg/ml inhibited radial growth more than fluconazole at 5.0 μg/ml while amphotericin B at 0.05 μg/ml was more effective than nystatin at 0.05 μg/ml. Morphological alterations in hyphae were observed in the presence of griseofulvin, ketoconazole and terbinafine at the established concentrations. The antifungal agents were more effective on vegetative growth than on conidial germination. Terbinafine markedly reduced growth unit length (GU by 54.89%, and caused mycelia to become hyperbranched. In all cases, there was a high correlation between hyphal length and number of tips (r > 0.9. All our results showed highly significant differences by ANOVA, (p Se investigó el efecto de seis agentes antimicóticos en concentraciones subinhibitorias sobre el crecimiento y la ramificación en Neurospora crassa. El agente azólico ketoconazol a la concentración de 0,5 μg/ml inhibió el crecimiento radial más que el fluconazol a 5,0 μg/ml, y la anfotericina B a 0,05 μg/ ml fue más eficiente que 0,05 μg/ml de nistatina, entre los agentes poliénicos usados. En presencia de griseofulvina, ketoconazol y terbinafina a las concentraciones establecidas se observaron alteraciones morfológicas en las hifas. Los agentes antimicóticos fueron más eficientes sobre el crecimiento vegetativo que sobre la germinación conidial. La terbinafina redujo marcadamente (54,89% la longitud de la unidad de crecimiento y provocó la hiperramificación del micelio. En todos los casos, existió gran correlación entre la longitud y el número de ápices de las hifas (r > 0,9. Todos los resultados mostraron diferencias altamente significativas de acuerdo con ANOVA (p < 0,001, α = 0,05. Considerando que el ápice de la hifa es la principal interfase entre

Inhibition of the NorA multi-drug transporter by oxygenated monoterpenes.

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Coêlho, Mayara Ladeira; Ferreira, Josie Haydée Lima; de Siqueira Júnior, José Pinto; Kaatz, Glenn W; Barreto, Humberto Medeiros; de Carvalho Melo Cavalcante, Ana Amélia

2016-10-01

The aim of this study was to investigate intrinsic antimicrobial activity of three monoterpenes nerol, dimethyl octanol and estragole, against bacteria and yeast strains, as well as, investigate if these compounds are able to inhibit the NorA efflux pump related to fluoroquinolone resistance in Staphylococcus aureus. Minimal inhibitory concentrations (MICs) of the monoterpenes against Staphylococcus aureus, Escherichia coli and Candida albicans strains were determined by micro-dilution assay. MICs of the norfloxacin against a S. aureus strain overexpressing the NorA protein were determined in the absence or in the presence of the monoterpenes at subinhibitory concentrations, aiming to verify the ability of this compounds act as efflux pump inhibitors. The monoterpenes were inactive against S. aureus however the nerol was active against E. coli and C. albicans. The addition of the compounds to growth media at sub-inhibitory concentrations enhanced the activity of norfloxacin against S. aureus SA1199-B. This result shows that bioactives tested, especially the nerol, are able to inhibit NorA efflux pump indicating a potential use as adjuvants of norfloxacin for therapy of infections caused by multi-drug resistant S. aureus strains. Copyright © 2016 Elsevier Ltd. All rights reserved.

Concentration Dependence of Gold Nanoparticles for Fluorescence Enhancement

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Solomon, Joel; Wittmershaus, Bruce

Noble metal nanoparticles possess a unique property known as surface plasmon resonance in which the conduction electrons oscillate due to incoming light, dramatically increasing their absorption and scattering of light. The oscillating electrons create a varying electric field that can affect nearby molecules. The fluorescence and photostability of fluorophores can be enhanced significantly when they are near plasmonic nanoparticles. This effect is called metal enhanced fluorescence (MEF). MEF from two fluorescence organic dyes, Lucifer Yellow CH and Riboflavin, was measured with different concentrations of 50-nm colloidal gold nanoparticles (Au-NP). The concentration range of Au-NP was varied from 2.5 to 250 pM. To maximize the interaction, the dyes were chosen so their emission spectra had considerable overlap with the absorption spectra of the Au-NP, which is common in MEF studies. If the dye molecules are too close to the surface of Au-NP, fluorescence quenching can occur instead of MEF. To try to observe this difference, silica-coated Au-NP were compared to citrate-based Au-NP; however, fluorescence quenching was observed with both Au-NP. This material is based upon work supported by the National Science Foundation under Grant Number NSF-ECCS-1306157.

Observation of Enhanced Hole Extraction in Br Concentration Gradient Perovskite Materials.

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Kim, Min-Cheol; Kim, Byeong Jo; Son, Dae-Yong; Park, Nam-Gyu; Jung, Hyun Suk; Choi, Mansoo

2016-09-14

Enhancing hole extraction inside the perovskite layer is the key factor for boosting photovoltaic performance. Realization of halide concentration gradient perovskite materials has been expected to exhibit rapid hole extraction due to the precise bandgap tuning. Moreover, a formation of Br-rich region on the tri-iodide perovskite layer is expected to enhance moisture stability without a loss of current density. However, conventional synthetic techniques of perovskite materials such as the solution process have not achieved the realization of halide concentration gradient perovskite materials. In this report, we demonstrate the fabrication of Br concentration gradient mixed halide perovskite materials using a novel and facile halide conversion method based on vaporized hydrobromic acid. Accelerated hole extraction and enhanced lifetime due to Br gradient was verified by observing photoluminescence properties. Through the combination of secondary ion mass spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy analysis, the diffusion behavior of Br ions in perovskite materials was investigated. The Br-gradient was found to be eventually converted into a homogeneous mixed halide layer after undergoing an intermixing process. Br-substituted perovskite solar cells exhibited a power conversion efficiency of 18.94% due to an increase in open circuit voltage from 1.08 to 1.11 V and an advance in fill-factor from 0.71 to 0.74. Long-term stability was also dramatically enhanced after the conversion process, i.e., the power conversion efficiency of the post-treated device has remained over 97% of the initial value under high humid conditions (40-90%) without any encapsulation for 4 weeks.

Concentric circular ring and nanodisk optical antenna enhanced multispectral quantum dot infrared photodetector with spectral localization

International Nuclear Information System (INIS)

Zhang, Yingjie; Kemsri, Thitikorn; Li, Lin; Lu, Xuejun; Gu, Guiru

2017-01-01

In this paper, we report a concentric circular ring and nanodisk plasmonic optical antenna (POA) enhanced multispectral quantum dot infrared photodetector (QDIP). The circular ring and the nanodisk POA structures are designed to have plasmonic resonant wavelengths in the longwave infrared (LWIR) and the midwave infrared (MWIR) spectral regimes, respectively. The electric field ( E -field) distributions are simulated and show spectral localization due to the distinct plasmonic resonant wavelengths of the POA structures. The circular ring is found to enhance the E -fields in the nanodisk regions due to the mutual coupling. A concentric circular ring and nanodisk POA enhanced multispectral QDIP was fabricated and tested. Multispectral enhancement was observed. The enhancement is compared to that of a QDIP with only the circular ring POA structure. The experiment data agree with the simulation. The concentric circular ring and nanodisk POA provides a compact planar structure for multispectral QDIP enhancement. (paper)

Modulation of the norfloxacin resistance in Staphylococcus aureus by Cordia verbenaceae DC.

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Matias, Edinardo F F; Santos, Karla K A; Falcão-Silva, Vivyanne S; Siqueira-Junior, Jose P; Costa, Jose G M; Coutinho, Henrique D M

2013-01-01

Several chemical compounds isolated from natural sources have antibacterial activity and some enhance the antibacterial activity of antibiotics reversing the natural resistance of bacteria to certain antibiotics. In this study, the hexane and methanol extract of Cordia verbenaceae were assessed for antibacterial activity alone and combinated with norfloxacin against the Staphylococcus aureus strain SA1199B. The minimum inhibitory concentration (MIC) of extracts was assayed using microdilution assay and the modulatory activity was evaluated using plate diffusion assay. The MIC observed varied between 256 to >1024 μg/ml. However, the antibiotic activity of norfloxacin was enhanced in the presence of subinhibitory concentrations of hexane extract of C. verbenaceae (HECV). INTERPRETATIONS & CONCLUSIONS: Our results indicate that Cordia verbenaceae DC. can be a source of plant derived products with antibiotic modifying activity.

Inhibition of Cell Differentiation in Bacillus subtilis by Pseudomonas protegens

Science.gov (United States)

Powers, Matthew J.; Sanabria-Valentín, Edgardo; Bowers, Albert A.

2015-01-01

ABSTRACT Interspecies interactions have been described for numerous bacterial systems, leading to the identification of chemical compounds that impact bacterial physiology and differentiation for processes such as biofilm formation. Here, we identified soil microbes that inhibit biofilm formation and sporulation in the common soil bacterium Bacillus subtilis. We did so by creating a reporter strain that fluoresces when the transcription of a biofilm-specific gene is repressed. Using this reporter in a coculture screen, we identified Pseudomonas putida and Pseudomonas protegens as bacteria that secrete compounds that inhibit biofilm gene expression in B. subtilis. The active compound produced by P. protegens was identified as the antibiotic and antifungal molecule 2,4-diacetylphloroglucinol (DAPG). Colonies of B. subtilis grown adjacent to a DAPG-producing P. protegens strain had altered colony morphologies relative to B. subtilis colonies grown next to a DAPG-null P. protegens strain (phlD strain). Using a subinhibitory concentration of purified DAPG in a pellicle assay, we saw that biofilm-specific gene transcription was delayed relative to transcription in untreated samples. These transcriptional changes also corresponded to phenotypic alterations: both biofilm biomass and spore formation were reduced in B. subtilis liquid cultures treated with subinhibitory concentrations of DAPG. Our results add DAPG to the growing list of antibiotics that impact bacterial development and physiology at subinhibitory concentrations. These findings also demonstrate the utility of using coculture as a means to uncover chemically mediated interspecies interactions between bacteria. IMPORTANCE Biofilms are communities of bacteria adhered to surfaces by an extracellular matrix; such biofilms can have important effects in both clinical and agricultural settings. To identify chemical compounds that inhibited biofilm formation, we used a fluorescent reporter to screen for bacteria that

Fluconazole affects the alkali-metal-cation homeostasis and susceptibility to cationic toxic compounds of Candida glabrata.

Science.gov (United States)

Elicharova, Hana; Sychrova, Hana

2014-08-01

Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane alkali-metal-cation exporters, a cation/proton antiporter and a cation ATPase to cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic alkali-metal cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more cations into the cells and affects cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various cationic drugs and toxic cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus cationic drug treatment was enhanced by the malfunction of alkali-metal-cation transporters that contribute to the regulation of membrane potential and cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and cationic drugs strongly affects the growth of C. glabrata cells. © 2014 The Authors.

Synergism Effect of the Essential Oil from Ocimum basilicum var. Maria Bonita and Its Major Components with Fluconazole and Its Influence on Ergosterol Biosynthesis

Science.gov (United States)

Cardoso, Nathalia N. R.; Alviano, Celuta S.; Blank, Arie F.; Romanos, Maria Teresa V.; Fonseca, Beatriz B.; Rozental, Sonia; Rodrigues, Igor A.; Alviano, Daniela S.

2016-01-01

The aim of this study was to evaluate the activity of the EO and its major components of Ocimum basilicum var. Maria Bonita, a genetically improved cultivar, against the fluconazole sensitive and resistant strains of Candida albicans and Cryptococcus neoformans. Geraniol presented better results than the EO, with a low MIC (76 μg/mL against C. neoformans and 152 μg/mL against both Candida strains). The combination of EO, linalool, or geraniol with fluconazole enhanced their antifungal activity, especially against the resistant strain (MIC reduced to 156, 197, and 38 μg/mL, resp.). The ergosterol assay showed that subinhibitory concentrations of the substances were able to reduce the amount of sterol extracted. The substances tested were able to reduce the capsule size which suggests they have an important mechanism of action. Transmission electron microscopy demonstrated cell wall destruction of C. neoformans after treatment with subinhibitory concentrations. In C. albicans ultrastructure alterations such as irregularities in the membrane, presence of vesicles, and cell wall thickening were observed. The biofilm formation was inhibited in both C. albicans strains at MIC and twice MIC. These results provide further support for the use of O. basilicum EO and its major components as a potential source of antifungal agents. PMID:27274752

Effect of passive concentration as instructional set for training enhancement of EEG alpha.

Science.gov (United States)

Knox, S S

1980-12-01

The technique of passive concentration, employed by autogenic training and Transcendental Meditation for achieving relaxation, was tested here as a technique for enhancing EEG alpha. Of 30 subjects displaying between 15% and 74% alpha in their resting EEGs recruited, 10 had to be eliminated. The remaining 20 constituted two groups. One was instructed only to attempt to maintain a tone indicating alpha but given no information about technique (control group). The other was given additional instructions in passive concentration (experimental group). Both were given four 5-min. trials a day for 4 consecutive days. Heart rate and skin conductance were measured to monitor autonomic arousal. The group receiving instructions in passive concentration had significantly less alpha than the control group, which did not increase amount of alpha above baseline. The reduction of alpha in the experimental group was interpreted as resulting from beginning long training periods (20 min. per day), a practice advocated by Transcendental Meditation but discouraged by autogenic training. It was concluded that the relevance of passive concentration for alpha enhancement is doubtful.

Enhancing Protease Activity Assay in Droplet-Based Microfluidics Using a Biomolecule Concentrator

Science.gov (United States)

Chen, Chia-Hung; Sarkar, Aniruddh; Song, Yong-Ak; Miller, Miles A.; Kim, Sung Jae; Griffith, Linda G.; Lauffenburger, Douglas A.; Han, Jongyoon

2011-01-01

We introduce an integrated microfluidic device consisting of a biomolecule concentrator and a microdroplet generator, which enhances the limited sensitivity of low-abundance enzyme assays by concentrating biomolecules before encapsulating them into droplet microreactors. We used this platform to detect ultra low levels of matrix metalloproteinases (MMPs) from diluted cellular supernatant and showed that it significantly (∼10-fold) reduced the time required to complete the assay and the sample volume used. PMID:21671557

Enhancing effect of marine oligotrophy on environmental concentrations of particle-reactive trace elements

International Nuclear Information System (INIS)

Jeffree, R.A.; Szymczak, R.

2000-01-01

A biogeochemical model has been previously developed that explains the inverse and nonlinear relationship between Po-210 concentration in zooplankton and their biomass, under oligotrophic conditions in French Polynesia. In this study the model structure was reviewed to determine a set of biogeochemical behaviors of Po-210, proposed to be critical to its environmental enhancement under oligotrophy: this set was then used to identify 25 other elements with comparable behaviors to Po-210. Field investigation in the Timor Sea showed that four of these a priori identified elements, viz. Cd, Co, Pb, and Mn as well as Cr and Ni, showed elevated water concentrations with reduced particle removal rates in the euphotic zone, results that are consistent with those previously obtained for Po-210 and the proposed explanatory model. These findings point to the enhanced susceptibility to contamination with particle-reactive elements of oligotrophic marine systems, whose degree and geographic extent may be enhanced by projected increases in sea surface temperatures from global warming

Krypton-enhanced ventilation CT with dual energy technique: experimental study for optimal krypton concentration.

Science.gov (United States)

Chung, Yong Eun; Hong, Sae Rom; Lee, Mi-Jung; Lee, Myungsu; Lee, Hye-Jeong

2014-11-01

To assess the feasibility of krypton-enhanced ventilation CT using dual energy (DE) technique for various krypton concentrations and to determine the appropriate krypton concentration for DE ventilation CT through an animal study. Baseline DECT was first performed on seven New Zealand white rabbits. The animals were then ventilated using 20%, 30%, 40%, 50%, 60%, to 70% krypton concentration, and DECT was performed for each concentration. Krypton extraction was performed through a workstation, and results were displayed on a color map. Overlay Hounsfield unit (HU) values were obtained by two observers in consensus readings. A linear mixed model was used to correlate overlay HU values and krypton concentrations. Visual assessments of the homogeneity of krypton maps were also performed. Mean overlay HU values according to krypton concentration were as follows; 20% krypton, 1.68 ± 5.15; 30% krypton, 3.73 ± 5.93; 40% krypton, 6.92 ± 5.51; 50% krypton, 10.88 ± 5.17; 60% krypton, 14.54 ± 4.23; and 70% krypton, 18.79 ± 3.63. We observed a significant correlation between overlay HU values on krypton maps and krypton concentrations (P krypton color maps, all observers determined universal enhancement on the 70% krypton map for all animals. It is feasible to evaluate lung ventilation function using DECT with a krypton concentration of at least 70%.

Liposomal Formulation of Turmerone-Rich Hexane Fractions from Curcuma longa Enhances Their Antileishmanial Activity

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Ana Claudia F. Amaral

2014-01-01

Full Text Available Promastigote forms of Leishmania amazonensis were treated with different concentrations of two fractions of Curcuma longa cortex rich in turmerones and their respective liposomal formulations in order to evaluate growth inhibition and the minimal inhibitory concentration (MIC. In addition, cellular alterations of treated promastigotes were investigated under transmission and scanning electron microscopies. LipoRHIC and LipoRHIWC presented lower MIC, 5.5 and 12.5 μg/mL, when compared to nonencapsulated fractions (125 and 250 μg/mL, respectively, and to ar-turmerone (50 μg/mL. Parasite growth inhibition was demonstrated to be dose-dependent. Important morphological changes as rounded body and presence of several roles on plasmatic membrane could be seen on L. amazonensis promastigotes after treatment with subinhibitory concentration (2.75 μg/mL of the most active LipoRHIC. In that sense, the hexane fraction from the turmeric cortex of Curcuma longa incorporated in liposomal formulation (LipoRHIC could represent good strategy for the development of new antileishmanial agent.

Liposomal Formulation of Turmerone-Rich Hexane Fractions from Curcuma longa Enhances Their Antileishmanial Activity

Science.gov (United States)

Amaral, Ana Claudia F.; Gomes, Luciana A.; Silva, Jefferson Rocha de A.; Ferreira, José Luiz P.; Ramos, Aline de S.; Rosa, Maria do Socorro S.; Vermelho, Alane B.; Rodrigues, Igor A.

2014-01-01

Promastigote forms of Leishmania amazonensis were treated with different concentrations of two fractions of Curcuma longa cortex rich in turmerones and their respective liposomal formulations in order to evaluate growth inhibition and the minimal inhibitory concentration (MIC). In addition, cellular alterations of treated promastigotes were investigated under transmission and scanning electron microscopies. LipoRHIC and LipoRHIWC presented lower MIC, 5.5 and 12.5 μg/mL, when compared to nonencapsulated fractions (125 and 250 μg/mL), respectively, and to ar-turmerone (50 μg/mL). Parasite growth inhibition was demonstrated to be dose-dependent. Important morphological changes as rounded body and presence of several roles on plasmatic membrane could be seen on L. amazonensis promastigotes after treatment with subinhibitory concentration (2.75 μg/mL) of the most active LipoRHIC. In that sense, the hexane fraction from the turmeric cortex of Curcuma longa incorporated in liposomal formulation (LipoRHIC) could represent good strategy for the development of new antileishmanial agent. PMID:25045693

Evaluation of the minimum iodine concentration for contrast-enhanced subtraction mammography

International Nuclear Information System (INIS)

Baldelli, P; Bravin, A; Maggio, C Di; Gennaro, G; Sarnelli, A; Taibi, A; Gambaccini, M

2006-01-01

Early manifestation of breast cancer is often very subtle and is displayed in a complex and variable pattern of normal anatomy that may obscure the disease. The use of dual-energy techniques, that can remove the structural noise, and contrast media, that enhance the region surrounding the tumour, could help us to improve the detectability of the lesions. The aim of this work is to investigate the use of an iodine-based contrast medium in mammography with two different double exposure techniques: K-edge subtraction mammography and temporal subtraction mammography. Both techniques have been investigated by using an ideal source, like monochromatic beams produced at a synchrotron radiation facility and a clinical digital mammography system. A dedicated three-component phantom containing cavities filled with different iodine concentrations has been developed and used for measurements. For each technique, information about the minimum iodine concentration, which provides a significant enhancement of the detectability of the pathology by minimizing the risk due to high dose and high concentration of contrast medium, has been obtained. In particular, for cavities of 5 and 8 mm in diameter filled with iodine solutions, the minimum concentration needed to obtain a contrast-to-noise ratio of 5 with a mean glandular dose of 2 mGy has been calculated. The minimum concentrations estimated with monochromatic beams and K-edge subtraction mammography are 0.9 mg ml -1 and 1.34 mg ml -1 for the biggest and smallest details, respectively, while for temporal subtraction mammography they are 0.84 mg ml -1 and 1.31 mg ml -1 . With the conventional clinical system the minimum concentrations for the K-edge subtraction mammography are 4.13 mg ml -1 (8 mm diameter) and 5.75 mg ml -1 (5 mm diameter), while for the temporal subtraction mammography they are 1.01 mg ml -1 (8 mm diameter) and 1.57 mg ml -1 (5 mm diameter)

Menadione (vitamin K enhances the antibiotic activity of drugs by cell membrane permeabilization mechanism

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Jacqueline C. Andrade

2017-01-01

Full Text Available Menadione, vitamin K3, belongs to the class of lipid-soluble vitamins and lipophilic substances as menadione cause disturbances in the bacterial membrane, resulting in damage to the fundamental elements for the integrity of the membrane, thus allowing increased permeability. Accordingly, the aim of this study was to evaluate in vitro the antibiotic-modifying activity of menadione in multiresistant strains of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, with a gradual increase in its subinhibitory concentration. In addition, menadione was compared with cholesterol and ergosterol for similarity in mechanism of drug modulatory action. Antibiotic-modifying activity and antibacterial effect were determined by the broth microdilution assay. Menadione, cholesterol and ergosterol showed modulatory activity at clinically relevant concentrations, characterizing them as modifiers of bacterial drug resistance, since they lowered the MIC of the antibiotics tested. This is the first report of the antibacterial activity of menadione and its potentiation of aminoglycosides against multiresistant bacteria.

Subinhibitory concentrations of imipenem induce increased resistance to methicillin and imipenem in vitro in methicillin-resistant Staphylococcus aureus.

OpenAIRE

Forbes, B A; McClatchey, K D; Schaberg, D R

1984-01-01

Methicillin-resistant (MR) Staphylococcus aureus that was susceptible to less than 0.75 micrograms of imipenem per ml demonstrated inducible resistance. MR S. aureus preincubated with 0.05 microgram of imipenem per ml grew in medium with an imipenem concentration of 32 micrograms/ml, and methicillin MICs increased 20-fold. Non-MR S. aureus exhibited no induction. Preincubation with methicillin produced no effect. Induction appeared to be a unique interaction of imipenem with MR S. aureus.

Microwave enhanced Fenton-like process for the treatment of high concentration pharmaceutical wastewater

International Nuclear Information System (INIS)

Yang Yu; Wang Peng; Shi Shujie; Liu Yuan

2009-01-01

This paper explored a novel process for wastewater treatment, i.e. microwave enhanced Fenton-like process. This novel process was introduced to treat high concentration pharmaceutical wastewater with initial COD loading of 49,912.5 mg L -1 . Operating parameters were investigated and the optimal condition included as follows: microwave power was 300 W, radiation time was 6 min, initial pH was 4.42, H 2 O 2 dosage was 1300 mg L -1 and Fe 2 (SO 4 ) 3 dosage was 4900 mg L -1 , respectively. Within the present experimental condition used, the COD removal and UV 254 removal reached to 57.53% and 55.06%, respectively, and BOD 5 /COD was enhanced from 0.165 to 0.470. The variation of molecular weight distribution indicated that both macromolecular substances and micromolecular substances were eliminated quite well. The structure of flocs revealed that one ferric hydrated ion seemed to connect with another ferric hydrated ion and/or organic compound molecule to form large-scale particles by means of van der waals force and/or hydrogen bond. Subsequently, these particles aggregated to form flocs and settled down. Comparing with traditional Fenton-like reaction and conventional heating assisted Fenton-like reaction, microwave enhanced Fenton-like process displayed superior treatment efficiency. Microwave was in favor of improving the degradation efficiency, the settling quality of sludge, as well as reducing the yield of sludge and enhancing the biodegradability of effluent. Microwave enhanced Fenton-like process is believed to be a promising treatment technology for high concentration and biorefractory wastewater.

The osmolyte xylitol reduces the salt concentration of airway surface liquid and may enhance bacterial killing

Science.gov (United States)

Zabner, Joseph; Seiler, Michael P.; Launspach, Janice L.; Karp, Philip H.; Kearney, William R.; Look, Dwight C.; Smith, Jeffrey J.; Welsh, Michael J.

2000-10-01

The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibrosis (CF). We tested the hypothesis that an osmolyte with a low transepithelial permeability may lower the ASL salt concentration, thereby enhancing innate immunity. We found that the five-carbon sugar xylitol has a low transepithelial permeability, is poorly metabolized by several bacteria, and can lower the ASL salt concentration in both CF and non-CF airway epithelia in vitro. Furthermore, in a double-blind, randomized, crossover study, xylitol sprayed for 4 days into each nostril of normal volunteers significantly decreased the number of nasal coagulase-negative Staphylococcus compared with saline control. Xylitol may be of value in decreasing ASL salt concentration and enhancing the innate antimicrobial defense at the airway surface.

High Glucose Concentration Promotes Vancomycin-Enhanced Biofilm Formation of Vancomycin-Non-Susceptible Staphylococcus aureus in Diabetic Mice.

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Chi-Yu Hsu

Full Text Available We previously demonstrated that vancomycin treatment increased acquisition of eDNA and enhanced biofilm formation of drug-resistant Staphylococcus aureus through a cidA-mediated autolysis mechanism. Recently we found that such enhancement became more significant under a higher glucose concentration in vitro. We propose that besides improper antibiotic treatment, increased glucose concentration environment in diabetic animals may further enhance biofilm formation of drug-resistant S. aureus. To address this question, the diabetic mouse model infected by vancomycin-resistant S. aureus (VRSA was used under vancomycin treatment. The capacity to form biofilms was evaluated through a catheter-associated biofilm assay. A 10- and 1000-fold increase in biofilm-bound bacterial colony forming units was observed in samples from diabetic mice without and with vancomycin treatment, respectively, compared to healthy mice. By contrast, in the absence of glucose vancomycin reduced propensity to form biofilms in vitro through the increased production of proteases and DNases from VRSA. Our study highlights the potentially important role of increased glucose concentration in enhancing biofilm formation in vancomycin-treated diabetic mice infected by drug-resistant S. aureus.

Enhanced electrocatalytic CO2 reduction via field-induced reagent concentration

Science.gov (United States)

Liu, Min; Pang, Yuanjie; Zhang, Bo; de Luna, Phil; Voznyy, Oleksandr; Xu, Jixian; Zheng, Xueli; Dinh, Cao Thang; Fan, Fengjia; Cao, Changhong; de Arquer, F. Pelayo García; Safaei, Tina Saberi; Mepham, Adam; Klinkova, Anna; Kumacheva, Eugenia; Filleter, Tobin; Sinton, David; Kelley, Shana O.; Sargent, Edward H.

2016-09-01

Electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the reaction suffers from slow kinetics owing to the low local concentration of CO2 surrounding typical CO2 reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO2 adsorption, but this comes at the cost of increased hydrogen (H2) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO2 close to the active CO2 reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO2 reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxide-derived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.

EVALUATION OF FERRIC CHLORIDE AND ALUM EFFICIENCIES IN ENHANCED COAGULATION FOR TOC REMOVAL AND RELATED RESIDUAL METAL CONCENTRATIONS

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A. Mesdaghinia, M. T. Rafiee, F. Vaezi and A. H. Mahvi

2005-07-01

Full Text Available Although the removal of colloidal particles continues to be an important reason for using coagulation, a newer objective, the removal of natural organic matter (NOM to reduce the formation of disinfection by-products (DBPs, is growing in importance. Enhanced coagulation is thus introduced to most water utilities treating surface water. Bench-scale experiments were conducted to compare the effectiveness of alum and ferric chloride in removing DBPs precursors from eight synthetic water samples, each representing a different element of the USEPA’s 3×3 enhanced coagulation matrix. The effect of enhanced coagulation on the residual metal (aluminum/iron concentration in the treated water was assessed as well. The removal of total organic carbon (TOC was dependent on the coagulant type and was enhanced with increasing coagulant dose, but the latter had no further considerable effect in case of increasing to high levels. For all the treated samples coagulation with ferric chloride proved to be more effective than alum at similar doses and the mean values of treatment efficiencies were 51% and 32% for ferric chloride and alum, respectively. Ferric chloride was therefore considered the better chemical for enhancing the coagulation process. Besides, due to less production of sludge by this coagulant, it would be predicted that treatment plants would be confronted to fewer problems with respect to final sludge disposal. Measurements of residual metal in treated water indicated that iron and aluminum concentrations had been increased as expected but the quality of water concerning the residual metal deteriorated much more in cases of under-dosing. Despite expecting high residual Al and Fe concentrations under enhanced coagulation, metal concentrations were frequently remained low and were not increased appreciably.

A Point Mutation in the Sensor Histidine Kinase SaeS of Staphylococcus aureus Strain Newman Alters the Response to Biocide Exposure

NARCIS (Netherlands)

Schaefer, Daniel; Lam, Thien-Tri; Geiger, Tobias; Mainiero, Markus; Engelmann, Susanne; Hussain, Muzaffar; Bosserhoff, Armin; Frosch, Matthias; Bischoff, Markus; Wolz, Christiane; Reidl, Joachim; Sinha, Bhanu

2009-01-01

Staphylococcus aureus reacts to changing environmental conditions such as heat, pH, and chemicals through global regulators such as the sae (S. aureus exoprotein expression) two-component signaling system. Subinhibitory concentrations of some antibiotics were shown to increase virulence factor

Enhancement of sludge granulation in anaerobic treatment of concentrated latex wastewater

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Nugul Intrasungkha

2008-04-01

Full Text Available Recently, the upflow anaerobic sludge blanket (UASB reactor has become attractive for wastewater treatment with low energy requirement and biogas production. However, the start-up of an UASB reactor depends on the formation of granules. Therefore, this research aims to study the effect of AlCl3, CaCl2 and temperature on the granule formation process using real concentrated latex wastewater. The result shows that the optimum chemicals concentration of AlCl3 at 300 mg/l enhanced the biomass accumulation and sludge formation process. Approximately 50% of large granular size (0.5 mm 0.8 mm within 35 days, whereas the large granular sizes in reactorwithout AlCl3 supplement (R2 became visible within 63 days. Moreover, this experiment found that R1, R2 and R3 could reach steady state within 40, 55 and 45 days, respectively.

Effect of Photon Beam Energy, Gold Nanoparticle Size and Concentration on the Dose Enhancement in Radiation Therapy

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Nahideh Gharehaghaji

2013-02-01

Full Text Available Introduction: Gold nanoparticles have been used as radiation dose enhancing materials in recent investigations. In the current study, dose enhancement effect of gold nanoparticles on tumor cells was evaluated using Monte Carlo (MC simulation. Methods: We used MCNPX code for MC modeling in the current study. A water phantom and a tumor region with a size of 1×1×1 cm3 loaded with gold nanoparticles were simulated. The macroscopic dose enhancement factor was calculated for gold nanoparticles with sizes of 30, 50, and 100 nm. Also, we simulated different photon beams including mono-energetic beams (50-120 keV, a Cobalt-60 beam, 6 & 18 MV photon beams of a conventional linear accelerator. Results: We found a dose enhancement factor (DEF of from 1.4 to 3.7 for monoenergetic kilovoltage beams, while the DEFs for megavoltage beams were negligible and less than 3% for all GNP sizes and concentrations. The optimum energy for higher DEF was found to be the 90 keV monoenergetic beam. The effect of GNP size was not considerable, but the GNP concentration had a substantial impact on achieved DEF in GNP-based radiation therapy. Conclusion: The results were in close agreement with some previous studies considering the effect of photon energy and GNP concentration on observed DEF. Application of GNP-based radiation therapy using kilovoltage beams is recommended.

Enhancement of delayed-rectifier potassium conductance by low concentrations of local anaesthetics in spinal sensory neurones

Science.gov (United States)

Olschewski, Andrea; Wolff, Matthias; Bräu, Michael E; Hempelmann, Gunter; Vogel, Werner; Safronov, Boris V

2002-01-01

Combining the patch-clamp recordings in slice preparation with the ‘entire soma isolation' method we studied action of several local anaesthetics on delayed-rectifier K+ currents in spinal dorsal horn neurones.Bupivacaine, lidocaine and mepivacaine at low concentrations (1–100 μM) enhanced delayed-rectifier K+ current in intact neurones within the spinal cord slice, while exhibiting a partial blocking effect at higher concentrations (>100 μM). In isolated somata 0.1–10 μM bupivacaine enhanced delayed-rectifier K+ current by shifting its steady-state activation characteristic and the voltage-dependence of the activation time constant to more negative potentials by 10–20 mV.Detailed analysis has revealed that bupivacaine also increased the maximum delayed-rectifier K+ conductance by changing the open probability, rather than the unitary conductance, of the channel.It is concluded that local anaesthetics show a dual effect on delayed-rectifier K+ currents by potentiating them at low concentrations and partially suppressing at high concentrations. The phenomenon observed demonstrated the complex action of local anaesthetics during spinal and epidural anaesthesia, which is not restricted to a suppression of Na+ conductance only. PMID:12055132

ADSORPTION OF CIPROFLOXACIN TO URINARY CATHETERS AND EFFECT ON SUBSEQUENT BACTERIAL ADHESION AND SURVIVAL

NARCIS (Netherlands)

REID, G; TIESZER, C; FOERCH, R; BUSSCHER, HJ; KHOURY, AE; BRUCE, AW

1993-01-01

The preincubation of urinary catheter material with minimum inhibitory and sub-inhibitory concentrations of ciprofloxacin caused a significant reduction in the adhesion of viable uropathogenic Escherichia coli subsequently exposed to the surfaces for periods of 1, 12, 24 and 48 h. In addition, the

Optimization of an enhanced ceramic micro-filter for concentrating E.coli in water

Science.gov (United States)

Zhang, Yushan; Guo, Tianyi; Xu, Changqing; Hong, Lingcheng

2017-02-01

Recently lower limit of detection (LOD) is necessary for rapid bacteria detection and analysis applications in clinical practices and daily life. A critical pre-conditioning step for these applications is bacterial concentration, especially for low level of pathogens. Sample volume can be largely reduced with an efficient pre-concentration process. Some approaches such as hollow-fiber ultra-filtration and electrokinetic technique have been applied to bacterial concentration. Since none of these methods can provide a concentrating method with a stable recovery efficiency, bacterial concentration still remains challenging Ceramic micro- filter can be used to concentrate the bacteria but the cross flow system keeps the bacteria in suspension. Similar harvesting bacteria using ultra-filtration showed an average recovery efficiency of 43% [1] and other studies achieved recovery rates greater than 50% [2]. In this study, an enhanced ceramic micro-filter with 0.14 μm pore size was proposed and demonstrated to optimize the concentration of E.coli. A high recovery rate (mean value >90%) and a high volumetric concentration ratio (>100) were achieved. Known quantities (104 to 106 CFU/ml) of E.coli cells were spiked to different amounts of phosphate buffered saline (0.1 to 1 L), and then concentrated to a final retentate of 5 ml to 10 ml. An average recovery efficiency of 95.3% with a standard deviation of 5.6% was achieved when the volumetric con- centration ratio was 10. No significant recovery rate loss was indicated when the volumetric concentration ratio reached up to 100. The effects of multiple parameters on E.coli recovery rate were also studied. The obtained results indicated that the optimized ceramic micro- filtration system can successfully concentrate E.coli cells in water with an average recovery rate of 90.8%.

In Vivo Transmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness.

Science.gov (United States)

Johnson, Timothy J; Singer, Randall S; Isaacson, Richard E; Danzeisen, Jessica L; Lang, Kevin; Kobluk, Kristi; Rivet, Bernadette; Borewicz, Klaudyna; Frye, Jonathan G; Englen, Mark; Anderson, Janet; Davies, Peter R

2015-05-15

IncA/C plasmids are broad-host-range plasmids enabling multidrug resistance that have emerged worldwide among bacterial pathogens of humans and animals. Although antibiotic usage is suspected to be a driving force in the emergence of such strains, few studies have examined the impact of different types of antibiotic administration on the selection of plasmid-containing multidrug resistant isolates. In this study, chlortetracycline treatment at different concentrations in pig feed was examined for its impact on selection and dissemination of an IncA/C plasmid introduced orally via a commensal Escherichia coli host. Continuous low-dose administration of chlortetracycline at 50 g per ton had no observable impact on the proportions of IncA/C plasmid-containing E. coli from pig feces over the course of 35 days. In contrast, high-dose administration of chlortetracycline at 350 g per ton significantly increased IncA/C plasmid-containing E. coli in pig feces (P IncA/C plasmid to other indigenous E. coli hosts. There was no evidence of conjugal transfer of the IncA/C plasmid to bacterial species other than E. coli. In vitro competition assays demonstrated that bacterial host background substantially impacted the cost of IncA/C plasmid carriage in E. coli and Salmonella. In vitro transfer and selection experiments demonstrated that tetracycline at 32 μg/ml was necessary to enhance IncA/C plasmid conjugative transfer, while subinhibitory concentrations of tetracycline in vitro strongly selected for IncA/C plasmid-containing E. coli. Together, these experiments improve our knowledge on the impact of differing concentrations of tetracycline on the selection of IncA/C-type plasmids. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Enhancement of antibiotic activity by efflux inhibitors against multidrug resistant Mycobacterium tuberculosis clinical isolates from Brazil

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Tatiane eCoelho

2015-04-01

Full Text Available Drug resistant tuberculosis continues to increase and new approaches for its treatment are necessary. The identification of M. tuberculosis clinical isolates presenting efflux as part of their resistant phenotype has a major impact in tuberculosis treatment. In this work, we used a checkerboard procedure combined with the tetrazolium microplate-based assay (TEMA to study single combinations between antituberculosis drugs and efflux inhibitors (EIs against multidrug resistant M. tuberculosis clinical isolates using the fully susceptible strain H37Rv as reference. Efflux activity was studied on a real-time basis by a fluorometric method that uses ethidium bromide as efflux substrate. Quantification of efflux pump genes mRNA transcriptional levels were performed by RT-qPCR. The fractional inhibitory concentrations (FIC indicated synergistic activity for the interactions between isoniazid, rifampicin, amikacin, ofloxacin, and ethidium bromide plus the EIs verapamil, thioridazine and chlorpromazine. The FICs ranged from 0.25, indicating a four-fold reduction on the MICs, to 0.015, 64-fold reduction. The detection of active efflux by real-time fluorometry showed that all strains presented intrinsic efflux activity that contributes to the overall resistance which can be inhibited in the presence of the EIs. The quantification of the mRNA levels of the most important efflux pump genes on these strains shows that they are intrinsically predisposed to expel toxic compounds as the exposure to subinhibitory concentrations of antibiotics were not necessary to increase the pump mRNA levels when compared with the non-exposed counterpart. The results obtained in this study confirm that the intrinsic efflux activity contributes to the overall resistance in multidrug resistant clinical isolates of M. tuberculosis and that the inhibition of efflux pumps by the EIs can enhance the clinical effect of antibiotics that are their substrates.

Integration of Multiplexed Microfluidic Electrokinetic Concentrators with a Morpholino Microarray via Reversible Surface Bonding for Enhanced DNA Hybridization.

Science.gov (United States)

Martins, Diogo; Wei, Xi; Levicky, Rastislav; Song, Yong-Ak

2016-04-05

We describe a microfluidic concentration device to accelerate the surface hybridization reaction between DNA and morpholinos (MOs) for enhanced detection. The microfluidic concentrator comprises a single polydimethylsiloxane (PDMS) microchannel onto which an ion-selective layer of conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) was directly printed and then reversibly surface bonded onto a morpholino microarray for hybridization. Using this electrokinetic trapping concentrator, we could achieve a maximum concentration factor of ∼800 for DNA and a limit of detection of 10 nM within 15 min. In terms of the detection speed, it enabled faster hybridization by around 10-fold when compared to conventional diffusion-based hybridization. A significant advantage of our approach is that the fabrication of the microfluidic concentrator is completely decoupled from the microarray; by eliminating the need to deposit an ion-selective layer on the microarray surface prior to device integration, interfacing between both modules, the PDMS chip for electrokinetic concentration and the substrate for DNA sensing are easier and applicable to any microarray platform. Furthermore, this fabrication strategy facilitates a multiplexing of concentrators. We have demonstrated the proof-of-concept for multiplexing by building a device with 5 parallel concentrators connected to a single inlet/outlet and applying it to parallel concentration and hybridization. Such device yielded similar concentration and hybridization efficiency compared to that of a single-channel device without adding any complexity to the fabrication and setup. These results demonstrate that our concentrator concept can be applied to the development of a highly multiplexed concentrator-enhanced microarray detection system for either genetic analysis or other diagnostic assays.

Bone Marrow Aspirate Concentrate-Enhanced Marrow Stimulation of Chondral Defects

Science.gov (United States)

Eichler, Hermann; Orth, Patrick

2017-01-01

Mesenchymal stem cells (MSCs) from bone marrow play a critical role in osteochondral repair. A bone marrow clot forms within the cartilage defect either as a result of marrow stimulation or during the course of the spontaneous repair of osteochondral defects. Mobilized pluripotent MSCs from the subchondral bone migrate into the defect filled with the clot, differentiate into chondrocytes and osteoblasts, and form a repair tissue over time. The additional application of a bone marrow aspirate (BMA) to the procedure of marrow stimulation is thought to enhance cartilage repair as it may provide both an additional cell population capable of chondrogenesis and a source of growth factors stimulating cartilage repair. Moreover, the BMA clot provides a three-dimensional environment, possibly further supporting chondrogenesis and protecting the subchondral bone from structural alterations. The purpose of this review is to bridge the gap in our understanding between the basic science knowledge on MSCs and BMA and the clinical and technical aspects of marrow stimulation-based cartilage repair by examining available data on the role and mechanisms of MSCs and BMA in osteochondral repair. Implications of findings from both translational and clinical studies using BMA concentrate-enhanced marrow stimulation are discussed. PMID:28607559

Importance of critical micellar concentration for the prediction of solubility enhancement in biorelevant media.

Science.gov (United States)

Ottaviani, G; Wendelspiess, S; Alvarez-Sánchez, R

2015-04-06

This study evaluated if the intrinsic surface properties of compounds are related to the solubility enhancement (SE) typically observed in biorelevant media like fasted state simulated intestinal fluids (FaSSIF). The solubility of 51 chemically diverse compounds was measured in FaSSIF and in phosphate buffer and the surface activity parameters were determined. This study showed that the compound critical micellar concentration parameter (CMC) correlates strongly with the solubility enhancement (SE) observed in FaSSIF compared to phosphate buffer. Thus, the intrinsic capacity of molecules to form micelles is also a determinant for each compound's affinity to the micelles of biorelevant surfactants. CMC correlated better with SE than lipophilicity (logD), especially over the logD range typically covered by drugs (2 < logD < 4). CMC can become useful to guide drug discovery scientists to better diagnose, improve, and predict solubility in biorelevant media, thereby enhancing oral bioavailability of drug candidates.

Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy

Directory of Open Access Journals (Sweden)

Andreas Pohlkötter

2010-09-01

Full Text Available Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS. With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sample gas that promote the radiationless de-excitation of the oxygen molecules.

Effect of curcumin on Helicobacter pylori biofilm formation ...

African Journals Online (AJOL)

Three-dimensional structure of biofilm was imaged by scanning electron microscopy. The effect of curcumin on H. pylori adherence to HEp-2 cells was also investigated. Subinhibitory concentrations of curcumin inhibited the biofilm in dose dependent manner. However, H.pylori could restore ability to form biofilm during ...

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new antibiotic discovery make the search for new antimicrobial agents or efforts at ... used to determine the modulation effects when sub-inhibitory concentrations of plant extracts ... good modulators as they reduced the MIC of ciprofloxacin and ketoconazole by factors that are ..... (2006). Bad bugs need drugs: An update on.

Antibiotic Stimulation of a Bacillus subtilis Migratory Response

Science.gov (United States)

Liu, Yongjin; Kyle, Steven

2018-01-01

ABSTRACT Competitive interactions between bacteria reveal physiological adaptations that benefit fitness. Bacillus subtilis is a Gram-positive species with several adaptive mechanisms for competition and environmental stress. Biofilm formation, sporulation, and motility are the outcomes of widespread changes in a population of B. subtilis. These changes emerge from complex, regulated pathways for adapting to external stresses, including competition from other species. To identify competition-specific functions, we cultured B. subtilis with multiple species of Streptomyces and observed altered patterns of growth for each organism. In particular, when plated on agar medium near Streptomyces venezuelae, B. subtilis initiates a robust and reproducible mobile response. To investigate the mechanistic basis for the interaction, we determined the type of motility used by B. subtilis and isolated inducing metabolites produced by S. venezuelae. Bacillus subtilis has three defined forms of motility: swimming, swarming, and sliding. Streptomyces venezuelae induced sliding motility specifically in our experiments. The inducing agents produced by S. venezuelae were identified as chloramphenicol and a brominated derivative at subinhibitory concentrations. Upon further characterization of the mobile response, our results demonstrated that subinhibitory concentrations of chloramphenicol, erythromycin, tetracycline, and spectinomycin all activate a sliding motility response by B. subtilis. Our data are consistent with sliding motility initiating under conditions of protein translation stress. This report underscores the importance of hormesis as an early warning system for potential bacterial competitors and antibiotic exposure. IMPORTANCE Antibiotic resistance is a major challenge for the effective treatment of infectious diseases. Identifying adaptive mechanisms that bacteria use to survive low levels of antibiotic stress is important for understanding pathways to

MR image enhancement as a function of tissue gadolinium concentration, measured with polarized X-ray fluorescence analysis

International Nuclear Information System (INIS)

Wang, S.C.; Morita, Y.; White, D.L.; Kaufman, L.; Brasch, R.C.

1988-01-01

MR imaging contrast agents alter intensities nonlinearly relative to their tissue concentrations. To extract Gd concentrations from image intensity data, a 13-tube phantom (Gd-DTPA dilutions, 0-10/sup -2/M) was imaged (2 T, 3 mm, spin echo, 300 = msec repetition time, 15 = msec echo time, 128 X 256, four excitations). Also, 18 rats were studied with Gd-DTPA or albumin-(Gd-DTPA)/sub 19/ (nine each, three doses). Liver and renal cortex were imaged before and 10 minutes after contrast material administration, with immediate killing and harvesting, and enhancement was calculated. These samples were assayed by x-ray fluorescent excitation analysis (150-kVp beam, B/sub 4/C ceramic polarizer, Mo-Cu-Ni filter, Si[Li] detector). Gd levels as low as 0.5 ppm (--3.18 x 10/sup -6/M) could be detected in liquid or solid samples. Enhancement increased with a nonlinear relationship to Gd in the range measured. This assay for Gd permits empiric assessment of the relationship between pulse variables, intensity, and paramagnet concentration, allowing Gd values to be estimated from image intensities

A paper-polymer centrifugal device for low-cost sample pre-concentration and colorimetric lateral flow assay enhancement

CSIR Research Space (South Africa)

Wiederoder, MS

2016-10-01

Full Text Available This study describes a novel hybrid paper-polymer centrifugal microfluidic device for pre-concentration of E.coli and lateral flow immunoassay enhancement for water quality verification. The device balances rotational centrifugal force...

Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli

Science.gov (United States)

Zhang, Haoshu; Dudley, Edward G.; Davidson, P. Michael

2017-01-01

ABSTRACT Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three Escherichia coli strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when E. coli cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects. IMPORTANCE Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens. PMID:28213539

Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli.

Science.gov (United States)

Zhang, Haoshu; Dudley, Edward G; Davidson, P Michael; Harte, Federico

2017-04-15

Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three Escherichia coli strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when E. coli cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects. IMPORTANCE Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens. Copyright © 2017 American Society for Microbiology.

Enhanced Cycling Stability of Rechargeable Li-O2 Batteries Using High Concentration Electrolytes

Energy Technology Data Exchange (ETDEWEB)

Liu, Bin; Xu, Wu; Yan, Pengfei; Sun, Xiuliang; Bowden, Mark E.; Read, Jeffrey; Qian, Jiangfeng; Mei, Donghai; Wang, Chong M.; Zhang, Jiguang

2016-01-26

The electrolyte stability against reactive reduced-oxygen species is crucial for the development of rechargeable Li-O2 batteries. In this work, we systematically investigated the effect of lithium salt concentration in 1,2-dimethoxyethane (DME)-based electrolytes on the cycling stability of Li-O2 batteries. Cells with high concentration electrolyte illustrate largely enhanced cycling stability under both the full discharge/charge (2.0-4.5 V vs. Li/Li+) and the capacity limited (at 1,000 mAh g-1) conditions. These cells also exhibit much less reaction-residual on the charged air electrode surface, and much less corrosion to the Li metal anode. The density functional theory calculations are conducted on the molecular orbital energies of the electrolyte components and the Gibbs activation barriers for superoxide radical anion to attack DME solvent and Li+-(DME)n solvates. In a highly concentrated electrolyte, all DME molecules have been coordinated with salt and the C-H bond scission of a DME molecule becomes more difficult. Therefore, the decomposition of highly concentrated electrolyte in a Li-O2 battery can be mitigated and both air-cathodes and Li-metal anodes exhibits much better reversibility. As a results, the cyclability of Li-O2 can be largely improved.

Contrast-enhanced magnetic resonance angiography: first-pass arterial enhancement as a function of gadolinium-chelate concentration, and the saline chaser volume and injection rate.

Science.gov (United States)

Husarik, Daniela B; Bashir, Mustafa R; Weber, Paul W; Nichols, Eli B; Howle, Laurens E; Merkle, Elmar M; Nelson, Rendon C

2012-02-01

To evaluate the effect of the contrast medium (CM) concentration and the saline chaser volume and injection rate on first-pass aortic enhancement characteristics in contrast-enhanced magnetic resonance angiography using a physiologic flow phantom. Imaging was performed on a 3.0-T magnetic resonance system (MAGNETOM Trio, Siemens Healthcare Solutions, Inc, Erlangen, Germany) using a 2-dimensional fast low angle shot T1-weighted sequence (repetition time, 500 milliseconds; echo time, 1.23 milliseconds; flip angle, 8 degrees; 1 frame/s × 60 seconds). The following CM concentrations injected at 2 mL/s were used with 3 different contrast agents (gadolinium [Gd]-BOPTA, Gd-HP-DO3A, Gd-DTPA): 20 mL of undiluted CM (100%) and 80%, 40%, 20%, 10%, 5%, and 2.5% of the full amount, all diluted in saline to a volume of 20 mL to ensure equal bolus volume. The CM was followed by saline chasers of 20 to 60 mL injected at 2 mL/s and 6 mL/s. Aortic signal intensity (SI) was measured, and normalized SI versus time (SI/Tn) curves were generated. The maximal SI (SI(max)), bolus length, and areas under the SI/Tn curve were calculated. Decreasing the CM concentration from 100% to 40% resulted in a decrease of SI(max) to 86.1% (mean). Further decreasing the CM concentration to 2.5% decreased SI(max) to 5.1% (mean). Altering the saline chaser volume had no significant effect on SI(max). Increasing the saline chaser injection rate had little effect (mean increase, 2.2%) on SI(max) when using ≥40% of CM. There was a larger effect (mean increase, 19.6%) when ≤20% of CM were used. Bolus time length was significantly shorter (P < 0.001), and area under the SI/T(n) curve was significantly smaller (P < 0.01) for the CM protocols followed by a saline chaser injected at 6 mL/s compared with a saline chaser injected at 2 mL/s. With 40% of CM and a fast saline chaser, SImax close to that with undiluted CM can be achieved. An increased saline chaser injection rate has a more pronounced effect on

APPLICATION OF METAL RESISTANT BACTERIA BY MUTATIONAL ENHANCMENT TECHNIQUE FOR BIOREMEDIATION OF COPPER AND ZINC FROM INDUSTRIAL WASTES

Directory of Open Access Journals (Sweden)

M. R. Shakibaie ، A. Khosravan ، A. Frahmand ، S. Zare

2008-10-01

Full Text Available In this research, using mutation in the metal resistant bacteria, the bioremediation of the copper and zinc from copper factory effluents was investigated. Wastewater effluents from flocculation and rolling mill sections of a factory in the city of Kerman were collected and used for further experiments. 20 strains of Pseudomonas spp. were isolated from soil and effluents surrounding factory and identified by microbiological methods. Minimum inhibitory concentrations for copper (Cu and zinc (Zn were determined by agar dilution method. Those strains that exhibited highest minimum inhibitory concentrations values to the metals (5mM were subjected to 400-3200 mg/L concentrations of the three mutagenic agents, acriflavine, acridine orange and ethidium bromide. After determination of subinhibitory concentrations, the minimum inhibitory concentrations values for copper and zinc metal ions were again determined, which showed more than 10 fold increase in minimum inhibitory concentrations value (10 mM for Cu and 20 mM for Zn with P≤0.05. The atomic absorption spectroscopy of dried biomass obtained from resistant strains after exposure to mutagenic agents revealed that strains 13 accumulate the highest amount of intracellular copper (0.35% Cu/mg dried biomass and strain 10 showed highest accumulation of zinc (0.3% Zn/mg dried biomass respectively with P≤0.05. From above results it was concluded that the treatment of industrial waste containing heavy metals by artificially mutated bacteria may be appropriate solution for effluent disposal problems.

Metal-enhanced fluorescence of mixed coumarin dyes by silver and gold nanoparticles: Towards plasmonic thin-film luminescent solar concentrator

Energy Technology Data Exchange (ETDEWEB)

El-Bashir, S.M., E-mail: elbashireg@yahoo.com [Department of Physics and Astronomy, Science College, King Saud University, Riyadh, KSA (Saudi Arabia); Department of Physics Faculty of Science, Benha University (Egypt); Barakat, F.M.; AlSalhi, M.S. [Department of Physics and Astronomy, Science College, King Saud University, Riyadh, KSA (Saudi Arabia)

2013-11-15

Poly(methyl methacrylate) (PMMA) nanocomposite films doped with mixed coumarin dyestuffs and noble metal nanoparticles (60 nm silver and 100 nm gold) were prepared by spin coating technique. The effect of silver and gold nanoparticles on the film properties was studied by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis absorption and fluorescence spectroscopy measurements. DSC measurements indicated the increase of the glass transition temperature of the films by increasing nanogold concentration, recommending their promising thermal stability towards hot climates. It was found that the fluorescence signals of the mixed coumarin dyes were amplified by 5.4 and 7.15 folds as a result of metal enhanced fluorescence (MEF). The research outcomes offered a potential application of these films in solar energy conversion by plasmonic thin film luminescent solar concentrator (PTLSC). -- Graphical abstract: Plasmonic thin film luminescent solar concentrators. Highlights: • Metal enhanced fluorescence was achieved for mixed coumarin dyes doped in PMMA nanocomposite films. • The amplification of the fluorescence signals is dependent on the concentration of silver and gold nanoparticles. • These films is considered as potential candidates for plasmonic thin film luminescent solar concentrators (PTLSCs)

Enhanced nutrition improves growth and increases blood adiponectin concentrations in very low birth weight infants

Directory of Open Access Journals (Sweden)

Elin W. Blakstad

2016-12-01

Full Text Available Background: Adequate nutrient supply is essential for optimal postnatal growth in very low birth weight (VLBW, birth weight<1,500 g infants. Early growth may influence the risk of metabolic syndrome later in life. Objective: To evaluate growth and blood metabolic markers (adiponectin, leptin, and insulin-like growth factor-1 (IGF-1 in VLBW infants participating in a randomized nutritional intervention study. Design: Fifty VLBW infants were randomized to an enhanced nutrient supply or a standard nutrient supply. Thirty-seven infants were evaluated with growth measurements until 2 years corrected age (CA. Metabolic markers were measured at birth and 5 months CA. Results: Weight gain and head growth were different in the two groups from birth to 2 years CA (weight gain: pinteraction=0.006; head growth: pinteraction=0.002. The intervention group improved their growth z-scores after birth, whereas the control group had a pronounced decline, followed by an increase and caught up with the intervention group after discharge. At 5 months CA, adiponectin concentrations were higher in the intervention group and correlated with weight gain before term (r=0.35 and nutrient supply (0.35≤r≤0.45. Leptin concentrations correlated with weight gain after term and IGF-1 concentrations with length growth before and after term and head growth after term (0.36≤r≤0.53. Conclusion: Enhanced nutrient supply improved early postnatal growth and may have prevented rapid catch-up growth later in infancy. Adiponectin concentration at 5 months CA was higher in the intervention group and correlated positively with early weight gain and nutrient supply. Early nutrition and growth may affect metabolic markers in infancy.Clinical Trial Registration (ClinicalTrials.gov no.: NCT01103219

Dibasic Ammonium Phosphate Application Enhances Aromatic Compound Concentration in Bog Bilberry Syrup Wine

Directory of Open Access Journals (Sweden)

Shao-Yang Wang

2016-12-01

Full Text Available A nitrogen deficiency always causes bog bilberry syrup wine to have a poor sensory feature. This study investigated the effect of nitrogen source addition on volatile compounds during bog bilberry syrup wine fermentation. The syrup was supplemented with 60, 90, 120 or 150 mg/L dibasic ammonium phosphate (DAP before fermentation. Results showed that an increase of DAP amounts accelerated fermentation rate, increased alcohol content, and decreased sugar level. Total phenol and total flavonoid content were also enhanced with the increase of DAP amounts. A total of 91 volatile compounds were detected in the wine and their concentrations were significantly enhanced with the increase of DAP. Ethyl acetate, isoamyl acetate, phenethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, isobutanol, isoamyl alcohol, levo-2,3-butanediol, 2-phenylethanol, meso-2,3-butanediol, isobutyric acid, hexanoic acid, and octanoic acid exhibited a significant increase of their odor activity value (OAV with the increase of DAP amounts. Bog bilberry syrup wine possessed fruity, fatty, and caramel flavors as its major aroma, whereas a balsamic note was the least present. The increase of DAP amounts significantly improved the global aroma attributes, thereby indicating that DAP supplementation could promote wine fermentation performance and enhance the sensory quality of bog bilberry syrup wine.

From the Cover: Selective Enhancement of Domoic Acid Toxicity in Primary Cultures of Cerebellar Granule Cells by Lowering Extracellular Na+ Concentration.

Science.gov (United States)

Pérez-Gómez, Anabel; Cabrera-García, David; Warm, Davide; Marini, Ann M; Salas Puig, Javier; Fernández-Sánchez, Maria Teresa; Novelli, Antonello

2018-01-01

Domoic acid (DOM) is an excitatory amino acid analog of kainic acid (KA) that acts through glutamic acid (GLU) receptors, inducing a fast and potent neurotoxic response. Here, we present evidence for an enhancement of excitotoxicity following exposure of cultured cerebellar granule cells to DOM in the presence of lower than physiological Na+ concentrations. The concentration of DOM that reduced by 50% neuronal survival was approximately 3 µM in Na+-free conditions and 16 µM in presence of a physiological concentration of extracellular Na+. The enhanced neurotoxic effect of DOM was fully prevented by AMPA/KA receptor antagonist, while N-methyl-D-aspartate-receptor-mediated neurotoxicity did not seem to be involved, as the absence of extracellular Na+ failed to potentiate GLU excitotoxicity under the same experimental conditions. Lowering of extracellular Na+ concentration to 60 mM eliminated extracellular recording of spontaneous electrophysiological activity from cultured neurons grown on a multi electrode array and prevented DOM stimulation of the electrical activity. Although changes in the extracellular Na+ concentration did not alter the magnitude of the rapid increase in intracellular Ca2+ levels associated to DOM exposure, they did change significantly the contribution of voltage-sensitive calcium channels (VScaCs) and the recovery time to baseline. The prevention of Ca2+ influx via VSCaCs by nifedipine failed to prevent DOM toxicity at any extracellular Na+ concentration, while the reduction of extracellular Ca2+ concentration ameliorated DOM toxicity only in the absence of extracellular Na+, enhancing it in physiological conditions. Our data suggest a crucial role for extracellular Na+ concentration in determining excitotoxicity by DOM. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

In Vitro Capability of Faropenem To Select for Resistant Mutants of Streptococcus pneumoniae and Haemophilus influenzae▿ †

Science.gov (United States)

Kosowska-Shick, Klaudia; Clark, Catherine; Credito, Kim; Dewasse, Bonifacio; Beachel, Linda; Ednie, Lois; Appelbaum, Peter C.

2008-01-01

When tested against nine strains of pneumococci and six of Haemophilus influenzae of various resistotypes, faropenem failed to select for resistant mutants after 50 days of consecutive subculture in subinhibitory concentrations. Faropenem also yielded low rates of spontaneous mutations against all organisms of both species. By comparison, resistant clones were obtained with macrolides, ketolides, and quinolones. PMID:18086853

In vitro capability of faropenem to select for resistant mutants of Streptococcus pneumoniae and Haemophilus influenzae.

Science.gov (United States)

Kosowska-Shick, Klaudia; Clark, Catherine; Credito, Kim; Dewasse, Bonifacio; Beachel, Linda; Ednie, Lois; Appelbaum, Peter C

2008-02-01

When tested against nine strains of pneumococci and six of Haemophilus influenzae of various resistotypes, faropenem failed to select for resistant mutants after 50 days of consecutive subculture in subinhibitory concentrations. Faropenem also yielded low rates of spontaneous mutations against all organisms of both species. By comparison, resistant clones were obtained with macrolides, ketolides, and quinolones.

Optimizing Tube Precurvature to Enhance Elastic Stability of Concentric Tube Robots.

Science.gov (United States)

Ha, Junhyoung; Park, Frank C; Dupont, Pierre E

2017-02-01

Robotic instruments based on concentric tube technology are well suited to minimally invasive surgery since they are slender, can navigate inside small cavities and can reach around sensitive tissues by taking on shapes of varying curvature. Elastic instabilities can arise, however, when rotating one precurved tube inside another. In contrast to prior work that considered only tubes of piecewise constant precurvature, we allow precurvature to vary along the tube's arc length. Stability conditions for a planar tube pair are derived and used to formulate an optimal design problem. An analytic formulation of the optimal precurvature function is derived that achieves a desired tip orientation range while maximizing stability and respecting bending strain limits. This formulation also includes straight transmission segments at the proximal ends of the tubes. The result, confirmed by both numerical and physical experiment, enables designs with enhanced stability in comparison to designs of constant precurvature.

The assessment of Proteus mirabilis susceptibility to ceftazidime and ciprofloxacin and the impact of these antibiotics at subinhibitory concentrations on Proteus mirabilis biofilms.

Science.gov (United States)

Kwiecińska-Piróg, Joanna; Skowron, Krzysztof; Zniszczol, Katarzyna; Gospodarek, Eugenia

2013-01-01

Rods of the Proteus genus are commonly isolated from patients, especially from the urinary tracts of the catheterised patients. The infections associated with biomaterials are crucial therapeutic obstacles, due to the bactericidal resistance of the biofilm. The aim of this study was to assess the susceptibility of P. mirabilis planktonic forms to ciprofloxacin and ceftazidime, the ability to form biofilm, and the impact of chosen sub-MIC concentrations of these antibiotics on biofilm at different stages of its formation. The research included 50 P. mirabilis strains isolated from wounds and the urinary tracts from patients of the University Hospital No. 1 in Bydgoszcz. The assessment of susceptibility to ciprofloxacin and ceftazidime was conducted using micromethods. The impact of sub-MIC concentrations of the chosen antibiotics on the biofilm was measured using the TTC method. The resistance to ciprofloxacin was confirmed for 20 strains (40.0%) while to ceftazidime for 32 (64.0%) of the tested P. mirabilis strains. All of the tested strains formed biofilm: 24.0% weakly, 26.0% moderately, and 50.0% strongly. It was determined that ciprofloxacin and ceftazidime caused eradication of the biofilm. Moreover, the connection between origin of the strains, biofilm maturity level, and resistance to antibiotics was proved.

The Assessment of Proteus mirabilis Susceptibility to Ceftazidime and Ciprofloxacin and the Impact of These Antibiotics at Subinhibitory Concentrations on Proteus mirabilis Biofilms

Science.gov (United States)

Kwiecińska-Piróg, Joanna; Zniszczol, Katarzyna; Gospodarek, Eugenia

2013-01-01

Rods of the Proteus genus are commonly isolated from patients, especially from the urinary tracts of the catheterised patients. The infections associated with biomaterials are crucial therapeutic obstacles, due to the bactericidal resistance of the biofilm. The aim of this study was to assess the susceptibility of P. mirabilis planktonic forms to ciprofloxacin and ceftazidime, the ability to form biofilm, and the impact of chosen sub-MIC concentrations of these antibiotics on biofilm at different stages of its formation. The research included 50 P. mirabilis strains isolated from wounds and the urinary tracts from patients of the University Hospital No. 1 in Bydgoszcz. The assessment of susceptibility to ciprofloxacin and ceftazidime was conducted using micromethods. The impact of sub-MIC concentrations of the chosen antibiotics on the biofilm was measured using the TTC method. The resistance to ciprofloxacin was confirmed for 20 strains (40.0%) while to ceftazidime for 32 (64.0%) of the tested P. mirabilis strains. All of the tested strains formed biofilm: 24.0% weakly, 26.0% moderately, and 50.0% strongly. It was determined that ciprofloxacin and ceftazidime caused eradication of the biofilm. Moreover, the connection between origin of the strains, biofilm maturity level, and resistance to antibiotics was proved. PMID:24151628

Nitric oxide concentration measurements in atmospheric pressure flames using electronic-resonance-enhanced coherent anti-Stokes Raman scattering

Science.gov (United States)

Chai, N.; Kulatilaka, W. D.; Naik, S. V.; Laurendeau, N. M.; Lucht, R. P.; Kuehner, J. P.; Roy, S.; Katta, V. R.; Gord, J. R.

2007-06-01

We report the application of electronic-resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) for measurements of nitric oxide concentration ([NO]) in three different atmospheric pressure flames. Visible pump (532 nm) and Stokes (591 nm) beams are used to probe the Q-branch of the Raman transition. A significant resonance enhancement is obtained by tuning an ultraviolet probe beam (236 nm) into resonance with specific rotational transitions in the (v’=0, v”=1) vibrational band of the A2Σ+-X2Π electronic system of NO. ERE-CARS spectra are recorded at various heights within a hydrogen-air flame producing relatively low concentrations of NO over a Hencken burner. Good agreement is obtained between NO ERE-CARS measurements and the results of flame computations using UNICORN, a two-dimensional flame code. Excellent agreement between measured and calculated NO spectra is also obtained when using a modified version of the Sandia CARSFT code for heavily sooting acetylene-air flames (φ=0.8 to φ=1.6) on the same Hencken burner. Finally, NO concentration profiles are measured using ERE-CARS in a laminar, counter-flow, non-premixed hydrogen-air flame. Spectral scans are recorded by probing the Q1 (9.5), Q1 (13.5) and Q1 (17.5) Raman transitions. The measured shape of the [NO] profile is in good agreement with that predicted using the OPPDIF code, even without correcting for collisional effects. These comparisons between [NO] measurements and predictions establish the utility of ERE-CARS for detection of NO in flames with large temperature and concentration gradients as well as in sooting environments.

A new turbine model for enhancing convective heat transfer in the presence of low volume concentration of Ag-Oil Nanofluids

Science.gov (United States)

Jafarimoghaddam, Amin; Aberoumand, Sadegh; Jafarimoghaddam, Reza

2018-05-01

This study aims to experimentally investigate and introduce a new model for enhancing convective heat transfer in the presence of Ag/ oil nanofluid. An annular tube was designed with a turbine element attached to the inner tube. The inner tube was a bearing shaft which could rotate with the rotation of turbine element. As the previous works by authors, the setup was conducted with a fully developed laminar flow regime with the Reynolds numbers less than 160. The outer surface of the annular tube was heated by an element with constant heat flux of 204 W. Ag/ oil nanofluid was used in different volume concentrations of 0.011%, 0.044% and 0.171%. The new model could enhance the convective heat transfer coefficient up to 54% (compared to the simple annular tube in the case of base fluid) for the best studied case (nanofluid with the volume concentration of 0.171%) while the friction factor remained low. The new model can be applied for related applications regarding Ag/ oil nanofluid as a new step in enhancing the convective heat transfer coefficient.

Enhancing the performance of blue GaN-based light emitting diodes with carrier concentration adjusting layer

Energy Technology Data Exchange (ETDEWEB)

Guo, Yao; Huang, Yang; Wang, Junxi; Wang, Guohong [R& D Center for Semiconductor Lighting, Chinese Academy of Sciences, Beijing 100083,P. R. China (China); Liu, Zhiqiang, E-mail: lzq@semi.ac.cn, E-mail: spring@semi.ac.cn; Yi, Xiaoyan, E-mail: lzq@semi.ac.cn, E-mail: spring@semi.ac.cn; Li, Jinmin [R& D Center for Semiconductor Lighting, Chinese Academy of Sciences, Beijing 100083,P. R. China (China); State Key Laboratory of Solid State Lighting, Beijing 100083 (China); Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application, Beijing 100083 (China)

2016-03-15

In this work, a novel carrier concentration adjusting insertion layer for InGaN/GaN multiple quantum wells light-emitting diodes was proposed to mitigate the efficiency droop and improve optical output properties at high current density. The band diagrams and carrier distributions were investigated numerically and experimentally. The results indicate that due to the newly formed electron barrier and the adjusted built-in field near the active region, the hole injection has been improved and a better radiative recombination can be achieved. Compared to the conventional LED, the light output power of our new structure with the carrier concentration adjusting layers is enhanced by 127% at 350 mA , while the efficiency only droops to be 88.2% of its peak efficiency.

Directional growth of Ag nanorod from polymeric silver cyanide: A potential substrate for concentration dependent SERS signal enhancement leading to melamine detection

Science.gov (United States)

Roy, Anindita; Sahoo, Ramkrishna; Chowdhury, Joydeep; Bhattacharya, Tara Shankar; Agarwal, Ratnesh; Pal, Tarasankar

2017-08-01

Attention has been directed to prepare exclusive one-dimensional silver nanostructure from the linear inorganic polymer AgCN. Successive color change from yellow to orange, to red and finally to green reflects the evolution of high yielding Ag nanorods (NRs) from well-known -[Ag-CN]- chains of polymeric AgCN at room temperature. The parental 1D morphology of AgCN is retained within the as-synthesized Ag NRs. So we could successfully exploit the Ag NR for surface-enhanced Raman scattering (SERS) studies for sensing a popular milk adulterant melamine down to picomolar level. We observed interesting concentration dependent selective SERS band enhancement of melamine. The enhanced 1327 cm- 1 SERS signal intensity at lower concentration (10- 9 and 10- 12 M) of melamine speaks for the preferential participation of -C-N of melamine molecule with Ag surface. On the other hand, '-NH2' group together with ring 'N' participation of melamine molecule onto Ag surface suggested an adsorptive stance at higher (10- 3-10- 7 M) concentration range. Thus the binding modes of the molecule at the Ag surface justify its fluxional behavior.

Potential Impact of the Resistance to Quaternary Ammonium Disinfectants on the Persistence of Listeria monocytogenes in Food Processing Environments.

Science.gov (United States)

Martínez-Suárez, Joaquín V; Ortiz, Sagrario; López-Alonso, Victoria

2016-01-01

The persistence of certain strains of Listeria monocytogenes, even after the food processing environment has been cleaned and disinfected, suggests that this may be related to phenomena that reduce the concentration of the disinfectants to subinhibitory levels. This includes (i) the existence of environmental niches or reservoirs that are difficult for disinfectants to reach, (ii) microorganisms that form biofilms and create microenvironments in which adequate concentrations of disinfectants cannot be attained, and (iii) the acquisition of resistance mechanisms in L. monocytogenes, including those that lead to a reduction in the intracellular concentration of the disinfectants. The only available data with regard to the resistance of L. monocytogenes to disinfectants applied in food production environments refer to genotypic resistance to quaternary ammonium compounds (QACs). Although there are several well-characterized efflux pumps that confer resistance to QACs, it is a low-level resistance that does not generate resistance to QACs at the concentrations applied in the food industry. However, dilution in the environment and biodegradation result in QAC concentration gradients. As a result, the microorganisms are frequently exposed to subinhibitory concentrations of QACs. Therefore, the low-level resistance to QACs in L. monocytogenes may contribute to its environmental adaptation and persistence. In fact, in certain cases, the relationship between low-level resistance and the environmental persistence of L. monocytogenes in different food production chains has been previously established. The resistant strains would have survival advantages in these environments over sensitive strains, such as the ability to form biofilms in the presence of increased biocide concentrations.

Tailored Algorithm for Sensitivity Enhancement of Gas Concentration Sensors Based on Tunable Laser Absorption Spectroscopy.

Science.gov (United States)

Vargas-Rodriguez, Everardo; Guzman-Chavez, Ana Dinora; Baeza-Serrato, Roberto

2018-06-04

In this work, a novel tailored algorithm to enhance the overall sensitivity of gas concentration sensors based on the Direct Absorption Tunable Laser Absorption Spectroscopy (DA-ATLAS) method is presented. By using this algorithm, the sensor sensitivity can be custom-designed to be quasi constant over a much larger dynamic range compared with that obtained by typical methods based on a single statistics feature of the sensor signal output (peak amplitude, area under the curve, mean or RMS). Additionally, it is shown that with our algorithm, an optimal function can be tailored to get a quasi linear relationship between the concentration and some specific statistics features over a wider dynamic range. In order to test the viability of our algorithm, a basic C 2 H 2 sensor based on DA-ATLAS was implemented, and its experimental measurements support the simulated results provided by our algorithm.

The Influence of the Toxin/Antitoxin mazEF on Growth and Survival of Listeria monocytogenes under Stress.

Science.gov (United States)

Curtis, Thomas D; Takeuchi, Ippei; Gram, Lone; Knudsen, Gitte M

2017-01-13

A major factor in the resilience of Listeria monocytogenes is the alternative sigma factor B (σ B ). Type II Toxin/Antitoxin (TA) systems are also known to have a role in the bacterial stress response upon activation via the ClpP or Lon proteases. Directly upstream of the σ B operon in L. monocytogenes is the TA system mazEF , which can cleave mRNA at UACMU sites. In this study, we showed that the mazEF TA locus does not affect the level of persister formation during treatment with antibiotics in lethal doses, but exerts different effects according to the sub-inhibitory stress added. Growth of a Δ mazEF mutant was enhanced relative to the wildtype in the presence of sub-inhibitory norfloxacin and at 42 °C, but was decreased when challenged with ampicillin and gentamicin. In contrast to studies in Staphylococcus aureus , we found that the mazEF locus did not affect transcription of genes within the σ B operon, but MazEF effected the expression of the σ B -dependent genes opuCA and lmo0880 , with a 0.22 and 0.05 fold change, respectively, compared to the wildtype under sub-inhibitory norfloxacin conditions. How exactly this system operates remains an open question, however, our data indicates it is not analogous to the system of S. aureus , suggesting a novel mode of action for MazEF in L. monocytogenes.

RpoS plays a central role in the SOS induction by sub-lethal aminoglycoside concentrations in Vibrio cholerae.

Science.gov (United States)

Baharoglu, Zeynep; Krin, Evelyne; Mazel, Didier

2013-01-01

Bacteria encounter sub-inhibitory concentrations of antibiotics in various niches, where these low doses play a key role for antibiotic resistance selection. However, the physiological effects of these sub-lethal concentrations and their observed connection to the cellular mechanisms generating genetic diversification are still poorly understood. It is known that, unlike for the model bacterium Escherichia coli, sub-minimal inhibitory concentrations (sub-MIC) of aminoglycosides (AGs) induce the SOS response in Vibrio cholerae. SOS is induced upon DNA damage, and since AGs do not directly target DNA, we addressed two issues in this study: how sub-MIC AGs induce SOS in V. cholerae and why they do not do so in E. coli. We found that when bacteria are grown with tobramycin at a concentration 100-fold below the MIC, intracellular reactive oxygen species strongly increase in V. cholerae but not in E. coli. Using flow cytometry and gfp fusions with the SOS regulated promoter of intIA, we followed AG-dependent SOS induction. Testing the different mutation repair pathways, we found that over-expression of the base excision repair (BER) pathway protein MutY relieved this SOS induction in V. cholerae, suggesting a role for oxidized guanine in AG-mediated indirect DNA damage. As a corollary, we established that a BER pathway deficient E. coli strain induces SOS in response to sub-MIC AGs. We finally demonstrate that the RpoS general stress regulator prevents oxidative stress-mediated DNA damage formation in E. coli. We further show that AG-mediated SOS induction is conserved among the distantly related Gram negative pathogens Klebsiella pneumoniae and Photorhabdus luminescens, suggesting that E. coli is more of an exception than a paradigm for the physiological response to antibiotics sub-MIC.

Enhanced growth of the red alga Porphyra-Yezoensis Ueda in high CO sub 2 concentrations

Energy Technology Data Exchange (ETDEWEB)

Gao, K.; Aruga, Y.; Asada, K.; Ishihara, T.; Akano, T.; Kiyohara, M. (Kansai Environmental Engineering Centre, Osaka (Japan))

1991-12-01

Leafy thalli of the red alga Porphyra yezoensis Ueda, initiated from conchospores released from free-living conchocelis, were cultured using aeration with high CO{sub 2}. It was found that the higher the CO{sub 2} concentration, the faster the growth of the thalli. Aeration with elevated CO{sub 2} lowered pH in dark, but raised pH remarkably in light with the thalli, because the photosynthetic conversion of HCO{sub 3} {sup -} to OH{sup -} and CO{sub 2} proceeded much faster than the dissociation of hydrated CO{sub 2} releasing H{sup +}. Photosynthesis of the alga was found to be enhanced in the seawater of elevated dissolved inorganic carbon DIC, CO{sub 2} + HCO{sub 3}{sup -} + CO{sub 3}{sup -}. It is concluded that the increased pH in the light resulted in the increase of DIC in the culture media, thus enhancing photosynthesis and growth. The relevance of the results to removal of atmospheric CO{sub 2} by marine algae is discussed.

Resistance development of cystic fibrosis respiratory pathogens when exposed to fosfomycin and tobramycin alone and in combination under aerobic and anaerobic conditions.

Science.gov (United States)

McCaughey, Gerard; Diamond, Paul; Elborn, J Stuart; McKevitt, Matt; Tunney, Michael M

2013-01-01

Although antibiotics from different classes are frequently prescribed in combination to prevent the development of resistance amongst Cystic Fibrosis (CF) respiratory pathogens, there is a lack of data as to the efficacy of this approach. We have previously shown that a 4:1 (w/w) combination of fosfomycin and tobramycin (F:T) has excellent activity against CF pathogens with increased activity under physiologically relevant anaerobic conditions. Therefore, the aim of this study was to determine whether F:T could delay or prevent the onset of resistance compared to either fosfomycin or tobramycin alone under aerobic and anaerobic conditions. The frequency of spontaneous mutants arising following exposure to fosfomycin, tobramycin and F:T was determined for clinical Pseudomonas aeruginosa and MRSA isolates under aerobic and anaerobic conditions. The effect of sub-inhibitory concentrations of fosfomycin, tobramycin and F:T on the induction of resistance was also investigated, with the stability of resistance and fitness cost associated with resistance assessed if it developed. P. aeruginosa and MRSA isolates had a lower frequency of spontaneous mutants to F:T compared to fosfomycin and tobramycin under both aerobic and anaerobic conditions. There was a maximum two-fold increase in F:T MICs when P. aeruginosa and MRSA isolates were passaged in sub-inhibitory F:T for 12 days. In contrast, sequential resistance to fosfomycin and tobramycin developed quickly (n = 3 days for both) after passage in sub-inhibitory concentrations. Once developed, both fosfomycin and tobramycin resistance was stable and not associated with a biological fitness cost to either P. aeruginosa or MRSA isolates. The results of this study suggest that F:T may prevent the development of resistance compared to fosfomycin or tobramycin alone under aerobic and physiologically relevant anaerobic conditions. F:T may be a potential treatment option in CF patients chronically colonised by MRSA and/or P

Dynamics of Intracellular Polymers in Enhanced Biological Phosphorus Removal Processes under Different Organic Carbon Concentrations

Directory of Open Access Journals (Sweden)

Lizhen Xing

2013-01-01

Full Text Available Enhanced biological phosphorus removal (EBPR may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

Root Fungal Endophytes Enhance Heavy-Metal Stress Tolerance of Clethra barbinervis Growing Naturally at Mining Sites via Growth Enhancement, Promotion of Nutrient Uptake and Decrease of Heavy-Metal Concentration.

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Keiko Yamaji

Full Text Available Clethra barbinervis Sieb. et Zucc. is a tree species that grows naturally at several mine sites and seems to be tolerant of high concentrations of heavy metals, such as Cu, Zn, and Pb. The purpose of this study is to clarify the mechanism(s underlying this species' ability to tolerate the sites' severe heavy-metal pollution by considering C. barbinervis interaction with root fungal endophytes. We measured the heavy metal concentrations of root-zone soil, leaves, branches, and fine roots collected from mature C. barbinervis at Hitachi mine. We isolated fungal endophytes from surface-sterilized root segments, and we examined the growth, and heavy metal and nutrient absorption of C. barbinervis seedlings growing in sterilized mine soil with or without root fungal endophytes. Field analyses showed that C. barbinervis contained considerably high amounts of Cu, Zn, and Pb in fine roots and Zn in leaves. The fungi, Phialocephala fortinii, Rhizodermea veluwensis, and Rhizoscyphus sp. were frequently isolated as dominant fungal endophyte species. Inoculation of these root fungal endophytes to C. barbinervis seedlings growing in sterilized mine soil indicated that these fungi significantly enhanced the growth of C. barbinervis seedlings, increased K uptake in shoots and reduced the concentrations of Cu, Ni, Zn, Cd, and Pb in roots. Without root fungal endophytes, C. barbinervis could hardly grow under the heavy-metal contaminated condition, showing chlorosis, a symptom of heavy-metal toxicity. Our results indicate that the tree C. barbinervis can tolerate high heavy-metal concentrations due to the support of root fungal endophytes including P. fortinii, R. veluwensis, and Rhizoscyphus sp. via growth enhancement, K uptake promotion and decrease of heavy metal concentrations.

Enhancement of Saharan groundwater quality by reducing its fluoride concentration using different materials

KAUST Repository

Ramdani, Amina

2014-04-15

According to the environmental protection regulations, fluoride concentration is considered as a substance of priority for assessment of drinking water quality to determine their impacts on the environment and public health. Saharan groundwater (Algeria) contains an excess of fluoride ions. Regular consumption of this water by the population of the region may cause endemic fluorosis. To solve this problem, we propose to treat this water by adsorption on different materials, such as activated alumina (AA), sodium clay (SC), and hydroxyapatite (HAP) in order to enhance its quality by reducing its fluoride concentration. The maximum adsorption is achieved with an adsorption capacity of the order of 0.9, 0.667, and 0.370 mg/g and with a percentage of 90, 83.4, and 73.95% for AA, HAP, and SC, respectively. Indeed, the acidity and alkalinity of the medium significantly affect the adsorption of fluoride ions. Results deduced from the curves of adsorption isotherms of fluoride ions showed that the retention is predictable from these isotherms in agreement with the Langmuir model. The low removal of fluoride ions was observed in presence of (Formula presented.), (Formula presented.), and (Formula presented.) ions. Finally, AA material proved to be the best adsorbent for fluoride ions removal. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

Flavonoid concentrations in three grass species and a sedge grown in the field and under controlled environment conditions in response to enhanced UV-B radiation.

NARCIS (Netherlands)

van de Staaij, J.W.M.; Bakker, N.; Oosthoek, A.; Broekman, R.A.; van Beem, A.P.; Stroetenga, M.J.; Aerts, R.; Rozema, J.

2002-01-01

An investigation was carried out to find whether enhanced levels of UV-B radiation induce increased concentrations of flavonoids in the leaves of the grass species Deschampsia antarctica, Deschampsia borealis and Calamagrostis epigeios and the sedge Carex arenaria. Whether the enhanced levels of

Comparison of the reaction of bone-derived cells to enhanced MgCl2-salt concentrations.

Science.gov (United States)

Burmester, Anna; Luthringer, Bérengère; Willumeit, Regine; Feyerabend, Frank

2014-01-01

Magnesium-based implants exhibit various advantages such as biodegradability and potential for enhanced in vivo bone formation. However, the cellular mechanisms behind this possible osteoconductivity remain unclear. To determine whether high local magnesium concentrations can be osteoconductive and exclude other environmental factors that occur during the degradation of magnesium implants, magnesium salt (MgCl2) was used as a model system. Because cell lines are preferred targets in studies of non-degradable implant materials, we performed a comparative study of 3 osteosarcoma-derived cell lines (MG63, SaoS2 and U2OS) with primary human osteoblasts. The correlation among cell count, viability, cell size and several MgCl2 concentrations was used to examine the influence of magnesium on proliferation in vitro. Moreover, bone metabolism alterations during proliferation were investigated by analyzing the expression of genes involved in osteogenesis. It was observed that for all cell types, the cell count decreases at concentrations above 10 mM MgCl2. However, detailed analysis showed that MgCl2 has a relevant but very diverse influence on proliferation and bone metabolism, depending on the cell type. Only for primary cells was a clear stimulating effect observed. Therefore, reliable results demonstrating the osteoconductivity of magnesium implants can only be achieved with primary osteoblasts.

Antimicrobial and enhancement of the antibiotic activity by phenolic compounds: Gallic acid, caffeic acid and pyrogallol.

Science.gov (United States)

Lima, Valéria N; Oliveira-Tintino, Cícera D M; Santos, Enaide S; Morais, Luís P; Tintino, Saulo R; Freitas, Thiago S; Geraldo, Yuri S; Pereira, Raimundo L S; Cruz, Rafael P; Menezes, Irwin R A; Coutinho, Henrique D M

2016-10-01

The indiscriminate use of antimicrobial drugs has increased the spectrum of exposure of these organisms. In our studies, these phenolic compounds were evaluated: gallic acid, caffeic acid and pyrogallol. The antibacterial, antifungal and modulatory of antibiotic activities of these compounds were assayed using microdilution method of Minimum Inhibitory Concentration (MIC) to bacteria and Minimum Fungicide Concentration (MFC) to fungi. The modulation was made by comparisons of the MIC and MFC of the compounds alone and combined with drugs against bacteria and fungi respectively, using a sub-inhibitory concentration of 128 μg/mL of substances (MIC/8). All substances not demonstrated clinically relevant antibacterial activity with a MIC above ≥1024 μg/mL. As a result, we observed that the caffeic acid presented a potentiating antibacterial effect over the 3 groups of bacteria studied. Pyrogallol showed a synergistic effect with two of the antibiotics tested, but only against Staphylococcus aureus. In general, caffeic acid was the substance that presented with the greatest number of antibiotics and with the greatest number of bacteria. In relation to the antifungal activity of all the compounds, the verified results were ≥1024 μg/mL, not demonstrating significant activity. Regarding potentiation of the effect of fluconazole, was observed synergistic effect only when assayed against Candida tropicalis, with all substances. Therefore, as can be seen, the compounds presented as substances that can be promising potentiating agents of antimicrobial drugs, even though they do not have direct antibacterial and antifungal action. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation and Treatment of Fusidic Acid Resistance Among Methicillin-Resistant Staphylococcal Isolates from Egypt.

Science.gov (United States)

Abouelfetouh, Alaa; Kassem, Mervat; Naguib, Marwa; El-Nakeeb, Moustafa

2017-01-01

Methicillin resistance among staphylococci isolated from patients in northern Egypt has escalated alarmingly in the past decade. Data about the prevalence of fusidic acid (FA) resistance in Egyptian clinical isolates are limited. This work investigates the prevalence and mechanism of FA resistance among 81 methicillin-resistant staphylococcal isolates from major hospitals of Alexandria, Egypt. Some combinations for treating infections due to resistant isolates were studied. Twenty-six isolates (32.1%) were FA resistant (minimum inhibitory concentrations [MICs] = 2-1,024 μg/ml), and fusB and fusC genes coding for FA resistance were detected in 30.77% and 34.62% of the FA-resistant strains, respectively. One highly resistant isolate, S502 (MIC = 1,024 μg/ml), possessed both genes. Plasmid curing resulted in fusB loss and MIC decrease by 16-64 folds. Conjugation caused acquisition of FA resistance among susceptible isolates. Serial passages in subinhibitory FA concentrations produced mutants with increased MIC by 4-32 folds. The combination of FA with rifampin, gentamicin, or ampicillin/sulbactam, in a subinhibitory concentration, was synergistic against the isolates, including serial passage mutants, decreasing number of survivors by an average of 2-4 logs. A relatively moderate rate of FA resistance was detected in Alexandria hospitals. Combination therapy with gentamicin, rifampin, or ampicillin/sulbactam is crucial to preserve the effectiveness of FA.

Resistance to phenicol compounds following adaptation to quaternary ammonium compounds in Escherichia coli.

Science.gov (United States)

Soumet, C; Fourreau, E; Legrandois, P; Maris, P

2012-07-06

Bacterial adaptation to quaternary ammonium compounds (QACs) is mainly documented for benzalkonium chloride (BC) and few data are available for other QACs. The aim of this study was to assess the effects of repeated exposure to different quaternary ammonium compounds (QACs) on the susceptibility and/or resistance of bacteria to other QACs and antibiotics. Escherichia coli strains (n=10) were adapted by daily exposure to increasingly sub-inhibitory concentrations of a QAC for 7 days. Three QACs were studied. Following adaptation, we found similar levels of reduction in susceptibility to QACs with a mean 3-fold increase in the minimum inhibitory concentration (MIC) compared to initial MIC values, whatever the QAC used during adaptation. No significant differences in antibiotic susceptibility were observed between the tested QACs. Antibiotic susceptibility was reduced from 3.5- to 7.5-fold for phenicol compounds, β lactams, and quinolones. Increased MIC was associated with a shift in phenotype from susceptible to resistant for phenicol compounds (florfenicol and chloramphenicol) in 90% of E. coli strains. Regardless of the QAC used for adaptation, exposure to gradually increasing concentrations of this type of disinfectant results in reduced susceptibility to QACs and antibiotics as well as cross-resistance to phenicol compounds in E. coli strains. Extensive use of QACs at sub-inhibitory concentrations may lead to the emergence of antibiotic-resistant bacteria and may represent a public health risk. Published by Elsevier B.V.

Tannic Acid as a Potential Modulator of Norfloxacin Resistance in Staphylococcus Aureus Overexpressing norA.

Science.gov (United States)

Diniz-Silva, Helena Taina; Cirino, Isis Caroline da Silva; Falcão-Silva, Vivyanne Dos Santos; Magnani, Marciane; de Souza, Evandro Leite; Siqueira-Júnior, José P

2016-01-01

Tannins have shown inhibitory effects against pathogenic bacteria, and these properties make tannins potential modifying agents in bacterial resistance. The minimum inhibitory concentration (MIC) of tannic acid (TA), gallic acid (GA) and norfloxacin (Nor) against Staphylococcus aureus SA-1119 (NorA-effluxing strain) was determined using broth microdilution tests. To assess the modulation of antibiotic resistance, the MIC of Nor was determined in growth media with or without TA or GA at a subinhibitory concentration (1/4 MIC). The checkerboard method was performed to obtain the fractional inhibitory concentration index (FICI) for the combined application of TA and Nor. TA displayed a weak inhibitory effect (MIC 512 μg/ml) against S. aureus SA-1119, while no inhibitory effect was displayed by GA (MIC >512 μg/ml). However, when TA was tested at a subinhibitory concentration in combination with Nor, the MIC of Nor against S. aureus SA-1119 decreased from 128 to 4 μg/ml (32-fold); this effect was not observed for GA. In the checkerboard assay, the MIC of TA and Nor decreased from 512 to 128 μg/ml (4-fold) and from 128 to 8 μg/ml (16-fold), respectively. The combination of TA and Nor presented an FICI as low as 0.31, which indicates a synergistic interaction. TA is a potential agent for increasing the clinical efficacy of Nor to control resistant S. aureus. © 2016 S. Karger AG, Basel.

Family-Concentrated Ownership in Chinese PLCs: Does Ownership Concentration Always Enhance Corporate Value?

Directory of Open Access Journals (Sweden)

Jin-Hui Luo

2014-02-01

Full Text Available In this paper we investigate the relationship between family ownership structure and corporate value across a sample of 1314 firm-year observations of China’s family publicly listed companies (PLCs, from 2004 to 2008. We find a significant inverse-U-shaped relationship between the controlling family’s ultimate cash-flow rights and corporate value; as measured by Tobin’s Q. That is, as family-ownership concentration increases, corporate value first increases and then decreases. This finding refreshes our understanding of the relationship between family-ownership concentration and corporate value in emerging economies such as found in China. We corroborate prior findings that when controlling families hold excess control over cash-flow rights, corporate value is significantly lowered, while multiple large shareholders structure is significantly associated with higher corporate value. In addition; board independence is found to significantly improve corporate value in the context of family-concentrated ownership. We also test for potential endogeneity between family ownership and corporate value and find our results to be robust.

Enhanced cycling performance of a Li metal anode in a dimethylsulfoxide-based electrolyte using highly concentrated lithium salt for a lithium-oxygen battery

Science.gov (United States)

Togasaki, Norihiro; Momma, Toshiyuki; Osaka, Tetsuya

2016-03-01

Stable charge-discharge cycling behavior for a lithium metal anode in a dimethylsulfoxide (DMSO)-based electrolyte is strongly desired of lithium-oxygen batteries, because the Li anode is rapidly exhausted as a result of side reactions during cycling in the DMSO solution. Herein, we report a novel electrolyte design for enhancing the cycling performance of Li anodes by using a highly concentrated DMSO-based electrolyte with a specific Li salt. Lithium nitrate (LiNO3), which forms an inorganic compound (Li2O) instead of a soluble product (Li2S) on a lithium surface, exhibits a >20% higher coulombic efficiency than lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium perchlorate, regardless of the loading current density. Moreover, the stable cycling of Li anodes in DMSO-based electrolytes depends critically on the salt concentration. The highly concentrated electrolyte 4.0 M LiNO3/DMSO displays enhanced and stable cycling performance comparable to that of carbonate-based electrolytes, which had not previously been achieved. We suppose this enhancement is due to the absence of free DMSO solvent in the electrolyte and the promotion of the desolvation of Li ions on the solid electrolyte interphase surface, both being consequences of the unique structure of the electrolyte.

Therapeutic relevance of penicillin-induced hypersensitivity of Staphylococcus aureus to killing by polymorphonuclear leukocytes.

OpenAIRE

Lam, C; Georgopoulos, A; Laber, G; Schütze, E

1984-01-01

There is an overwhelming body of evidence that certain Staphylococcus aureus strains become more sensitive to killing by polymorphonuclear leukocytes after their growth in media containing subinhibitory concentrations of penicillin. However, it is not clear to what extent this phenomenon contributes to the curative effect of penicillin in vivo. To explore its therapeutic relevance, we evaluated the interaction of staphylococci pretreated with penicillin in vitro with leukocytes in cell-proof ...

A Monte Carlo Study of dose enhancement according to the enhancement agents

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung Hoon; Kim, Chang Soo [Dept. of Radiological Science, College of Health Sciences, Catholic University of Pusan, Busan (Korea, Republic of); Hwang, Chul Hwan [Dept. of Radiation Oncology, Pusan National University Hospital, Busan (Korea, Republic of)

2017-03-15

Dose enhancement effects at megavoltage (MV) X and γ-ray energies, and the effects of different energy levels on incident energy, dose enhancement agents, and concentrations were analyzed using Monte Carlo simulations. Gold, gadolinium, Iodine, and iron oxide (Fe2O3) were compared as dose enhancement agents. For incident energy, 4, 6, 10 and 15 MV X-ray spectra produced by a linear accelerator and a Co60 γ-ray were used. The dose enhancement factor (DEF) was calculated using an ICRU Slab phantom for concentrations of 7, 18, and 30 mg/g. The DEF was higher at higher concentrations of dose enhancement agents and at lower incident energies. The calculated DEF ranged from 1.035 to 1.079, and dose enhancement effects were highest for iron oxide, followed by iodine, gadolinium, and gold. Thus, this study contributes to improving the therapeutic ratio by delivering larger doses of radiation to tumor volume, and provides data to support further in vivo and in vitro studies.

Enrofloxacin at environmentally relevant concentrations enhances uptake and toxicity of cadmium in the earthworm Eisenia fetida in farm soils

Energy Technology Data Exchange (ETDEWEB)

Li, Yinsheng, E-mail: yinshengli@sjtu.edu.cn [School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240 (China); Tang, Hao; Hu, Yingxiu; Wang, Xiuhong; Ai, Xiaojie; Tang, Li [School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240 (China); Matthew, Cory [Institute of Agriculture & Environment, Massey University, Private Bag 11-222, Palmerston North 4442 (New Zealand); Cavanagh, Jo [Landcare Research, PO Box 40, Lincoln 7640 (New Zealand); Qiu, Jiangping [School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240 (China)

2016-05-05

Highlights: • Enrofloxacin (EF) and cadmium (Cd) were independently adsorbed in soils. • EF accelerated and increased Cd bioaccumulation in earthworms. • At high concentration EF (10 mg kg{sup −1}) was toxic to earthworms. • EF enhanced Cd induced oxidative stress, and increased burrowing and respiration. • EF did not affect the Cd induced increase in metallothionein in earthworms. - Abstract: Individual and combined effects of enrofloxacin (EF) and cadmium (Cd) on the earthworm Eisenia fetida at environmentally relevant concentrations were investigated. EF is a veterinary antibiotic; Cd is an impurity in phosphatic fertiliser. For both, residues may accumulate in farm soils. In laboratory tests, over 98% of spiked EF was adsorbed by farm soils, with a half-life >8 weeks. However, earthworms absorbed less than 20% of spiked EF. Earthworms in soil with EF concentration 10 mg kg{sup −1} soil experienced transient oxidative stress and exhibited reduced burrowing activity and respiration after an 8-week exposure; EF at 0.1 and 1.0 mg kg{sup −1} soil did not elicit toxicity symptoms. When both were added, Cd did not affect EF uptake, but each increment of spiked EF increased Cd bioaccumulation and associated oxidative stress of earthworms, and also caused decreased burrow length and CO{sub 2} production. However, metallothionein induction was not affected. The enhanced toxicity of Cd to earthworms in the presence of EF at low environmental concentrations may have implications for the health and reproductive success of earthworm populations and highlights the importance of understanding effects of antibiotic contamination of farm soils, and of awareness of environmental effects from interaction between multiple contaminants.

Enrofloxacin at environmentally relevant concentrations enhances uptake and toxicity of cadmium in the earthworm Eisenia fetida in farm soils

International Nuclear Information System (INIS)

Li, Yinsheng; Tang, Hao; Hu, Yingxiu; Wang, Xiuhong; Ai, Xiaojie; Tang, Li; Matthew, Cory; Cavanagh, Jo; Qiu, Jiangping

2016-01-01

Highlights: • Enrofloxacin (EF) and cadmium (Cd) were independently adsorbed in soils. • EF accelerated and increased Cd bioaccumulation in earthworms. • At high concentration EF (10 mg kg"−"1) was toxic to earthworms. • EF enhanced Cd induced oxidative stress, and increased burrowing and respiration. • EF did not affect the Cd induced increase in metallothionein in earthworms. - Abstract: Individual and combined effects of enrofloxacin (EF) and cadmium (Cd) on the earthworm Eisenia fetida at environmentally relevant concentrations were investigated. EF is a veterinary antibiotic; Cd is an impurity in phosphatic fertiliser. For both, residues may accumulate in farm soils. In laboratory tests, over 98% of spiked EF was adsorbed by farm soils, with a half-life >8 weeks. However, earthworms absorbed less than 20% of spiked EF. Earthworms in soil with EF concentration 10 mg kg"−"1 soil experienced transient oxidative stress and exhibited reduced burrowing activity and respiration after an 8-week exposure; EF at 0.1 and 1.0 mg kg"−"1 soil did not elicit toxicity symptoms. When both were added, Cd did not affect EF uptake, but each increment of spiked EF increased Cd bioaccumulation and associated oxidative stress of earthworms, and also caused decreased burrow length and CO_2 production. However, metallothionein induction was not affected. The enhanced toxicity of Cd to earthworms in the presence of EF at low environmental concentrations may have implications for the health and reproductive success of earthworm populations and highlights the importance of understanding effects of antibiotic contamination of farm soils, and of awareness of environmental effects from interaction between multiple contaminants.

Micro-evaporation electrolyte concentrator

NARCIS (Netherlands)

Timmer, B.H.; van Delft, K.M.; Olthuis, Wouter; Bergveld, Piet; van den Berg, Albert

2003-01-01

The sensitivity of miniaturized chemical analysis systems depends most of the time on the obtainable detection limit. Concentrating the analyte prior to the detection system can enhance the detection limit. In this writing an analyte concentrator is presented that makes use of evaporation to

Death and population dynamics affect mutation rate estimates and evolvability under stress in bacteria.

Science.gov (United States)

Frenoy, Antoine; Bonhoeffer, Sebastian

2018-05-01

The stress-induced mutagenesis hypothesis postulates that in response to stress, bacteria increase their genome-wide mutation rate, in turn increasing the chances that a descendant is able to better withstand the stress. This has implications for antibiotic treatment: exposure to subinhibitory doses of antibiotics has been reported to increase bacterial mutation rates and thus probably the rate at which resistance mutations appear and lead to treatment failure. More generally, the hypothesis posits that stress increases evolvability (the ability of a population to generate adaptive genetic diversity) and thus accelerates evolution. Measuring mutation rates under stress, however, is problematic, because existing methods assume there is no death. Yet subinhibitory stress levels may induce a substantial death rate. Death events need to be compensated by extra replication to reach a given population size, thus providing more opportunities to acquire mutations. We show that ignoring death leads to a systematic overestimation of mutation rates under stress. We developed a system based on plasmid segregation that allows us to measure death and division rates simultaneously in bacterial populations. Using this system, we found that a substantial death rate occurs at the tested subinhibitory concentrations previously reported to increase mutation rate. Taking this death rate into account lowers and sometimes removes the signal for stress-induced mutagenesis. Moreover, even when antibiotics increase mutation rate, we show that subinhibitory treatments do not increase genetic diversity and evolvability, again because of effects of the antibiotics on population dynamics. We conclude that antibiotic-induced mutagenesis is overestimated because of death and that understanding evolvability under stress requires accounting for the effects of stress on population dynamics as much as on mutation rate. Our goal here is dual: we show that population dynamics and, in particular, the

Problems of the inclusion of workplaces with enhanced radon and radon daughter concentrations into occupational radiation protection control

International Nuclear Information System (INIS)

Przyborowski, S.

1993-01-01

New international recommendations (ICRP-60) on inclusion of workplaces with enhanced radon and radon daughter concentrations into occupational control are expected. Based on present regulations in Germany the problems of their implementation into radiation protection practice will be discussed. For underground workplaces and workplaces in radon spas and waterworks problems may be exist in particular points, whereas inclusion of workplaces in buildings seems to be problematicly in general. (orig./HP) [de

Effect of concentration and pH on the surface-enhanced Raman scattering of captopril on nano-colloidal silver surface

Science.gov (United States)

Gao, Junxiang; Gu, Huaimin; Liu, Fangfang; Dong, Xiao; Xie, Min; Hu, Yongjun

2011-07-01

In this report, Raman and surface-enhanced Raman scattering (SERS) spectra of captopril are studied in detail. Herein, the Raman bands are assigned by the density functional theory (DFT) calculations and potential energy distributions (PED) based on internal coordinates of the molecule, which are found to be in good agree with the experimental values. Furthermore, the concentration and pH dependence of the SERS intensity of the molecule is discussed. By analyzing the intensities variation of SERS bands of the different concentrations of captopril solution, it can be concluded that the molecules orientation adsorbed on the silver nanoparticles surface change with the change of the concentrations. The variation of SERS spectra of captopril with the change of pH suggests that the interaction among the adsorbates with Ag cluster depend on the protonated state of the adsorbate and the aggregation of silver nanoparticles.

Study of a Greek area with enhanced indoor radon concentrations

International Nuclear Information System (INIS)

Louizi, A.; Nikolopoulos, D.; Koukouliou, V.; Kehagia, K.

2003-01-01

In this paper the focus is on Arnea Chalkidikis, an area in Greece with granitic geological background and indications of possible elevated radon concentration indoors. Data are reported of indoor radon measurements with etched track detectors and those used for dosimetric estimations. Moreover, data are reported on soil gas and soil radon concentrations in Arnea, as well as radon and uranium concentrations in water samples. From the measured radon concentrations in water samples the contribution to the overall dose has been calculated. For a period of 1 month, indoor radon and progeny activity has also been monitored in the dwelling that has the maximum indoor radon concentration in Greece. This dwelling is in Arnea and the dose delivered to the inhabitants has been calculated. Mean annual effective dose due to indoor radon was 4.5 mSv and about 11% of this was due to the use of water. Mean soil gas concentration and soil radon concentration were (90 ± 30) kBq m -3 (P -3 (P -1 (P<0.05). (author)

Eugenol reduces the expression of virulence-related exoproteins in Staphylococcus aureus.

Science.gov (United States)

Qiu, Jiazhang; Feng, Haihua; Lu, Jing; Xiang, Hua; Wang, Dacheng; Dong, Jing; Wang, Jianfeng; Wang, Xiaoliang; Liu, Juxiong; Deng, Xuming

2010-09-01

Eugenol, an essential oil component in plants, has been demonstrated to possess activity against both gram-positive and gram-negative bacteria. This study examined the influence that subinhibitory concentrations of eugenol may have on the expression of the major exotoxins produced by Staphylococcus aureus. The results from a tumor necrosis factor (TNF) release assay and a hemolysin assay indicated that S. aureus cultured with graded subinhibitory concentrations of eugenol (16 to 128 microg/ml) dose dependently decreased the TNF-inducing and hemolytic activities of culture supernatants. Western blot analysis showed that eugenol significantly reduced the production of staphylococcal enterotoxin A (SEA), SEB, and toxic shock syndrome toxin 1 (the key exotoxins to induce TNF release), as well as the expression of alpha-hemolysin (the major hemolysin to cause hemolysis). In addition, this suppression was also evaluated at the transcriptional level via real-time reverse transcription (RT)-PCR analysis. The transcriptional analysis indicated that 128 microg/ml of eugenol remarkably repressed the transcription of the S. aureus sea, seb, tst, and hla genes. According to these results, eugenol has the potential to be rationally applied on food products as a novel food antimicrobial agent both to inhibit the growth of bacteria and to suppress the production of exotoxins by S. aureus.

Cdr2p contributes to fluconazole resistance in Candida dubliniensis clinical isolates.

LENUS (Irish Health Repository)

2011-05-01

The development of resistance to azole antifungals used in the treatment of fungal infections can be a serious medical problem. Here, we investigate the molecular mechanisms associated with reduced susceptibility to fluconazole in clinical isolates of Candida dubliniensis , showing evidence of the trailing growth phenomenon. The changes in membrane sterol composition were studied in the presence of subinhibitory fluconazole concentrations. Despite lanosterol and eburicol accumulating as the most prevalent sterols after fluconazole treatment, these ergosterol precursors still support growth of Candida isolates. The overexpression of ABC transporters was demonstrated by immunoblotting employing specific antibodies against Cdr1p and Cdr2p. The presence of a full-length 170 kDa protein Cdr1p was detected in two isolates, while a truncated form of Cdr1p with the molecular mass of 85 kDa was observed in isolate 966\\/3(2). Notably, Cdr2p was detected in this isolate, and the expression of this transporter was modulated by subinhibitory concentrations of fluconazole. These results suggest that C. dubliniensis can display the trailing growth phenomenon, and such isolates express similar molecular mechanisms like that of fluconazole-resistant isolates and can therefore be associated with recurrent infections.

Plant-Derived Antimicrobials Reduce E. coli O157:H7 Virulence Factors Critical for Colonization in Cattle Gastrointestinal Tract In Vitro

OpenAIRE

Sangeetha Ananda Baskaran; Kumar Venkitanarayanan

2014-01-01

This study investigated the effect of subinhibitory concentrations (SIC) of five plant-derived antimicrobials (PDAs), namely, trans cinnamaldehyde, eugenol, carvacrol, thymol, and β-resorcylic acid, on E. coli O157:H7 (EHEC) attachment and invasion of cultured bovine colonic (CO) and rectoanal junction (RAJ) epithelial cells. In addition, PDAs' effect on EHEC genes critical for colonization of cattle gastrointestinal tract (CGIT) was determined in bovine rumen fluid (RF) and intestinal conten...

Biofortified orange maize enhances β-cryptoxanthin concentrations in egg yolks of laying hens better than tangerine peel fortificant.

Science.gov (United States)

Heying, Emily K; Tanumihardjo, Jacob P; Vasic, Vedran; Cook, Mark; Palacios-Rojas, Natalia; Tanumihardjo, Sherry A

2014-12-10

The xanthophyll β-cryptoxanthin provides vitamin A and has other purported health benefits. Laying hens deposit xanthophyll carotenoids into egg yolk. Hens (n = 8/group) were fed conventional-bred high β-cryptoxanthin biofortified (orange) maize, tangerine peel-fortified white maize, lutein-fortified yellow maize, or white maize for 40 d to investigate yolk color changes using L*a*b* scales, yolk carotenoid enhancement, and hen vitamin A status. Yolks from hens fed orange maize had scores indicating a darker, orange color and mean higher β-cryptoxanthin, zeaxanthin, and β-carotene concentrations (8.43 ± 1.82, 23.1 ± 4.8, 0.16 ± 0.08 nmol/g, respectively) than other treatments (P eggs could be another choice for consumers, providing enhanced color through a provitamin A carotenoid and supporting eggs' status as a functional food.

Enhanced separation efficiency of photoinduced charges for antimony-doped tin oxide (Sb-SnO{sub 2})/TiO{sub 2} heterojunction semiconductors with varied Sb doping concentration

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhen-Long [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Ma, Wen-Hai [School of Physical Education, Henan University, Kaifeng 475004 (China); Mao, Yan-Li, E-mail: ylmao1@163.com [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Institute for Computational Materials Science, Henan University, Kaifeng 475004 (China)

2014-09-07

In this paper, antimony-doped tin oxide (Sb-SnO{sub 2}) nanoparticles were synthesized with varied Sb doping concentration, and the Sb-SnO{sub 2}/TiO{sub 2} heterojunction semiconductors were prepared with Sb-SnO{sub 2} and TiO{sub 2}. The separation efficiency of photoinduced charges was characterized with surface photovoltage (SPV) technique. Compared with Sb-SnO{sub 2} and TiO{sub 2}, Sb-SnO{sub 2}/TiO{sub 2} presents an enhanced separation efficiency of photoinduced charges, and the SPV enhancements were estimated to be 1.40, 1.43, and 1.99 for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. To understand the enhancement, the band structure of Sb-SnO{sub 2} and TiO{sub 2} in the heterojunction semiconductor was determined, and the conduction band offsets (CBO) between Sb-SnO{sub 2} and TiO{sub 2} were estimated to be 0.56, 0.64, and 0.98 eV for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. These results indicate that the separation efficiency enhancement is resulting from the energy level matching, and the increase of enhancement is due to the rising of CBO.

Low acetate concentrations favor polyphosphate-accumulating organisms over glycogen-accumulating organisms in enhanced biological phosphorus removal from wastewater.

Science.gov (United States)

Tu, Yunjie; Schuler, Andrew J

2013-04-16

Glycogen-accumulating organisms (GAOs) are thought to compete with polyphosphate-accumulating organisms (PAOs) in enhanced biological phosphorus removal (EBPR) wastewater treatment systems. A laboratory sequencing batch reactor (SBR) was operated for one year to test the hypothesis that PAOs have a competitive advantage at low acetate concentrations, with a focus on low pH conditions previously shown to favor GAOs. PAOs dominated the system under conventional SBR operation with rapid acetate addition (producing high in-reactor concentrations) and pH values of 7.4-8.4. GAOs dominated when the pH was decreased (6.4-7.0). Decreasing the acetate addition rate led to very low reactor acetate concentrations, and PAOs recovered, supporting the study hypothesis. When the acetate feed rate was increased, EBPR failed again. Dominant PAOs and GAOs were Candidatus Accumulibacter phosphatis and Defluviicoccus Cluster 2, respectively, according to fluorescent in situ hybridization and 454 pyrosequencing. Surprisingly, GAOs were not the immediate causes of PAO failures, based on functional and population measurements. Pyrosequencing results suggested Dechloromonas and Tetrasphaera spp. may have also been PAOs, and additional potential GAOs were also identified. Full-scale systems typically have lower in-reactor acetate concentrations than laboratory SBRs, and so, previous laboratory studies may have overestimated the practical importance of GAOs as causes of EBPR failure.

Global transcriptional responses of Bacillus subtilis to xenocoumacin 1.

Science.gov (United States)

Zhou, T; Zeng, H; Qiu, D; Yang, X; Wang, B; Chen, M; Guo, L; Wang, S

2011-09-01

To determine the global transcriptional response of Bacillus subtilis to an antimicrobial agent, xenocoumacin 1 (Xcn1). Subinhibitory concentration of Xcn1 applied to B. subtilis was measured according to Hutter's method for determining optimal concentrations. cDNA microarray technology was used to study the global transcriptional response of B. subtilis to Xcn1. Real-time RT-PCR was employed to verify alterations in the transcript levels of six genes. The subinhibitory concentration was determined to be 1 μg ml(-1). The microarray data demonstrated that Xcn1 treatment of B. subtilis led to more than a 2.0-fold up-regulation of 480 genes and more than a 2.0-fold down-regulation of 479 genes (q ≤ 0.05). The transcriptional responses of B. subtilis to Xcn1 were determined, and several processes were affected by Xcn1. Additionally, cluster analysis of gene expression profiles after treatment with Xcn1 or 37 previously studied antibiotics indicated that Xcn1 has similar mechanisms of action to protein synthesis inhibitors. These microarray data showed alterations of gene expression in B. subtilis after exposure to Xcn1. From the results, we identified various processes affected by Xcn1. This study provides a whole-genome perspective to elucidate the action of Xcn1 as a potential antimicrobial agent. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Anti-adhesion and antibiotic modulatory evaluation of grapefruit (Citrus paradisi juice and seed extract on bacteria isolated from urine and catheter

Directory of Open Access Journals (Sweden)

Michael Oluwole Osungunna

2016-02-01

Full Text Available Context: The in vivo use of grapefruit seed in the treatment of urinary tract infections (UTIs has been reported but the mechanism of action is yet to be explained. Aims: Evaluate the anti-adhesion and antibiotic modulatory activities of grapefruit seed extract and juice as their possible mechanisms of action. Methods: Sub-inhibitory concentrations of 2.5 and 5 mg/mL as well as 10.3 and 5.15 mg/mL of grapefruit seed extract and juice respectively were evaluated for modulatory activity of ciprofloxacin, streptomycin and nalidixic acid against one hundred and twenty seven bacterial isolates from mid-stream urine (MSU (100, catheter-stream urine (CSU (14 and catheter tips (CT (13 using the agar dilution method. Anti-adhesion activity of grapefruit seed extract and juice at sub-inhibitory concentrations of 2.5 and 1.03 mg/mL respectively was evaluated against twenty three (23 moderately adherent bacterial isolates from MSU (10, CSU (7 and CT (6 using the tissue culture plate method. Results: The results revealed that grapefruit juice (5.15 mg/mL showed more effect on nalidixic acid activity than seed extract (2.5 mg/mL. Grapefruit juice showed more anti-adhesion activity than grapefruit seed extract at the concentration tested. Conclusions: The study concluded that grapefruit seed extract and juice had anti-adhesion and antibiotic modulatory effects on bacteria associated with UTIs.

Application of low dose radiation and low concentration contrast media in enhanced CT scans in children with congenital heart disease.

Science.gov (United States)

Liu, Zhimin; Song, Lei; Yu, Tong; Gao, Jun; Zhang, Qifeng; Jiang, Ling; Liu, Yong; Peng, Yun

2016-09-01

The aim of this study was to explore the feasibility of using low dose radiation and low concentration contrast media in enhanced CT examinations in children with congenital heart disease. Ninety patients with congenital heart disease were randomly divided into three groups of 30 patients each who underwent contrast-enhanced cardiac scans on a Discovery CT750 HD scanner. Group A received 270 mg I/mL iodixanol, and group B received 320 mg I/mL iodixanol contrast media and was scanned with prospective ECG triggering mode. Group C received 320 mg I/mL iodixanol and was scanned with conventional retrospective ECG gating mode. The same weight-based contrast injection protocol was used for all three groups. Images were reconstructed using a 30% adaptive statistical iterative reconstruction (ASIR) algorithm and a 50% ASIR in groups A and B and a 30% ASIR in group C. The subjective and objective image quality evaluations, diagnostic accuracies, radiation doses and amounts of contrast media in the three groups were measured and compared. All images in the three groups met the diagnostic requirements, with the same diagnostic accuracy and image quality scores greater than 3 in a 4-point scoring system. However, ventricular enhancement and the objective noise, signal-to-noise ratio, contrast-to-noise ratio and subjective image quality scores in group C were better than those in groups A and B (all Pcontrast dose (14% lower than that of groups B and C). Enhanced CT scan images with low dose radiation and low concentration contrast media can meet the diagnostic requirements for examining children with congenital heart disease while reducing the potential risk of radiation damage and contrast-induced nephropathy. © 2016 John Wiley & Sons Ltd.

WE-G-BRE-06: New Potential for Enhancing External Beam Radiotherapy for Lung Cancer Using FDA-Approved Concentrations of Cisplatin Or Carboplatin Nanoparticles Administered Via Inhalation

International Nuclear Information System (INIS)

Hao, Y; Altundal, Y; Sajo, E; Detappe, A; Makrigiorgos, G; Berbeco, R; Ngwa, W

2014-01-01

Purpose: This study investigates, for the first time, the dose enhancement to lung tumors due to cisplatin nanoparticles (CNPs) and carboplatin nanoparticles (CBNPs) administered via inhalation route (IR) during external beam radiotherapy. Methods: Using Monte Carlo generated 6 MV energy fluence spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumor due to radiation-induced photoelectrons from CNPs administered via IR in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung tumor via IV. Meanwhile recent experimental studies indicate that 3.5–14.6 times higher concentrations of CNPs can reach the lung tumors by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the dose with and without CNPs was calculated for field size of 10 cm × 10 cm (sweeping gap), for a range of tumor depths and tumor sizes. Similar calculations were done for CBNPs. Results: For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of 1.19–1.30 were obtained for CNPs at 3–10 cm depth, respectively, in comparison to 1.06–1.09 for IV. For CBNPs, DEF values of 1.26–1.41 were obtained in comparison to 1.07–1.12 for IV. For IR with 14.6 times higher concentrations, higher DEF values were obtained e.g. 1.81–2.27 for CNPs. DEF increased with increasing field size or decreasing tumor size. Conclusions: Our preliminary results indicate that major dose enhancement to lung tumors can be achieved using CNPs/CBNPs administered via IR, in contrast to IV administration during external beam radiotherapy. These findings highlight a potential new approach for radiation boosting to lung tumors using CNPs/CBNPs administered via IR. This would, especially, be applicable during concomitant chemoradiotherapy, potentially allowing for dose enhancement while

Increased Milk Protein Concentration in a Rehydration Drink Enhances Fluid Retention Caused by Water Reabsorption in Rats.

Science.gov (United States)

Ito, Kentaro; Saito, Yuri; Ashida, Kinya; Yamaji, Taketo; Itoh, Hiroyuki; Oda, Munehiro

2015-01-01

A fluid-retention effect is required for beverages that are designed to prevent dehydration. That is, fluid absorbed from the intestines should not be excreted quickly; long-term retention is desirable. Here, we focused on the effect of milk protein on fluid retention, and propose a new effective oral rehydration method that can be used daily for preventing dehydration. We first evaluated the effects of different concentrations of milk protein on fluid retention by measuring the urinary volumes of rats fed fluid containing milk protein at concentrations of 1, 5, and 10%. We next compared the fluid-retention effect of milk protein-enriched drink (MPD) with those of distilled water (DW) and a sports drink (SD) by the same method. Third, to investigate the mechanism of fluid retention, we measured plasma insulin changes in rats after ingesting these three drinks. We found that the addition of milk protein at 5 or 10% reduced urinary volume in a dose-dependent manner. Ingestion of the MPD containing 4.6% milk protein resulted in lower urinary volumes than DW and SD. MPD also showed a higher water reabsorption rate in the kidneys and higher concentrations of plasma insulin than DW and SD. These results suggest that increasing milk protein concentration in a beverage enhances fluid retention, which may allow the possibility to develop rehydration beverages that are more effective than SDs. In addition, insulin-modifying renal water reabsorption may contribute to the fluid-retention effect of MPD.

Feeding hydroalcoholic extract powder of Lepidium meyenii (maca) increases serum testosterone concentration and enhances steroidogenic ability of Leydig cells in male rats.

Science.gov (United States)

Ohta, Y; Yoshida, K; Kamiya, S; Kawate, N; Takahashi, M; Inaba, T; Hatoya, S; Morii, H; Takahashi, K; Ito, M; Ogawa, H; Tamada, H

2016-04-01

Although Lepidium meyenii (maca), a plant growing in Peru's central Andes, has been traditionally used for enhancing fertility and reproductive performance in domestic animals and human beings, effects of maca on reproductive organs are still unclear. This study examined whether feeding the hydroalcoholic extract powder of maca for 6 weeks affects weight of the reproductive organs, serum concentrations of testosterone and luteinising hormone (LH), number and cytoplasmic area of immunohistochemically stained Leydig cells, and steroidogenesis of cultured Leydig cells in 8-week-old male rats. Feeding the extract powder increased weight of seminal vesicles, serum testosterone level and cytoplasmic area of Leydig cells when compared with controls. Weight of prostate gland, serum LH concentration and number of Leydig cells were not affected by the maca treatment. The testosterone production by Leydig cells significantly increased when cultured with 22R-hydroxycholesterol or pregnenolone and tended to increase when cultured with hCG by feeding the extract powder. The results show that feeding the hydroalcoholic extract powder of maca for 6 weeks increases serum testosterone concentration associated with seminal vesicle stimulation in male rats, and this increase in testosterone level may be related to the enhanced ability of testosterone production by Leydig cells especially in the metabolic process following cholesterol. © 2015 Blackwell Verlag GmbH.

The effect of sub-inhibitory concentrations of rifaximin on urease production and on other virulence factors expressed by Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus.

Science.gov (United States)

Ricci, Annalisa; Coppo, Erika; Barbieri, Ramona; Debbia, Eugenio A; Marchese, Anna

2017-04-01

Rifaximin, a topical derivative of rifampin, inhibited urease production and other virulence factors at sub-MIC concentrations in strains involved in hepatic encephalopathy and the expression of methicillin resistance in Staphylococcus aureus. In particular, urease production was affected in all Proteus mirabilis and Klebsiella pneumoniae strains as well as in all tested Pseudomonas aeruginosa isolates. Other exotoxins, synthesized by P. aeruginosa, such as protease, gelatinase, lipase, lecithinase and DNAse were also not metabolized in the presence of rifaximin. This antibiotic inhibited pigment production in both P. aeruginosa and Chromobacterium violaceum, a biosensor control strain. Lastly, rifaximin affected haemolysin production in S. aureus and was able to restore cefoxitin susceptibility when the strain was cultured in the presence of sub-MICs of the drug. The present findings confirm and extend previous observations about the beneficial effects of rifaximin for the treatment of gastrointestinal diseases, since in this anatomic site, it reaches a large array of concentrations which prevents enterobacteria from thriving and/or producing their major virulence factors.

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration.

Science.gov (United States)

Luo, Dan; Wang, Feng; Zhu, Jingyi; Cao, Feng; Liu, Yuan; Li, Xiaogang; Willson, Richard C; Yang, Zhaozhong; Chu, Ching-Wu; Ren, Zhifeng

2016-07-12

The current simple nanofluid flooding method for tertiary or enhanced oil recovery is inefficient, especially when used with low nanoparticle concentration. We have designed and produced a nanofluid of graphene-based amphiphilic nanosheets that is very effective at low concentration. Our nanosheets spontaneously approached the oil-water interface and reduced the interfacial tension in a saline environment (4 wt % NaCl and 1 wt % CaCl2), regardless of the solid surface wettability. A climbing film appeared and grew at moderate hydrodynamic condition to encapsulate the oil phase. With strong hydrodynamic power input, a solid-like interfacial film formed and was able to return to its original form even after being seriously disturbed. The film rapidly separated oil and water phases for slug-like oil displacement. The unique behavior of our nanosheet nanofluid tripled the best performance of conventional nanofluid flooding methods under similar conditions.

Action of caffeine on x-irradiated HeLa cells. IV. Progression delays and enhanced cell killing at high caffeine concentrations

International Nuclear Information System (INIS)

Tolmach, L.J.; Busse, P.M.

1980-01-01

The response of x-irradiated and unirradiated HeLa S3 cells to treatment with caffeine at concentrations between 1 and 10 nM has been examined with respect to both delay in progression through the cell generation cycle and enhancement of the expression of potentially lethal x-ray damage. Progression is delayed in a concentration-dependent fashion: the generation time is doubled at about 4 mM. The duration of G 1 is lengthened, and the rate of DNA synthesis is reduced, although the kinetics are different in the two phases; the rate of DNA synthesis is usually unaffected at 1 or 2 mM, while there is no concentration threshold for the slowing of progression through G 1 . Progression through G 2 appears to be unaffected by concentrations up to at least 10 mM. Killing of irradiated cells in G 2 is somewhat greater after treatment with the higher caffeine concentrations than reported previously for 1 mM. Moreover, an additional mode of killing is observed in irradiated G 1 cells which had been found previously to be only slightly affected by 1 mM caffeine; they suffer extensive killing at concentrations above 5 mM. The time-survival curves for irradiated, caffeine-treated G 1 and G 2 cells have characteristically different shapes. The dose-survival curves for cells treated with the higher caffeine concentrations display steeper terminal slopes and narrower shoulders

Simultaneous enhancement of carrier mobility and concentration via tailoring of Al-chemical states in Al-ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Kumar, Manish, E-mail: manishk@skku.edu; Wen, Long; Sahu, Bibhuti B. [Center for Advance Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma-Nano Materials (IPNM), School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon-440746 (Korea, Republic of); Han, Jeon Geon [Center for Advance Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma-Nano Materials (IPNM), School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon-440746 (Korea, Republic of); Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai-50200 (Thailand)

2015-06-15

Simultaneously achieving higher carriers concentration and mobility is a technical challenge against up-scaling the transparent-conductive performances of transparent-conductive oxides. Utilizing one order higher dense (∼1 × 10{sup 11} cm{sup −3}) plasmas (in comparison to the conventional direct current plasmas), highly c-axis oriented Al-doped ZnO films have been prepared with precise control over relative composition and chemical states of constituting elements. Tailoring of intrinsic (O vacancies) and extrinsic (ionic Al and zero-valent Al) dopants provide simultaneous enhancement in mobility and concentration of charge carriers. Room-temperature resistivity as low as 4.89 × 10{sup −4} Ω cm along the carrier concentration 5.6 × 10{sup 20} cm{sup −3} is obtained in 200 nm thick transparent films. Here, the control of atomic Al reduces the charge trapping at grain boundaries and subdues the effects of grain boundary scattering. A mechanism based on the correlation between electron-hole interaction and carrier mobility is proposed for degenerately doped wide band-gap semiconductors.

Inhibitory effect of totarol on exotoxin proteins hemolysin and enterotoxins secreted by Staphylococcus aureus.

Science.gov (United States)

Shi, Ce; Zhao, Xingchen; Li, Wenli; Meng, Rizeng; Liu, Zonghui; Liu, Mingyuan; Guo, Na; Yu, Lu

2015-10-01

Staphylococcus aureus (S. aureus) causes a wide variety of infections, which are of major concern worldwide. S. aureus produces multiple virulence factors, resulting in food infection and poisoning. These virulence factors include hyaluronidases, proteases, coagulases, lipases, deoxyribonucleases and enterotoxins. Among the extracellular proteins produced by S. aureus that contribute to pathogenicity, the exotoxins α-hemolysin, staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin B (SEB) are thought to be of major significance. Totarol, a plant extract, has been revealed to inhibit the proliferation of several pathogens effectively. However, there are no reports on the effects of totarol on the production of α-hemolysin, SEA or SEB secreted by S. aureus. The aim of this study was to evaluate the effects of totarol on these three exotoxins. Hemolysis assay, western blotting and real-time reverse transcriptase-PCR assay were performed to identify the influence of graded subinhibitory concentrations of totarol on the production of α-hemolysin and the two major enterotoxins, SEA and SEB, by S. aureus in a dose-dependent manner. Moreover, an enzyme linked immunosorbent assay showed that the TNF-α production of RAW264.7 cells stimulated by S. aureus supernatants was inhibited by subinhibitory concentrations of totarol. Form the data, we propose that totarol could potentially be used as a promising natural compound in the food and pharmaceutical industries.

Phase evolution and photoluminescence enhancement of CePO4 nanowires from a low phosphate concentration system

International Nuclear Information System (INIS)

Xu Pengfei; Yu Ranbo; Zong Lingbo; Wang Jiali; Wang Dan; Deng Jinxia; Chen Jun; Xing Xianran

2013-01-01

Uniform CePO 4 nanowires have been successfully synthesized in a low phosphate concentration system through a single-step hydrothermal process. The low phosphate concentration might decrease the surface PO 4 3− adsorption of the as-synthesized CePO 4 nanowires efficiently and benefit their photoluminescence. The CePO 4 nanowires were identified to go through phase evolution from pure monoclinic to mixed hexagonal and monoclinic phase by only increasing the initial molar ratio of cerium and phosphate source (denoted as Ce/P). Interestingly, the strongest photoluminescence was observed in the CePO 4 nanowires synthesized with the initial Ce/P of 4:1, which proved to be the critical phase evolution point between the hexagonal and monoclinic CePO 4 . Therefore, the strong photoluminescence could be explained by the existence of the structure-sensitive energy level in the CePO 4 . This kind of photoluminescence enhancement would be a meaningful reference for design of other photoluminescent materials, in which the photoluminescent emission might be related to the structure-sensitive energy level. Additionally, the growth processes of CePO 4 nanowires based on related well-designed experiments were proposed.

Bone Marrow Aspirate Concentrate versus Platelet Rich Plasma to Enhance Osseous Integration Potential for Osteochondral Allografts.

Science.gov (United States)

Stoker, Aaron M; Baumann, Charles A; Stannard, James P; Cook, James L

2018-04-01

Fresh osteochondral allograft (OCA) transplantation is an attractive treatment option for symptomatic articular cartilage lesions in young, healthy patients. Since a lack of OCA bone integration can be a cause of treatment failure, methods for speeding and enhancing OCA bone integration to mitigate this potential complication are highly desirable. This study sought to determine and compare the potential of bone marrow aspirate concentrate (BMC) and leukoreduced platelet rich plasma (PRP) to repopulate the osseous portion of an OCA with cells and deliver osteogenic proteins. It was hypothesized that BMC would have significantly higher colony forming units (CFUs)/mL and seed the osseous portion of OCA with more cells than PRP. Finally, we hypothesized that the media of BMC and PRP treated OCAs would have significantly higher concentrations of osteogenic proteins compared with negative control OCAs. Cylindrical OCAs ( n  = 36) created from tissue stored for 21 days were treated with BMC ( n  = 12) or PRP ( n  = 12) obtained for 6 dogs, or left untreated as a negative control ( n  = 12). After treatment, OCAs were cultured for 7 or 14 days. Media were collected for analysis of osteogenic biomarker concentration. Samples of each BMC and PRP were tested for CFU concentration. On day 7 or 14, the grafts were assessed for cell surface adhesion and penetration using fluorescent microscopy. Significant differences in CFU and media biomarker concentration between the groups were determined using one-way analysis of variance (ANOVA) and Tukey's post-hoc test with the significance set at p  BMC had viable cells detectable on the osseous portion of the allografts at day 7 and 14 of culture. BMC samples had a significantly higher ( p  = 0.029) CFU/mL compared with PRP samples. At day 3 and/or 7 of culture, the concentration of several osteogenic proteins was significantly higher in both BMC and PRP samples. Autogenous BMC can be used to deliver both a cell

Using NASA Satellite Aerosol Optical Depth to Enhance PM2.5 Concentration Datasets for Use in Human Health and Epidemiology Studies

Science.gov (United States)

Huff, A. K.; Weber, S.; Braggio, J.; Talbot, T.; Hall, E.

2012-12-01

Fine particulate matter (PM2.5) is a criterion air pollutant, and its adverse impacts on human health are well established. Traditionally, studies that analyze the health effects of human exposure to PM2.5 use concentration measurements from ground-based monitors and predicted PM2.5 concentrations from air quality models, such as the U.S. EPA's Community Multi-scale Air Quality (CMAQ) model. There are shortcomings associated with these datasets, however. Monitors are not distributed uniformly across the U.S., which causes spatially inhomogeneous measurements of pollutant concentrations. There are often temporal variations as well, since not all monitors make daily measurements. Air quality model output, while spatially and temporally uniform, represents predictions of PM2.5 concentrations, not actual measurements. This study is exploring the potential of combining Aerosol Optical Depth (AOD) data from the MODIS instrument on NASA's Terra and Aqua satellites with PM2.5 monitor data and CMAQ predictions to create PM2.5 datasets that more accurately reflect the spatial and temporal variations in ambient PM2.5 concentrations on the metropolitan scale, with the overall goal of enhancing capabilities for environmental public health decision-making. AOD data provide regional information about particulate concentrations that can fill in the spatial and temporal gaps in the national PM2.5 monitor network. Furthermore, AOD is a measurement, so it reflects actual concentrations of particulates in the atmosphere, in contrast to PM2.5 predictions from air quality models. Results will be presented from the Battelle/U.S. EPA statistical Hierarchical Bayesian Model (HBM), which was used to combine three PM2.5 concentration datasets: monitor measurements, AOD data, and CMAQ model predictions. The study is focusing on the Baltimore, MD and New York City, NY metropolitan regions for the period 2004-2006. For each region, combined monitor/AOD/CMAQ PM2.5 datasets generated by the HBM

Measuring a 10,000-fold enhancement of singlet molecular oxygen (1O2*) concentration on illuminated ice relative to the corresponding liquid solution

Science.gov (United States)

Bower, Jonathan P.; Anastasio, Cort

2013-08-01

Much attention has focused on the highly reactive hydroxyl radical in the oxidation of trace organic compounds on snow and ice (and subsequent release of volatile organics to the atmospheric boundary layer) but other oxidants are likely also important in this processing. Here we examine the ice chemistry of singlet molecular oxygen (1O2*), which can be significant in atmospheric water drops but has not been examined in ice or snow. To examine 1O2* on ice we illuminate laboratory ices containing Rose Bengal (RB) as the source of 1O2*, furfuryl alcohol (FFA) as the probe, and Na2SO4 to control the total solute concentration. We find that the 1O2*-mediated loss of FFA (and, thus, the 1O2* concentration) is up to 11,000 times greater on ice than in the equivalent liquid sample at the same photon flux. We attribute this large increase in the 1O2* steady-state concentration to the freeze-concentration of solutes into liquid-like regions (LLRs) in/on ice: compared to the initial solution, in the LLRs of ice the sources for 1O2* are highly concentrated, while the concentration of the dominant sink for 1O2* (i.e., water) remains largely unchanged. Similar to results expected in liquid solution, rates of FFA loss in ice depend on both the initial sensitizer concentration and temperature, providing evidence that these reactions occur in LLRs. However, we find that the enhancement in 1O2* concentrations on ice does not follow predictions from freezing-point depression, likely because experiments were conducted below the eutectic temperature for sodium sulfate, where all of the salt should have precipitated. We also explore a method for separating 1O2* and rad OH contributions to FFA oxidation in laboratory ices and show its application to two natural snow samples. We find that 1O2* concentrations in these snows are approximately 100 times higher than observed in polluted, mid-latitude fog waters, showing that the enhancement of 1O2* on ice is environmentally relevant and that

Design of nonimaging concentrators as second stages in tandem with image-forming first-stage concentrators

Science.gov (United States)

Winston, R.; Welford, W. T.

1980-02-01

The paper discusses the paraboloidal mirror as a tracking solar concentrator, fitting a nonimaging second stage to the paraboloidal mirror, other image-forming systems as first stages, and tracking systems in two-dimensional geometry. Because of inherent aberrations, the paraboloidal mirror cannot achieve the thermodynamic limit. It is shown how paraboloidal mirrors of short focal ratio and similar systems can have their flux concentration enhanced to near the thermodynamic limit by the addition of nonimaging compound elliptical concentrators.

Design of nonimaging concentrators as second stages in tandem with image-forming first-stage concentrators

Science.gov (United States)

Winston, R.; Welford, W. T.

1980-01-01

The paper discusses the paraboloidal mirror as a tracking solar concentrator, fitting a nonimaging second stage to the paraboloidal mirror, other image-forming systems as first stages, and tracking systems in two-dimensional geometry. Because of inherent aberrations, the paraboloidal mirror cannot achieve the thermodynamic limit. It is shown how paraboloidal mirrors of short focal ratio and similar systems can have their flux concentration enhanced to near the thermodynamic limit by the addition of nonimaging compound elliptical concentrators.

Antibacterial activity of exogenous glutathione and its synergism on antibiotics sensitize carbapenem-associated multidrug resistant clinical isolates of Acinetobacter baumannii.

Science.gov (United States)

Alharbe, Roaa; Almansour, Ayidh; Kwon, Dong H

2017-10-01

A major clinical impact of A. baumannii is hospital-acquired infections including ventilator-associated pneumonia. The treatment of this pathogen is often difficult due to its innate and acquired resistance to almost all commercially available antibiotics. Infections with carbapenem-associated multidrug resistant A. baumannii is the most problematic. Glutathione is a tripeptide thiol-antioxidant and antibacterial activity of exogenous glutathione was reported in some bacteria. However, clinical relevance and molecular details of the antibacterial activity of glutathione are currently unclear. Seventy clinical isolates of A. baumannii including 63 carbapenem-associated multidrug resistant isolates and a type strain A. baumannii ATCC 19606 were used to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Fractional inhibitory concentration (FIC) and time-killing activity with meropenem and/or glutathione were also determined in the carbapenem-associated multidrug resistant isolates. In addition, the roles of exogenous glutathione in multidrug efflux pumps and β-lactamase production were examined. Levels of MIC and MBC were ranged from 10 to 15mM of exogenous glutathione. All tested carbapenem-associated multidrug resistant isolates were sensitized by all tested antibiotics in combination with subinhibitory concentrations of glutathione. FIC levels of glutathione with carbapenem (meropenem) were allcarbapenem-associated multidrug resistant isolates were killed by subinhibitory concentrations of both glutathione and meropenem at>2log10 within 12h, suggesting glutathione synergistically interacts with meropenem. The roles of multidrug efflux pumps and β-lactamase production were excluded for the glutathione-mediated antibiotic susceptibility. Overall results demonstrate that the antibacterial activity of glutathione is clinically relevant and its synergism on antibiotics sensitizes clinical isolates of A. baumannii regardless

Genomic and transcriptomic insights into how bacteria withstand high concentrations of benzalkonium chloride biocides.

Science.gov (United States)

Kim, Minjae; Hatt, Janet K; Weigand, Michael R; Krishnan, Raj; Pavlostathis, Spyros G; Konstantinidis, Konstantinos T

2018-04-13

Benzalkonium chlorides (BAC) are commonly used biocides in broad-spectrum disinfectant solutions. How microorganisms cope with BAC exposure remains poorly understood, despite its importance for disinfection and disinfectant-induced antibiotic resistance. To provide insights into these issues, we exposed two isolates of an opportunistic pathogen, Pseudomonas aeruginosa , to increasing concentrations of BAC. One isolate was pre-adapted to BAC as it originated from a bioreactor fed with sub-inhibitory concentrations of BAC for 3 years, while the other originated from a bioreactor that received no BAC. Replicated populations of both isolates were able to survive high concentrations of BAC, up to 1200 and 1600mg/L for the non- and pre-adapted ones, respectively, exceeding typical application doses. RNA-seq analysis revealed up-regulation of efflux pump genes and decreased expression of porins related to BAC transport as well as reduced growth rate. Increased expression of spermidine (a polycation) synthase genes and mutations in the pmrB (polymyxin resistance) gene, which cause a reduction in membrane negative charge, suggested that a major adaptation to exposure to the cationic surfactant BAC was to actively stabilize cell surface charge. Collectively, these results revealed that P. aeruginosa adapts to BAC exposure by a combination of mechanisms, and provided genetic markers to monitor BAC-resistant organisms that may have applications in the practice of disinfection. Importance Benzalkonium chlorides (BAC) are widely used as biocides in disinfectant solutions, food processing lines, domestic households, and healthcare facilities. Due to their wide use and mode of action, there has been rising concern that BAC may promote antibiotic resistance. Consistently, at least 40 outbreaks have been attributed to infection by disinfectant- and antibiotic-resistant pathogens such as Pseudomonas aeruginosa However, the underlying molecular mechanisms that bacteria deal with BAC

Low-concentration tailing and subsequent quicklime-enhanced remediation of volatile chlorinated hydrocarbon-contaminated soils by mechanical soil aeration.

Science.gov (United States)

Ma, Yan; Du, Xiaoming; Shi, Yi; Xu, Zhu; Fang, Jidun; Li, Zheng; Li, Fasheng

2015-02-01

Mechanical soil aeration has long been regarded as an effective ex-situ remediation technique and as suitable for remediation of large-scale sites contaminated by volatile organic compounds (VOCs) at low cost. However, it has been reported that the removal efficiency of VOCs from soil is relatively low in the late stages of remediation, in association with tailing. Tailing may extend the remediation time required; moreover, it typically results in the presence of contaminants residues at levels far exceeding regulations. In this context, the present study aimed to discuss the tailing that occurs during the process of remediation of soils contaminated artificially with volatile chlorinated hydrocarbons (VCHs) and to assess possible quicklime-enhanced removal mechanisms. The results revealed the following conclusions. First, temperature and aeration rate can be important controls on both the timing of appearance of tailing and the levels of residual contaminants. Furthermore, the addition of quicklime to soil during tailing can reduce the residual concentrations rapidly to below the remedial target values required for site remediation. Finally, mechanical soil aeration can be enhanced using quicklime, which can improve the volatilization of VCHs via increasing soil temperature, reducing soil moisture, and enhancing soil permeability. Our findings give a basic understanding to the elimination of the tailing in the application of mechanical soil aeration, particularly for VOCs-contaminated soils. Copyright © 2014 Elsevier Ltd. All rights reserved.

Large-volume constant-concentration sampling technique coupling with surface-enhanced Raman spectroscopy for rapid on-site gas analysis

Science.gov (United States)

Zhang, Zhuomin; Zhan, Yisen; Huang, Yichun; Li, Gongke

2017-08-01

In this work, a portable large-volume constant-concentration (LVCC) sampling technique coupling with surface-enhanced Raman spectroscopy (SERS) was developed for the rapid on-site gas analysis based on suitable derivatization methods. LVCC sampling technique mainly consisted of a specially designed sampling cell including the rigid sample container and flexible sampling bag, and an absorption-derivatization module with a portable pump and a gas flowmeter. LVCC sampling technique allowed large, alterable and well-controlled sampling volume, which kept the concentration of gas target in headspace phase constant during the entire sampling process and made the sampling result more representative. Moreover, absorption and derivatization of gas target during LVCC sampling process were efficiently merged in one step using bromine-thiourea and OPA-NH4+ strategy for ethylene and SO2 respectively, which made LVCC sampling technique conveniently adapted to consequent SERS analysis. Finally, a new LVCC sampling-SERS method was developed and successfully applied for rapid analysis of trace ethylene and SO2 from fruits. It was satisfied that trace ethylene and SO2 from real fruit samples could be actually and accurately quantified by this method. The minor concentration fluctuations of ethylene and SO2 during the entire LVCC sampling process were proved to be samples were achieved in range of 95.0-101% and 97.0-104% respectively. It is expected that portable LVCC sampling technique would pave the way for rapid on-site analysis of accurate concentrations of trace gas targets from real samples by SERS.

Anti-adhesion and antibiotic modulatory evaluation of grapefruit (Citrus paradisi) juice and seed extract on bacteria isolated from urine and catheter

OpenAIRE

Michael Oluwole Osungunna; Grace O. Onawunmi

2016-01-01

Context: The in vivo use of grapefruit seed in the treatment of urinary tract infections (UTIs) has been reported but the mechanism of action is yet to be explained. Aims: Evaluate the anti-adhesion and antibiotic modulatory activities of grapefruit seed extract and juice as their possible mechanisms of action. Methods: Sub-inhibitory concentrations of 2.5 and 5 mg/mL as well as 10.3 and 5.15 mg/mL of grapefruit seed extract and juice respectively were evaluated for modulatory activit...

Intravenous digital subtraction angiography contrast media time-concentration curves

International Nuclear Information System (INIS)

Burbank, F.H.; Brody, W.R.

1985-01-01

At any specified radiation dose and system signal-to-noise ratio, temporal (masked-mode) intravenous digital subtraction angiography (IV-DSA) image quality is dependent upon the shape of the arterial time-concentration curve produced by the intravenous injection of iodinated contrast media. If contrast media appears in the arterial circulation as a compact bolus and reaches a high peak, images containing low or no iodine (the mask image or images) and high iodine concentration (the enhanced image or images) can be obtained close together in time, maximizing contrast media enhancement and minimizing the potential for spatial movement (misregistration). However, if the contrast media bolus is broad, rising slowly to a low concentration peak, sufficient time may pass for movement to occur and the opacification difference between the mask image and the enhanced image may be too small to visualize vessels of interest. Consequently, knowledge of the rules which govern the formation of time-concentration curves is central to IV-DSA

Large-volume constant-concentration sampling technique coupling with surface-enhanced Raman spectroscopy for rapid on-site gas analysis.

Science.gov (United States)

Zhang, Zhuomin; Zhan, Yisen; Huang, Yichun; Li, Gongke

2017-08-05

In this work, a portable large-volume constant-concentration (LVCC) sampling technique coupling with surface-enhanced Raman spectroscopy (SERS) was developed for the rapid on-site gas analysis based on suitable derivatization methods. LVCC sampling technique mainly consisted of a specially designed sampling cell including the rigid sample container and flexible sampling bag, and an absorption-derivatization module with a portable pump and a gas flowmeter. LVCC sampling technique allowed large, alterable and well-controlled sampling volume, which kept the concentration of gas target in headspace phase constant during the entire sampling process and made the sampling result more representative. Moreover, absorption and derivatization of gas target during LVCC sampling process were efficiently merged in one step using bromine-thiourea and OPA-NH 4 + strategy for ethylene and SO 2 respectively, which made LVCC sampling technique conveniently adapted to consequent SERS analysis. Finally, a new LVCC sampling-SERS method was developed and successfully applied for rapid analysis of trace ethylene and SO 2 from fruits. It was satisfied that trace ethylene and SO 2 from real fruit samples could be actually and accurately quantified by this method. The minor concentration fluctuations of ethylene and SO 2 during the entire LVCC sampling process were proved to be gas targets from real samples by SERS. Copyright © 2017 Elsevier B.V. All rights reserved.

The impact of enhanced atmospheric carbon dioxide on yield, proximate composition, elemental concentration, fatty acid and vitamin C contents of tomato (Lycopersicon esculentum).

Science.gov (United States)

Khan, Ikhtiar; Azam, Andaleeb; Mahmood, Abid

2013-01-01

The global average temperature has witnessed a steady increase during the second half of the twentieth century and the trend is continuing. Carbon dioxide, a major green house gas is piling up in the atmosphere and besides causing global warming, is expected to alter the physico-chemical composition of plants. The objective of this work was to evaluate the hypothesis that increased CO(2) in the air is causing undesirable changes in the nutritional composition of tomato fruits. Two varieties of tomato (Lycopersicon esculentum) were grown in ambient (400 μmol mol(-1)) and elevated (1,000 μmol mol(-1)) concentration of CO(2) under controlled conditions. The fruits were harvested at premature and fully matured stages and analyzed for yield, proximate composition, elemental concentration, fatty acid, and vitamin C contents. The amount of carbohydrates increased significantly under the enhanced CO(2) conditions. The amount of crude protein and vitamin C, two important nutritional parameters, decreased substantially. Fatty acid content showed a mild decrease with a slight increase in crude fiber. Understandably, the effect of enhanced atmospheric CO(2) was more pronounced at the fully matured stage. Mineral contents of the fruit samples changed in an irregular fashion. Tomato fruit has been traditionally a source of vitamin C, under the experimental conditions, a negative impact of enhanced CO(2) on this source of vitamin C was observed. The nutritional quality of both varieties of tomato has altered under the CO(2) enriched atmosphere.

Global expression profile of biofilm resistance to antimicrobial compounds in the plant-pathogenic bacterium Xylella fastidiosa reveals evidence of persister cells.

Science.gov (United States)

Muranaka, Lígia S; Takita, Marco A; Olivato, Jacqueline C; Kishi, Luciano T; de Souza, Alessandra A

2012-09-01

Investigations of biofilm resistance response rarely focus on plant-pathogenic bacteria. Since Xylella fastidiosa is a multihost plant-pathogenic bacterium that forms biofilm in the xylem, the behavior of its biofilm in response to antimicrobial compounds needs to be better investigated. We analyzed here the transcriptional profile of X. fastidiosa subsp. pauca in response to inhibitory and subinhibitory concentrations of copper and tetracycline. Copper-based products are routinely used to control citrus diseases in the field, while antibiotics are more widely used for bacterial control in mammals. The use of antimicrobial compounds triggers specific responses to each compound, such as biofilm formation and phage activity for copper. Common changes in expression responses comprise the repression of genes associated with metabolic functions and movement and the induction of toxin-antitoxin systems, which have been associated with the formation of persister cells. Our results also show that these cells were found in the population at a ca. 0.05% density under inhibitory conditions for both antimicrobial compounds and that pretreatment with subinhibitory concentration of copper increases this number. No previous report has detected the presence of these cells in X. fastidiosa population, suggesting that this could lead to a multidrug tolerance response in the biofilm under a stressed environment. This is a mechanism that has recently become the focus of studies on resistance of human-pathogenic bacteria to antibiotics and, based on our data, it seems to be more broadly applicable.

Synergies of carvacrol and 1,8-cineole to inhibit bacteria associated with minimally processed vegetables.

Science.gov (United States)

de Sousa, Jossana Pereira; de Azerêdo, Geíza Alves; de Araújo Torres, Rayanne; da Silva Vasconcelos, Margarida Angélica; da Conceição, Maria Lúcia; de Souza, Evandro Leite

2012-03-15

This study assessed the occurrence of an enhancing inhibitory effect of the combined application of carvacrol and 1,8-cineole against bacteria associated with minimally processed vegetables using the determination of Fractional Inhibitory Concentration (FIC) index, time-kill assay in vegetable broth and application in vegetable matrices. Their effects, individually and in combination, on the sensory characteristics of the vegetables were also determined. Carvacrol and 1,8-cineole displayed Minimum Inhibitory Concentration (MIC) in a range of 0.6-2.5 and 5-20 μL/mL, respectively, against the organisms studied. FIC indices of the combined application of the compounds were 0.25 against Listeria monocytogenes, Aeromonas hydrophila and Pseudomonas fluorescens, suggesting a synergic interaction. Application of carvacrol and 1,8-cineole alone (MIC) or in a mixture (1/8 MIC+1/8 MIC or 1/4 MIC+1/4 MIC) in vegetable broth caused a significant decrease (pvegetable broth and in experimentally inoculated fresh-cut vegetables. A similar efficacy was observed in the reduction of naturally occurring microorganisms in vegetables. Sensory evaluation revealed that the scores of the most-evaluated attributes fell between "like slightly" and "neither like nor dislike." The combination of carvacrol and 1,8-cineole at sub-inhibitory concentrations could constitute an interesting approach to sanitizing minimally processed vegetables. Copyright © 2011 Elsevier B.V. All rights reserved.

Diversity and natural functions of antibiotics produced by beneficial and plant pathogenic bacteria.

Science.gov (United States)

Raaijmakers, Jos M; Mazzola, Mark

2012-01-01

Soil- and plant-associated environments harbor numerous bacteria that produce antibiotic metabolites with specific or broad-spectrum activities against coexisting microorganisms. The function and ecological importance of antibiotics have long been assumed to yield a survival advantage to the producing bacteria in the highly competitive but resource-limited soil environments through direct suppression. Although specific antibiotics may enhance producer persistence when challenged by competitors or predators in soil habitats, at subinhibitory concentrations antibiotics exhibit a diversity of other roles in the life history of the producing bacteria. Many processes modulated by antibiotics may be inherently critical to the producing bacterium, such as the acquisition of substrates or initiation of developmental changes that will ensure survival under stressful conditions. Antibiotics may also have roles in more complex interactions, including in virulence on host plants or in shaping the outcomes of multitrophic interactions. The innate functions of antibiotics to producing bacteria in their native ecosystem are just beginning to emerge, but current knowledge already reveals a breadth of activities well beyond the historical perspective of antibiotics as weaponry in microbial conflicts.

Limitations on the concentration of radioactive elements substances (natural or enhanced by human activity) in building materials - a proposal for draft Israeli regulations

International Nuclear Information System (INIS)

Schlesinger, T.; Hareuveny, R.; Margaliot, M.

1997-01-01

Natural radioactive elements 40 K 228 U and 232 Th and their decay product such as 226 Ra and its short lived daughters occur in building materials in relatively high concentrations. 40 K and part of the above mentioned radionuclides cause external exposure while the inhalation of 222 Ra and its short lived progeny lead to internal exposure of the respiratory tract to alpha particles. In recent years there is a growing tendency to use new construction materials with naturally or technologically enhanced levels of radioactivity (e.g. phosphogypsum, fly ash, exotic minerals etc). This trend causes a growing health concern.The result of this concern is legislation activity and publication of guidance notes by national authorities and international professional organizations related to the radiological implications of these novel technologies. The Ministry of the Environment in Israel is authorized by Israeli legislation to control the exposure of the public to ionising radiation. The ministry asked in 1996 a professional group in the Radiation Protection Division in the Soreq NRC (the authors of this presentation) to study the radiological implications of the use of building materials with naturally or technologically enhanced concentrations of radioactive substances, and to submit draft regulations setting primary limits on excess exposure of the public to ionizing radiation from building materials, and derived limits related to concentrations of specific radionuclides in these materials.The draft regulations will be presented and the way of their derivation will be reviewed (authors)

Efficacy of high iodine concentration contrast medium with saline pushing in hepatic CT in patients with chronic liver disease. Comparison of high doses-standard contrast medium concentration

International Nuclear Information System (INIS)

Matoba, Munetaka; Kondo, Tamaki; Nishikawa, Takahiro; Kuginuki, Yasuaki; Yokota, Hajime; Higashi, Kotaro; Tonami, Hisao

2006-01-01

The aim of this study was to compare the enhancement of liver parenchyama with high iodine concentration contrast medium with saline pushing to that with high doses standard iodine concentration in hepatic CT in patients with chronic liver disease. There was no statistically significant difference regarding to the enhancement of liver parenchyama between the 370 mgI/ml of contrast medium with saline pushing and high doses standard iodine concentration contrast medium. (author)

Inhibition effect of tea tree oil on Listeria monocytogenes growth and exotoxin proteins listeriolysin O and p60 secretion.

Science.gov (United States)

Liu, Z; Meng, R; Zhao, X; Shi, C; Zhang, X; Zhang, Y; Guo, N

2016-12-01

Listeria monocytogenes (L. monocytogenes) is a Gram-positive bacterium that causes infections in humans. In this study, the effects of tea tree oil (TTO) at subinhibitory concentrations on L. monocytogenes growth and two important exotoxin proteins secreted by L. monocytogenes were researched. Treatment with half of minimal inhibitory concentration of TTO demonstrated very little or no reduction in numbers of viable ATCC 19115 cells. Listeriolysin O (LLO) and p60, were investigated. A listeriolysin assay was used to investigate the hemolytic activities of L. monocytogenes exposed to TTO, and the secretion of LLO and p60 was detected by immunoblot analysis. Additionally, real-time RT-PCR was used to analyse the influence of TTO on the transcription of LLO and p60 encoded genes hly and iap respectively. According to our experimental results, we propose that TTO could be used as a promising natural compound against L. monocytogenes and its virulence factors. This is the first report on the influence of subinhibitory concentrations of tea tree oil (TTO) on the secretion of listeriolysin O (LLO) and p60, the critical virulence factors involved in Listeria pathogenesis. The results showed that TTO at 0·25 mg ml -1 reduced the secretion of LLO and p60 to 10 and 34·9% respectively, in addtion, the transcription of hly and iap was reduced to 10 and 4·3% at 0·5 mg ml -1 respectively. We propose that TTO could be used as a promising antimicrobial compound and virulence inhibitor against L. monocytogenes. © 2016 The Society for Applied Microbiology.

Mass Spectrometry-Based Metabolomics of Agave Sap (Agave salmiana after Its Inoculation with Microorganisms Isolated from Agave Sap Concentrate Selected to Enhance Anticancer Activity

Directory of Open Access Journals (Sweden)

Luis M. Figueroa

2017-11-01

Full Text Available Saponins have been correlated with the reduction of cancer cell growth and the apoptotic effect of agave sap concentrate. Empirical observations of this artisanal Mexican food have shown that fermentation occurs after agave sap is concentrated, but little is known about the microorganisms that survive after cooking, or their effects on saponins and other metabolites. The aim of this study was to evaluate the changes in metabolites found in agave (A. salmiana sap after its fermentation with microorganisms isolated from agave sap concentrate, and demonstrate its potential use to enhance anticancer activity. Microorganisms were isolated by dilution plating and identified by 16S rRNA analysis. Isolates were used to ferment agave sap, and their corresponding butanolic extracts were compared with those that enhanced the cytotoxic activity on colon (Caco-2 and liver (Hep-G2 cancer cells. Metabolite changes were investigated by mass spectrometry-based metabolomics. Among 69 isolated microorganisms, the actinomycetes Arthrobacter globiformis and Gordonia sp. were used to analyze the metabolites, along with bioactivity changes. From the 939 ions that were mainly responsible for variation among fermented samples at 48 h, 96 h, and 192 h, four were correlated to anticancer activity. It was shown that magueyoside B, a kammogenin glycoside, was found at higher intensities in the samples fermented with Gordonia sp. that reduced Hep-G2 viability better than controls. These findings showed that microorganisms from agave sap concentrate change agave sap metabolites such as saponins. Butanolic extracts obtained after agave sap fermentation with Arthrobacter globiformis or Gordonia sp. increased the cancer cell growth inhibitory effect on colon or liver cancer cells, respectively.

The yeast Saccharomyces cerevisiae Pdr16p restricts changes in ergosterol biosynthesis caused by the presence of azole antifungals.

Science.gov (United States)

Šimová, Zuzana; Poloncová, Katarína; Tahotná, Dana; Holič, Roman; Hapala, Ivan; Smith, Adam R; White, Theodore C; Griač, Peter

2013-06-01

Pdr16p belongs to the family of phosphatidylinositol transfer proteins in yeast. The absence of Pdr16p results in enhanced susceptibility to azole antifungals in Saccharomyces cerevisiae. In the major fungal human pathogen Candida albicans, CaPDR16 is a contributing factor to clinical azole resistance. The current study was aimed at better understanding the function of Pdr16p, especially in relation to azole resistance in S. cerevisiae. We show that deletion of the PDR16 gene increased susceptibility of S. cerevisiae to azole antifungals that are used in clinical medicine and agriculture. Significant differences in the inhibition of the sterol biosynthetic pathway were observed between the pdr16Δ strain and its corresponding wild-type (wt) strain when yeast cells were challenged by sub-inhibitory concentrations of the azoles miconazole or fluconazole. The increased susceptibility to azoles, and enhanced changes in sterol biosynthesis upon exposure to azoles of the pdr16Δ strain compared to wt strain, are not the results of increased intracellular concentration of azoles in the pdr16Δ cells. We also show that overexpression of PDR17 complemented the azole susceptible phenotype of the pdr16Δ strain and corrected the enhanced sterol alterations in pdr16Δ cells in the presence of azoles. Pdr17p was found previously to be an essential part of a complex required for intermembrane transport of phosphatidylserine at regions of membrane apposition. Based on these observations, we propose a hypothesis that Pdr16p assists in shuttling sterols or their intermediates between membranes or, alternatively, between sterol biosynthetic enzymes or complexes. Copyright © 2013 John Wiley & Sons, Ltd.

Raltegravir cerebrospinal fluid concentrations in HIV-1 infection.

Directory of Open Access Journals (Sweden)

Aylin Yilmaz

2009-09-01

Full Text Available Raltegravir is an HIV-1 integrase inhibitor currently used in treatment-experienced HIV-1-infected patients resistant to other drug classes. In order to assess its central nervous system penetration, we measured raltegravir concentrations in cerebrospinal fluid (CSF and plasma in subjects receiving antiretroviral treatment regimens containing this drug.Raltegravir concentrations were determined by liquid chromatography tandem mass spectrometry in 25 paired CSF and plasma samples from 16 HIV-1-infected individuals. The lower limit of quantitation was 2.0 ng/ml for CSF and 10 ng/ml for plasma.Twenty-four of the 25 CSF samples had detectable raltegravir concentrations with a median raltegravir concentration of 18.4 ng/ml (range, <2.0-126.0. The median plasma raltegravir concentration was 448 ng/ml (range, 37-5180. CSF raltegravir concentrations correlated with CSF:plasma albumin ratios and CSF albumin concentrations.Approximately 50% of the CSF specimens exceeded the IC(95 levels reported to inhibit HIV-1 strains without resistance to integrase inhibitors. In addition to contributing to control of systemic HIV-1 infection, raltegravir achieves local inhibitory concentrations in CSF in most, but not all, patients. Blood-brain and blood-CSF barriers likely restrict drug entry, while enhanced permeability of these barriers enhances drug entry.

Raltegravir cerebrospinal fluid concentrations in HIV-1 infection.

Science.gov (United States)

Yilmaz, Aylin; Gisslén, Magnus; Spudich, Serena; Lee, Evelyn; Jayewardene, Anura; Aweeka, Francesca; Price, Richard W

2009-09-01

Raltegravir is an HIV-1 integrase inhibitor currently used in treatment-experienced HIV-1-infected patients resistant to other drug classes. In order to assess its central nervous system penetration, we measured raltegravir concentrations in cerebrospinal fluid (CSF) and plasma in subjects receiving antiretroviral treatment regimens containing this drug. Raltegravir concentrations were determined by liquid chromatography tandem mass spectrometry in 25 paired CSF and plasma samples from 16 HIV-1-infected individuals. The lower limit of quantitation was 2.0 ng/ml for CSF and 10 ng/ml for plasma. Twenty-four of the 25 CSF samples had detectable raltegravir concentrations with a median raltegravir concentration of 18.4 ng/ml (range, <2.0-126.0). The median plasma raltegravir concentration was 448 ng/ml (range, 37-5180). CSF raltegravir concentrations correlated with CSF:plasma albumin ratios and CSF albumin concentrations. Approximately 50% of the CSF specimens exceeded the IC(95) levels reported to inhibit HIV-1 strains without resistance to integrase inhibitors. In addition to contributing to control of systemic HIV-1 infection, raltegravir achieves local inhibitory concentrations in CSF in most, but not all, patients. Blood-brain and blood-CSF barriers likely restrict drug entry, while enhanced permeability of these barriers enhances drug entry.

Response of Bacillus cereus ATCC 14579 to challenges with sublethal concentrations of enterocin AS-48

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Gálvez Antonio

2009-10-01

Full Text Available Abstract Background Enterocin AS-48 is produced by Enterococcus faecalis S48 to compete with other bacteria in their environment. Due to its activity against various Gram positive and some Gram negative bacteria it has clear potential for use as a food preservative. Here, we studied the effect of enterocin AS-48 challenges on vegetative cells of Bacillus cereus ATCC 14579 by use of transcriptome analysis. Results Of the 5200 genes analysed, expression of 24 genes was found to change significantly after a 30 min treatment with a subinhibitory bacteriocin concentration of 0.5 μg/ml. Most of up-regulated genes encode membrane-associated or secreted proteins with putative transmembrane segments or signal sequences, respectively. One operon involved in arginine metabolism was significantly downregulated. The BC4206-BC4207 operon was found to be the most upregulated target in our experiments. BC4206 codes for a PadR type transcriptional regulator, while BC4207 codes for a hypothetical membrane protein. The operon structure and genes are conserved in B. cereus and B. thuringiensis species, but are not present in B. anthracis and B. subtilis. Using real-time qPCR, we show that these genes are upregulated when we treated the cells with AS-48, but not upon nisin treatment. Upon overexpression of BC4207 in B. cereus, we observed an increased resistance against AS-48. Expression of BC4207 in B. subtilis 168, which lacks this operon also showed increased resistance against AS-48. Conclusion BC4207 membrane protein is involved in the resistance mechanism of B. cereus cells against AS-48.

Polyphenol-Rich Extract from Propolis Reduces the Expression and Activity of Streptococcus mutans Glucosyltransferases at Subinhibitory Concentrations

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Jorge Jesús Veloz

2016-01-01

Full Text Available Tooth decay is an infectious disease, whose main causative agent identified is Streptococcus mutans (S. mutans. Diverse treatments have been used to eradicate this microorganism, including propolis. To date, it has been shown that polyphenols from Chilean propolis inhibit S. mutans growth and biofilm formation. However, the molecular mechanisms underlying this process are unclear. In the present study, we assessed the effect of Chilean propolis on the expression and activity of the glycosyltransferases enzymes and their related genes. Polyphenol-rich extract from propolis inhibited gene expression of glycosyltransferases (GtfB, GtfC, and GtfD and their related regulatory genes, for example, VicK, VicR, and CcpA. Moreover, the treatment inhibited glucosyltransferases activity measured by the formation of sucrose-derived glucans. Additionally, an inhibitory effect was observed in the expression of SpaP involved in sucrose-independent virulence of S. mutans. In summary, our results suggest that Chilean propolis has a dose-dependent effect on the inhibition of genes involved in S. mutans virulence and adherence through the inhibition of glucosyltransferases, showing an anticariogenic potential of polyphenols from propolis beyond S. mutans growth inhibition.

Subinhibitory Concentrations of Bacteriostatic Antibiotics Induce relA-Dependent and relA-Independent Tolerance to beta-Lactams

Czech Academy of Sciences Publication Activity Database

Kudrin, P.; Varik, V.; Oliveira, S. R. A.; Beljantseva, J.; Del Peso Santos, T.; Dzhygyr, I.; Rejman, Dominik; Cava, F.; Tenson, T.; Hauryliuk, V.

2017-01-01

Roč. 61, č. 4 (2017), č. článku e02173-16. ISSN 0066-4804 R&D Projects: GA ČR GA15-11711S Institutional support: RVO:61388963 Keywords : beta-lactam * RelA * antibiotics * mupirocin * persistence * ppGpp Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.302, year: 2016 http://aac.asm.org/content/61/4/e02173-16.full

Enhancement of gold recovery using bioleaching from gold concentrate

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Choi, S. H.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

2012-04-01

The gold in refractory ores is encapsulated as fine particles (sometimes at a molecular level) in the crystal structure of the sulfide (typically pyrite with or without arsenopyrite) matrix. This makes it impossible to extract a significant amount of refractory gold by cyanidation since the cyanide solution cannot penetrate the pyrite/arsenopyrite crystals and dissolve gold particles, even after fine grinding. To effectively extract gold from these ores, an oxidative pretreatment is necessary to break down the sulfide matrix. The most popular methods of pretreatment include nitric acid oxidation, roasting, pressure oxidation and biological oxidation by microorganisms. This study investigated the bioleaching efficiency of Au concentrate under batch experimental conditions (adaptation cycles and chemical composition adaptation) using the indigenous acidophilic bacteria collected from gold mine leachate in Sunsin gold mine, Korea. We conducted the batch experiments at two different chemical composition (CuSO4 and ZnSO4), two different adaptation cycles 1'st (3 weeks) and 2'nd (6 weeks). The results showed that the pH in the bacteria inoculating sample decreased than initial condition and Eh increased. In the chemical composition adaptation case, the leached accumulation content of Fe and Pb was exhibited in CuSO4 adaptation bacteria sample more than in ZnSO4 adaptation bacteria samples, possibly due to pre-adaptation effect on chalcopyrite (CuFeS2) in gold concentrate. And after 21 days on the CuSO4 adaptation cycles case, content of Fe and Pb was appeared at 1'st adaptation bacteria sample(Fe - 1.82 and Pb - 25.81 times per control sample) lower than at 2'nd adaptation bacteria sample(Fe - 2.87 and Pb - 62.05 times per control sample). This study indicates that adaptation chemical composition and adaptation cycles can play an important role in bioleaching of gold concentrate in eco-/economic metallurgy process.

Cerium enhances germination and shoot growth, and alters mineral nutrient concentration in rice

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García-Morales, Soledad; Pérez-Sato, Juan Antonio

2018-01-01

Cerium (Ce) belongs to the rare earth elements (REEs), and although it is not essential for plants, it can stimulate growth and other physiological processes. The objective of this research was to evaluate the effect of Ce on seed germination, initial seedling growth, and vegetative growth in rice (Oryza sativa L.) cv. Morelos A-98. During the germination process, the seeds were treated with Ce concentrations of 0, 4, 8, and 12 μM; after 5 d, germination percentage was recorded and after 10 d seedling growth was measured. For vegetative growth, a hydroponic system was established where 14-d-old plants without previous Ce treatment were transferred into nutrient solution. After two weeks of acclimatizing, 0, 25, 50, and 100 μM Ce were added to the nutrient solution for 28 d. Ce significantly increased germination and the initial growth variables of the seedlings. During vegetative growth, Ce increased plant height, number of tillers, root volume, and shoot fresh and dry biomass, without affecting root biomass weight. With low Ce concentrations (25 and 50 μM), the concentrations of chlorophylls and amino acids in the shoots were similar to those in the control, like amino acid concentration in the roots at a concentration of 25 μM Ce. Conversely, the concentration of total sugars increased in the shoot with the application of 25, 50, and 100 μM Ce, and in the roots with the application of 50 μM Ce. Also, Ce did not affect the concentration of macro or micronutrients in the shoots. However, in the roots, the high Ce concentration decreased the concentrations of Ca, Fe, Mn, and Zn, while the Mg concentration increased. Our results indicate that Ce, at the right concentrations, can function as a biostimulant in rice germination and growth. PMID:29579100

Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: a two-dimensional flow cell study

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Wu, Bin; Li, Huiying; Du, Xiaoming; Zhong, Lirong; Yang, Bin; Du, Ping; Gu, Qingbao; Li, Fasheng

2016-02-01

During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significant positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.

Enhancement of antioxidant activity and physicochemical properties of yogurt enriched with concentrated strawberry pulp obtained by block freeze concentration.

Science.gov (United States)

Jaster, Henrique; Arend, Giordana Demaman; Rezzadori, Katia; Chaves, Vitor Clasen; Reginatto, Flávio Henrique; Petrus, José Carlos Cunha

2018-02-01

Strawberry juice was concentrated using block freeze concentration process. The concentrate was used to produce two yogurts with different concentrations of cryoconcentrated strawberry pulp (15% and 30%). Total lactic acid bacteria count, physicochemical and rheological properties was evaluated during storage (7days) for all yogurts. Also, the beverages produced were compared with two commercial trademarks. It was observed that the total lactic acid bacteria count remained higher than 10 8 CFU·mL -1 during the storage time for all beverages studied. The viscosity of the yogurts decreased when the ratio of strawberry cryoconcentrate was increased. The Power Law model was successfully applied to describe the flow of the yogurts, which had a thixotropic behaviour. The incorporation of the cryoconcentrated strawberry pulp in the yogurt resulted in a product with 3-fold more anthocyanins content and antioxidant activity. The enrichment of natural yogurt with strawberry cryoconcentrated pulp proved to be effective in the production of a beverage with higher nutritional characteristics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancement of BDNF Concentration and Restoration of the Hypothalamic-Pituitary-Adrenal Axis Accompany Reduced Depressive-Like Behaviour in Stressed Ovariectomised Rats Treated with Either Tualang Honey or Estrogen

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Badriya Al-Rahbi

2014-01-01

Full Text Available A possible interaction between glucocorticoids and estrogen-induced increases in brain-derived-neurotrophic factor (BDNF expression in enhancing depressive-like behaviour has been documented. Here we evaluated the effects of Tualang honey, a phytoestrogen, and 17β-estradiol (E2 on the depressive-like behaviour, stress hormones, and BDNF concentration in stressed ovariectomised (OVX rats. The animals were divided into six groups: (i nonstressed sham-operated control, (ii stressed sham-operated control, (iii nonstressed OVX, (iv stressed OVX, (v stressed OVX treated with E2 (20 μg daily, sc, and (vi stressed OVX treated with Tualang honey (0.2 g/kg body weight daily, orally. Two months after surgery, the animals were subjected to social instability stress procedure followed by forced swimming test. Struggling time, immobility time, and swimming time were scored. Serum adrenocorticotropic hormone (ACTH and corticosterone levels, and the BDNF concentration were determined using commercially available ELISA kits. Stressed OVX rats displayed increased depressive-like behaviour with significantly increased serum ACTH and corticosterone levels, while the BDNF concentration was significantly decreased compared to other experimental groups. These changes were notably reversed by both E2 and Tualang honey. In conclusion, both Tualang honey and E2 mediate antidepressive-like effects in stressed OVX rats, possibly acting via restoration of hypothalamic-pituitary-adrenal axis and enhancement of the BDNF concentration.

Porous Silicon Covered with Silver Nanoparticles as Surface-Enhanced Raman Scattering (SERS) Substrate for Ultra-Low Concentration Detection.

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Kosović, Marin; Balarin, Maja; Ivanda, Mile; Đerek, Vedran; Marciuš, Marijan; Ristić, Mira; Gamulin, Ozren

2015-12-01

Microporous and macro-mesoporous silicon templates for surface-enhanced Raman scattering (SERS) substrates were produced by anodization of low doped p-type silicon wafers. By immersion plating in AgNO3, the templates were covered with silver metallic film consisting of different silver nanostructures. Scanning electron microscopy (SEM) micrographs of these SERS substrates showed diverse morphology with significant difference in an average size and size distribution of silver nanoparticles. Ultraviolet-visible-near-infrared (UV-Vis-NIR) reflection spectroscopy showed plasmonic absorption at 398 and 469 nm, which is in accordance with the SEM findings. The activity of the SERS substrates was tested using rhodamine 6G (R6G) dye molecules and 514.5 nm laser excitation. Contrary to the microporous silicon template, the SERS substrate prepared from macro-mesoporous silicon template showed significantly broader size distribution of irregular silver nanoparticles as well as localized surface plasmon resonance closer to excitation laser wavelength. Such silver morphology has high SERS sensitivity that enables ultralow concentration detection of R6G dye molecules up to 10(-15) M. To our knowledge, this is the lowest concentration detected of R6G dye molecules on porous silicon-based SERS substrates, which might even indicate possible single molecule detection.

The potentiation effect makes the difference: Non-toxic concentrations of ZnO nanoparticles enhance Cu nanoparticle toxicity in vitro

Energy Technology Data Exchange (ETDEWEB)

Li, Lingxiangyu [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Fernández-Cruz, María Luisa; Connolly, Mona [Departamento de Medio Ambiente, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid 28040 (Spain); Conde, Estefanía; Fernández, Marta [Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid 28040 (Spain); Schuster, Michael [Department of Chemistry, Technische Universität München, Garching 85747 (Germany); Navas, José María, E-mail: jmnavas@inia.es [Departamento de Medio Ambiente, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid 28040 (Spain)

2015-02-01

Here we examined whether the addition of a non-toxic concentration (6.25 μg/mL) of zinc oxide nanoparticles (ZnONPs: 19, 35 and 57 nm, respectively) modulates the cytotoxicity of copper nanoparticles (CuNPs, 63 nm in size) in the human hepatoma cell line HepG2. The cytotoxic effect of CuNPs on HepG2 cells was markedly enhanced by the ZnONPs, the largest ZnONPs causing the highest increase in toxicity. However, CuNPs cytotoxicity was not affected by co-incubation with medium containing only zinc ions, indicating the increase in toxicity might be attributed to the particle form of ZnONPs. Transmission electron microscopy (TEM) revealed the presence of CuNPs and ZnONPs inside the cells co-exposed to both types of NP and outflow of cytoplasm through the damaged cell membrane. Inductively coupled plasma mass spectrometry (ICP-MS) determined an increase in the concentration of zinc and a decrease in that of copper in co-exposed cells. On the basis of these results, we propose that accumulation of large numbers of ZnONPs in the cells alters cellular membranes and the cytotoxicity of CuNPs is increased. - Highlights: • ZnONPs at non-toxic concentrations increased the toxicity of CuNPs in vitro. • ZnONPs of larger size provoked a stronger synergistic effect with CuNPs. • The synergistic effect was attributed to the particle fraction of ZnONPs.

Surfactant-enhanced flushing enhances colloid transport and alters macroporosity in diesel-contaminated soil.

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Guan, Zhuo; Tang, Xiang-Yu; Nishimura, Taku; Katou, Hidetaka; Liu, Hui-Yun; Qing, Jing

2018-02-01

Soil contamination by diesel has been often reported as a result of accidental spillage, leakage and inappropriate use. Surfactant-enhanced soil flushing is a common remediation technique for soils contaminated by hydrophobic organic chemicals. In this study, soil flushing with linear alkylbenzene sulfonates (LAS, an anionic surfactant) was conducted for intact columns (15cm in diameter and 12cm in length) of diesel-contaminated farmland purple soil aged for one year in the field. Dynamics of colloid concentration in column outflow during flushing, diesel removal rate and resulting soil macroporosity change by flushing were analyzed. Removal rate of n-alkanes (representing the diesel) varied with the depth of the topsoil in the range of 14%-96% while the n-alkanes present at low concentrations in the subsoil were completely removed by LAS-enhanced flushing. Much higher colloid concentrations and larger colloid sizes were observed during LAS flushing in column outflow compared to water flushing. The X-ray micro-computed tomography analysis of flushed and unflushed soil cores showed that the proportion of fine macropores (30-250μm in diameter) was reduced significantly by LAS flushing treatment. This phenomenon can be attributed to enhanced clogging of fine macropores by colloids which exhibited higher concentration due to better dispersion by LAS. It can be inferred from this study that the application of LAS-enhanced flushing technique in the purple soil region should be cautious regarding the possibility of rapid colloid-associated contaminant transport via preferential pathways in the subsurface and the clogging of water-conducting soil pores. Copyright © 2017. Published by Elsevier B.V.

Isonicotinamide Enhances Sir2 Protein-mediated Silencing and Longevity in Yeast by Raising Intracellular NAD+ Concentration*

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McClure, Julie M.; Wierman, Margaret B.; Maqani, Nazif; Smith, Jeffrey S.

2012-01-01

Sirtuins are an evolutionarily conserved family of NAD+-dependent protein deacetylases that function in the regulation of gene transcription, cellular metabolism, and aging. Their activity requires the maintenance of an adequate intracellular NAD+ concentration through the combined action of NAD+ biosynthesis and salvage pathways. Nicotinamide (NAM) is a key NAD+ precursor that is also a byproduct and feedback inhibitor of the deacetylation reaction. In Saccharomyces cerevisiae, the nicotinamidase Pnc1 converts NAM to nicotinic acid (NA), which is then used as a substrate by the NAD+ salvage pathway enzyme NA phosphoribosyltransferase (Npt1). Isonicotinamide (INAM) is an isostere of NAM that stimulates yeast Sir2 deacetylase activity in vitro by alleviating the NAM inhibition. In this study, we determined that INAM stimulates Sir2 through an additional mechanism in vivo, which involves elevation of the intracellular NAD+ concentration. INAM enhanced normal silencing at the rDNA locus but only partially suppressed the silencing defects of an npt1Δ mutant. Yeast cells grown in media lacking NA had a short replicative life span, which was extended by INAM in a SIR2-dependent manner and correlated with increased NAD+. The INAM-induced increase in NAD+ was strongly dependent on Pnc1 and Npt1, suggesting that INAM increases flux through the NAD+ salvage pathway. Part of this effect was mediated by the NR salvage pathways, which generate NAM as a product and require Pnc1 to produce NAD+. We also provide evidence suggesting that INAM influences the expression of multiple NAD+ biosynthesis and salvage pathways to promote homeostasis during stationary phase. PMID:22539348

Isonicotinamide enhances Sir2 protein-mediated silencing and longevity in yeast by raising intracellular NAD+ concentration.

Science.gov (United States)

McClure, Julie M; Wierman, Margaret B; Maqani, Nazif; Smith, Jeffrey S

2012-06-15

Sirtuins are an evolutionarily conserved family of NAD(+)-dependent protein deacetylases that function in the regulation of gene transcription, cellular metabolism, and aging. Their activity requires the maintenance of an adequate intracellular NAD(+) concentration through the combined action of NAD(+) biosynthesis and salvage pathways. Nicotinamide (NAM) is a key NAD(+) precursor that is also a byproduct and feedback inhibitor of the deacetylation reaction. In Saccharomyces cerevisiae, the nicotinamidase Pnc1 converts NAM to nicotinic acid (NA), which is then used as a substrate by the NAD(+) salvage pathway enzyme NA phosphoribosyltransferase (Npt1). Isonicotinamide (INAM) is an isostere of NAM that stimulates yeast Sir2 deacetylase activity in vitro by alleviating the NAM inhibition. In this study, we determined that INAM stimulates Sir2 through an additional mechanism in vivo, which involves elevation of the intracellular NAD(+) concentration. INAM enhanced normal silencing at the rDNA locus but only partially suppressed the silencing defects of an npt1Δ mutant. Yeast cells grown in media lacking NA had a short replicative life span, which was extended by INAM in a SIR2-dependent manner and correlated with increased NAD(+). The INAM-induced increase in NAD(+) was strongly dependent on Pnc1 and Npt1, suggesting that INAM increases flux through the NAD(+) salvage pathway. Part of this effect was mediated by the NR salvage pathways, which generate NAM as a product and require Pnc1 to produce NAD(+). We also provide evidence suggesting that INAM influences the expression of multiple NAD(+) biosynthesis and salvage pathways to promote homeostasis during stationary phase.

PgTeL, the lectin found in Punica granatum juice, is an antifungal agent against Candida albicans and Candida krusei.

Science.gov (United States)

da Silva, Pollyanna Michelle; de Moura, Maiara Celine; Gomes, Francis Soares; da Silva Trentin, Danielle; Silva de Oliveira, Ana Patrícia; de Mello, Gabriela Souto Vieira; da Rocha Pitta, Maira Galdino; de Melo Rego, Moacyr Jesus Barreto; Coelho, Luana Cassandra Breitenbach Barroso; Macedo, Alexandre José; de Figueiredo, Regina Celia Bressan Queiroz; Paiva, Patrícia Maria Guedes; Napoleão, Thiago Henrique

2018-03-01

The pomegranate (Punica granatum) sarcotesta contains a chitin-binding lectin (PgTeL) with antibacterial activity against human pathogenic species. In this work, the structural stability of PgTeL was evaluated by fluorimetric analysis and the lectin was evaluated for cytotoxicity to human peripheral blood mononuclear cells (PBMCs) and antifungal activity against Candida albicans and Candida krusei. PgTeL folding was impaired when lectin was incubated at pH≥6.0. On the other hand, the lectin did not undergo unfolding even when heated at 100°C. PgTeL (1, 10, and 100μg/mL) was not cytotoxic to PBMCs. Antifungal activity was detected for C. albicans (MIC: 25μg/mL; MFC: 50μg/mL) and C. krusei (MIC and MFC of 12.5μg/mL). Treatment of yeast cells with PgTeL resulted in decrease of intracellular ATP content even at sub-inhibitory concentrations (½MIC and ¼MIC) and induced lipid peroxidation. In addition, PgTeL damaged the integrity of fungal cell wall of both species, with more pronounced effects in C. krusei. The lectin showed significant antibiofilm activity on C. albicans at sub-inhibitory concentrations (0.195 and 0.39μg/mL). In conclusion, PgTeL is an anti-Candida agent whose action mechanism involves oxidative stress, energetic collapse, damage to the cell wall and rupture of yeast cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced Temperature During Grain Filling Reduces Protein Concentration of Durum Wheat

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Franco Miglietta

2011-02-01

Full Text Available Durum wheat is cultivated over more than 13 millions of hectares (ha world wide and Italy is the main European producer with 3.5 millions tons per year. The protein concentration of durum wheat is very important, it ensures high nutritional value and is highly appreciated by the pasta production industries. The protein concentration of wheat is determined during the grain filling period when carbon and nitrogen compounds are translocated into the grains. Air temperature affects translocation rates and contributes to final protein concentration of wheat grains. Two common commercial varieties of durum and bread wheat were exposed from anthesis to harvest, to a source of infrared radiation in the field. This allowed to investigate the relative effect of temperature on translocation of carbon and nitrogen compound during grain filling. The heat treatment imposed affected marginally dry mass accumulation of the grains in bread wheat and didn’t affect dry mass in durum wheat. Grain protein was affected by heat treatment in durum but not in bread wheat. Carbon accumulation rate was higher for durum than for bread wheat. The protein concentration was greater in durum than in bread wheat and we can assume that the absolute nitrogen accumulation rates were higher for the former species. Such difference may be either caused by a faster nitrogen uptake rate and translocation or a more efficient relocation of nitrogen accumulated in reserve organs.

Use of β-caryophyllene to combat bacterial dental plaque formation in dogs.

Science.gov (United States)

Pieri, Fábio Alessandro; Souza, Marina Campos de Castro; Vermelho, Ligia Lobato Ramos; Vermelho, Marina Lobato Ramos; Perciano, Pedro Griffo; Vargas, Fabiano Souza; Borges, Andréa Pacheco Batista; da Veiga-Junior, Valdir Florêncio; Moreira, Maria Aparecida Scatamburlo

2016-10-01

Periodontal disease is a highly prevalent illness that affects many dogs, reaching up to 85 % prevalence in individuals over the age of 4 years. Currently the drug of choice for combating the formation of dental plaque in these animals, the etiologic agent of the disease, is chlorhexidine, which has several side effects reported. Thus, surveys are conducted throughout the world in order to identify potential substitutes for antimicrobial therapy and prevention of periodontal disease. The objective of the work was to evaluate the antimicrobial activity of β-caryophyllene against bacteria from dog's dental plaque in vitro and in vivo. The minimum inhibitory concentration was evaluated by agar microdilution assay, the induction or inhibition of bacterial adherence by sub-inhibitory concentrations in 96-well plates, and reduction of dental plaque formation in mongrel dogs subjected to topical solution with β-caryophyllene for 15 days. Results showed minimum inhibitory concentrations above 100 mg/mL for 25 % of the isolates, 100 mg/mL for 3 %, 50 mg/mL for 25 %, 25 mg/mL for 12 %, 12.5 mg/mL for 19 % and 6.25 mg/mL for 16 %. Bacterial adherences of three Enterococcus sp., one Streptococcus sp., one Haemophilus sp., one Aerococcus sp., one Bacillus sp. and one Lactococcus sp. isolates were inhibited by subinhibitory concentration. One Lactococcus sp., one Bacillus sp. and one Streptococcus sp. were stimulated to adhere by concentrations of 0.19, 1.56 and 0.78 mg/mL, respectively. In vivo assay showed reduction in dental plaque formation by β-caryophyllene, with final plaque coverage of 23.3 ± 2.6 % of the total area of the teeth, with significant difference compared with chlorhexidine group (37.5 ± 3.7 % - p dog's dental plaque-forming bacteria representing a suitable alternative to the use of chlorhexidine in prophylaxis and treatment of periodontal disease of dogs.

Effect of high calcium concentration influents on enhanced biological phosphorus removal process

International Nuclear Information System (INIS)

Montoya Martinez, T.; Aguado Garcia, D.; Ferrer Polo, J.

2010-01-01

In this work, the effect of calcium concentration in wastewater on the polyphosphate accumulating organisms (PAO) is investigated as well as its influence in PAO metabolism, specifically in the Y P O4 (ratio between phosphorus release and acetic acid uptake). For this study a sequencing batch reactor (SBR) anaerobic-aerobic was used, in which the PAO enriched biomass was exposed to different calcium concentrations in the influent wastewater. The results indicate that until a given calcium level in the influent wastewater (35 mg Ca/l) the metabolism is not affect, but higher calcium concentrations lead to significant Y P O4 decline. (Author) 18 refs.

Carbon-concentrating mechanisms in seagrasses.

Science.gov (United States)

Larkum, Anthony William D; Davey, Peter A; Kuo, John; Ralph, Peter J; Raven, John A

2017-06-01

Seagrasses are unique angiosperms that carry out growth and reproduction submerged in seawater. They occur in at least three families of the Alismatales. All have chloroplasts mainly in the cells of the epidermis. Living in seawater, the supply of inorganic carbon (Ci) to the chloroplasts is diffusion limited, especially under unstirred conditions. Therefore, the supply of CO2 and bicarbonate across the diffusive boundary layer on the outer side of the epidermis is often a limiting factor. Here we discuss the evidence for mechanisms that enhance the uptake of Ci into the epidermal cells. Since bicarbonate is plentiful in seawater, a bicarbonate pump might be expected; however, the evidence for such a pump is not strongly supported. There is evidence for a carbonic anhydrase outside the outer plasmalemma. This, together with evidence for an outward proton pump, suggests the possibility that local acidification leads to enhanced concentrations of CO2 adjacent to the outer tangential epidermal walls, which enhances the uptake of CO2, and this could be followed by a carbon-concentrating mechanism (CCM) in the cytoplasm and/or chloroplasts. The lines of evidence for such an epidermal CCM are discussed, including evidence for special 'transfer cells' in some but not all seagrass leaves in the tangential inner walls of the epidermal cells. It is concluded that seagrasses have a CCM but that the case for concentration of CO2 at the site of Rubisco carboxylation is not proven. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Radiochromic film dosimetry of contrast-enhanced radiotherapy (CERT)

International Nuclear Information System (INIS)

Morris, Kevin N; Weil, Michael D; Malzbender, Rainer

2006-01-01

Contrast-enhanced radiotherapy (CERT) employs elevated concentrations of high-Z contrast media in targets to dramatically increase the absorbed dose of radiation relative to the surrounding tissues. However, it is difficult to measure the dose enhancement with routine clinical instruments because the photoelectrons and Auger electrons produced by the interaction of kilovoltage x-rays with the contrast agent travel extremely short distances. We have developed a technique utilizing unlaminated radiochromic film to measure the maximum dose enhancement factor attainable in solutions of contrast agent with iodine concentrations ranging from 0% to 37% (w/v). The films were also used to simultaneously measure the dose enhancement and beam attenuation through solutions containing 0%, 5% and 10% iodine (w/v). These depth-dose measurements were made in phantoms representing 3 cm targets located 0 and 4.8 cm deep in acrylic. Higher concentrations of contrast yielded greater dose enhancement and target-to-surface dose ratios, but caused more rapid attenuation of the beam as it traversed the target. The dose distribution across the entire target could be improved by employing multiple beams. These results, using concentrations of contrast that are clinically achievable by intratumoural injection, illustrate the potential of CERT for the specific delivery of high doses of radiation to targets at depth

Effects of Al concentrations on the microstructure and mechanical properties of Ti–Al–N films deposited by RF-ICPIS enhanced magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Li, Dongke [The School of Physics and Telecommunication Engineering, SCNU, Guangzhou 510000 (China); Chen, JunFang, E-mail: chenjf@scnu.edu.com [The School of Physics and Telecommunication Engineering, SCNU, Guangzhou 510000 (China); Research Resources Center, SCNU, Guangzhou 510000 (China); Zou, Changwei, E-mail: qingyihaiyanas@163.com [Department of Physics and Development Center for New Materials Engineering and Technology in University of Guangdong, Zhanjiang Normal University, Zhanjiang 524048 (China); Ma, Junhui; Li, Pengfei; Li, Ye [The School of Physics and Telecommunication Engineering, SCNU, Guangzhou 510000 (China)

2014-10-01

Highlights: • RF-ICPIS enhanced magnetron sputtering technique is used for Ti–Al–N deposition. • Al contents has closed relation with total gas pressure. • Ti–Al–N films with high Al contents of 34.16 at.% are obtained. • Effects of Al on the microstructure and mechanical properties are discussed. - Abstract: Ti–Al–N films were deposited on Si (1 0 0) and mirror-polished stainless steel at 300 °C by RF-ICPIS enhanced magnetron sputtering technique. Focusing on the effects of Al concentrations on the microstructure and mechanical properties of Ti–Al–N films, the structure and the growth morphology were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). Ti–Al–N films with highest Al contents of were deposited at total gas pressure of 1.0 Pa. XRD experiments exhibited that the Ti–Al–N films were f.c.c structure with diffraction peaks at 2θ = 37.1°, 43.5°, 63.2°, and 75.1°, respectively. The FWHM values of (1 1 1) diffraction peaks showed a decrease while the (2 2 0) diffraction peaks showed an increase trend with the increasing of Al concentrations. With the variation of total gas pressure from 0.5 to 1.5 Pa, the RMS values of Ti–Al–N films increased from 1.286 to 7.751 nm. The hardness of the Ti–Al–N films was in the range of 28.4–36.2 GPa while the friction coefficients were in the range of 0.339–0.732.

Subinhibitory concentrations of fluconazole increase the intracellular sodium content in both fluconazole-resistant and -sensitive Candida albicans strains

Czech Academy of Sciences Publication Activity Database

Kolecká, A.; Krauke, Yannick; Bujdáková, H.; Sychrová, Hana

2009-01-01

Roč. 55, č. 5 (2009), s. 605-610 ISSN 0008-4166 R&D Projects: GA MŠk(CZ) LC531 Grant - others:EC(XE) MRTN-CT-2004-512481 Institutional research plan: CEZ:AV0Z50110509 Keywords : Candida albicans * fluconazol * salt tolerance Subject RIV: EE - Microbiology, Virology Impact factor: 1.262, year: 2009

Paper-based microfluidic approach for surface-enhanced raman spectroscopy and highly reproducible detection of proteins beyond picomolar concentration.

Science.gov (United States)

Saha, Arindam; Jana, Nikhil R

2015-01-14

Although microfluidic approach is widely used in various point of care diagnostics, its implementation in surface enhanced Raman spectroscopy (SERS)-based detection is challenging. This is because SERS signal depends on plasmonic nanoparticle aggregation induced generation of stable electromagnetic hot spots and in currently available microfluidic platform this condition is difficult to adapt. Here we show that SERS can be adapted using simple paper based microfluidic system where both the plasmonic nanomaterials and analyte are used in mobile phase. This approach allows analyte induced controlled particle aggregation and electromagnetic hot spot generation inside the microfluidic channel with the resultant SERS signal, which is highly reproducible and sensitive. This approach has been used for reproducible detection of protein in the pico to femtomolar concentration. Presented approach is simple, rapid, and cost-effective, and requires low sample volume. Method can be extended for SERS-based detection of other biomolecules.

Effect of paracentesis on ocular cloxacillin concentration

International Nuclear Information System (INIS)

Salminen, L.

1978-01-01

The effect of interior chamber puncture on cloxacillin concentration in the rabbit eye after intravenous injection was studied using a radioactive tracer method. The enhancement in drug concentration caused by paracentesis was most immediate and significant in the iris-ciliary body preparation. It was soon followed by high cloxacillin concentration in the aqueous humour, which contributed to elevated cloxacillin levels in the cornea, lens and anterior vitreous body, when compared to normal material. Contrary to normal eyes, cloxacillin concentration in the cornea of the punctured eyes was higher than in the limbal area. The morphological changes occurring after paracentesis are discussed. The breakdown of the hydrodynamic equilibrium in the eye, suggested as the only change after paracentesis by Raviola (1974), cannot merely explain the cloxacillin concentration changes measured in the punctured eye. (author)

Changes in power and force generation during coupled eccentric-concentric versus concentric muscle contraction with training and aging

DEFF Research Database (Denmark)

Caserotti, Paolo; Aagaard, Per; Puggaard, Lis

2008-01-01

Age-related decline in maximal concentric muscle power is associated with frailty and functional impairments in the elderly. Compared to concentric contraction, mechanical muscle output is generally enhanced when muscles are rapidly pre-stretched (eccentric contraction), albeit less pronounced...... with increasing age. Exercise has been recommended to prevent loss of muscle power and function and recent guidelines indicate training program for increasing muscle power highly relevant for elderly subjects. This study examined the differences in muscle power, force and movement pattern during concentric......) and JH increased in training group (P age-related decline in muscle power and functional performance observed in the control subjects, while substantial gains...

Boeravinone B, A Novel Dual Inhibitor of NorA Bacterial Efflux Pump of Staphylococcus aureus and Human P-Glycoprotein, Reduces the Biofilm Formation and Intracellular Invasion of Bacteria.

Science.gov (United States)

Singh, Samsher; Kalia, Nitin P; Joshi, Prashant; Kumar, Ajay; Sharma, Parduman R; Kumar, Ashok; Bharate, Sandip B; Khan, Inshad A

2017-01-01

This study elucidated the role of boeravinone B, a NorA multidrug efflux pump inhibitor, in biofilm inhibition. The effects of boeravinone B plus ciprofloxacin, a NorA substrate, were evaluated in NorA-overexpressing, wild-type, and knocked-out Staphylococcus aureus (SA-1199B, SA-1199, and SA-K1758, respectively). The mechanism of action was confirmed using the ethidium bromide accumulation and efflux assay. The role of boeravinone B as a human P -glycoprotein ( P -gp) inhibitor was examined in the LS-180 (colon cancer) cell line. Moreover, its role in the inhibition of biofilm formation and intracellular invasion of S. aureus in macrophages was studied. Boeravinone B reduced the minimum inhibitory concentration (MIC) of ciprofloxacin against S. aureus and its methicillin-resistant strains; the effect was stronger in SA-1199B. Furthermore, time-kill kinetics revealed that boeravinone B plus ciprofloxacin, at subinhibitory concentration (0.25 × MIC), is as equipotent as that at the MIC level. This combination also had a reduced mutation prevention concentration. Boeravinone B reduced the efflux of ethidium bromide and increased the accumulation, thus strengthening the role as a NorA inhibitor. Biofilm formation was reduced by four-eightfold of the minimal biofilm inhibitory concentration of ciprofloxacin, effectively preventing bacterial entry into macrophages. Boeravinone B effectively inhibited P -gp with half maximal inhibitory concentration (IC 50 ) of 64.85 μM. The study concluded that boeravinone B not only inhibits the NorA-mediated efflux of fluoroquinolones but also considerably inhibits the biofilm formation of S. aureus. Its P -gp inhibition activity demonstrates its potential as a bioavailability and bioefficacy enhancer.

Enhancing reproducibility of SALDI MS detection by concentrating analytes within laser spot.

Science.gov (United States)

Teng, Fei; Zhu, Qunyan; Wang, Yalei; Du, Juan; Lu, Nan

2018-03-01

Surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI TOF MS) has become one of the most important analytical methods due to its less interference at low molecular weight range. However, it is still a challenge to obtain a good reproducibility of SALDI TOF MS because of the inhomogeneous distribution of analyte molecules induced by coffee ring effect. We propose a universal and reliable method to eliminate the coffee ring effect by concentrating all the analyte molecules within the laser spot. This method exhibits an excellent reproducibility of spot-to-spot and substrate-to-substrate, and the relative standard deviations (RSDs) for different concentrations are lower than 12.6%. It also performs good linear dependency (R 2 > 0.98) in the log-log plot with the concentration range of 1nM to 1μM, and the limit of detection for R6G is down to 1fmol. Copyright © 2017 Elsevier B.V. All rights reserved.

Nonimaging optics in luminescent solar concentration.

Science.gov (United States)

Markman, B D; Ranade, R R; Giebink, N C

2012-09-10

Light trapped within luminescent solar concentrators (LSCs) is naturally limited in angular extent by the total internal reflection critical angle, θcrit, and hence the principles of nonimaging optics can be leveraged to increase LSC concentration ratio by appropriately reshaping the edges. Here, we use rigorous ray-tracing simulations to explore the potential of this concept for realistic LSCs with compound parabolic concentrator (CPC)-tapered edges and show that, when applied to a single edge, the concentration ratio is increased by 23% while maintaining >90% of the original LSC optical efficiency. Importantly, we find that CPC-tapering all of the edges enables a significantly greater intensity enhancement up to 35% at >90% of the original optical efficiency, effectively enabling two-dimensional concentration through a cooperative, ray-recycling effect in which rays rejected by one CPC are accepted by another. These results open up a significant opportunity to improve LSC performance at virtually no added manufacturing cost by incorporating nonimaging optics into their design.

Amphibian antimicrobial peptide fallaxin analogue FL9 affects virulence gene expression and DNA replication in Staphylococcus aureus

DEFF Research Database (Denmark)

Gottschalk, Sanne; Gottlieb, Caroline Trebbien; Vestergaard, Martin

2015-01-01

antimicrobials. In the present study, the analogue FL9, based on the amphibian AMP fallaxin, was studied to elucidate its mode of action and antibacterial activity against the human pathogen Staphylococcus aureus. Our data showed that FL9 may have a dual mode of action against S. aureus. At concentrations around...... and at alkaline pH, while it was compromised by acidic pH and exposure to serum. Furthermore, at subinhibitory concentrations of FL9, S. aureus responded by increasing the expression of two major virulence factor genes, namely the regulatory rnaIII and hla, encoding α-haemolysin. In addition, the S. aureus...... the MIC, FL9 bound DNA, inhibited DNA synthesis and induced the SOS DNA damage response, whereas at concentrations above the MIC the interaction between S. aureus and FL9 led to membrane disruption. The antibacterial activity of the peptide was maintained over a wide range of NaCl and MgCl2 concentrations...

Multiphase contrast-enhanced CT with highly concentrated contrast agent can be used for PET attenuation correction in integrated PET/CT imaging

International Nuclear Information System (INIS)

Aschoff, Philip; Plathow, Christian; Lichy, Matthias P.; Claussen, Claus D.; Pfannenberg, Christina; Beyer, Thomas; Erb, Gunter; Oeksuez, Mehmet Oe.

2012-01-01

State-of-the-art positron emission tomography/computed tomography (PET/CT) systems incorporate multislice CT technology, thus facilitating the acquisition of multiphase, contrast-enhanced CT data as part of integrated PET/CT imaging protocols. We assess the influence of a highly concentrated iodinated contrast medium (CM) on quantification and image quality following CT-based attenuation correction (CT-AC) in PET/CT. Twenty-eight patients with suspected malignant liver lesions were enrolled prospectively. PET/CT was performed 60 min after injection of 400 MBq of 18 F-fluorodeoxyglucose (FDG) and following the biphasic administration of an intravenous CM (400 mg iodine/ml, Iomeron 400). PET images were reconstructed with CT-AC using any of four acquired CT image sets: non-enhanced, pre-contrast (n-PET), arterial phase (art-PET), portal venous phase (pv-PET) and late phase (late-PET). Normal tissue activity and liver lesions were assessed visually and quantitatively on each PET/CT image set. Visual assessment of PET following CT-AC revealed no noticeable difference in image appearance or quality when using any of the four CT data sets for CT-AC. A total of 44 PET-positive liver lesions was identified in 21 of 28 patients. There were no false-negative or false-positive lesions on PET. Mean standardized uptake values (SUV) in 36 evaluable lesions were: 5.5 (n-PET), 5.8 (art-PET), 5.8 (pv-PET) and 5.8 (late-PET), with the highest mean increase in mean SUV of 6%. Mean SUV changes in liver background increased by up to 10% from n-PET to pv-PET. Multiphase CT data acquired with the use of highly concentrated CM can be used for qualitative assessment of liver lesions in torso FDG PET/CT. The influence on quantification of FDG uptake is small and negligible for most clinical applications. (orig.)

Pharmacodynamics of beta-lactam antibiotics. Studies on the paradoxical and postantibiotic effects in vitro and in an animal model.

Science.gov (United States)

Odenholt-Tornqvist, I

1989-01-01

The pharmacodynamics of antibiotics, i.e. the rate of killing and the time before regrowth of surviving bacteria, may be important factors for determination of the dosage interval. In the present study the effect of protein binding, antibiotic concentrations, bacterial growth phase and bacterial inoculum on the rate of bacterial killing was investigated. The postantibiotic effect (PAE) was also studied in vitro and in vivo. The killing rate of S. aureus did not differ when the bacteria were exposed to the same free concentrations of dicloxacillin in medium with and without albumin. Protein binding per se did thus not diminish the bactericidal activity. A paradoxically reduced bactericidal effect was noted when S. aureus was exposed to high concentrations of dicloxacillin, cloxacillin and benzylpenicillin. For determination of PAE of imipenem on Ps. aeruginosa, counts of viable bacteria were compared with assay of bacterial intracellular ATP. Both methods demonstrated a PAE for the strains tested at an inoculum of 10(6) cfu/ml. At an inoculum of 10(8) cfu/ml no PAE was found, which coincided with a lack of bactericidal effect. Both the PAE and the bactericidal effect were restored with aeration of the cultures, indicating insufficient penetration of imipenem to the target sites at low oxygen tension. An in vivo model in rabbits with implanted tissue cages was developed for evaluation of the PAE. Group A beta-hemolytic streptococci showed a PAE of approximately 2 h in vivo, which correlated well with the PAE found in vitro. Despite that streptococci in postantibiotic phase (PA-phase) were non-multiplying, such bacteria were killed as efficiently as previously untreated controls when exposed to 10xMIC of penicillin both in vitro and in vivo. However, streptococci in PA-phase were much more sensitive to the repeated challenge to subinhibitory concentrations of penicillin than previously untreated controls. In vivo, no difference in sensitivity to sub-MIC penicillin

Cavity enhancement by controlled directional scattering

Science.gov (United States)

Winston, R.

1980-01-01

A method for designing cavity enclosures is presented that can be applied to the design of a nonimaging concentrator. The method maintains high transmission at the expense of some concentration in the presence of a gap between the reflector and the receiver. The slight loss of concentration may be partly offset by enhanced absorption of radiation by the receiver, resulting from the cavity effect.

Buildings with enhanced radioactivity in Sweden

International Nuclear Information System (INIS)

Swedjemark, G.A.

1980-12-01

Enhanced radon/radon daughter concentrations indoors have been found in some houses in Sweden, especially in combination with low air exchange rates. The radon sources have been found to be some types of building materials, some types of filling materials, some types of ground and any combination of these sources. The radon source may also be radon-rich tap water. The same types of building materials also give an enhanced gamma radiation level. In all houses, both lower and higher concentrations of radon than the average levels given here have been found in individual rooms and with single measurements. (author)

Transcriptome analysis of responses to rhodomyrtone in methicillin-resistant Staphylococcus aureus.

Directory of Open Access Journals (Sweden)

Wipawadee Sianglum

Full Text Available Rhodomyrtone, purified from Rhodomyrtus tomentosa (Aiton Hassk, exhibits a high degree of potency against methicillin-resistant Staphylococcus aureus (MRSA. We recently demonstrated that exposure of MRSA to a subinhibitory concentration (0.174 µg/ml of rhodomyrtone resulted in the alteration of expression of several functional classes of bacterial proteins. To provide further insight into the antibacterial mode of action of this compound, we determined the impact of exposure to rhodomyrtone on the gene transcriptional profile of MRSA using microarray analysis. Exposure of MRSA to subinhibitory concentrations (0.5MIC; 0.5 µg/ml of rhodomyrtone revealed significant modulation of gene expression, with induction of 64 genes and repression of 35 genes. Prominent changes in response to exposure to rhodomyrtone involved genes encoding proteins essential to metabolic pathways and processes such as amino acid metabolism, membrane function, ATP-binding cassette (ABC transportation and lipoprotein and nucleotide metabolism. Genes involved in the synthesis of the aspartate family of amino acids, in particular proteins encoded by the dap operon were prominent. The diaminopimelate (DAP biosynthetic pathway is the precursor of lysine synthesis and is essential for peptidoglycan biosynthesis. However, phenotypic analysis of the peptidoglycan amino acid content of rhodomyrtone-treated MRSA did not differ significantly from that extracted from control cells. Genes involved in the biosynthesis of amino acids and peptidoglycan, and a high affinity ATP-driven K ((+ transport system, were investigated by quantitative reverse transcription-PCR (qRT-PCR using EMRSA-16 1, 4, or 18 h after exposure to rhodomyrtone and in general the data concurred with that obtained by microarray, highlighting the relevance of the DAP biosynthetic pathway to the mode of action of rhodomyrtone.

Beta- Lactam Antibiotics Stimulate Biofilm Formation in Non-Typeable Haemophilus influenzae by Up-Regulating Carbohydrate Metabolism

Science.gov (United States)

Wu, Siva; Li, Xiaojin; Gunawardana, Manjula; Maguire, Kathleen; Guerrero-Given, Debbie; Schaudinn, Christoph; Wang, Charles; Baum, Marc M.; Webster, Paul

2014-01-01

Non-typeable Haemophilus influenzae (NTHi) is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth) stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10 µg/mL) of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended. PMID:25007395

Modeling and design of energy concentrating laser weld joints

Energy Technology Data Exchange (ETDEWEB)

Milewski, J.O. [Los Alamos National Lab., NM (United States); Sklar, E. [OptiCad Corp., Santa Fe, NM (United States)

1997-04-01

The application of lasers for welding and joining has increased steadily over the past decade with the advent of high powered industrial laser systems. Attributes such as high energy density and precise focusing allow high speed processing of precision assemblies. Other characteristics of the process such as poor coupling of energy due to highly reflective materials and instabilities associated with deep penetration keyhole mode welding remain as process limitations and challenges to be overcome. Reflective loss of laser energy impinging on metal surfaces can in some cases exceed ninety five percent, thus making the process extremely inefficient. Enhanced coupling of the laser beam can occur when high energy densities approach the vaporization point of the materials and form a keyhole feature which can trap laser energy and enhance melting and process efficiency. The extreme temperature, pressure and fluid flow dynamics of the keyhole make control of the process difficult in this melting regime. The authors design and model weld joints which through reflective propagation and concentration of the laser beam energy significantly enhance the melting process and weld morphology. A three dimensional computer based geometric optical model is used to describe the key laser parameters and joint geometry. Ray tracing is used to compute the location and intensity of energy absorption within the weld joint. Comparison with experimentation shows good correlation of energy concentration within the model to actual weld profiles. The effect of energy concentration within various joint geometry is described. This method for extending the design of the laser system to include the weld joint allows the evaluation and selection of laser parameters such as lens and focal position for process optimization. The design of narrow gap joints which function as energy concentrators is described. The enhanced laser welding of aluminum without keyhole formation has been demonstrated.

INFLUENCE OF DOXORUBICIN ON ADHESIVE PROPERTIES OF E.COLI

Directory of Open Access Journals (Sweden)

O.G. Shapoval

2008-09-01

Full Text Available Influence ofantineoplastic drug doxorubicin and amikacin, the aminoglycoside family on adhesive activity of Escherichia coli was studied. Antimicrobialactivity(minimum inhibitory concentration-MIC ofboth drugs against experimental strains using serial two-fold dilution method was determined. Susceptibility of E.coli to amikacin in the presence of Sand j MIC doxorubicin was studied. After 10 passages in beef-extract broth with constant and increasing doxorubicin concentrations in the presence of Sand j MIC doxorubicin, the adhesive activity of initial and passage variants according to theirability to absorb human erythrocytes 1(0 Rh+ was determined. Itwas observed that experimental strains were susceptible to amikacin (MIC 1,5-6,2 mkg/ml butwere resistantto doxorubicin (MIC 1000 mkg/ml. Subinhibitory concentrations of this cytostatic (S and j MIC raised the sensitivity of experimental strains to amikacin and differently effected on adhesive activity of passage variants of E.coli.

1-Deoxynojirimycins with dansyl capped N-substituents as probes for Morbus Gaucher affected cell lines.

Science.gov (United States)

Fröhlich, Richard F G; Furneaux, Richard H; Mahuran, Don J; Rigat, Brigitte A; Stütz, Arnold E; Tropak, Michael B; Wicki, Jacqueline; Withers, Stephen G; Wrodnigg, Tanja M

2010-07-02

Cyclization by double reductive amination of d-xylo-hexos-5-ulose with methyl 6-aminohexanoate gave (methoxycarbonyl)pentyl-1-deoxynojirimycin. Reaction of the terminal carboxylic acid with N-dansyl-1,6-diaminohexane provided the corresponding chain-extended fluorescent derivative. By reaction with bis(6-dansylaminohexyl)amine, the corresponding branched di-N-dansyl compound was obtained. Both compounds are strong inhibitors of d-glucosidases and could also be shown to distinctly improve, at sub-inhibitory concentrations, the activity of beta-glucocerebrosidase in a Gaucher fibroblast (N370S) cell-line through chaperoning of the enzyme to the lysosome. Copyright 2010 Elsevier Ltd. All rights reserved.

Metabolites with Gram-negative bacteria quorum sensing inhibitory activity from the marine animal endogenic fungus Penicillium sp. SCS-KFD08.

Science.gov (United States)

Kong, Fan Dong; Zhou, Li Man; Ma, Qing Yun; Huang, Sheng Zhuo; Wang, Pei; Dai, Hao Fu; Zhao, You Xing

2017-01-01

Three new compounds named penicitor A, aculene E and penicitor B, as well as four known compounds, were isolated from the fermentation broth of Penicillium sp. SCS-KFD08 associated with a marine animal Sipunculus nudus from the Haikou bay of China. Their planar structures and absolute configurations were unambiguously elucidated by spectroscopic data, Mosher's method, CD spectrum analysis along with quantum ECD calculation. Among them, compounds 2-7 showed quorum sensing inhibitory activity against Chromobacterium violaceum CV026, and could significantly reduce violacein production in N-hexanoyl-l-homoserine lactone (C6-HSL) induced C. violaceum CV026 cultures at sub-inhibitory concentrations.

Selective inhibition of Bacillus subtilis sporulation by acridine orange and promethazine.

Science.gov (United States)

Burke, W F; Spizizen, J

1977-03-01

Two structurally similar compounds were found to inhibit sporulation in Bacillus subtilis 168. A dye, acridine orange, and an antischizophrenic drug, promethazine, blocked spore formation at concentrations subinhibitory to vegetative growth, while allowing synthesis of serine protease, antibiotic, and certain catabolite-repressed enzymes. The sporulation process was sensitive to promethazine through T2, whereas acridine orange was inhibitory until T4. The drug-treated cells were able to support the replication of phages phie and phi29, although the lytic cycles were altered slightly. The selective inhibition of sporulation by these compounds may be related to the affinity of some sporulation-specific genes to intercalating compounds.

Nonimaging achromatic shaped Fresnel lenses for ultrahigh solar concentration.

Science.gov (United States)

Languy, Fabian; Habraken, Serge

2013-05-15

The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore achromatic doublets made with poly(methyl methacrylate) and polycarbonate are of great interest to enhance the concentration ratio and to achieve a spectrally uniform flux on the receiver. In this Letter, shaped achromatic Fresnel lenses are investigated. One lossless design is of high interest since it provides spectrally and spatially uniform flux without being affected by soiling problems. With this design an optical concentration ratio of about 8500× can be achieved.

Enhancement of encaged electron concentration by Sr(2+) doping and improvement of Gd(3+) emission through controlling encaged anions in conductive C12A7 phosphors.

Science.gov (United States)

Zhang, Meng; Liu, Yuxue; Zhu, Hancheng; Yan, Duanting; Yang, Jian; Zhang, Xinyang; Liu, Chunguang; Xu, Changshan

2016-07-28

Conductive C12A7:0.1%Gd(3+),y%Sr(2+) powders with different Sr(2+) doping concentrations have been prepared in a H2 atmosphere by a solid state method in combination with subsequent UV-irradiation. The encaged electron concentration could be modulated through tuning Sr(2+) doping and its maximum value reaches 2.3 × 10(19) cm(-3). This is attributed to the competition between enhanced uptake and the release of the encaged anions during their formation and diffusion processes and the suppression of encaged electrons generation due to the increased encaged OH(-) anions and the decreased encaged O(2-) anions. Although there exists encaged electrons and different encaged anions (O(2-), H(-) and OH(-)) in C12A7 conductive powders prepared through the hydrogen route, a dominant local environment around Gd(3+) could be observed using electron spin resonance (ESR) detection. It can be ascribed to the stronger coupling of the encaged OH(-) to the framework of C12A7 than those of the encaged electrons, O(2-) and H(-) anions. In addition, emission of Gd(3+) ions is enhanced under UV or low voltage electron beam excitation and a new local environment around Gd(3+) ions appears through the thermal annealing in air because of the decrease of the encaged OH(-) anions and the increase of the encaged O(2-) anions. Our results suggested that Sr(2+) doping in combination with thermal annealing in air is an effective strategy for increasing the conductive performance and enhancing the emission of rare earth ions doped into C12A7 conductive phosphors for low-voltage field emission displays (FEDs).

Nutrient concentrations in a Littorella uniflora community at higher CO₂ concentrations and reduced light intensities

DEFF Research Database (Denmark)

Andersen, T.; Pedersen, O.; Andersen, F. Ø.

2005-01-01

laboratory experiments with isoetid vegetation (Littorella uniflora) where water column CO2 and light could be manipulated in order to test whether (i) light and CO2 availability affect nutrient concentrations in isoetid vegetation, and (ii) if changes in light and CO2 climate affect fluxes of inorganic...... nitrogen (N) and phosphorus (P) from sediment to water column, which potentially could result in increased growth of epiphytic algae. 3. The results showed that the standing stocks of phosphorus and nitrogen in the L. uniflora vegetation were significantly influenced by CO2 concentration and light...... intensity. Both standing stocks of P and N were significantly higher in the mesocosm treatments with high CO2 concentration than in those at low CO2 concentration. Similarly, standing stocks of P and N enhanced with increasing light intensity. 4. Measurements of nutrient fluxes both in the field...

Quantitative contrast-enhanced optical coherence tomography

Energy Technology Data Exchange (ETDEWEB)

Winetraub, Yonatan; SoRelle, Elliott D. [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Liba, Orly [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Zerda, Adam de la [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States)

2016-01-11

We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

Dielectric compound parabolic concentrating solar collector with frustrated total internal reflection absorber

Science.gov (United States)

Hull, J. R.

Since its introduction, the concept of nonimaging solar concentrators, as exemplified by the compound parabolic concentrator (CPC) design, has greatly enhanced the ability to collect solar energy efficiently in thermal and photovoltaic devices. When used as a primary concentrator, a CPC can provide significant concentration without the complication of a tracking mechanism and its associated maintenance problems. When used as a secondary, a CPC provides higher total concentration, or for a fixed concentration, tolerates greater tracking error in the primary.

Progress In Fresnel-Köhler Concentrators

Science.gov (United States)

Mohedano, Rubén; Cvetković, Aleksandra; Benítez, Pablo; Chaves, Julio; Miñano, Juan C.; Zamora, Pablo; Hernandez, Maikel; Vilaplana, Juan

2011-12-01

The Fresnel Köhler (FK) concentrator was first presented in 2008. Since then, various CPV companies have adopted this technology as base for their future commercial product. The key for this rapid penetration is a mixture of simplicity (the FK is essentially a Fresnel lens concentrator, a technology that dominates the market) and excellent performance: high concentration without giving up large manufacturing/aiming tolerances, enabling high efficiency even at the array level. All these features together have a great potential to lower energy costs. This work shows recent results and progress regarding this device, covering new design features, measurements and tests along with first performance achievements at the array level (pilot 6.5 Kwp plant). The work also discusses the potential impact of the FK enhanced performance on the Levelized Cost Of Electricity (LCOE).

Transparent Solar Concentrator for Flat Panel Display

Science.gov (United States)

Yeh, Chia-Hung; Chang, Fuh-Yu; Young, Hong-Tsu; Hsieh, Tsung-Yen; Chang, Chia-Hsiung

2012-06-01

A new concept of the transparent solar concentrator for flat panel display is experimentally demonstrated without adversely affecting the visual effects. The solar concentrator is based on a solar light-guide plate with micro prisms, not only increasing the absorption area of solar energy but also enhancing the conversion efficiency. The incident light is guided by the designed solar light-guide plate according to the total internal reflection (TIR), and converted into electrical power by photovoltaic solar cells. The designed transparent solar concentrator was made and measured with high transparency, namely 94.8%. The developed solar energy system for display can store energy and supply the bias voltage to light on two light-emitting diodes (LEDs) successfully.

Chelant-aided enhancement of lead mobilization in residential soils

International Nuclear Information System (INIS)

Sarkar, Dibyendu; Andra, Syam S.; Saminathan, Sumathi K.M.; Datta, Rupali

2008-01-01

Chelation of metals is an important factor in enhancing solubility and hence, availability to plants to promote phytoremediation. We compared the effects of two chelants, namely, ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) in enhancing mobilized lead (Pb) in Pb-based paint contaminated residential soils collected from San Antonio, Texas and Baltimore, Maryland. Batch incubation studies were performed to investigate the effectiveness of the two chelants in enhancing mobilized Pb, at various concentrations and treatment durations. Over a period of 1 month, the mobilized Pb pool in the San Antonio study soils increased from 52 mg kg -1 to 287 and 114 mg kg -1 in the presence of 15 mM kg -1 EDTA and EDDS, respectively. Stepwise linear regression analysis demonstrated that pH and organic matter content significantly affected the mobilized Pb fraction. The regression models explained a large percentage, from 83 to 99%, of the total variation in mobilized Pb concentrations. - Complexation by a biodegradable chelating agent, EDDS enhances mobilized Pb concentrations in Pb-paint contaminated residential soils

Repeat exposure to ciguatoxin leads to enhanced and sustained thermoregulatory, pain threshold and motor activity responses in mice: relationship to blood ciguatoxin concentrations.

Science.gov (United States)

Bottein Dechraoui, Marie-Yasmine; Rezvani, Amir H; Gordon, Christopher J; Levin, Edward D; Ramsdell, John S

2008-04-03

Ciguatera is a common illness in tropical and subtropical regions that manifests in complex and long-lived symptoms which are more severe in subsequent exposures. This study measures central and peripheral neurologic signs, in parallel with blood toxin levels, in mice exposed once or twice (at 3 days interval) to a sublethal dose of ciguatoxin P-CTX-1 (0.26ng/g via i.p.). Mice were implanted with radiotransmitters to monitor motor activity and core temperature. A single exposure to ciguatoxin elicited an immediate and transient decrease in motor activity and temperature, and subsequent long-lasting thermoregulatory dysfunction resulting in stabilized body temperature around 36.0 degrees C with no observable circadian rhythm. The hypothermic response and the reduced activity were enhanced with a second exposure with 30% of the mice dying within 7h. Measurement of the peripheral nervous system by the tail flick assay revealed increased latency with a single ciguatoxin exposure, and a greater effect following the second exposure. Toxin was measurable in blood up to 3 days following the first exposure; at the 1h time point the concentrations were significantly elevated after a second exposure. These findings indicate an early response to ciguatoxin manifest in a central response to lower body temperature and reduce motor activity and a more persistent effect on the peripheral system leading to spinal heat antinociception and delayed fever-like response. The greater neurological response to a second ciguatoxin exposure was associated with elevated concentrations of ciguatoxin in the blood solely over the first hour of exposure. In conclusion, a single exposure to toxin exerts a significant neurological response which may be enhanced with subsequent exposure.

Pressurized capillary electrochromatographic analysis of water-soluble vitamins by combining with on-line concentration technique.

Science.gov (United States)

Jia, Li; Liu, Yaling; Du, Yanyan; Xing, Da

2007-06-22

A pressurized capillary electrochromatography (pCEC) system was developed for the separation of water-soluble vitamins, in which UV absorbance was used as the detection method and a monolithic silica-ODS column as the separation column. The parameters (type and content of organic solvent in the mobile phase, type and concentration of electrolyte, pH of the electrolyte buffer, applied voltage and flow rate) affecting the separation resolution were evaluated. The combination of two on-line concentration techniques, namely, solvent gradient zone sharpening effect and field-enhanced sample stacking, was utilized to improve detection sensitivity, which proved to be beneficial to enhance the detection sensitivity by enabling the injection of large volumes of samples. Coupling electrokinetic injection with the on-line concentration techniques was much more beneficial for the concentration of positively charged vitamins. Comparing with the conventional injection mode, the enhancement in the detection sensitivities of water-soluble vitamins using the on-line concentration technique is in the range of 3 to 35-fold. The developed pCEC method was applied to evaluate water-soluble vitamins in corns.

Concentrated dark matter: Enhanced small-scale structure from codecaying dark matter

OpenAIRE

Dror, Jeff A.; Kuflik, Eric; Melcher, Brandon; Watson, Scott

2018-01-01

We study the cosmological consequences of codecaying dark matter—a recently proposed mechanism for depleting the density of dark matter through the decay of nearly degenerate particles. A generic prediction of this framework is an early dark matter dominated phase in the history of the Universe, that results in the enhanced growth of dark matter perturbations on small scales. We compute the duration of the early matter dominated phase and show that the perturbations are robust against washout...

Microwave Pretreatment for Thiourea Leaching for Gold Concentrate

Directory of Open Access Journals (Sweden)

Nag-Choul Choi

2017-10-01

Full Text Available In this research, we studied the use of microwave pretreatment to enhance the efficiency of Au leaching from gold concentrate. The gold concentrate was pretreated using microwaves with different irradiation time. The sample temperature was increased up to 950 °C by the microwave irradiation. A scanning electron microscope-energy dispersive spectrometer showed the evolution of microcracks and the reduction of sulfur on the mineral surface. X-ray diffraction data also showed the mineral phase shift from pyrite to hematite or pyrrhotite. A leaching test was conducted for the microwave-treated and untreated gold concentrates using thiourea. Although the thiourea leaching recovered 80% of Au from the untreated concentrate, from the treated concentration, the Au could be recovered completely. Au leaching efficiency increased as the microwave irradiation time increased, as well as with a higher composition of thiourea.

Comparison of the Force-, Velocity- and Power-Time Curves Between the Concentric-Only and Eccentric-Concentric Bench Press Exercises.

Science.gov (United States)

Pérez-Castilla, Alejandro; Comfort, Paul; McMahon, John J; Pestaña-Melero, Francisco Luis; García-Ramos, Amador

2018-01-17

The aim of this study was to compare the temporal and mechanical variables between the concentric-only and eccentric-concentric bench press (BP) variants. Twenty-one men (age: 22.0±4.2 years, body mass: 73.4±7.7 kg, height: 177.2±8.0 cm; one-repetition maximum [1RM]: 1.12±0.12 kg⋅kg) were evaluated during the concentric-only and eccentric-concentric BP variants using 80% 1RM. Temporal (concentric phase duration, propulsive phase duration, and time to reach the maximum values of force, velocity, and power) and mechanical variables (force, velocity, and power), determined using a linear velocity transducer, were compared between both BP variants. All temporal variables were significantly lower during the eccentric-concentric BP compared to the concentric-only BP (P velocity and power were significantly higher for the eccentric-concentric BP compared to the concentric-only BP (all P velocity (ES: 0.40) and power (ES: 0.41). The stretch-shortening cycle (i.e., eccentric-concentric BP) mainly enhanced force production at the early portion of the concentric phase, but this potentiation effect gradually reduced over the latter part of the movement. Finally, force was higher for the concentric-only BP during 49% of the concentric phase duration. These results suggest that both BP variants should be included during resistance training programs in order to optimize force output at different points of the concentric phase.

Quantum mechanical limit to plasmonic enhancement as observed by surface-enhanced Raman scattering.

Science.gov (United States)

Zhu, Wenqi; Crozier, Kenneth B

2014-10-14

Plasmonic nanostructures enable light to be concentrated into nanoscale 'hotspots', wherein the intensity of light can be enhanced by orders of magnitude. This plasmonic enhancement significantly boosts the efficiency of nanoscale light-matter interactions, enabling unique linear and nonlinear optical applications. Large enhancements are often observed within narrow gaps or at sharp tips, as predicted by the classical electromagnetic theory. Only recently has it become appreciated that quantum mechanical effects could emerge as the feature size approaches atomic length-scale. Here we experimentally demonstrate, through observations of surface-enhanced Raman scattering, that the emergence of electron tunnelling at optical frequencies limits the maximum achievable plasmonic enhancement. Such quantum mechanical effects are revealed for metallic nanostructures with gap-widths in the single-digit angstrom range by correlating each structure with its optical properties. This work furthers our understanding of quantum mechanical effects in plasmonic systems and could enable future applications of quantum plasmonics.

Tannin concentration enhances seed caching by scatter-hoarding rodents: An experiment using artificial ‘seeds’

Science.gov (United States)

Wang, Bo; Chen, Jin

2008-11-01

Tannins are very common among plant seeds but their effects on the fate of seeds, for example, via mediation of the feeding preferences of scatter-hoarding rodents, are poorly understood. In this study, we created a series of artificial 'seeds' that only differed in tannin concentration and the type of tannin, and placed them in a pine forest in the Shangri-La Alpine Botanical Garden, Yunnan Province of China. Two rodent species ( Apodemus latronum and A. chevrieri) showed significant preferences for 'seeds' with different tannin concentrations. A significantly higher proportion of seeds with low tannin concentration were consumed in situ compared with seeds with a higher tannin concentration. Meanwhile, the tannin concentration was significantly positively correlated with the proportion of seeds cached. The different types of tannin (hydrolysable tannin vs condensed tannin) did not differ significantly in their effect on the proportion of seeds eaten in situ vs seeds cached. Tannin concentrations had no significant effect on the distance that cached seeds were carried, which suggests that rodents may respond to different seed traits in deciding whether or not to cache seeds and how far they will transport seeds.

Effects of the multi-step activation process on the carrier concentration of p-type GaN

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Kwan [Department of Materials Science and Metallurgical Engineering, Sunchon National University, Sunchon, Chonnam 540-742 (Korea, Republic of); Jeon, Seong-Ran [LED Research and Business Division, Korea Photonics Technology Institute, Gwanju 500-779 (Korea, Republic of); Lee, Ji-Myon, E-mail: jimlee@sunchon.ac.kr [Department of Printed Electronics Engineering, Sunchon National University, Sunchon, Chonnam 540-742 (Korea, Republic of)

2014-06-25

Highlights: • Hole concentration of p-GaN was enhanced by multi-step activation process. • The O{sub 2} plasma treatment is attributed to the enhanced hole concentration of p-GaN. • PL peak intensity was also enhanced by MS activation process. - Abstract: A multi-step activation method, which include an oxygen plasma treatment, chemical treatment, and post annealing in N{sub 2} was proposed to enhance the hole concentration of a p-type GaN epitaxial layer. This process was found to effectively activate p-GaN by increasing the hole concentration compared to that of the conventionally annealed sample. After the optimal oxygen plasma treatment (10 min at a source and table power of 500 W and 100 W, respectively), followed by a HCl and buffered oxide etchant treatment, and then by a post-RTA process in a N{sub 2} environment, the hole concentration was increased from 4.0 × 10{sup 17} to 2.0 × 10{sup 18} cm{sup −3}. The oxygen plasma was found to effectively remove the remaining H atoms and subsequent wet treatment can effectively remove the GaO{sub x} that had formed during O plasma treatment, resulting in the higher intensity of photoluminescence.

Enhancing radiolytic stability upon concentration of tritium-labeled pharmaceuticals utilizing centrifugal evaporation.

Science.gov (United States)

Marques, Rosemary; Helmy, Roy; Waterhouse, David

2015-05-30

Tritium radiopharmaceuticals are often used in drug development because of their desirable specific activity. The inherent instability of these radioactive tracers often leads to a requirement to purify prior to use. Purification methodologies such as preparative chromatography and solid/liquid extractions often utilize water as a solvent, which is not suitable for long-term storage and necessitates removal. Rotary evaporation has traditionally been utilized for the removal of this unwanted solvent, however, this method has been shown to lead to decomposition of the tritium species in some cases. Centrifugal evaporation is a milder concentration method which has been demonstrated to effectively remove solvents. In this study, we show that centrifugal evaporation leads to effective concentration of tritium samples without the decomposition typically observed by rotary evaporation. Copyright © 2015 John Wiley & Sons, Ltd.

Interactions of plaunotol with bacterial membranes.

Science.gov (United States)

Koga, T; Watanabe, H; Kawada, H; Takahashi, K; Utsui, Y; Domon, H; Ishii, C; Narita, T; Yasuda, H

1998-08-01

Plaunotol, a cytoprotective antiulcer agent, has a bactericidal effect against Helicobacter pylori, which may result from interaction of this compound with the bacterial cell membrane. The purpose of the present study was to confirm that plaunotol interacts with the H. pylori membrane. Membrane fluidities were measured using two stearic acid spin labels, namely 5-doxyl-stearic acid (in which the nitroxide group is located in the upper portion of the bacterial cell membrane) and 16-doxyl-stearic acid methyl ester (in which the nitroxide group is located deeper in the bacterial cell membrane), by means of electron spin resonance. The membrane fluidities of plaunotol-treated cells were significantly increased in the measurements made using the two spin labels. We also attempted to isolate plaunotol-resistant H. pylori in vitro by two different methods. To assess the level of resistance that could be reached, H. pylori was passaged five times on an agar plate containing subinhibitory concentrations of plaunotol or metronidazole. To measure the rate of development of resistance, H. pylori was grown with subinhibitory concentrations (0.25 x MIC) of plaunotol or metronidazole, and quantitatively plated on to medium containing 4 x MIC of the compounds. This treatment was repeated once more. No plaunotol-resistant colonies were selected by the two methods. H. pylori developed resistance to metronidazole easily and at a relatively high rate. The mechanism by which plaunotol directly fluidizes and destroys the H. pylori membrane might make it difficult for this organism to develop resistance to plaunotol. It was confirmed that the bactericidal effects of plaunotol were also shown against Staphylococcus aureus, Streptococcus pneumoniae, Neisseria gonorrhoeae, Moraxella catarrhalis and Haemophilus influenzae. No such effect was seen against Escherichia coli and Pseudomonas aeruginosa.

Beta- lactam antibiotics stimulate biofilm formation in non-typeable haemophilus influenzae by up-regulating carbohydrate metabolism.

Directory of Open Access Journals (Sweden)

Siva Wu

Full Text Available Non-typeable Haemophilus influenzae (NTHi is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10 µg/mL of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended.

Antipneumococcal activity of DK-507k, a new quinolone, compared with the activities of 10 other agents.

Science.gov (United States)

Browne, Frederick A; Bozdogan, Bülent; Clark, Catherine; Kelly, Linda M; Ednie, Lois; Kosowska, Klaudia; Dewasse, Bonifacio; Jacobs, Michael R; Appelbaum, Peter C

2003-12-01

Agar dilution MIC determination was used to compare the activity of DK-507k with those of ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, sitafloxacin, amoxicillin, cefuroxime, erythromycin, azithromycin, and clarithromycin against 113 penicillin-susceptible, 81 penicillin-intermediate, and 67 penicillin-resistant pneumococci (all quinolone susceptible). DK-507k and sitafloxacin had the lowest MICs of all quinolones against quinolone-susceptible strains (MIC at which 50% of isolates were inhibited [MIC50] and MIC90 of both, 0.06 and 0.125 microg/ml, respectively), followed by moxifloxacin, gatifloxacin, levofloxacin, and ciprofloxacin. MICs of beta-lactams and macrolides rose with those of penicillin G. Against 26 quinolone-resistant pneumococci with known resistance mechanisms, DK-507k and sitafloxacin were also the most active quinolones (MICs, 0.125 to 1.0 microg/ml), followed by moxifloxacin, gatifloxacin, levofloxacin, and ciprofloxacin. Mutations in quinolone resistance-determining regions of quinolone-resistant strains were in the usual regions of the parC and gyrA genes. Time-kill testing showed that both DK-507k and sitafloxacin were bactericidal against all 12 quinolone-susceptible and -resistant strains tested at twice the MIC at 24 h. Serial broth passages in subinhibitory concentrations of 10 strains for a minimum of 14 days showed that development of resistant mutants (fourfold or greater increase in the original MIC) occurred most rapidly for ciprofloxacin, followed by moxifloxacin, DK-507k, gatifloxacin, sitafloxacin, and levofloxacin. All parent strains demonstrated a fourfold or greater increase in initial MIC in DK-507k against resistant mutants were lowest, followed by those of sitafloxacin, moxifloxacin, gatifloxacin, ciprofloxacin, and levofloxacin. Four strains were subcultured in subinhibitory concentrations of each drug for 50 days: MICs of DK-507k against resistant mutants were lowest, followed by those of sitafloxacin

Brachial and Cerebrovascular Functions Are Enhanced in Postmenopausal Women after Ingestion of Chocolate with a High Concentration of Cocoa.

Science.gov (United States)

Marsh, Channa E; Carter, Howard H; Guelfi, Kym J; Smith, Kurt J; Pike, Kerryn E; Naylor, Louise H; Green, Daniel J

2017-09-01

Background: Cocoa contains polyphenols that are thought to be beneficial for vascular health. Objective: We assessed the impact of chocolate containing distinct concentrations of cocoa on cerebrovascular function and cognition. Methods: Using a counterbalanced within-subject design, we compared the acute impact of consumption of energy-matched chocolate containing 80%, 35%, and 0% single-origin cacao on vascular endothelial function, cognition, and cerebrovascular function in 12 healthy postmenopausal women (mean ± SD age: 57.3 ± 5.3 y). Participants attended a familiarization session, followed by 3 experimental trials, each separated by 1 wk. Outcome measures included cerebral blood flow velocity (CBF v ) responses, recorded before and during completion of a computerized cognitive assessment battery (CogState); brachial artery flow-mediated dilation (FMD); and hemodynamic responses (heart rate and blood pressure). Results: When CBF v data before and after chocolate intake were compared between conditions through the use of 2-factor ANOVA, an interaction effect ( P = 0.003) and main effects for chocolate ( P = 0.043) and time ( P = 0.001) were evident. Post hoc analysis revealed that both milk chocolate (MC; 35% cocoa; P = 0.02) and dark chocolate (DC; 80% cocoa; P = 0.003) induced significantly lower cerebral blood flow responses during the cognitive tasks, after normalizing for changes in arterial pressure. DC consumption also increased brachial FMD compared with the baseline value before chocolate consumption ( P = 0.002), whereas MC and white chocolate (0% cocoa) caused no change ( P- interaction between conditions = 0.034). Conclusions: Consumption of chocolate containing high concentrations of cocoa enhanced vascular endothelial function, which was reflected by improvements in FMD. Cognitive function outcomes did not differ between conditions; however, cerebral blood flow responses during these cognitive tasks were lower in those consuming MC and DC. These

Freeze concentration of dairy products Phase 2. Final report

Energy Technology Data Exchange (ETDEWEB)

Best, D.E.; Vasavada, K.C.

1993-09-01

An efficient, electrically driven freeze concentration system offers potential for substantially increasing electricity demand while providing the mature dairy industry with new products for domestic and export markets together with enhanced production efficiencies. Consumer tests indicate that dairy products manufactured from freeze-concentrated ingredients are either preferred or considered equivalent in quality to fresh milk-based products. Economic analyses indicate that this technology should be competitive with thermal evaporation processes on a commercial basis.

Glutamate Concentration in the Superior Temporal Sulcus Relates to Neuroticism in Schizophrenia

Directory of Open Access Journals (Sweden)

Johanna Balz

2018-05-01

Full Text Available Clinical studies suggest aberrant neurotransmitter concentrations in the brains of patients with schizophrenia (SCZ. Numerous studies have indicated deviant glutamate concentrations in SCZ, although the findings are inconsistent. Moreover, alterations in glutamate concentrations could be linked to personality traits in SCZ. Here, we examined the relationships between personality dimensions and glutamate concentrations in a voxel encompassing the occipital cortex (OCC and another voxel encompassing the left superior temporal sulcus (STS. We used proton magnetic resonance spectroscopy to examine glutamate concentrations in the OCC and the STS in 19 SCZ and 21 non-psychiatric healthy control (HC participants. Personality dimensions neuroticism, extraversion, openness, agreeableness and conscientiousness were assessed using the NEO-FFI questionnaire. SCZ compared to HC showed higher glutamate concentrations in the STS, reduced extraversion scores, and enhanced neuroticism scores. No group differences were observed for the other personality traits and for glutamate concentrations in the OCC. For the SCZ group, glutamate concentrations in STS were negatively correlated with the neuroticism scores [r = -0.537, p = 0.018] but this was not found in HC [r(19 = 0.011, p = 0.962]. No other significant correlations were found. Our study showed an inverse relationship between glutamate concentrations in the STS and neuroticism scores in SCZ. Elevated glutamate in the STS might serve as a compensatory mechanism that enables patients with enhanced concentrations to control and prevent the expression of neuroticism.

Stilbazolium Merocyanine Dye Determination in Different Solutions, Concentrations and Colloids Using SERS

DEFF Research Database (Denmark)

Pajchrowski, Grzegorz; Abdali, Salim; Nørbygaard, Thomas

2006-01-01

Surface Enhanced Raman Scattering (SERS) measurements were carried out on stilbazolium merocyanine dye in methanol and pyridine solvents. Both solutions were measured in series of concentrations, covering a range of 5·10-5 M to 5·10-8 M. In these measurements Ag and Au colloids were used and the ......Surface Enhanced Raman Scattering (SERS) measurements were carried out on stilbazolium merocyanine dye in methanol and pyridine solvents. Both solutions were measured in series of concentrations, covering a range of 5·10-5 M to 5·10-8 M. In these measurements Ag and Au colloids were used...... report here on the success of using SERS to obtain Raman spectra of merocyanine dye at very low concentration in an attempt of new approach, which can be used for further investigations of the dye. The SERS spectra will here be reported and the results from different solutions, colloids, concentrations...

Recent and projected increases in atmospheric CO2 concentration can enhance gene flow between wild and genetically altered rice (Oryza sativa.

Directory of Open Access Journals (Sweden)

Lewis H Ziska

Full Text Available Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO(2 between genetically modified crops and wild, weedy relatives increase the spread of novel genes, potentially altering evolutionary fitness? Here we show that increasing CO(2 from an early 20(th century concentration (300 µmol mol(-1 to current (400 µmol mol(-1 and projected, mid-21(st century (600 µmol mol(-1 values, enhanced the flow of genes from wild, weedy rice to the genetically altered, herbicide resistant, cultivated population, with outcrossing increasing from 0.22% to 0.71% from 300 to 600 µmol mol(-1. The increase in outcrossing and gene transfer was associated with differential increases in plant height, as well as greater tiller and panicle production in the wild, relative to the cultivated population. In addition, increasing CO(2 also resulted in a greater synchronicity in flowering times between the two populations. The observed changes reported here resulted in a subsequent increase in rice dedomestication and a greater number of weedy, herbicide-resistant hybrid progeny. Overall, these data suggest that differential phenological responses to rising atmospheric CO(2 could result in enhanced flow of novel genes and greater success of feral plant species in agroecosystems.

Recent and projected increases in atmospheric CO2 concentration can enhance gene flow between wild and genetically altered rice (Oryza sativa).

Science.gov (United States)

Ziska, Lewis H; Gealy, David R; Tomecek, Martha B; Jackson, Aaron K; Black, Howard L

2012-01-01

Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO(2) between genetically modified crops and wild, weedy relatives increase the spread of novel genes, potentially altering evolutionary fitness? Here we show that increasing CO(2) from an early 20(th) century concentration (300 µmol mol(-1)) to current (400 µmol mol(-1)) and projected, mid-21(st) century (600 µmol mol(-1)) values, enhanced the flow of genes from wild, weedy rice to the genetically altered, herbicide resistant, cultivated population, with outcrossing increasing from 0.22% to 0.71% from 300 to 600 µmol mol(-1). The increase in outcrossing and gene transfer was associated with differential increases in plant height, as well as greater tiller and panicle production in the wild, relative to the cultivated population. In addition, increasing CO(2) also resulted in a greater synchronicity in flowering times between the two populations. The observed changes reported here resulted in a subsequent increase in rice dedomestication and a greater number of weedy, herbicide-resistant hybrid progeny. Overall, these data suggest that differential phenological responses to rising atmospheric CO(2) could result in enhanced flow of novel genes and greater success of feral plant species in agroecosystems.

Estimating the arterial input function from dynamic contrast-enhanced MRI data with compensation for flow enhancement (I): Theory, method, and phantom experiments

NARCIS (Netherlands)

van Schie, Jeroen J. N.; Lavini, Cristina; van Vliet, Lucas J.; Vos, Frans M.

2017-01-01

The arterial input function (AIF) represents the time-dependent arterial contrast agent (CA) concentration that is used in pharmacokinetic modeling. To develop a novel method for estimating the AIF from dynamic contrast-enhanced (DCE-) MRI data, while compensating for flow enhancement. Signal

Electromagnetic theories of surface-enhanced Raman spectroscopy.

Science.gov (United States)

Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin

2017-07-07

Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical

Importance of hemoglobin concentration to exercise: acute manipulations

DEFF Research Database (Denmark)

Calbet, José A L; Lundby, Carsten; Koskolou, Maria

2006-01-01

An acute reduction of blood hemoglobin concentration ([Hb]), even when the circulating blood volume is maintained, results in lower (.)V(O(2)(max) and endurance performance, due to the reduction of the oxygen carrying capacity of blood. Conversely, an increase of [Hb] is associated with enhanced...

Day lighting Simulation and Thermoacoustic Laser Development for the Enhanced Utilization of Highly Concentrated Solar Radiation

Energy Technology Data Exchange (ETDEWEB)

Oh, Won Jong

2011-02-15

Solar energy has been used in various fields, because it is clean and reliable. The present study explored the use of sunlight in two important areas which make it competitive and also attractive. First, we carried out a series of computer simulations for using sun pipes to introduce sunlight into the interior of a building. The focus was made onto the enhancement of visual environment when natural daylight is delivered to a classroom. While daylighting provides efficient means to harness the sun's abundant energy, it still leaves much room for further exploitation. With the aid of simple optical devices, sunlight could be easily concentrated and utilized. Solar-powered Thermal Acoustic(TA) lasers make one of these applications, which we explored as the other important area of solar utilization. 1) Daylighting simulation A lightless space with the dimension of a typical classroom at Jeju National University was modeled by ECOTECT. Two different cases were simulated and analyzed by RADIANCE. In the first case, a comparative analysis of illuminance was carried out to estimate the basic performance of sun pipe systems. In the other case, different designs of sun pipe systems were analyzed to elicit the most efficient model of operation. Simulations were performed for solar noon which indicates the time (or point) in the sun's path at which the sun is on the local meridian. Results show that indoor visual environment could be greatly enhanced with the application of sun pipe systems. The maximum illuminance took place with the sun pipe system of 1.0m in diameter and 0.5m in height. 2) Thermo-Acoustic Laser(TAL) development A series of experiments were carried out to find the most optimum operating conditions for the maximum SPL(Sound Pressure Level) and frequency of the acoustic waves generated by ThermoAcoustic(TA) lasers. Among various experimental variables, we focused our research on the stack position, stack length, length of the resonance tube and input

Day lighting Simulation and Thermoacoustic Laser Development for the Enhanced Utilization of Highly Concentrated Solar Radiation

International Nuclear Information System (INIS)

Oh, Won Jong

2011-02-01

Solar energy has been used in various fields, because it is clean and reliable. The present study explored the use of sunlight in two important areas which make it competitive and also attractive. First, we carried out a series of computer simulations for using sun pipes to introduce sunlight into the interior of a building. The focus was made onto the enhancement of visual environment when natural daylight is delivered to a classroom. While daylighting provides efficient means to harness the sun's abundant energy, it still leaves much room for further exploitation. With the aid of simple optical devices, sunlight could be easily concentrated and utilized. Solar-powered Thermal Acoustic(TA) lasers make one of these applications, which we explored as the other important area of solar utilization. 1) Daylighting simulation A lightless space with the dimension of a typical classroom at Jeju National University was modeled by ECOTECT. Two different cases were simulated and analyzed by RADIANCE. In the first case, a comparative analysis of illuminance was carried out to estimate the basic performance of sun pipe systems. In the other case, different designs of sun pipe systems were analyzed to elicit the most efficient model of operation. Simulations were performed for solar noon which indicates the time (or point) in the sun's path at which the sun is on the local meridian. Results show that indoor visual environment could be greatly enhanced with the application of sun pipe systems. The maximum illuminance took place with the sun pipe system of 1.0m in diameter and 0.5m in height. 2) Thermo-Acoustic Laser(TAL) development A series of experiments were carried out to find the most optimum operating conditions for the maximum SPL(Sound Pressure Level) and frequency of the acoustic waves generated by ThermoAcoustic(TA) lasers. Among various experimental variables, we focused our research on the stack position, stack length, length of the resonance tube and input power

Evaluation of antibacterial and antibiofilm mechanisms by usnic acid against methicillin-resistant Staphylococcus aureus.

Science.gov (United States)

Pompilio, Arianna; Riviello, Antonella; Crocetta, Valentina; Di Giuseppe, Fabrizio; Pomponio, Stefano; Sulpizio, Marilisa; Di Ilio, Carmine; Angelucci, Stefania; Barone, Luana; Di Giulio, Andrea; Di Bonaventura, Giovanni

2016-10-01

To evaluate the antibacterial and antibiofilm mechanisms of usnic acid (USN) against methicillin-resistant Staphylococcus aureus from cystic fibrosis patients. The effects exerted by USN at subinhibitory concentrations on S. aureus Sa3 strain was evaluated by proteomic, real-time PCR and electron microscopy analyses. Proteomic analysis showed that USN caused damage in peptidoglycan synthesis, as confirmed by microscopy. Real-time PCR analysis showed that antibiofilm activity of USN is mainly due to impaired adhesion to the host matrix binding proteins, and decreasing lipase and thermonuclease expression. Our data show that USN exerts anti-staphylococcal effects through multitarget inhibitory effects, thus confirming the rationale for considering it 'lead compound' for the treatment of cystic fibrosis infections.

Concentration of rare earths ore from Pocos de Caldas - MG, Brazil

International Nuclear Information System (INIS)

Sampaio, J.A.; Lins, F.F.; Porphirio, N.H.

1990-01-01

The objective of this research was to concentrate, mainly by flotation, a rare-earth ore body. The valuable mineral is bastnaesite which occurs intimately associated with iron oxides and other gangue minerals, making difficult to get a concentrate of commercial grade. The use of oleic acid at a pulp temperature of -80 sup(0)C gave a concentrate of 23% rare-earth oxides at 72% overall recovery. The magnetic separation could enhance the grade of the flotation feed. (author)

Platelet concentrates: Bioengineering dentistry′s regenerative dreams

Directory of Open Access Journals (Sweden)

Sushma Naag

2015-01-01

Full Text Available Technological advances in the fields of medicine and allied sciences had given much needed momentum into the field of molecular biology and regenerative medicine. They indeed provided a boost to innovate new yields for both hard tissue and soft tissue regeneration in dentistry. One among them is the use of platelet concentrates (platelet rich plasma [PRP], platelet rich fibrin [PRF]. Autologous concentrate of blood platelets with a suspension of growth factors offers an enhanced healing of hard and soft tissues. It is an auxiliary benefit for an operator to be aware of platelet concentrates and its healing properties for delivering unsurpassed oral health care to patients. The current article outlines the principles, objectives and clinical insight to the regenerative potential of platelet concentrates in various fields of dentistry. The search words of the PubMed data base were PRF and other permutations of keywords such as "PRP dentistry", PRF dentistry, PRF regenerative dentistry.

Use of enhanced nisin derivatives in combination with food-grade oils or citric acid to control Cronobacter sakazakii and Escherichia coli O157:H7.

Science.gov (United States)

Campion, Alicia; Morrissey, Ruth; Field, Des; Cotter, Paul D; Hill, Colin; Ross, R Paul

2017-08-01

Cronobacter sakazakii and Escherichia coli O157:H7 are well known food-borne pathogens that can cause severe disease. The identification of new alternatives to heating to control these pathogens in foods, while reducing the impact on organoleptic properties and nutritional value, is highly desirable. In this study, nisin and its bioengineered variants, nisin V and nisin S29A, are used alone, or in combination with plant essential oils (thymol, carvacrol and trans-cinnamaldehyde) or citric acid, with a view to controlling C. sakazakii and E. coli O157:H7 in laboratory-based assays and model food systems. The use of nisin variants (30 μM) with low concentrations of thymol (0.015%), carvacrol (0.03%) and trans-cinnamaldehyde (0.035%) resulted in extended lag phases of growth compared to those for corresponding nisin A-essential oil combinations. Furthermore, nisin variants (60 μM) used in combination with carvacrol (0.03%) significantly reduced viable counts of E. coli O157:H7 (3-log) and C. sakazakii (4-log) compared to nisin A-carvacrol treatment. Importantly, this increased effectiveness translated into food. More specifically, sub-inhibitory concentrations of nisin variants and carvacrol caused complete inactivation of E. coli O157:H7 in apple juice within 3 h at room temperature compared to that of the equivalent nisin A combination. Furthermore, combinations of commercial Nisaplin and the food additive citric acid reduced C. sakazakii numbers markedly in infant formula within the same 3 h period. These results highlight the potential benefits of combining nisin and variants thereof with carvacrol and/or citric acid for the inhibition of Gram negative food-borne pathogens. Copyright © 2017 Elsevier Ltd. All rights reserved.

Diverse modulation of spa transcription by cell wall active antibiotics in Staphylococcus aureus

DEFF Research Database (Denmark)

Nielsen, Lene Nørby; Roggenbuck, Michael; Haaber, Jakob Krause

2012-01-01

ABSTRACT: BACKGROUND: The aim of this study was to investigate the effect of various classes of clinically relevant antibiotics at sub-lethal concentrations on virulence gene expression and biofilm formation in Staphylococcus aureus. FINDINGS: LacZ promoter fusions of genes related to staphylococ......ABSTRACT: BACKGROUND: The aim of this study was to investigate the effect of various classes of clinically relevant antibiotics at sub-lethal concentrations on virulence gene expression and biofilm formation in Staphylococcus aureus. FINDINGS: LacZ promoter fusions of genes related...... to staphylococcal virulence were used to monitor the effects of antibiotics on gene expression in a disc diffusion assay. The selected genes were hla and spa encoding alpha-hemolysin and Protein A, respectively and RNAIII, the effector molecule of the agr quorum sensing system. The results were confirmed...... by quantitative real-time PCR. Additionally, we monitored the effect of subinhibitory concentrations of antibiotics on the ability of S. aureus to form biofilm in a microtiter plate assay. The results show that sub-lethal antibiotic concentrations diversely modulate expression of RNAIII, hla and spa. Consistently...

Optimization of Rice Bran Fermentation Conditions Enhanced by ...

African Journals Online (AJOL)

The rice bran fermentation conditions for extraction of protein concentrate was enhanced by the use of baker's yeast at optimized conditions using response surface methodology (RSM). A central composite design with three independent variables: fermentation temperature (25 to 35oC), yeast concentration (1 to 5%) and ...

Combined radiation-protective and radiation-sensitizing agents. IV. Measurement of intracellular protector concentrations

International Nuclear Information System (INIS)

Koch, C.J.; Stobbe, C.C.; Hettiaratchi, P.

1989-01-01

Radiosensitization of hypoxic V79 Chinese hamster cells by 0.5 mM misonidazole at approximately 0-4 degrees C is substantially enhanced by pretreating the cells overnight with 0.1 mM buthionine sulfoximine, which lowers the cellular glutathione content to 5% of control values (from 4 mM to approximately 0.2 mM). The enhanced sensitization is reversed by concentrations of exogenous cysteine that are much lower (0.02 mM) than the original glutathione content. Reduced Co-enzyme A affords reversal of the enhancing effect at concentrations of about 1 mM. Sodium ascorbate gives no protection at all even at concentrations of 2 mM. The intracellular concentration of the reducing agents was measured using a spin-through oil technique. There was no diffusion of Co-A (MW greater than 750) or ascorbate (excluded by charge) into the cells. In contrast, cysteine was rapidly concentrated by factors of 4-10, even at the low temperatures used. Extracellular ascorbate's inability to radioprotect argues against electron transfer across the cell membrane as a mechanism for radioprotection. This mechanism could have explained the ability of exogenous thiols to radioprotect in former studies using glutathione, and in the present studies using Co-A. The potential of cysteine to be concentrated by cells poses a problem in the interpretation of exogenous protection by non-diffusing thiols, since trace contamination by cysteine could lead to the actual protection observed. Cysteine could also be formed by exchange reactions of exogenous thiols with the disulfide of cysteine, present in all media formulations

Effect of enterocin AS-48 in combination with biocides on planktonic and sessile Listeria monocytogenes.

Science.gov (United States)

Gómez, Natacha Caballero; Abriouel, Hikmate; Grande, M A José; Pulido, Rubén Pérez; Gálvez, Antonio

2012-05-01

Enterocin AS-48 was tested on a cocktail of Listeria monocytogenes strains in planktonic and sessile states, singly or in combination with biocides benzalkonium chloride, cetrimide, hexadecylpyridinium chloride, didecyldimethylammonium bromide, triclosan, poly-(hexamethylen guanidinium) hydrochloride, chlorhexidine, hexachlorophene, and the commercial sanitizers P3 oxonia and P3 topax 66. Combinations of sub-inhibitory bacteriocin concentrations and biocide concentrations 4 to 10-fold lower than their minimum inhibitory concentrations (MIC) completely inhibited growth of the planktonic listeriae. Inactivation of Listeria in biofilms formed on polystyrene microtiter plates required concentrations of enterocin AS-48 greater than 50 μg/ml, and biocide concentrations ten to 100-fold higher. In combination with enterocin AS-48 (25 or 50 μg/ml), microbial inactivation increased remarkably for all biocides except P3 oxonia and P3 topax 66 solutions. Polystyrene microtiter plates conditioned with enterocin solutions (0.5-25 μg/ml) decreased the adherence and biofilm formation of the L. monocytogenes cell cocktail, avoiding biofilm formation for at least 24 h at a bacteriocin concentration of 25 μg/ml. Copyright © 2011 Elsevier Ltd. All rights reserved.

Salt at concentrations relevant to meat processing enhances Shiga toxin 2 production in Escherichia coli O157:H7.

Science.gov (United States)

Harris, Shaun M; Yue, Wan-Fu; Olsen, Sarena A; Hu, Jia; Means, Warrie J; McCormick, Richard J; Du, Min; Zhu, Mei-Jun

2012-10-15

Escherichia coli (E. coli) O157:H7 remains a major food safety concern associated with meat, especially beef products. Shiga toxins (Stx) are key virulence factors produced by E. coli O157:H7 that are responsible for hemorrhagic colitis and Hemolytic Uremic Syndrome. Stx are heat stable and can be absorbed after oral ingestion. Despite the extensive study of E. coli O157:H7 survival during meat processing, little attention is paid to the production of Stx during meat processing. The objective of this study was to elucidate the effect of salt, an essential additive to processed meat, at concentrations relevant to meat processing (0%, 1%, 2%, 3%, W/V) on Stx2 production and Stx2 prophage induction by E. coli O157:H7 strains. For both E. coli O157:H7 86-24 and EDL933 strains, including 2% salt in LB broth decreased (Pmeat processing enhances Stx production, a process linked to bacterial stress response and lambdoid prophage induction. Published by Elsevier B.V.

Illumination uniformity issue explored via two-stage solar concentrator system based on Fresnel lens and compound flat concentrator

International Nuclear Information System (INIS)

Yeh, Naichia

2016-01-01

This paper illustrates details about the solar radiation distribution on the target of a two-stage solar concentrator that combines the Fresnel lens (FL) and the compound flat concentrator (CFC). The paper starts with a review of some FL development milestones such as the two-stage systems and the comparisons of flat vs. curved lenses in addition to the most noteworthy FL-based solar energy application, concentration photovoltaic (CPV). Through the review of the FL based CPV and two-stage concentrators, this study leads to the development of an algorithm to explore the spectrum distribution insight on the receiver of a two-stage (FL plus CFC) solar concentration system. It established the potential for using a correctly positioned 2nd stage reflector of right dimension to selectively redirect the desired spectrum on the target area so as to enhance the concentration flux intensity and uniformity at the same time. The study also helped to chart out the approximate locations of certain spectrum segments on the FL's target area, which is useful for exploring the spectrum control mechanism via the Fresnel lenses. - Highlights: • Map out the approximate locations of spectrum segments on FL's focal area. • Use the 2nd stage reflector to selectively reflect the desired spectrum on target. • Explore the spectrum distribution insight on FL solar concentrators' target area.

Identification of an algal carbon fixation-enhancing factor extracted from Paramecium bursaria.

Science.gov (United States)

Kato, Yutaka; Imamura, Nobutaka

2011-01-01

The green ciliate Paramecium bursaria contains several hundred symbiotic Chlorella species. We previously reported that symbiotic algal carbon fixation is enhanced by P. bursaria extracts and that the enhancing factor is a heat-stable, low-molecular-weight, water-soluble compound. To identify the factor, further experiments were carried out. The enhancing activity remained even when organic compounds in the extract were completely combusted at 700 degrees C, suggesting that the factor is an inorganic substance. Measurement of the major cations, K+, Ca2+, and Mg2+, by an electrode and titration of the extract resulted in concentrations of 0.90 mM, 0.55 mM, and 0.21 mM, respectively. To evaluate the effect of these cations, a mixture of the cations at the measured concentrations was prepared, and symbiotic algal carbon fixation was measured in the solution. The results demonstrated that the fixation was enhanced to the same extent as with the P. bursaria extract, and thus this mixture of K+, Ca2+, and Mg2+ was concluded to be the carbon fixation-enhancing factor. There was no effect of the cation mixture on free-living C. vulgaris. Comparison of the cation concentrations of nonsymbiotic and symbiotic Paramecium extracts revealed that the concentrations of K+ and Mg2+ in nonsymbiotic Paramecium extracts were too low to enhance symbiotic algal carbon fixation, suggesting that symbiotic P. bursaria provide suitable cation conditions for photosynthesis to its symbiotic Chlorella.

Water solar distiller productivity enhancement using concentrating solar water heater and phase change material (PCM

Directory of Open Access Journals (Sweden)

Miqdam T. Chaichan

2015-03-01

Full Text Available This paper investigates usage of thermal energy storage extracted from concentrating solar heater for water distillation. Paraffin wax selected as a suitable phase change material, and it was used for storing thermal energy in two different insulated treasurers. The paraffin wax is receiving hot water from concentrating solar dish. This solar energy stored in PCM as latent heat energy. Solar energy stored in a day time with a large quantity, and some heat retrieved for later use. Water’s temperature measured in a definite interval of time. Four cases were studied: using water as storage material with and without solar tracker. Also, PCM was as thermal storage material with and without solar tracker.The system working time was increased to about 5 h with sun tracker by concentrating dish and adding PCM to the system. The system concentrating efficiency, heating efficiency, and system productivity, has increased by about 64.07%, 112.87%, and 307.54%, respectively. The system working time increased to 3 h when PCM added without sun tracker. Also, the system concentrating efficiency increased by about 50.47%, and the system heating efficiency increased by about 41.63%. Moreover, the system productivity increased by about 180%.

Three-dimensional hybrid silicon nanostructures for surface enhanced Raman spectroscopy based molecular detection

Science.gov (United States)

Vendamani, V. S.; Nageswara Rao, S. V. S.; Venugopal Rao, S.; Kanjilal, D.; Pathak, A. P.

2018-01-01

Three-dimensional silver nanoparticles decorated vertically aligned Si nanowires (Si NWs) are effective surface-enhanced Raman spectroscopy (SERS) substrates for molecular detection at low concentration levels. The length of Si NWs prepared by silver assisted electroless etching is increased with an increase in etching time, which resulted in the reduced optical reflection in the visible region. These substrates were tested and optimized by measuring the Raman spectrum of standard dye Rhodamine 6G (R6G) of 10 nM concentration. Further, effective SERS enhancements of ˜105 and ˜104 were observed for the cytosine protein (concentration of 50 μM) and ammonium perchlorate (oxidizer used in explosives composition with a concentration of 10 μM), respectively. It is established that these three-dimensional SERS substrates yielded considerably higher enhancement factors for the detection of R6G when compared to previous reports. The sensitivity can further be increased and optimized since the Raman enhancement was found to increase with an increase in the density of silver nanoparticles decorated on the walls of Si NWs.

Biochemically enhanced oil recovery and oil treatment

Science.gov (United States)

Premuzic, Eugene T.; Lin, Mow

1994-01-01

This invention relates to the preparation of new, modified organisms, through challenge growth processes, that are viable in the extreme temperature, pressure and pH conditions and salt concentrations of an oil reservoir and that are suitable for use in microbial enhanced oil recovery. The modified microorganisms of the present invention are used to enhance oil recovery and remove sulfur compounds and metals from the crude oil.

Fiber Bragg Grating Sensor for Detection of Nitrate Concentration in Water

Directory of Open Access Journals (Sweden)

A. S. LALASANGI

2011-02-01

Full Text Available The concentrations of chemical species in drinking water are of great interest. We demonstrated etched fiber Bragg grating (FBG as a concentration sensor for nitrate by analyzing the Bragg wavelength shift with concentration of chemical solution. The FBG is fabricated by phase mask technique on single mode Ge-B co-doped photosensitive fiber. Sensitivity of FBGs to the surrounding solution concentration can be enhanced by reducing diameter of the cladding with 40 % HF solution. The maximum sensitivity achieved is 1.322 ´ 10-3 nm/ppm. The overall shift of Bragg wavelength is of the order of 6.611 ´ 10-2 nm for 10 to 50 ppm concentration.

Use of high concentration contrast media (HCCM): principles and rationale--body CT

International Nuclear Information System (INIS)

Brink, James A.

2003-01-01

Numerous complex pharmacokinetic interrelationships affect the use of contrast media for computed tomography (CT) imaging. The volume, concentration, and rate of injection, all affect the degree of enhancement that is achieved with an injection of contrast material. In addition, the injection technique, whether the contrast is infused with a constant injection rate (uniphasic injection) or whether the rate is altered during the injection (multiphasic injection) also affect the magnitude and duration of contrast enhancement. In body CT imaging, the liver poses unique challenges in managing the use of intravenous contrast material because of its dual blood supply and the need to complete imaging before equilibrium occurs between the intravascular and extravascular compartments. The magnitude of hepatic enhancement that is ultimately achieved is related primarily to the amount of iodinated contrast material that accumulates in the extravascular space within the target organ, independent of the speed of the CT scanner. The key determinant of the onset of the equilibrium phase is the injection duration. Given that a high injection flow rate (4-5 ml/s) is desirable for arterial phase imaging, the injection duration is maintained with use of an appropriate contrast volume. Thus, modifications of total iodine dose are best done with alterations in contrast concentration. The magnitude of arterial enhancement that is achieved is related to both the concentration and rate of contrast administration. The speed of the scanner determines its ability to record image data during the most advantageous time period, the peak of arterial enhancement. Thus, rapid imaging is particularly advantageous for optimal contrast use in CT angiography as well as in multiphasic imaging of the parenchymal organs

Sonophoresis Using Ultrasound Contrast Agents: Dependence on Concentration.

Directory of Open Access Journals (Sweden)

Donghee Park

Full Text Available Sonophoresis can increase skin permeability to various drugs in transdermal drug delivery. Cavitation is recognized as the predominant mechanism of sonophoresis. Recently, a new logical approach to enhance the efficiency of transdermal drug delivery was tried. It is to utilize the engineered microbubble and its resonant frequency for increase of cavitation activity. Actively-induced cavitation with low-intensity ultrasound (less than ~1 MPa causes disordering of the lipid bilayers and the formation of aqueous channels by stable cavitation which indicates a continuous oscillation of bubbles. Furthermore, the mutual interactions of microbubble determined by concentration of added bubble are also thought to be an important factor for activity of stable cavitation, even in different characteristics of drug. In the present study, we addressed the dependence of ultrasound contrast agent concentration using two types of drug on the efficiency of transdermal drug delivery. Two types of experiment were designed to quantitatively evaluate the efficiency of transdermal drug delivery according to ultrasound contrast agent concentration. First, an experiment of optical clearing using a tissue optical clearing agent was designed to assess the efficiency of sonophoresis with ultrasound contrast agents. Second, a Franz diffusion cell with ferulic acid was used to quantitatively determine the amount of drug delivered to the skin sample by sonophoresis with ultrasound contrast agents. The maximum enhancement ratio of sonophoresis with a concentration of 1:1,000 was approximately 3.1 times greater than that in the ultrasound group without ultrasound contrast agent and approximately 7.5 times greater than that in the control group. These results support our hypothesis that sonophoresis becomes more effective in transdermal drug delivery due to the presence of engineered bubbles, and that the efficiency of transdermal drug delivery using sonophoresis with

Sonophoresis Using Ultrasound Contrast Agents: Dependence on Concentration.

Science.gov (United States)

Park, Donghee; Song, Gillsoo; Jo, Yongjun; Won, Jongho; Son, Taeyoon; Cha, Ohrum; Kim, Jinho; Jung, Byungjo; Park, Hyunjin; Kim, Chul-Woo; Seo, Jongbum

2016-01-01

Sonophoresis can increase skin permeability to various drugs in transdermal drug delivery. Cavitation is recognized as the predominant mechanism of sonophoresis. Recently, a new logical approach to enhance the efficiency of transdermal drug delivery was tried. It is to utilize the engineered microbubble and its resonant frequency for increase of cavitation activity. Actively-induced cavitation with low-intensity ultrasound (less than ~1 MPa) causes disordering of the lipid bilayers and the formation of aqueous channels by stable cavitation which indicates a continuous oscillation of bubbles. Furthermore, the mutual interactions of microbubble determined by concentration of added bubble are also thought to be an important factor for activity of stable cavitation, even in different characteristics of drug. In the present study, we addressed the dependence of ultrasound contrast agent concentration using two types of drug on the efficiency of transdermal drug delivery. Two types of experiment were designed to quantitatively evaluate the efficiency of transdermal drug delivery according to ultrasound contrast agent concentration. First, an experiment of optical clearing using a tissue optical clearing agent was designed to assess the efficiency of sonophoresis with ultrasound contrast agents. Second, a Franz diffusion cell with ferulic acid was used to quantitatively determine the amount of drug delivered to the skin sample by sonophoresis with ultrasound contrast agents. The maximum enhancement ratio of sonophoresis with a concentration of 1:1,000 was approximately 3.1 times greater than that in the ultrasound group without ultrasound contrast agent and approximately 7.5 times greater than that in the control group. These results support our hypothesis that sonophoresis becomes more effective in transdermal drug delivery due to the presence of engineered bubbles, and that the efficiency of transdermal drug delivery using sonophoresis with microbubbles depends on the

Study on Enhancement Principle and Stabilization for the Luminol-H2O2-HRP Chemiluminescence System.

Directory of Open Access Journals (Sweden)

Lihua Yang

Full Text Available A luminol-H2O2-HRP chemiluminescence system with high relative luminescent intensity (RLU and long stabilization time was investigated. First, the comparative study on the enhancement effect of ten compounds as enhancers to the luminol-H2O2-HRP chemiluminescence system was carried out, and the results showed that 4-(imidazol-1-ylphenol (4-IMP, 4-iodophenol (4-IOP, 4-bromophenol (4-BOP and 4-hydroxy-4'-iodobiphenyl (HIOP had the best performance. Based on the experiment, the four enhancers were dissolved in acetone, acetonitrile, methanol, and dimethylformamide (DMF with various concentrations, the results indicated that 4-IMP, 4-IOP, 4-BOP and HIOP dissolved in DMF with the concentrations of 0.2%, 3.2%, 1.6% and 3.2% could get the highest RLU values. Subsequently, the influences of pH, ionic strength, HRP, 4-IMP, 4-IOP, 4-BOP, HIOP, H2O2 and luminol on the stabilization of the luminol-H2O2-HRP chemiluminescence system were studied, and we found that pH value, ionic strength, 4-IMP, 4-IOP, 4-BOP, HIOP, H2O2 and luminol have little influence on luminescent stabilization, while HRP has a great influence. In different ranges of HRP concentration, different enhancers should be selected. When the concentration is within the range of 0~6 ng/mL, 4-IMP should be selected. When the concentration of HRP ranges from 6 to 25 ng/mL, 4-IOP was the best choice. And when the concentration is within the range of 25~80 ng/mL, HIOP should be selected as the enhancer. Finally, the three well-performing chemiluminescent enhanced solutions (CESs have been further optimized according to the three enhancers (4-IMP, 4-IOP and HIOP in their utilized HRP concentration ranges.

Comparative cardiopulmonary effects of particulate matter- and ozone-enhanced smog atmospheres in mice

Science.gov (United States)

This study was conducted to compare the cardiac effects of particulate matter (PM)-enhanced and ozone(O3)-enhanced smog atmospheres in mice. We hypothesized that O3-enhanced smog would cause greater cardiac dysfunction than PM-enhanced smog due to the higher concentrations of irr...

A Defensin from the Model Beetle Tribolium castaneum Acts Synergistically with Telavancin and Daptomycin against Multidrug Resistant Staphylococcus aureus.

Science.gov (United States)

Rajamuthiah, Rajmohan; Jayamani, Elamparithi; Conery, Annie L; Fuchs, Beth Burgwyn; Kim, Wooseong; Johnston, Tatiana; Vilcinskas, Andreas; Ausubel, Frederick M; Mylonakis, Eleftherios

2015-01-01

The red flour beetle Tribolium castaneum is a common insect pest and has been established as a model beetle to study insect development and immunity. This study demonstrates that defensin 1 from T. castaneum displays in vitro and in vivo antimicrobial activity against drug resistant Staphylococcus aureus strains. The minimum inhibitory concentration (MIC) of defensin 1 against 11 reference and clinical staphylococcal isolates was between 16-64 μg/ml. The putative mode of action of the defensin peptide is disruption of the bacterial cell membrane. The antibacterial activity of defensin 1 was attenuated by salt concentrations of 1.56 mM and 25 mM for NaCl and CaCl2 respectively. Treatment of defensin 1 with the reducing agent dithiothreitol (DTT) at concentrations 1.56 to 3.13 mM abolished the antimicrobial activity of the peptide. In the presence of subinhibitory concentrations of antibiotics that also target the bacterial cell envelope such as telavancin and daptomycin, the MIC of the peptide was as low as 1 μg/ml. Moreover, when tested against an S. aureus strain that was defective in D-alanylation of the cell wall, the MIC of the peptide was 0.5 μg/ml. Defensin 1 exhibited no toxicity against human erythrocytes even at 400 μg/ml. The in vivo activity of the peptide was validated in a Caenorhabditis elegans-MRSA liquid infection assay. These results suggest that defensin 1 behaves similarly to other cationic AMPs in its mode of action against S. aureus and that the activity of the peptide can be enhanced in combination with other antibiotics with similar modes of action or with compounds that have the ability to decrease D-alanylation of the bacterial cell wall.

A Defensin from the Model Beetle Tribolium castaneum Acts Synergistically with Telavancin and Daptomycin against Multidrug Resistant Staphylococcus aureus.

Directory of Open Access Journals (Sweden)

Rajmohan Rajamuthiah

Full Text Available The red flour beetle Tribolium castaneum is a common insect pest and has been established as a model beetle to study insect development and immunity. This study demonstrates that defensin 1 from T. castaneum displays in vitro and in vivo antimicrobial activity against drug resistant Staphylococcus aureus strains. The minimum inhibitory concentration (MIC of defensin 1 against 11 reference and clinical staphylococcal isolates was between 16-64 μg/ml. The putative mode of action of the defensin peptide is disruption of the bacterial cell membrane. The antibacterial activity of defensin 1 was attenuated by salt concentrations of 1.56 mM and 25 mM for NaCl and CaCl2 respectively. Treatment of defensin 1 with the reducing agent dithiothreitol (DTT at concentrations 1.56 to 3.13 mM abolished the antimicrobial activity of the peptide. In the presence of subinhibitory concentrations of antibiotics that also target the bacterial cell envelope such as telavancin and daptomycin, the MIC of the peptide was as low as 1 μg/ml. Moreover, when tested against an S. aureus strain that was defective in D-alanylation of the cell wall, the MIC of the peptide was 0.5 μg/ml. Defensin 1 exhibited no toxicity against human erythrocytes even at 400 μg/ml. The in vivo activity of the peptide was validated in a Caenorhabditis elegans-MRSA liquid infection assay. These results suggest that defensin 1 behaves similarly to other cationic AMPs in its mode of action against S. aureus and that the activity of the peptide can be enhanced in combination with other antibiotics with similar modes of action or with compounds that have the ability to decrease D-alanylation of the bacterial cell wall.

Microbial based strategies for assessing rhizosphere-enhanced phytoremediation

Energy Technology Data Exchange (ETDEWEB)

Reynolds, C M [US Army Cold Regions Research and Engineering Lab., Hanover, NH (United States); Wolf, D C [Arkansas Univ., Fayetteville, AR (United States)

1999-01-01

The U.S. Department of Defense has considered phytoremediation to be a feasible technology to clean up contaminated sites in remote, cold regions. In cold regions, contaminated soil treatment rates are reduced by low temperatures and short treatment seasons. One technology that overcomes these limitations is rhizosphere-enhanced biotreatment which is a low-cost, simple technology that stimulates indigenous microorganisms. A study was conducted in which rhizosphere-enhanced treatment was compared to natural attenuation at a petroleum-contaminated site in Fairbanks, Alaska. The effects of vegetation and nutrient additions on remediation of soils contaminated with both diesel and crude oil were examined. Soil total petroleum hydrocarbon (TPH) concentrations in both treatments decreased relative to the initial TPH concentrations. After 640 days of treatment, the rhizosphere treatment had significantly lower TPH concentrations. It was concluded that an improved understanding of the time-dependent relationships between contaminant concentration changes and microbial community changes, along with improved techniques to characterize microbial communities, could provide a useful tool for monitoring the functioning of phytoremediation. 25 refs., 8 figs.

Microbial based strategies for assessing rhizosphere-enhanced phytoremediation

International Nuclear Information System (INIS)

Reynolds, C.M.; Wolf, D.C.

1999-01-01

The U.S. Department of Defense has considered phytoremediation to be a feasible technology to clean up contaminated sites in remote, cold regions. In cold regions, contaminated soil treatment rates are reduced by low temperatures and short treatment seasons. One technology that overcomes these limitations is rhizosphere-enhanced biotreatment which is a low-cost, simple technology that stimulates indigenous microorganisms. A study was conducted in which rhizosphere-enhanced treatment was compared to natural attenuation at a petroleum-contaminated site in Fairbanks, Alaska. The effects of vegetation and nutrient additions on remediation of soils contaminated with both diesel and crude oil were examined. Soil total petroleum hydrocarbon (TPH) concentrations in both treatments decreased relative to the initial TPH concentrations. After 640 days of treatment, the rhizosphere treatment had significantly lower TPH concentrations. It was concluded that an improved understanding of the time-dependent relationships between contaminant concentration changes and microbial community changes, along with improved techniques to characterize microbial communities, could provide a useful tool for monitoring the functioning of phytoremediation. 25 refs., 8 figs

Enhancement of Saharan groundwater quality by reducing its fluoride concentration using different materials

KAUST Repository

Ramdani, Amina; Taleb, Safia; Benghalem, Abderazzak; Deratani, André ; Ghaffour, NorEddine

2014-01-01

According to the environmental protection regulations, fluoride concentration is considered as a substance of priority for assessment of drinking water quality to determine their impacts on the environment and public health. Saharan groundwater

Contrast agent enhanced pQCT of articular cartilage

Energy Technology Data Exchange (ETDEWEB)

Kallioniemi, A S [Department of Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland); Jurvelin, J S [Department of Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland); Nieminen, M T [Department of Diagnostic Radiology, POB 50, 90029 OYS, Oulu University Hospital, Oulu (Finland); Lammi, M J [Department of Anatomy, Institute of Biomedicine, University of Kuopio, POB 1627, 70211 Kuopio (Finland); Toeyraes, J [Department of Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland)

2007-02-21

The delayed gadolinium enhanced MRI of cartilage (dGEMRIC) technique is the only non-invasive means to estimate proteoglycan (PG) content in articular cartilage. In dGEMRIC, the anionic paramagnetic contrast agent gadopentetate distributes in inverse relation to negatively charged PGs, leading to a linear relation between T{sub 1,Gd} and spatial PG content in tissue. In the present study, for the first time, contrast agent enhanced peripheral quantitative computed tomography (pQCT) was applied, analogously to dGEMRIC, for the quantitative detection of spatial PG content in cartilage. The suitability of two anionic radiographic contrast agents, gadopentetate and ioxaglate, to detect enzymatically induced PG depletion in articular cartilage was investigated. First, the interrelationships of x-ray absorption, as measured with pQCT, and the contrast agent solution concentration were investigated. Optimal contrast agent concentrations for the following experiments were selected. Second, diffusion rates for both contrast agents were investigated in intact (n = 3) and trypsin-degraded (n 3) bovine patellar cartilage. The contrast agent concentration of the cartilaginous layer was measured prior to and 2-27 h after immersion. Optimal immersion time for the further experiments was selected. Third, the suitability of gadopentetate and ioxaglate enhanced pQCT to detect the enzymatically induced specific PG depletion was investigated by determining the contrast agent concentrations and uronic acid and water contents in digested and intact osteochondral samples (n = 16). After trypsin-induced PG loss (-70%, p < 0.05) the penetration of gadopentetate and ioxaglate increased (p < 0.05) by 34% and 48%, respectively. Gadopentetate and ioxaglate concentrations both showed strong correlation (r = -0.95, r -0.94, p < 0.01, respectively) with the uronic acid content. To conclude, contrast agent enhanced pQCT provides a technique to quantify PG content in normal and experimentally

Contrast agent enhanced pQCT of articular cartilage

Science.gov (United States)

Kallioniemi, A. S.; Jurvelin, J. S.; Nieminen, M. T.; Lammi, M. J.; Töyräs, J.

2007-02-01

The delayed gadolinium enhanced MRI of cartilage (dGEMRIC) technique is the only non-invasive means to estimate proteoglycan (PG) content in articular cartilage. In dGEMRIC, the anionic paramagnetic contrast agent gadopentetate distributes in inverse relation to negatively charged PGs, leading to a linear relation between T1,Gd and spatial PG content in tissue. In the present study, for the first time, contrast agent enhanced peripheral quantitative computed tomography (pQCT) was applied, analogously to dGEMRIC, for the quantitative detection of spatial PG content in cartilage. The suitability of two anionic radiographic contrast agents, gadopentetate and ioxaglate, to detect enzymatically induced PG depletion in articular cartilage was investigated. First, the interrelationships of x-ray absorption, as measured with pQCT, and the contrast agent solution concentration were investigated. Optimal contrast agent concentrations for the following experiments were selected. Second, diffusion rates for both contrast agents were investigated in intact (n = 3) and trypsin-degraded (n = 3) bovine patellar cartilage. The contrast agent concentration of the cartilaginous layer was measured prior to and 2-27 h after immersion. Optimal immersion time for the further experiments was selected. Third, the suitability of gadopentetate and ioxaglate enhanced pQCT to detect the enzymatically induced specific PG depletion was investigated by determining the contrast agent concentrations and uronic acid and water contents in digested and intact osteochondral samples (n = 16). After trypsin-induced PG loss (-70%, p < 0.05) the penetration of gadopentetate and ioxaglate increased (p < 0.05) by 34% and 48%, respectively. Gadopentetate and ioxaglate concentrations both showed strong correlation (r = -0.95, r = -0.94, p < 0.01, respectively) with the uronic acid content. To conclude, contrast agent enhanced pQCT provides a technique to quantify PG content in normal and experimentally

Contrast agent enhanced pQCT of articular cartilage

International Nuclear Information System (INIS)

Kallioniemi, A S; Jurvelin, J S; Nieminen, M T; Lammi, M J; Toeyraes, J

2007-01-01

The delayed gadolinium enhanced MRI of cartilage (dGEMRIC) technique is the only non-invasive means to estimate proteoglycan (PG) content in articular cartilage. In dGEMRIC, the anionic paramagnetic contrast agent gadopentetate distributes in inverse relation to negatively charged PGs, leading to a linear relation between T 1,Gd and spatial PG content in tissue. In the present study, for the first time, contrast agent enhanced peripheral quantitative computed tomography (pQCT) was applied, analogously to dGEMRIC, for the quantitative detection of spatial PG content in cartilage. The suitability of two anionic radiographic contrast agents, gadopentetate and ioxaglate, to detect enzymatically induced PG depletion in articular cartilage was investigated. First, the interrelationships of x-ray absorption, as measured with pQCT, and the contrast agent solution concentration were investigated. Optimal contrast agent concentrations for the following experiments were selected. Second, diffusion rates for both contrast agents were investigated in intact (n = 3) and trypsin-degraded (n 3) bovine patellar cartilage. The contrast agent concentration of the cartilaginous layer was measured prior to and 2-27 h after immersion. Optimal immersion time for the further experiments was selected. Third, the suitability of gadopentetate and ioxaglate enhanced pQCT to detect the enzymatically induced specific PG depletion was investigated by determining the contrast agent concentrations and uronic acid and water contents in digested and intact osteochondral samples (n = 16). After trypsin-induced PG loss (-70%, p < 0.05) the penetration of gadopentetate and ioxaglate increased (p < 0.05) by 34% and 48%, respectively. Gadopentetate and ioxaglate concentrations both showed strong correlation (r = -0.95, r -0.94, p < 0.01, respectively) with the uronic acid content. To conclude, contrast agent enhanced pQCT provides a technique to quantify PG content in normal and experimentally degraded

Synergistic enhancement in the co-gelation of salt-soluble pea proteins and whey proteins.

Science.gov (United States)

Wong, Douglas; Vasanthan, Thava; Ozimek, Lech

2013-12-15

This paper investigated the enhancement of thermal gelation properties when salt-soluble pea proteins were co-gelated with whey proteins in NaCl solutions, using different blend ratios, total protein concentrations, pH, and salt concentrations. Results showed that the thermal co-gelation of pea/whey proteins blended in ratio of 2:8 in NaCl solutions showed synergistic enhancement in storage modulus, gel hardness, paste viscosity and minimum gelation concentrations. The highest synergistic enhancement was observed at pH 6.0 as compared with pH 4.0 and 8.0, and at the lower total protein concentration of 10% as compared with 16% and 22% (w/v), as well as in lower NaCl concentrations of 0.5% and 1.0% as compared with 1.5%, 2.0%, 2.5%, and 3.0% (w/v). The least gelation concentrations were also lower in the different pea/whey protein blend ratios than in pure pea or whey proteins, when dissolved in 1.0% or 2.5% (w/v) NaCl aqueous solutions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Real-Time Monitoring of nfxB Mutant Occurrence and Dynamics in Pseudomonas aeruginosa Biofilm Exposed to Subinhibitory Concentrations of Ciprofloxacin

DEFF Research Database (Denmark)

Zaborskytė, Greta; Andersen, Jens Bo; Kragh, Kasper Nørskov

2017-01-01

Biofilm infections caused by Pseudomonas aeruginosa are frequently treated with ciprofloxacin (CIP); however, resistance rapidly develops. One of the primary resistance mechanisms is the overexpression of the MexCD-OprJ pump due to a mutation in nfxB, encoding the transcriptional repressor...

Enhanced photothermal lens using a photonic crystal surface

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yunfei; Liu, Longju [Department of Electrical and Computer Engineering, 2128 Coover Hall, Iowa State University, Ames,Iowa 50011 (United States); Zhao, Xiangwei [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering,Southeast University, Nanjing, Jiangsu 211189 (China); Lu, Meng, E-mail: menglu@iastate.edu [Department of Electrical and Computer Engineering, 2128 Coover Hall, Iowa State University, Ames,Iowa 50011 (United States); Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

2016-08-15

A photonic crystal (PC)-enhanced photothermal lens (PTL) is demonstrated for the detection of optically thin light absorption materials. The PC-enhanced PTL system is based on a pump-probe scheme consisting of a PC surface, pump laser beam, and probe laser beam. Heated by the pump beam, light absorption materials on the PC surface generate the PTL and cause a substantial change to the guided-mode resonance supported by the PC structure. The change of the PC resonance is detected using the probe laser beam by measuring its reflectivity from the PC surface. When applied to analyze dye molecules deposited on the PC substrate, the developed system is capable of enhancing the PTL signal by 10-fold and reducing the lowest distinguishable concentration by 8-fold, in comparison to measuring without utilizing the PC resonance. The PC-enhanced PTL was also used to detect gold nanoparticles on the PC surface and exhibited a 20-fold improvement of the lowest distinguishable concentration. The PC-enhanced PTL technology offers a potential tool to obtain the absorption signatures of thin films in a broad spectral range with high sensitivity and inexpensive instrumentation. As a result, this technology will enable a broad range of applications of photothermal spectroscopy in chemical analysis and biomolecule sensing.

Enhanced radiation resistant fiber optics

Science.gov (United States)

Lyons, P.B.; Looney, L.D.

1993-11-30

A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures.

Enhanced radiation resistant fiber optics

International Nuclear Information System (INIS)

Lyons, P.B.; Looney, L.D.

1993-01-01

A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures

Boron-enhanced diffusion of boron from ultralow-energy boron implantation

International Nuclear Information System (INIS)

Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C.

1998-01-01

The authors have investigated the diffusion enhancement mechanism of BED (boron enhanced diffusion), wherein the boron diffusivity is enhanced three to four times over the equilibrium diffusivity at 1,050 C in the proximity of a silicon layer containing a high boron concentration. It is shown that BED is associated with the formation of a fine-grain polycrystalline silicon boride phase within an initially amorphous Si layer having a high B concentration. For 0.5 keV B + , the threshold implantation dose which leads to BED lies between 3 x 10 14 and of 1 x 10 15 /cm -2 . Formation of the shallowest possible junctions by 0.5 keV B + requires that the implant dose be kept lower than this threshold

Investigation on physical behavior of styrene wood-polymer in different concentrations of monomer

Directory of Open Access Journals (Sweden)

maryam ghorbani

2016-09-01

Full Text Available This research was conducted to study the effect of different concentrations of styrene lumen monomer on the physical properties of beech wood. Physical test samples were prepared according to ASTM-D1037 standard and treated with vacuum-pressure method at five concentration levels; 0, 40, 60, 80 and 100 percent of soluble monomer. For polymerization, treated samples were heated in oven for two 24-hour period at 90 and 103ºC respectively. Monomer and polymer absorption, density variation, water absorption, swelling and anti-swelling efficiency (ASE were determined. According to the results, Monomer and polymer absorption were increment by monomer concentration increase, and they were reported 38.2% and 26% in highest level. With polymer absorption enhancement, density of wood increased from 0/63g/cm³ in control to 0/91g/cm³ in the highest monomer concentration level that reduces pores in wood-polymer structure. Absorbed polymer enhancement decreased hydrophilicity and dimensional changes of treated samples, so that water absorption and swelling volume of the samples saturated with 100% concentration of monomer were decreased 64% and 45.3% after the longest immersion time. Highest Anti-swelling efficiency of Styrene-saturated samples was determined 56.15% in the maximum concentration level of treatment.

Concentration Fluctuations and Capacitive Response in Dense Ionic Solutions.

Science.gov (United States)

Uralcan, Betul; Aksay, Ilhan A; Debenedetti, Pablo G; Limmer, David T

2016-07-07

We use molecular dynamics simulations in a constant potential ensemble to study the effects of solution composition on the electrochemical response of a double layer capacitor. We find that the capacitance first increases with ion concentration following its expected ideal solution behavior but decreases upon approaching a pure ionic liquid in agreement with recent experimental observations. The nonmonotonic behavior of the capacitance as a function of ion concentration results from the competition between the independent motion of solvated ions in the dilute regime and solvation fluctuations in the concentrated regime. Mirroring the capacitance, we find that the characteristic decay length of charge density correlations away from the electrode is also nonmonotonic. The correlation length first decreases with ion concentration as a result of better electrostatic screening but increases with ion concentration as a result of enhanced steric interactions. When charge fluctuations induced by correlated ion-solvent fluctuations are large relative to those induced by the pure ionic liquid, such capacitive behavior is expected to be generic.

Relation of major volcanic center concentration on Venus to global tectonic patterns

Science.gov (United States)

Crumpler, L. S.; Head, James W.; Aubele, Jayne C.

1993-01-01

Global analysis of Magellan image data indicates that a major concentration of volcanic centers covering about 40 percent of the surface of Venus occurs between the Beta, Atla, and Themis regions. Associated with this enhanced concentration are geological characteristics commonly interpreted as rifting and mantle upwelling. Interconnected low plains in an annulus around this concentration are characterized by crustal shortening and infrequent volcanic centers that may represent sites of mantle return flow and net downwelling. Together, these observations suggest the existence of relatively simple, large-scale patterns of mantle circulation similar to those associated with concentrations of intraplate volcanism on earth.

Levamisole and cocaine synergism: a prevalent adulterant enhances cocaine's action in vivo.

Science.gov (United States)

Tallarida, Christopher S; Egan, Erin; Alejo, Gissel D; Raffa, Robert; Tallarida, Ronald J; Rawls, Scott M

2014-04-01

Levamisole is estimated by the Drug Enforcement Agency (DEA) to be present in about 80% of cocaine seized in the United States and linked to debilitating, and sometimes fatal, immunologic effects in cocaine abusers. One explanation for the addition of levamisole to cocaine is that it increases the amount of product and enhances profits. An alternative possibility, and one investigated here, is that levamisole alters cocaine's action in vivo. We specifically investigated effects of levamisole on cocaine's stereotypical and place-conditioning effects in an established invertebrate (planarian) assay. Acute exposure to levamisole or cocaine produced concentration-dependent increases in stereotyped movements. For combined administration of the two agents, isobolographic analysis revealed that the observed stereotypical response was enhanced relative to the predicted effect, indicating synergism for the interaction. In conditioned place preference (CPP) experiments, cocaine produced a significant preference shift; in contrast, levamisole was ineffective at all concentrations tested. For combination experiments, a submaximal concentration of cocaine produced CPP that was enhanced by inactive concentrations of levamisole, indicating synergism. The present results provide the first experimental evidence that levamisole enhances cocaine's action in vivo. Most important is the identification of synergism for the levamisole/cocaine interaction, which now requires further study in mammals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biosurfactant and enhanced oil recovery

Science.gov (United States)

McInerney, Michael J.; Jenneman, Gary E.; Knapp, Roy M.; Menzie, Donald E.

1985-06-11

A pure culture of Bacillus licheniformis strain JF-2 (ATCC No. 39307) and a process for using said culture and the surfactant lichenysin produced thereby for the enhancement of oil recovery from subterranean formations. Lichenysin is an effective surfactant over a wide range of temperatures, pH's, salt and calcium concentrations.

Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters.

Science.gov (United States)

Kujawa-Roeleveld, K; Elmitwalli, T; Zeeman, G

2006-01-01

Anaerobic digestion of concentrated domestic wastewater streams--black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR--decentralised sanitation and reuse). A simple anaerobic digester can be implemented for an enhanced primary treatment or, in some situations, as a main treatment. Two reactor configurations were extensively studied; accumulation system (AC) and UASB septic tank at 15, 20 and 25 degrees C. Due to long retention times in an AC reactor, far stabilisation of treated medium can be accomplished with methanisation up to 60%. The AC systems are the most suitable to apply when the volume of waste to be treated is minimal and when a direct reuse of a treated medium in agriculture is possible. Digested effluent contains both liquid and solids. In a UASB septic tank, efficient separation of solids and liquid is accomplished. The total COD removal was above 80% at 25 degrees C. The effluent contains COD and nutrients, mainly in a soluble form. The frequency of excess sludge removal is low and sludge is well stabilised due to a long accumulation time.

Enhanced defects recombination in ion irradiated SiC

International Nuclear Information System (INIS)

Izzo, G.; Litrico, G.; Grassia, F.; Calcagno, L.; Foti, G.

2010-01-01

Point defects induced in SiC by ion irradiation show a recombination at temperatures as low as 320 K and this process is enhanced after running current density ranging from 80 to 120 A/cm 2 . Ion irradiation induces in SiC the formation of different defect levels and low-temperature annealing changes their concentration. Some levels (S 0 , S x and S 2 ) show a recombination and simultaneously a new level (S 1 ) is formed. An enhanced recombination of defects is besides observed after running current in the diode at room temperature. The carriers introduction reduces the S 2 trap concentration, while the remaining levels are not modified. The recombination is negligible up to a current density of 50 A/cm 2 and increases at higher current density. The enhanced recombination of the S 2 trap occurs at 300 K, which otherwise requires a 400 K annealing temperature. The process can be related to the electron-hole recombination at the associated defect.

Plasmon enhanced fluorescence with aggregated shell-isolated nanoparticles.

Science.gov (United States)

Osorio-Román, Igor O; Guerrero, Ariel R; Albella, Pablo; Aroca, Ricardo F

2014-10-21

Shell-isolated nanoparticles (SHINs) nanostructures provide a versatile substrate where the localized surface plasmon resonances (LSPRs) are well-defined. For SHINEF, the silver (or gold) metal core is protected by the SiO2 coating, which is thicker than the critical distance for minimum quenching by the metal. In the present work, it is shown that an increase in the SHINEF enhancement factor may be achieved by inducing SHIN aggregation with electrolytes in solution. The proof of concept is demonstrated using NaCl as aggregating agent, although other inorganic salts will also aggregate SHIN nanoparticles. As much as a 10-fold enhancement in the SHINEF enhancement factor (EF) may be achieved by tuning the electrolyte concentrations in solution. The SHINEF experiments include the study of the aggregation effect controlling gold SHIN's surface concentration via spraying. Au-SHINs are sprayed onto layer-by-layer (LbL) and Langmuir-Blodgett (LB) films, and samples are fabricated using fluorophores with low and also high quantum yield.

ω-Hydroxyemodin Limits Staphylococcus aureus Quorum Sensing-Mediated Pathogenesis and Inflammation

Science.gov (United States)

Daly, Seth M.; Elmore, Bradley O.; Kavanaugh, Jeffrey S.; Triplett, Kathleen D.; Figueroa, Mario; Raja, Huzefa A.; El-Elimat, Tamam; Crosby, Heidi A.; Femling, Jon K.; Cech, Nadja B.; Horswill, Alexander R.; Oberlies, Nicholas H.

2015-01-01

Antibiotic-resistant pathogens are a global health threat. Small molecules that inhibit bacterial virulence have been suggested as alternatives or adjuncts to conventional antibiotics, as they may limit pathogenesis and increase bacterial susceptibility to host killing. Staphylococcus aureus is a major cause of invasive skin and soft tissue infections (SSTIs) in both the hospital and community settings, and it is also becoming increasingly antibiotic resistant. Quorum sensing (QS) mediated by the accessory gene regulator (agr) controls virulence factor production essential for causing SSTIs. We recently identified ω-hydroxyemodin (OHM), a polyhydroxyanthraquinone isolated from solid-phase cultures of Penicillium restrictum, as a suppressor of QS and a compound sought for the further characterization of the mechanism of action. At concentrations that are nontoxic to eukaryotic cells and subinhibitory to bacterial growth, OHM prevented agr signaling by all four S. aureus agr alleles. OHM inhibited QS by direct binding to AgrA, the response regulator encoded by the agr operon, preventing the interaction of AgrA with the agr P2 promoter. Importantly, OHM was efficacious in a mouse model of S. aureus SSTI. Decreased dermonecrosis with OHM treatment was associated with enhanced bacterial clearance and reductions in inflammatory cytokine transcription and expression at the site of infection. Furthermore, OHM treatment enhanced the immune cell killing of S. aureus in vitro in an agr-dependent manner. These data suggest that bacterial disarmament through the suppression of S. aureus QS may bolster the host innate immune response and limit inflammation. PMID:25645827

Hormones and Antibiotics in Nature: A Laboratory Module Designed to Broaden Undergraduate Perspectives on Typically Human-Centered Topics

Directory of Open Access Journals (Sweden)

Carolyn F. Weber

2014-07-01

Full Text Available Bringing discovery-based research into undergraduate laboratory courses increases student motivation and learning gains over traditional exercises that merely teach technique or demonstrate well-documented phenomena. Laboratory experiences are further enhanced when they are designed to challenge student perspectives on topics relevant to their lives. To this end, a laboratory module on antibiotics and hormones, which are generally discussed in the context of human health, was developed for students to explore the multifaceted roles of antibiotics and hormones in nature (e.g. interspecies communication via reading primary scientific literature and performing discovery-based experiments. The main objective of this module was to increase the general biological literacy of students as determined by their ability to connect the Five Core Concepts of Biological Literacy (American Association for the Advancement of Science, Vision and Change in Undergraduate Education: A Call to Action, 2011 to the topics “hormones” and “antibiotics” in pre- and postmodule surveys. After discussing unpublished research findings, cell biology students performed experiments demonstrating that: 1 fungi may promote fern growth via hormone production, 2 novel bacterial isolates in the genus Streptomyces produce antifungal compounds, and 3 subinhibitory antibiotic concentrations may enhance soil bacterial growth. The third finding provided evidence supporting a hypothesis framed in a scientific article that students read and discussed. Student perspectives on premodule surveys focused on roles of hormones and antibiotics in the human body (e.g. development, fighting infection, but their broadened postmodule perspectives encompassed the roles of these molecules in organismal communication and possibly the evolution of multicellularity.

Thioridazine Induces Major Changes in Global Gene Expression and Cell Wall Composition in Methicillin-Resistant Staphylococcus aureus USA300

DEFF Research Database (Denmark)

Thorsing, Mette; Klitgaard, Janne Kudsk; Atilano, Magda L.

2013-01-01

and the transcriptomic response of S. aureus to known inhibitors of cell wall synthesis suggests that TDZ disturbs PGN biosynthesis at a stage that precedes transpeptidation by penicillin-binding proteins (PBPs). In support of this notion, dramatic changes in the muropeptide profile of USA300 were observed following....... In the present study, we have examined the effect of a subinhibitory concentration of TDZ on antimicrobial resistance, the global transcriptome, and the cell wall composition of MRSA USA300. We show that TDZ is able to sensitize the bacteria to several classes of antimicrobials targeting the late stages...... a major impact on the cell wall biosynthesis pathway in S. aureus and provides new insights into how MRSA may be sensitized towards β-lactam antibiotics....

Single Channel Analysis of Isoflurane and Ethanol Enhancement of Taurine-Activated Glycine Receptors.

Science.gov (United States)

Kirson, Dean; Todorovic, Jelena; Mihic, S John

2018-01-01

The amino acid taurine is an endogenous ligand acting on glycine receptors (GlyRs), which is released by astrocytes in many brain regions, such as the nucleus accumbens and prefrontal cortex. Taurine is a partial agonist with an efficacy significantly lower than that of glycine. Allosteric modulators such as ethanol and isoflurane produce leftward shifts of glycine concentration-response curves but have no effects at saturating glycine concentrations. In contrast, in whole-cell electrophysiology studies these modulators increase the effects of saturating taurine concentrations. A number of possible mechanisms may explain these enhancing effects, including modulator effects on conductance, channel open times, or channel closed times. We used outside-out patch-clamp single channel electrophysiology to investigate the mechanism of action of 200 mM ethanol and 0.55 mM isoflurane in enhancing the effects of a saturating concentration of taurine. Neither modulator enhanced taurine-mediated conductance. Isoflurane increased the probability of channel opening. Isoflurane also increased the lifetimes of the two shortest open dwell times while both agents decreased the likelihood of occurrence of the longest-lived intracluster channel-closing events. The mechanism of enhancement of GlyR functioning by these modulators is dependent on the efficacy of the agonist activating the receptor and the concentration of agonist tested. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

CT angiography of intracranial arterial vessels: impact of tube voltage and contrast media concentration on image quality

International Nuclear Information System (INIS)

Ramgren, Birgitta; Holtaas, Stig; Siemund, Roger; Dept. of Radiology, Lund Univ., Lund

2012-01-01

Background Computed tomography angiography (CTA) of intracranial arteries has high demands on image quality. Important parameters influencing vessel enhancement are injection rate, concentration of contrast media and tube voltage. Purpose To evaluate the impact of an increase of contrast media concentration from 300 to 400 mg iodine/mL (mgI/mL) and the effect of a decrease of tube voltage from 120 to 90 kVp on vessel attenuation and image quality in CT angiography of intracranial arteries. Material and Methods Sixty-three patients were included into three protocol groups: Group I, 300 mgI/mL 120 kVp; Group II, 400 mgI/mL 120 kVp; Group III, 400 mgI/mL 90 kVp. Hounsfield units (HU) were measured in the internal carotid artery (ICA) and the M1 and M2 segments of the middle cerebral artery. Image quality grading was performed regarding M1 and M2 segments, volume rendering and general image impression. Results The difference in mean HU in ICA concerning the effect of contrast media concentration was statistically significant (P = 0.03) in favor of higher concentration. The difference in ICA enhancement due to the effect of tube voltage was statistically significant (P < 0.01) in favor of lower tube voltage. The increase of contrast medium concentration raised the mean enhancement in ICA with 18% and the decrease of tube voltage raised the mean enhancement with 37%. Image quality grading showed a trend towards improved grading for higher contrast concentration and lower tube voltage. Statistically significant better grading was found for the combined effect of both measures except for general impression (P 0.01-0.05). Conclusion The uses of highly concentrated contrast media and low tube voltage are easily performed measures to improve image quality in CTA of intracranial vessel

Modeling of enhanced catalysis in multienzyme nanostructures: effect of molecular scaffolds, spatial organization, and concentration.

Science.gov (United States)

Roberts, Christopher C; Chang, Chia-en A

2015-01-13

Colocalized multistep enzymatic reaction pathways within biological catabolic and metabolic processes occur with high yield and specificity. Spatial organization on membranes or surfaces may be associated with increased efficiency of intermediate substrate transfer. Using a new Brownian dynamics package, GeomBD, we explored the geometric features of a surface-anchored enzyme system by parallel coarse-grained Brownian dynamics simulations of substrate diffusion over microsecond (μs) to millisecond (ms) time scales. We focused on a recently developed glucose oxidase (GOx), horseradish peroxidase (HRP), and DNA origami-scaffold enzyme system, where the H2O2 substrate of HRP is produced by GOx. The results revealed and explained a significant advantage in catalytic enhancement by optimizing interenzyme distance and orientation in the presence of the scaffold model. The planar scaffold colocalized the enzymes and provided a diffusive barrier that enhanced substrate transfer probability, becoming more relevant with increasing interenzyme distance. The results highlight the importance of protein geometry in the proper assessment of distance and orientation dependence on the probability of substrate transfer. They shed light on strategies for engineering multienzyme complexes and further investigation of enhanced catalytic efficiency for substrate diffusion between membrane-anchoring proteins.

Heat transfer enhancement on nucleate boiling

International Nuclear Information System (INIS)

Zhuang, M.; Guibai, L.

1990-01-01

This paper reports on enhancement of nucleate boiling heat transfer with additives that was investigated experimentally. More than fifteen kinds of additives were chosen and tested. Eight kinds of effective additives which can enhance nucleate boiling heat transfer were selected. Experimental results showed that boiling heat transfer coefficient of water was increased by 1 to 5 times and that of R-113 was increased by 1 to 4 times when trace amount additives were put in the two boiling liquids. There exist optimum concentrations for the additives, respectively, which can enhance nucleate boiling heat transfer rate best. In order to analyze the mechanism of the enhancement of boiling heat transfer with additives, the surface tension and the bubble departure diameter were measured. The nucleation sites were investigated by use of high-speed photograph. Experimental results showed that nucleation sites increase with additive amount increasing and get maximum. Increasing nucleation sites is one of the most important reason why nucleate boiling heat transfer can be enhanced with additives

Refractive Secondary Solar Concentrator Being Designed and Developed

Science.gov (United States)

Macosko, Robert P.; Donovan, Richard M.

1998-01-01

As the need for achieving super high temperatures (2000 K and above) in solar heat receivers has developed so has the need for secondary concentrators. These concentrators refocus the already highly concentrated solar energy provided by a primary solar collector, thereby significantly reducing the light entrance aperture of the heat receiver and the resulting infrared radiation heat loss from the receiver cavity. Although a significant amount of research and development has been done on nonimaging hollow reflective concentrators, there has been no other research or development to date on solid, single crystal, refractive concentrators that can operate at temperatures above 2000 K. The NASA Lewis Research Center recently initiated the development of single-crystal, optically clear, refractive secondary concentrators that, combined with a flux extractor, offer a number of significant advantages over the more conventional, hollow, reflective concentrators at elevated temperatures. Such concentrators could potentially provide higher throughput (efficiency), require no special cooling device, block heat receiver material boiloff from the receiver cavity, provide for flux tailoring in the cavity via the extractor, and potentially reduce infrared heat loss via an infrared block coating.The many technical challenges of designing and fabricating high-temperature refractive secondary concentrators and flux extractors include identifying optical materials that can survive the environment (high-temperature, vacuum and/or hydrogen atmosphere), developing coatings for enhanced optical and thermal performance, and developing crystal joining techniques and hardware that can survive launch loads.

Enhanced radiometric detection of Mycobacterium paratuberculosis by using filter-concentrated bovine fecal specimens

International Nuclear Information System (INIS)

Collins, M.T.; Kenefick, K.B.; Sockett, D.C.; Lambrecht, R.S.; McDonald, J.; Jorgensen, J.B.

1990-01-01

A commercial radiometric medium, BACTEC 12B, was modified by addition of mycobactin, egg yolk suspension, and antibiotics (vancomycin, amphotericin B, and nalidixic acid). Decontaminated bovine fecal specimens were filter concentrated by using 3-microns-pore-size, 13-mm-diameter polycarbonate filters, and the entire filter was placed into the radiometric broth. Comparison of the radiometric technique with conventional methods on 603 cattle from 9 Mycobacterium paratuberculosis-infected herds found that of 75 positive specimens, the radiometric technique detected 92% while conventional methods detected 60% (P less than 0.0005). Only 3.9% of radiometric cultures were contaminated. To measure the effect of filter concentration of specimens on the detection rate, 5 cattle with minimal and 5 with moderate ileum histopathology were sampled weekly for 3 weeks. M. paratuberculosis was detected in 33.3% of nonfiltered specimens and 76.7% of filtered specimens (P less than 0.005). Detection rates were directly correlated with the severity of disease, and the advantage of specimen concentration was greatest on fecal specimens from cattle with low-grade infections. Detection times were also correlated with infection severity: 13.4 +/- 5.9 days with smear-positive specimens, 27.9 +/- 8.7 days with feces from cows with typical subclinical infections, and 38.7 +/- 3.8 days with fecal specimens from cows with low-grade infections. Use of a cocktail of vancomycin, amphotericin B, and nalidixic acid for selective suppression of nonmycobacterial contaminants was better than the commercial product PANTA (Becton Dickinson Microbiologic Systems, Towson, Md.) only when specimens contained very low numbers of M. paratuberculosis

Concentration of High Level Radioactive Liquid Waste. Basic data acquisition

Energy Technology Data Exchange (ETDEWEB)

Juvenelle, A.; Masson, M.; Garrido, M.H. [DEN/VRH/DRCP/SCPS/LPCP, BP 17171 - 30207 Bagnols sur Ceze Cedex (France)

2008-07-01

Full text of publication follows: In order to enhance its knowledge about the concentration of high level liquid waste (HLLW) from the nuclear fuel reprocessing process, a program of studies was defined by Cea. In a large field of acidity, it proposes to characterize the concentrated solution and the obtained precipitates versus the concentration factor. Four steps are considered: quantification of the salting-out effect on the concentrate acidity, acquisition of solubility data, precipitates characterisation versus the concentration factor through aging tests and concentration experimentation starting from simulated fission products solutions. The first results, reported here, connect the acidity of the concentrated solution to the concentration factor and allow us to precise the field of acidity (4 to 12 N) for the next experiments. In this field, solubility data of various elements (Ba, Sr, Zr...) are separately measured at room temperature, in nitric acid in a first time, then in the presence of various species present in medium (TBP, PO{sub 4}{sup 3-}). The reactions between these various elements are then investigated (formation of insoluble mixed compounds) by following the concentration cations in solution and characterising the precipitates. (authors)

Coupling of Luminescent Solar Concentrators to Plasmonic Solar Cells

Science.gov (United States)

Wang, Shu-Yi

To make inexpensive solar cells is a continuous goal for solar photovoltaic (PV) energy industry. Thin film solar cells of various materials have been developed and continue to emerge in order to replace bulk silicon solar cells. A thin film solar cell not only uses less material but also requires a less expensive refinery process. In addition, other advantages coming along with small thickness are higher open circuit voltage and higher conversion efficiency. However, thin film solar cells, especially those made of silicon, have significant optical losses. In order to address this problem, this thesis investigates the spectral coupling of thin films PV to luminescent solar concentrators (LSC). LSC are passive devices, consisting of plastic sheets embedded with fluorescent dyes which absorb part of the incoming radiation spectrum and emit at specific wavelength. The emitted light is concentrated by total internal reflection to the edge of the sheet, where the PVs are placed. Since the light emitted from the LSC edge is usually in a narrow spectral range, it is possible to employ diverse strategies to enhance PV absorption at the peak of the emission wavelength. Employing plasmonic nanostructures has been shown to enhance absorption of thin films via forward scattering, diffraction and localized surface plasmon. These two strategies are theoretically investigated here for improving the absorption and elevating the output power of a thin film solar cell. First, the idea of spectral coupling of luminescent solar concentrators to plasmonic solar cells is introduced to assess its potential for increasing the power output. This study is carried out employing P3HT/PC60BM organic solar cells and LSC with Lumogen Red dyes. A simplified spectral coupling analysis is employed to predict the power density, considering the output spectrum of the LSC equivalent to the emission spectrum of the dye and neglecting any angular dependence. Plasmonic tuning is conducted to enhance

Heat transfer enhancement of car radiator using aqua based magnesium oxide nanofluids

OpenAIRE

Ali Hafiz Muhammad; Azhar Muhammad Danish; Saleem Musab; Saeed Qazi Samie; Saieed Ahmed

2015-01-01

The focus of this research paper is on the application of water based MgO nanofluids for thermal management of a car radiator. Nanofluids of different volumetric concentrations (i.e. 0.06%, 0.09% and 0.12%) were prepared and then experimentally tested for their heat transfer performance in a car radiator. All concentrations showed enhancement in heat transfer compared to the pure base fluid. A peak heat transfer enhancement of 31% was obtained at 0.12 % vol...

A Comparison of the Use of Contrast Media with Different Iodine Concentrations for Multidetector CT of the Kidney

Energy Technology Data Exchange (ETDEWEB)

Jung, Seung Chai; Kim, Seung Hyup; Cho, Jeong Yeon [Seoul National University College of Medicine, Seoul (Korea, Republic of)

2011-11-15

To determine the optimal iodine concentration of contrast media for kidney multidetector computed tomography (MDCT) by comparing the degree of renal parenchymal enhancement and the severity of the renal streak artifact with contrast media of different iodine concentrations. A 16-row MDCT was performed in 15 sedated rabbits by injection of 2 mL contrast media/kg body weight at a rate of 0.3 mL/sec. Monomeric nonionic contrast media of 250, 300, and 370 mg iodine/mL were injected at 1-week intervals. Mean attenuation values were measured in each renal structure with attenuation differences among the structures. The artifact was evaluated by CT window width/level and three grading methods. The values were compared with iodine concentrations. The 370 mg iodine/mL concentration showed significantly higher cortical enhancement than 250 mg iodine/mL in all phases (p < 0.05). There was however no significant difference in the degree of enhancement between the 300 mg iodine/mL and 370 mg iodine/mL concentrations in all phases. There is a significant difference in attenuation for the cortex-outer medulla between 250 mg iodine/mL and 300 mg iodine/mL (p < 0.05). The artifact was more severe with a medium of 370 mg iodine/mL than with 250 mg iodine/mL by all grading methods (p < 0.05). The 300 mg iodine/mL is considered to be the most appropriate iodine concentration in an aspect of the enhancement and artifact on a kidney MDCT scan.

An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

Science.gov (United States)

Cox, Georgina; Koteva, Kalinka; Wright, Gerard D.

2014-01-01

Objectives An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. Methods E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. Results The anthracycline Antibiotic 301A1 was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure–activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A1 abolishes activity. Conclusions Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. PMID:24627312

Microfabricated ratchet structures for concentrating and patterning motile bacterial cells

International Nuclear Information System (INIS)

Kim, Sang Yub; Lee, Eun Se; Lee, Ho Jae; Lee, Se Yeon; Lee, Sung Kuk; Kim, Taesung

2010-01-01

We present a novel microfabricated concentrator for Escherichia coli that can be a stand-alone and self-contained microfluidic device because it utilizes the motility of cells. First of all, we characterize the motility of E. coli cells and various ratcheting structures that can guide cells to move in a desired direction in straight and circular channels. Then, we combine these ratcheting microstructures with the intrinsic tendency of cells to swim on the right side in microchannels to enhance the concentration rates up to 180 fold until the concentrators are fully filled with cells. Furthermore, we demonstrate that cells can be positioned and concentrated with a constant spacing distance on a surface, allowing spatial patterning of motile cells. These results can be applied to biosorption or biosensor devices that are powered by motile cells because they can be highly concentrated without any external mechanical and electrical energy sources. Hence, we believe that the concentrator design holds considerable potential to be applied for concentrating and patterning other motile microbes and providing a versatile structure for motility study of bacterial cells.

Enhancement of electrical conductivity in the Gum Arabica complex

International Nuclear Information System (INIS)

Pradhan, Sourav S.; Sarkar, A.

2009-01-01

Gum Arabica is a natural biopolymer obtained from plant Acacia Arabica. In this present study the electro-active nature of its complex has been investigated. The complexes were developed using pure Gum Arabica and pure Citric acid by the sol-gel process. The scope of complex formation has been investigated and their natures were examined experimentally. The experiments which were carried out in this work are namely d.c V-I characteristics, d.c Arrhenius, ion transference number measurement, UV-VIS and IR photo-absorption. Solid specimen of the complex at various concentration of Citric acid has been developed for d.c experiments and adequate specimens were also developed for UV-VIS experiment. The result of d.c V-I characteristics on specimens at different Citric acid concentrations shows that d.c conductivity increases with concentration of the acid. The said enhancement is observed to be about 100 times that of pure hosts. The ion transference number measurement shows that the total conductivity increases with external acid concentration of which d.c conductivity enhance many times compared to that of ionic part. The result from d.c Arrhenius study shows that electro-thermal activation energy decreases with increasing acid concentration leading to enhancement of electronic conductivity of the complex. The result of UV-VIS study confirms the formation of the acid complex of Gum Arabica. The nature of photo-absorption indicates very clearly that main absorption region shows gradual shifts towards longer wavelength with increase of acid concentration. The result of FTIR absorption shows the structural concepts of electro-activity and complex formation indication of pure Gum Arabica. The overall analysis shows that the electro-activity of the mentioned biopolymer may be tailored.

Microwave enhanced digestion of aerobic SBR sludge | Kennedy ...

African Journals Online (AJOL)

MWs) for improving characteristics of aerobic sequencing batch reactor (SBR) sludge to enhance mesophilic anaerobic digestion. Effects of pretreatment temperature, MW irradiation intensity and solids concentration on sludge characterisation ...

EDDS and EDTA-enhanced phytoextraction of metals from artificially contaminated soil and residual effects of chelant compounds

Energy Technology Data Exchange (ETDEWEB)

Luo Chunling [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Shen Zhenguo [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); College of Life Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Lou Laiqing [College of Life Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Li Xiangdong [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)]. E-mail: cexdli@polyu.edu.hk

2006-12-15

The potential of 18 different plants to be used in the chemically enhanced phytoextraction of Cu, Pb, Zn and Cd was assessed using pot experiments. Chrysanthemum coronarium L. was the species most sensitive to the application of EDTA, and had the highest enhancement of Cu and Pb concentrations in its shoots. Compared with EDTA, EDDS was more effective in enhancing the concentration of Cu in the shoots of Chrysanthemum coronarium L. and Zea mays L. grown on multi-metal contaminated soils. The EDTA-treated soil still had a significant ability to enhance the concentrations of Cu and Pb in the shoots of Zea mays L. six months after the chelant treatment. However, the EDDS-treated soil did not have any effect in enhancing the concentrations of metals in the shoots of Zea mays L. in the second crop test. The results may indicate that EDDS biodegrades more rapidly than EDTA in soil and is better in limiting potential metal leaching. - Chrysanthemum coronarium L. was the most sensitive species to the application of chelants, and EDDS biodegrades much more rapidly than EDTA in soil.

EDDS and EDTA-enhanced phytoextraction of metals from artificially contaminated soil and residual effects of chelant compounds

International Nuclear Information System (INIS)

Luo Chunling; Shen Zhenguo; Lou Laiqing; Li Xiangdong

2006-01-01

The potential of 18 different plants to be used in the chemically enhanced phytoextraction of Cu, Pb, Zn and Cd was assessed using pot experiments. Chrysanthemum coronarium L. was the species most sensitive to the application of EDTA, and had the highest enhancement of Cu and Pb concentrations in its shoots. Compared with EDTA, EDDS was more effective in enhancing the concentration of Cu in the shoots of Chrysanthemum coronarium L. and Zea mays L. grown on multi-metal contaminated soils. The EDTA-treated soil still had a significant ability to enhance the concentrations of Cu and Pb in the shoots of Zea mays L. six months after the chelant treatment. However, the EDDS-treated soil did not have any effect in enhancing the concentrations of metals in the shoots of Zea mays L. in the second crop test. The results may indicate that EDDS biodegrades more rapidly than EDTA in soil and is better in limiting potential metal leaching. - Chrysanthemum coronarium L. was the most sensitive species to the application of chelants, and EDDS biodegrades much more rapidly than EDTA in soil

Enhancing crystalline silicon solar cell efficiency with SixGe1-x layers

Science.gov (United States)

Ali, Adnan; Cheow, S. L.; Azhari, A. W.; Sopian, K.; Zaidi, Saleem H.

Crystalline silicon (c-Si) solar cell represents a cost effective, environment-friendly, and proven renewable energy resource. Industrially manufacturing of c-Si solar has now matured in terms of efficiency and cost. Continuing cost-effective efficiency enhancement requires transition towards thinner wafers in near term and thin-films in the long term. Successful implementation of either of these alternatives must address intrinsic optical absorption limitation of Si. Bandgap engineering through integration with SixGe1-x layers offers an attractive, inexpensive option. With the help of PC1D software, role of SixGe1-x layers in conventional c-Si solar cells has been intensively investigated in both wafer and thin film configurations by varying Ge concentration, thickness, and placement. In wafer configuration, increase in Ge concentration leads to enhanced absorption through bandgap broadening with an efficiency enhancement of 8% for Ge concentrations of less than 20%. At higher Ge concentrations, despite enhanced optical absorption, efficiency is reduced due to substantial lowering of open-circuit voltage. In 5-25-μm thickness, thin-film solar cell configurations, efficiency gain in excess of 30% is achievable. Therefore, SixGe1-x based thin-film solar cells with an order of magnitude reduction in costly Si material are ideally-suited both in terms of high efficiency and cost. Recent research has demonstrated significant improvement in epitaxially grown SixGe1-x layers on nanostructured Si substrates, thereby enhancing potential of this approach for next generation of c-Si based photovoltaics.

Unphysiologically high magnesium concentrations support chondrocyte proliferation and redifferentiation.

Science.gov (United States)

Feyerabend, Frank; Witte, Frank; Kammal, Michael; Willumeit, Regine

2006-12-01

The effect of unphysiologically high extracellular magnesium concentrations on chondrocytes, induced by the supplementation of magnesium sulfate, was studied using a 3-phase tissue engineering model. The experiments showed that chondrocyte proliferation and redifferentiation, on the gene and protein expression level, are enhanced. A negative influence was found during chondrogenesis where an inhibition of extracellular matrix formation was observed. In addition, a direct impact on chondrocyte metabolism, elevated magnesium concentrations also affected growth factor effectiveness by consecutive influences during chondrogenesis. All observations were dosage dependent. The results of this study indicate that magnesium may be a useful tool for cartilage tissue engineering.

The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence.

Science.gov (United States)

Holland, Brendan J; Adcock, Jacqui L; Nesterenko, Pavel N; Peristyy, Anton; Stevenson, Paul G; Barnett, Neil W; Conlan, Xavier A; Francis, Paul S

2014-09-09

Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV). Copyright © 2014 Elsevier B.V. All rights reserved.

Plasmon-enhanced luminescence of Sm complex using silver nanoparticles in Polyvinyl Alcohol

Energy Technology Data Exchange (ETDEWEB)

Kaur, Gagandeep; Verma, R.K.; Rai, D.K. [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, India 221005 (India); Rai, S.B., E-mail: sbrai49@yahoo.co.in [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, India 221005 (India)

2012-07-15

Silver (Ag) nanoparticles (NPs) were prepared by laser ablation in water with an aim to enhance the luminescence of rare earth coordinated complex in polymer host. A fixed concentration of the complex containing Samarium (Sm), Salicylic acid (Sal) and 1, 10-phenanthroline (Phen) were combined with different concentrations of silver NPs in PolyVinyl Alcohol at room temperature. Absorption spectrum and XRD patterns of the sample show that the Sm(Sal){sub 3}Phen complex is accompanied by Ag NPs. The luminescence from the complex was recorded in the presence and absence of Ag NPs using two different excitation wavelengths viz. 400 and 355 nm. Of these, 400 nm radiation falls in the surface plasmon resonance of Ag NPs. It was found that the Ag NPs led to a significant enhancement in luminescence of the complex. Surprisingly, a high concentration of Ag NPs tends to quench the luminescence. - Highlights: Black-Right-Pointing-Pointer Sm complex with Ag nanoparticles in PVA was prepared at room temperature. Black-Right-Pointing-Pointer UV-vis absorption and XRD confirms the presence of Sm complex and Ag NPs. Black-Right-Pointing-Pointer Enhancement in luminescence of complex was observed with Ag NPs. Black-Right-Pointing-Pointer Coupling between radiative transitions of Sm and SPR of NPs enhances the emission. Black-Right-Pointing-Pointer The higher concentration of Ag NPs quenches the luminescence of the complex.

Human Lysozyme Synergistically Enhances Bactericidal Dynamics and Lowers the Resistant Mutant Prevention Concentration for Metronidazole to Helicobacter pylori by Increasing Cell Permeability

Directory of Open Access Journals (Sweden)

Xiaolin Zhang

2016-10-01

Full Text Available Metronidazole (MNZ is an effective agent that has been employed to eradicate Helicobacter pylori (H. pylori. The emergence of broad MNZ resistance in H. pylori has affected the efficacy of this therapeutic agent. The concentration of MNZ, especially the mutant prevention concentration (MPC, plays an important role in selecting or enriching resistant mutants and regulating therapeutic effects. A strategy to reduce the MPC that can not only effectively treat H. pylori but also prevent resistance mutations is needed. H. pylori is highly resistant to lysozyme. Lysozyme possesses a hydrolytic bacterial cell wall peptidoglycan and a cationic dependent mode. These effects can increase the permeability of bacterial cells and promote antibiotic absorption into bacterial cells. In this study, human lysozyme (hLYS was used to probe its effects on the integrity of the H. pylori outer and inner membranes using as fluorescent probe hydrophobic 1-N-phenyl-naphthylamine (NPN and the release of aspartate aminotransferase. Further studies using a propidium iodide staining method assessed whether hLYS could increase cell permeability and promote cell absorption. Finally, we determined the effects of hLYS on the bactericidal dynamics and MPC of MNZ in H. pylori. Our findings indicate that hLYS could dramatically increase cell permeability, reduce the MPC of MNZ for H. pylori, and enhance its bactericidal dynamic activity, demonstrating that hLYS could reduce the probability of MNZ inducing resistance mutations.

Experimental study on a parabolic concentrator assisted solar desalting system

International Nuclear Information System (INIS)

Arunkumar, T.; Denkenberger, David; Velraj, R.; Sathyamurthy, Ravishankar; Tanaka, Hiroshi; Vinothkumar, K.

2015-01-01

Highlights: • We optimized the augmentation of condense by enhanced desalination methodology. • Parabolic concentrator has been integrated with solar distillation systems. • We measured ambient together with solar radiation intensity. - Abstract: This paper presents a modification of parabolic concentrator (PC) – solar still with continuous water circulation using a storage tank to enhance the productivity. Four modes of operation were studied experimentally: (i) PC-solar still without top cover cooling; (ii) PC-solar still with top cover cooling, PC-solar still integrated with phase change material (PCM) without top cover cooling and PC-solar still integrated PCM with cooling. The experiments were carried out for the cooling water flow rates of 40 ml/min; 50 ml/min, 60 ml/min, 80 ml/min and 100 ml/min. Diurnal variations of water temperature (T_w), ambient air temperature (T_a), top cover temperature (T_o_c) and production rate are measured with frequent time intervals. Water cooling was not cost effective, but adding PCM was.

Elevated CO2 concentration around alfalfa nodules increases N2 fixation

OpenAIRE

Fischinger, Stephanie A.; Hristozkova, Marieta; Mainassara, Zaman-Allah; Schulze, Joachim

2009-01-01

Nodule CO2 fixation via PEPC provides malate for bacteroids and oxaloacetate for N assimilation. The process is therefore of central importance for efficient nitrogen fixation. Nodule CO2 fixation is known to depend on external CO2 concentration. The hypothesis of the present paper was that nitrogen fixation in alfalfa plants is enhanced when the nodules are exposed to elevated CO2 concentrations. Therefore nodulated plants of alfalfa were grown in a hydroponic system that allowed separate ae...

Enhanced photocatalytic disinfection of indoor air

Energy Technology Data Exchange (ETDEWEB)

Vohra, Amit; Goswami, D.Y.; Deshpande, D.A.; Block, S.S. [Solar Energy and Energy Conversion Laboratory, Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

2006-04-18

A silver ion doped TiO{sub 2} based photocatalyst, with improved destruction of airborne microbes, has been developed. The performance of the silver ion doped photocatalyst is demonstrated using a catalyst coated filter in a recirculating air experimental facility. Bacillus cereus, Staphylococcus aureus, Escherichia coli, Aspergillus niger, and MS2 Bacteriophage have been used as indexes to demonstrate the high disinfection efficiency of the enhanced photocatalysis process. The microbial destruction performance of the enhanced photocatalyst is found to be an order of magnitude higher than that of a conventional TiO{sub 2} photocatalyst. The process of enhanced photocatalysis can thus be used effectively against high concentrations of airborne microorganisms, making it an attractive option as a defense against bio-terrorism. (author)

Fortification and Elevated Alcohol Concentration Affect the Concentration of Rotundone and Volatiles in Vitis vinifera cv. Shiraz Wine

Directory of Open Access Journals (Sweden)

Pangzhen Zhang

2017-06-01

Full Text Available Rotundone is a key aromatic compound for cool-climate Shiraz. This compound is produced in the skin of grape berries and extracted into wine during fermentation. This project investigated the influence of fermentation techniques on the concentration of rotundone in the resultant wine. Wine was fortified with ethanol and sucrose on the 1st and 5th days of fermentation and rotundone, volatile aroma compounds and colour were assessed in the resultant wine. The relationship between the concentration of rotundone and alcoholic strength during fermentation process was also investigated. Wine alcoholic strength and skin–wine contact time were two factors affecting rotundone extraction rate from grapes into wine. Fortification significantly enhanced rotundone extraction rate, and improved wine colour and phenolics and affects the concentration of ethyl acetate, 3-methylbutyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, methyl nonanoate, isopentanol and phenylethyl alcohol in the resultant wine. Understanding how ethanol produced during fermentation can change the extraction of skin-bound aroma compounds and the colour and flavour of wine allows greater control of fermentation parameters to produce quality wine.

Novel Apparatus for the Real-Time Quantification of Dissolved Gas Concentrations and Isotope Ratios

Science.gov (United States)

Gupta, M.; Leen, J.; Baer, D. S.; Owano, T. G.; Liem, J.

2013-12-01

Measurements of dissolved gases and their isotopic composition are critical in studying a variety of phenomena, including underwater greenhouse gas generation, air-surface exchange, and pollution migration. These studies typically involve obtaining water samples from streams, lakes, or ocean water and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line methodology is time consuming, significantly limits the number of the samples that can be measured and thus severely inhibits detailed spatial and temporal mapping of gas concentrations and isotope ratios. In this work, we describe the development of a new membrane-based degassing device that interfaces directly to Los Gatos Research (cavity enhanced laser absorption or Off-Axis ICOS) gas analyzers (cavity enhanced laser absorption or Off-Axis ICOS analyzers) to create an autonomous system that can continuously and quickly measure concentrations and isotope ratios of dissolved gases in real time in the field. By accurately controlling the water flow rate through the membrane degasser, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the system is able to generate precise and highly reproducible results. Moreover, by accurately measuring the gas flow rates in and out of the degasser, the gas-phase concentrations (ppm) could be converted into dissolved gas concentrations (nM). We will present detailed laboratory test data that quantifies the linearity, precision, and dynamic range of the system for the concentrations and isotope ratios of dissolved methane, carbon dioxide, and nitrous oxide. By interfacing the degassing device to a novel cavity-enhanced spectrometer (developed by LGR), preliminary data will also be presented for dissolved volatile organics (VOC) and other

Enhanced electrochemical oxidation of methanol on copper electrodes modified by electrocorrosion and electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Carugno, Sofía [INQUIMAE – DQIAQF, Facultad de Ciencias, Exactas y Naturales, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires (Argentina); Chassaing, Elisabeth [IRDEP (UMR7174), EDF R and D, 6 Quai Watier, 78401 Chatou (France); Rosso, Michel [LPMC (UMR7643), CNRS, Ecole Polytechnique, F91128 Palaiseau Cedex (France); González, Graciela A., E-mail: graciela@qi.fcen.uba.ar [INQUIMAE – DQIAQF, Facultad de Ciencias, Exactas y Naturales, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires (Argentina)

2014-02-14

In this paper, we report a study of electrocatalytic oxidation of methanol on copper electrodes subjected to different surface treatments, either electrocorrosion or electrodeposition in the absence of strong hydrogen co-deposition. The surface morphology of treated electrodes was examined by Field Emission Scanning Electron Microscopy (FE-SEM). The effect of different treatment conditions and the methanol concentration dependence were evaluated by cyclic voltammetric technique. The results indicate that the oxidation of methanol can be enhanced by a suitable micro and nano structure generated by these treatments. This enhanced electrode activity is related to an increase of the effective surface area and/or to an increase of the surface concentration of electroactive molecules or intermediates. - Highlights: • We presented simple treatments to increase the response of copper electrodes. • Copper electrodes were modified by electrocorrosion and electrodeposition. • Scanning Electron Microscopy images reveal the effects of the different treatments. • The response is enhanced by an area increase and/or intermediates concentration. • For each treatment the concentration range of the diffusion control is analyzed.

Feasibility and parametric evaluation of hybrid concentrated photovoltaic-thermoelectric system

DEFF Research Database (Denmark)

Rezaniakolaei, Alireza; Rosendahl, Lasse Aistrup

2017-01-01

Concentrated photovoltaic (CPV) system integrated with thermoelectric generators (TEGs) is a novel technology that has potential to offer high efficient system. In this study, a thermally coupled model of concentrated photovoltaic-thermoelctric (CPV/TEG) system is established to investigate...... than CPV-only system. The results indicate that contribution of the TEG in power generation enhances at high sun concentrations. Depending to critical design parameters of the CPV and the TEG, there are optimal values for heat transfer coefficient in the heat sink that offer minimum energy cost....... feasibility of the hybrid system over wide range of solar concentrations and different types of heat sinks. The model takes into account critical design parameters in the CPV and the TEG module. The results of this study show that for thermoelectric materials with ZT ≈ 1, the CPV/TEG system is more efficient...

Enhanced micropollutant biodegradation and assessment of nitrous oxide concentration reduction in wastewater treated by acclimatized sludge bioaugmentation.

Science.gov (United States)

Boonnorat, Jarungwit; Techkarnjanaruk, Somkiet; Honda, Ryo; Ghimire, Anish; Angthong, Sivakorn; Rojviroon, Thammasak; Phanwilai, Supaporn

2018-05-11

This research investigated the micropollutant biodegradation and nitrous oxide (N 2 O) concentration reduction in high strength wastewater treated by two-stage activated sludge (AS) systems with (bioaugmented) and without (non-bioaugmented) acclimatized sludge bioaugmentation. The bioaugmented and non-bioaugmented systems were operated in parallel for 228 days, with three levels of concentrations of organics, nitrogen, and micropollutants in the influent: conditions 1 (low), 2 (moderate), and 3 (high). The results showed that, under condition 1, both systems efficiently removed the organic and nitrogen compounds. However, the bioaugmented system was more effective in the micropollutant biodegradation and N 2 O concentration reduction than the non-bioaugmented one. Under condition 2, the nitrogen and micropollutant biodegradation efficiency of the non-bioaugmented system slightly decreased, while the N 2 O concentration declined in the bioaugmented system. Under condition 3, the treatment performance and N 2 O concentration abatement were substantially lowered as the compounds concentration increased. Further analysis also showed that the acclimatized sludge bioaugmentation increased the bacterial diversity in the system. In essence, the acclimatized sludge bioaugmentation strategy was highly effective for the influent with low compounds concentration, achieving the organics and nitrogen removal efficiencies of 92-97%, relative to 71-97% of the non-bioaugmented system. The micropollutant treatment efficiency of the bioaugmented system under condition 1 was 75-92%, indicating significant improvement in the treatment performance (p < 0.05), compared with 60-79% of the non-bioaugmented system. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced Tendon-to-Bone Healing of Chronic Rotator Cuff Tears by Bone Marrow Aspirate Concentrate in a Rabbit Model

Science.gov (United States)

Liu, Xiao Ning; Yang, Cheol-Jung; Kim, Ji Eui; Du, Zhen Wu; Ren, Ming; Zhang, Wei; Zhao, Hong Yu; Kim, Kyung Ok

2018-01-01

Background To evaluate the influence of bone marrow aspirate concentrate (BMAC) on tendon-to-bone healing in a rabbit rotator cuff model and to characterize the composition of growth factors in BMAC. Methods In this in vivo study, 40 rabbits were allocated into five groups: control (C), repair + saline (RS), repair + platelet-rich plasma (PRP; RP), repair + BMAC (RB) and repair + PRP + BMAC (RPB). A tear model was created by supraspinatus tendon transection at the footprint. Six weeks after transection, the torn tendon was repaired along with BMAC or PRP administration. Six weeks after repair, shoulder samples were harvested for biomechanical and histological testing. Ten rabbits were used for processing PRP and BMAC, followed by analysis of blood cell composition and the levels of growth factors in vitro. Results The ultimate load-to-failure was significantly higher in RPB group compared to RS group (p = 0.025). BMAC-treated groups showed higher values of biomechanical properties than RS group. The histology of BMAC-treated samples showed better collagen fiber continuity and orientation than RS group. BMAC contained significantly higher levels of the several growth factors than PRP. Conclusions Locally administered BMAC enhanced tendon-to-bone healing and has potential for clinical applications. PMID:29564054

High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrator Application

Energy Technology Data Exchange (ETDEWEB)

Hubbard, Seth

2012-09-12

The High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrators project seeks to provide new photovoltaic cells for Concentrator Photovoltaics (CPV) Systems with higher cell efficiency, more favorable temperature coefficients and less sensitivity to changes in spectral distribution. The main objective of this project is to provide high efficiency III-V solar cells that will reduce the overall cost per Watt for power generation using CPV systems.This work is focused both on a potential near term application, namely the use of indium arsenide (InAs) QDs to spectrally "tune" the middle (GaAs) cell of a SOA triple junction device to a more favorable effective bandgap, as well as the long term goal of demonstrating intermediate band solar cell effects. The QDs are confined within a high electric field i-region of a standard GaAs solar cell. The extended absorption spectrum (and thus enhanced short circuit current) of the QD solar cell results from the increase in the sub GaAs bandgap spectral response that is achievable as quantum dot layers are introduced into the i-region. We have grown InAs quantum dots by OMVPE technique and optimized the QD growth conditions. Arrays of up to 40 layers of strain balanced quantum dots have been experimentally demonstrated with good material quality, low residual stain and high PL intensity. Quantum dot enhanced solar cells were grown and tested under simulated one sun AM1.5 conditions. Concentrator solar cells have been grown and fabricated with 5-40 layers of QDs. Testing of these devices show the QD cells have improved efficiency compared to baseline devices without QDs. Device modeling and measurement of thermal properties were performed using Crosslight APSYS. Improvements in a triple junction solar cell with the insertion of QDs into the middle current limiting junction was shown to be as high as 29% under one sun illumination for a 10 layer stack QD enhanced triple junction solar cell. QD devices have strong

Coastal zone color scanner pigment concentrations in the southern ocean and relationships to geophysical surface features

Science.gov (United States)

Comiso, J. C.; Mcclain, C. R.; Sullivan, C. W.; Ryan, J. P.; Leonard, C. L.

1993-01-01

Climatological data on the distribution of surface pigment fields in the entire southern ocean over a seasonal cycle are examined. The occurrence of intense phytoplankton blooms during austral summer months and during other seasons in different regions is identified and analyzed. The highest pigment concentrations are observed at high latitudes and over regions with water depths usually less than 600 m. Basin-scale pigment distribution shows a slightly asymmetric pattern of enhanced pigment concentrations about Antarctica, with enhanced concentrations extending to lower latitudes in the Atlantic and Indian sectors than in the Pacific sector. A general increase in pigment concentrations is evident from the low latitudes toward the Antarctic circumpolar region. Spatial relationships between pigment and archived geophysical data reveal significant correlation between pigment distributions and both bathymetry and wind stress, while general hemispheric scale patterns of pigment distributions are most coherent with the geostrophic flow of the Antarctic Circumpolar Current.

A Comparison of the Use of Contrast Media with Different Iodine Concentrations for Multidetector CT of the Kidney

Science.gov (United States)

Jung, Seung Chai; Cho, Jeong Yeon

2011-01-01

Objective To determine the optimal iodine concentration of contrast media for kidney multidetector computed tomography (MDCT) by comparing the degree of renal parenchymal enhancement and the severity of the renal streak artifact with contrast media of different iodine concentrations. Materials and Methods A 16-row MDCT was performed in 15 sedated rabbits by injection of 2 mL contrast media/kg body weight at a rate of 0.3 mL/sec. Monomeric nonionic contrast media of 250, 300, and 370 mg iodine/mL were injected at 1-week intervals. Mean attenuation values were measured in each renal structure with attenuation differences among the structures. The artifact was evaluated by CT window width/level and three grading methods. The values were compared with iodine concentrations. Results The 370 mg iodine/mL concentration showed significantly higher cortical enhancement than 250 mg iodine/mL in all phases (p < 0.05). There was however no significant difference in the degree of enhancement between the 300 mg iodine/mL and 370 mg iodine/mL concentrations in all phases. There is a significant difference in attenuation for the cortex-outer medulla between 250 mg iodine/mL and 300 mg iodine/mL (p < 0.05). The artifact was more severe with a medium of 370 mg iodine/mL than with 250 mg iodine/mL by all grading methods (p < 0.05). Conclusion The 300 mg iodine/mL is considered to be the most appropriate iodine concentration in an aspect of the enhancement and artifact on a kidney MDCT scan. PMID:22043154

Impact of Contrast Media Concentration on Low-Kilovolt Computed Tomography Angiography: A Systematic Preclinical Approach.

Science.gov (United States)

Fleischmann, Ulrike; Pietsch, Hubertus; Korporaal, Johannes G; Flohr, Thomas G; Uder, Michael; Jost, Gregor; Lell, Michael M

2018-05-01

Low peak kilovoltage (kVp) protocols in computed tomography angiography (CTA) demand a review of contrast media (CM) administration practices. The aim of this study was to systematically evaluate different iodine concentrations of CM in a porcine model. Dynamic 70 kVp CTA was performed on 7 pigs using a third-generation dual-source CT system. Three CM injection protocols (A-C) with an identical total iodine dose and iodine delivery rate (150 mg I/kg, 12 s, 0.75 g I/s) differed in iodine concentration and flow rate (protocol A: 400 mg I/mL, 1.9 mL/s; B: 300 mg I/mL, 2.5 mL/s; C: 150 mg I/mL, 5 mL/s). All protocols were applied in a randomized order and compared intraindividually. Arterial enhancement at different locations in the pulmonary artery, the aorta, and aortic branches was measured over time. Time attenuation curves, peak enhancement, time to peak, and bolus tracking delay times needed for static CTA were calculated. The reproducibility of optimal parameters was tested in single-phase CTA. The heart rates of the pigs were comparable for all protocols (P > 0.7). The injection pressure was significantly higher for protocol A (64 ± 5 psi) and protocol C (55 ± 3 psi) compared with protocol B (39 ± 2 psi) (P < 0.001). Average arterial peak enhancement in the dynamic scans was 359 ± 51 HU (protocol A), 382 ± 36 HU (B), and 382 ± 60 HU (C) (A compared with B and C: P < 0.01; B compared with C: P = 0.995). Time to peak enhancement decreased with increasing injection rate. The delay time for bolus tracking depended on the injection rate as well and was highest for protocol A (4.7 seconds) and lowest for protocol C (3.9 seconds) (P = 0.038). The peak enhancement values of the dynamic scans highly correlated with those of the single-phase CTA scans. In 70 kVp CTA, 300 mg I/mL iodine concentrations showed to be superior to high-concentration CM when keeping the iodine delivery rate constant. Besides, iodine concentrations as low as 150 mg I/mL can be administered

Cell wall targeted in planta iron accumulation enhances biomass conversion and seed iron concentration in Arabidopsis and rice

Energy Technology Data Exchange (ETDEWEB)

Yang, Haibing [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Department of Biological Sciences, Purdue University, West Lafayette IN USA; Wei, Hui [Biosciences Center, National Renewable Energy Laboratory, Golden CO USA; Ma, Guojie [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Antunes, Mauricio S. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Biological Sciences, Purdue University, West Lafayette IN USA; Vogt, Stefan [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL USA; Cox, Joseph [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Zhang, Xiao [Department of Horticulture, Purdue University, West Lafayette IN USA; Liu, Xiping [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Bu, Lintao [National Bioenergy Center, National Renewable Energy Laboratory, Golden CO USA; Gleber, S. Charlotte [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL USA; Carpita, Nicholas C. [Department of Biological Sciences, Purdue University, West Lafayette IN USA; Department of Botany and Plant Pathology, Purdue University, West Lafayette IN USA; Makowski, Lee [Department of Bioengineering, Northeastern University, Boston MA USA; Department of Chemistry and Chemical Biology, Northeastern University, Boston MA USA; Himmel, Michael E. [Biosciences Center, National Renewable Energy Laboratory, Golden CO USA; Tucker, Melvin P. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL USA; McCann, Maureen C. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Biological Sciences, Purdue University, West Lafayette IN USA; Murphy, Angus S. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Department of Plant Science and Landscape Architecture, University of Maryland, College Park MD USA; Peer, Wendy A. [Center for Direct Catalytic Conversion Of Biomass to Biofuels (C3Bio), Purdue University, West Lafayette IN USA; Department of Horticulture, Purdue University, West Lafayette IN USA; Department of Plant Science and Landscape Architecture, University of Maryland, College Park MD USA; Department of Environmental Science and Technology, University of Maryland, College Park MD USA

2016-04-07

Conversion of nongrain biomass into liquid fuel is a sustainable approach to energy demands as global population increases. Previously, we showed that iron can act as a catalyst to enhance the degradation of lignocellulosic biomass for biofuel production. However, direct addition of iron catalysts to biomass pretreatment is diffusion-limited, would increase the cost and complexity of biorefinery unit operations and may have deleterious environmental impacts. Here, we show a new strategy for in planta accumulation of iron throughout the volume of the cell wall where iron acts as a catalyst in the deconstruction of lignocellulosic biomass. We engineered CBM-IBP fusion polypeptides composed of a carbohydrate-binding module family 11 (CBM11) and an iron-binding peptide (IBP) for secretion into Arabidopsis and rice cell walls. CBM-IBP transformed Arabidopsis and rice plants show significant increases in iron accumulation and biomass conversion compared to respective controls. Further, CBM-IBP rice shows a 35% increase in seed iron concentration and a 40% increase in seed yield in greenhouse experiments. CBM-IBP rice potentially could be used to address iron deficiency, the most common and widespread nutritional disorder according to the World Health Organization.

"I am a scientist": How setting conditions that enhance focused concentration positively relate to student motivation and achievement outcomes in inquiry-based science

Science.gov (United States)

Ellwood, Robin B.

This research investigated how student social interactions within two approaches to an inquiry-based science curriculum could be related to student motivation and achievement outcomes. This qualitative case study consisted of two cases, Off-Campus and On-Campus, and used ethnographic techniques of participant observation. Research participants included eight eighth grade girls, aged thirteen to fourteen years old. Data sources included formal and informal participant interviews, participant journal reflections, curriculum artifacts including quizzes, worksheets, and student-generated research posters, digital video and audio recordings, photographs, and researcher field notes. Data were transcribed verbatim and coded, then collapsed into emergent themes using NVIVO 9. The results of this research illustrate how setting conditions that promote focused concentration and communicative interactions can be positively related to student motivation and achievement outcomes in inquiry-based science. Participants in the Off-Campus case experienced more frequent states of focused concentration and out performed their peers in the On-Campus case on forty-six percent of classroom assignments. Off-Campus participants also designed and implemented a more cognitively complex research project, provided more in-depth analyses of their research results, and expanded their perceptions of what it means to act like a scientist to a greater extent than participants in the On-Campus case. These results can be understood in relation to Flow Theory. Student interactions that promoted the criteria necessary for initiating flow, which included having clearly defined goals, receiving immediate feedback, and maintaining a balance between challenges and skills, fostered enhanced student motivation and achievement outcomes. This research also illustrates the positive gains in motivation and achievement outcomes that emerge from student experiences with extended time in isolated areas referred to

The CHF enhancement on pool boiling using nano-fluids

International Nuclear Information System (INIS)

Chang, Won Joon; Jeong, Yong Hoon

2009-01-01

A increase of CHF was observed with nano-fluid. The addition of nano-particle helped to increase the wettability. This happens with the decrease in bubble diameter, breakup of bubbles and avoidance of bubble coalescence. CHF increase or decrease depends upon competition between high wettability and high instability. An optimum nano-fluid concentration is needed which must have high crystalline content. When the concentration reaches at a critical value, CHF will tend to a constant value. Deposition of nano-particles increasing the wettability and the rewetting are cause of CHF enhancement. It delay the growth of dry patch by increasing of wettability and lead to CHF enhancement. Now, we must define the wettability of nano-fluids. At case of nano-fluids using metallic particle, the explanation using contact angle using was reasonable. But, at case of nan-fluids using hydrophobic CNT, this explanation can't be acceptable. Moreover, at case of surfactant solution, contact angle was very low. But CHF enhancement was not great. So, wettability about nano-fluids must be defined anew for explanation of CHF enhancement. I suggest the extension of micro layer are acceptable concept for increasing wettability using nano-fluids

Nanoparticles as image enhancing agents for ultrasonography

Energy Technology Data Exchange (ETDEWEB)

Liu Jun [Biomedical Engineering Department, Ohio State University, 270 Bevis Hall, 1080 Carmack Rd, Columbus, OH 43210 (United States); Levine, Andrea L [Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Rd, Columbus, OH 43210 (United States); Mattoon, John S [Department of Veterinary Clinical Sciences, Ohio State University, 1151 Veterinary Hospital, 601 Vernon Tharp St., Columbus, OH 43210 (United States); Yamaguchi, Mamoru [Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Rd, Columbus, OH 43210 (United States); Lee, Robert J [Division of Pharmaceutics, College of Pharmacy, NCI Comprehensive Cancer Center, and NSF Nanoscale Science and Engineering Center, Ohio State University, 500 West 12th Avenue, Columbus, OH 43210 (United States); Pan Xueliang [Department of Statistics, Ohio State University, 1958 Neil Avenue, Columbus, OH 43210 (United States); Rosol, Thomas J [Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Rd, Columbus, OH 43210 (United States)

2006-05-07

Nanoparticles have drawn great attention as targeted imaging and/or therapeutic agents. The small size of the nanoparticles allows them to target cells that are beyond capillary vasculature, such as cancer cells. We investigated the effect of solid nanoparticles for enhancing ultrasonic grey scale images in tissue phantoms and mouse livers in vivo. Silica nanospheres (100 nm) were dispersed in agarose at 1-2.5% mass concentration and imaged by a high-resolution ultrasound imaging system (transducer centre frequency: 30 MHz). Polystyrene particles of different sizes (500-3000 nm) and concentrations (0.13-0.75% mass) were similarly dispersed in agarose and imaged. Mice were injected intravenously with nanoparticle suspensions in saline. B-mode images of the livers were acquired at different time points after particle injection. An automated computer program was used to quantify the grey scale changes. Ultrasonic reflections were observed from nanoparticle suspensions in agarose gels. The image brightness, i.e., mean grey scale level, increased with particle size and concentration. The mean grey scale of mouse livers also increased following particle administration. These results indicated that it is feasible to use solid nanoparticles as contrast enhancing agents for ultrasonic imagin000.

Combined application of sub-toxic level of silver nanoparticles with low powers of 2450 MHz microwave radiation lead to kill Escherichia coli in a short time

Directory of Open Access Journals (Sweden)

Bardia Varastehmoradi

2013-09-01

Full Text Available   Objective(s: Electromagnetic radiations which have lethal effects on the living cells are currently also considered as a disinfective physical agent.   Materials and Methods: In this investigation, silver nanoparticles were applied to enhance the lethal action of low powers (100 and 180 W of 2450 MHZ electromagnetic radiation especially against Escherichia coli ATCC 8739. Silver nanoparticles were biologically prepared and used for next experiments. Sterile normal saline solution was prepared and supplemented by silver nanoparticles to reach the sub-inhibitory concentration (6.25 μg/mL. Such diluted silver colloid as well as free-silver nanoparticles solution was inoculated along with test microorganisms, particularly E. coli. These suspensions were separately treated by 2450 MHz electromagnetic radiation for different time intervals in a microwave oven operated at low powers (100 W and 180 W. The viable counts of bacteria before and after each radiation time were determined by colony-forming unit (CFU method. Results: Results showed that the addition of silver nanoparticles significantly decreased the required radiation time to kill vegetative forms of microorganisms. However, these nanoparticles had no combined effect with low power electromagnetic radiation when used against Bacillus subtilis spores. Conclusion: The cumulative effect of silver nanoparticles and low powers electromagnetic radiation may be useful in medical centers to reduce contamination in polluted derange and liquid wastes materials and some devices.

Ciprofloxacin and Trimethoprim Cause Phage Induction and Virulence Modulation in Staphylococcus aureus

Science.gov (United States)

Goerke, Christiane; Köller, Johanna; Wolz, Christiane

2006-01-01

In Staphylococcus aureus strains of human origin, phages which integrate into the chromosomal gene coding for β-hemolysin (hlb) are widely distributed. Most of them encode accessory virulence determinants such as staphylokinase (sak) or enterotoxins. Here, we analyzed the effects of ciprofloxacin and trimethoprim on phage induction and expression of phage-encoded virulence factors by using isolates from patients with cystic fibrosis for which the induction of hlb-converting phages was demonstrated in vivo (C. Goerke, S. Matias y Papenberg, S. Dasbach, K. Dietz, R. Ziebach, B. C. Kahl, and C. Wolz, J. Infect. Dis. 189:724-734, 2004) as well as a φ13 lysogen of phage-cured strain 8325-4. Treatment of lysogens with subinhibitory concentrations of either antibiotic resulted in (i) delysogenization of strains resembling the isolates picked up after chronic lung infection and (ii) replication of phages in the bacterial host in a dose-dependent manner. Ciprofloxacin treatment resulted in enhanced recA transcription, indicating involvement of the SOS response in phage mobilization. Induction of φ13 was linked to elevated expression of the phage-encoded virulence gene sak, chiefly due to the activation of latent phage promoters. In summary, we could show the induction of hlb-converting phages and a subsequent virulence modulation of the host bacterium by ciprofloxacin and trimethoprim. PMID:16377683

A survey of indoor radon and particular concentration

International Nuclear Information System (INIS)

Ohta, Yukiko

1993-01-01

Lung disease risk from inhalation of radon can be enhanced by the presence of particular pollutants in indoor air. The indoor concentration of radon and particulates were measured in homes, a department store, and offices in a high building in Tokyo metropolis, as well as in homes in both northern and western Japan. Passive radon monitors were located in living rooms and offices for more than three months at 99 sites during the winter of 1988 and 1989. Indoor radon concentration ranged from 11.1 Bq/m 3 to 148 Bq/m 3 (n=99) and averaged value S.D. was 36.5±14.2 Bq/m 3 . However, the average concentration in air conditional buildings was 21.8±9.51 Bq/m 3 (n=17). Simultaneously at 65 of the radon sites, indoor particulates were collected using personal dust samplers by impaction methods. Deposited particulate concentrations on the sampler were measured and calculated in a unit of μm/m 3 . Concentrations were determined for particle sizes above and below 2.5 μm, for both smoking or non smoking sites. Consequently, concentration of particle size below 2.5 μm was high in smoking rooms. Finally, it was considered that smoking was a complex indoor pollutant as adherence of radon daughter to aerosols. (author)

Is the enhancement of global warming important?

International Nuclear Information System (INIS)

Symons, M.C.R.; Barrett, J.

2001-01-01

There is no doubt that global warming is important; without it the Earth's surface would have a mean temperature of 33 o C lower than it has currently. The IPCC maintains that human activities are to blame for the observed increase in the concentration of carbon dioxide in the atmosphere since pre-industrial times. There are some doubts about whether global warming is being enhanced by the activities of the human race. This article reviews these doubts and the proposed remedies to the alleged enhancement. (author)

Enhanced oxidation of arsenite to arsenate using tunable K+ concentration in the OMS-2 tunnel.

Science.gov (United States)

Hou, Jingtao; Sha, Zhenjie; Hartley, William; Tan, Wenfeng; Wang, Mingxia; Xiong, Juan; Li, Yuanzhi; Ke, Yujie; Long, Yi; Xue, Shengguo

2018-03-29

Cryptomelane-type octahedral molecular sieve manganese oxide (OMS-2) possesses high redox potential and has attracted much interest in its application for oxidation arsenite (As(III)) species of arsenic to arsenate (As(V)) to decrease arsenic toxicity and promote total arsenic removal. However, coexisting ions such as As(V) and phosphate are ubiquitous and readily bond to manganese oxide surface, consequently passivating surface active sites of manganese oxide and reducing As(III) oxidation. In this study, we present a novel strategy to significantly promote As(III) oxidation activity of OMS-2 by tuning K + concentration in the tunnel. Batch experimental results reveal that increasing K + concentration in the tunnel of OMS-2 not only considerably improved As(III) oxidation kinetics rate from 0.027 to 0.102 min -1 , but also reduced adverse effect of competitive ion on As(III) oxidation. The origin of K + concentration effect on As(III) oxidation was investigated through As(V) and phosphate adsorption kinetics, detection of Mn 2+ release in solution, surface charge characteristics, and density functional theory (DFT) calculations. Experimental results and theoretical calculations confirm that by increasing K + concentration in the OMS-2 tunnel not only does it improve arsenic adsorption on K + doped OMS-2, but also accelerates two electrons transfers from As(III) to each bonded Mn atom on OMS-2 surface, thus considerably improving As(III) oxidation kinetics rate, which is responsible for counteracting the adverse adsorption effects by coexisting ions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Image quality in CT perfusion imaging of the brain. The role of iodine concentration

Energy Technology Data Exchange (ETDEWEB)

Koenig, Matthias; Bueltmann, Eva; Bode-Schnurbus, Lucas; Koenen, Dirk; Mielke, Eckhart; Heuser, Lothar [Knappschaftskrankenhaus Langendreer, Department of Diagnostic and Interventional Radiology and Nuclear Medicine, Ruhr-University Bochum, Bochum (Germany)

2007-01-15

The purpose of this study was to evaluate the impact of various iodine contrast concentrations on image quality in computed tomography (CT) perfusion studies. Twenty-one patients with suspicion of cerebral ischemia underwent perfusion CT using two different iodine contrast concentrations: 11 patients received iomeprol 300 (iodine concentration: 300 mg/ml) while ten received the same volume of iomeprol 400 (iodine concentration: 400 mg/ml). Scan parameters were kept constant for both groups. Maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and time to peak (TTP) were calculated from two adjacent slices. Quantitative comparisons were based on measurements of the maximum enhancement [Hounsfield units (HU)] and signal-to-noise index (SNI) on CBF, CBV, and TTP images. Determinations of grey-to-white-matter delineation for each iodine concentration were performed by two blinded readers. Only data from the non-ischemic hemispheres were considered. Both maximum enhancement and SNI values were higher after iomeprol 400, resulting in significantly better image quality in areas of low perfusion. No noteworthy differences were found for normal values of CBF, CBV, and TTP. Qualitative assessment of grey/white matter contrast on CBF and CBV maps revealed better performance for iomeprol 400. For brain perfusion studies, highly concentrated contrast media such as iomeprol 400 is superior to iomeprol 300. (orig.)

Ethanol production from concentrated food waste hydrolysates with yeast cells immobilized on corn stalk

Energy Technology Data Exchange (ETDEWEB)

Yan, Shoubao [Huainan Normal Univ., Anhui (China). School of Life Science; Chen, Xiangsong; Wu, Jingyong; Wang, Pingchao [Chinese Academy of Sciences, Hefei (China). Key Lab. of Ion Beam Bio-engineering of Inst. of Plasma Physics

2012-05-15

The aim of the present study was to examine ethanol production from concentrated food waste hydrolysates using whole cells of S. cerevisiae immobilized on corn stalks. In order to improve cell immobilization efficiency, biological modification of the carrier was carried out by cellulase hydrolysis. The results show that proper modification of the carrier with cellulase hydrolysis was suitable for cell immobilization. The mechanism proposed, cellulase hydrolysis, not only increased the immobilized cell concentration, but also disrupted the sleek surface to become rough and porous, which enhanced ethanol production. In batch fermentation with an initial reducing sugar concentration of 202.64 {+-} 1.86 g/l, an optimal ethanol concentration of 87.91 {+-} 1.98 g/l was obtained using a modified corn stalk-immobilized cell system. The ethanol concentration produced by the immobilized cells was 6.9% higher than that produced by the free cells. Ethanol production in the 14th cycle repeated batch fermentation demonstrated the enhanced stability of the immobilized yeast cells. Under continuous fermentation in an immobilized cell reactor, the maximum ethanol concentration of 84.85 g/l, and the highest ethanol yield of 0.43 g/g (of reducing sugar) were achieved at hydraulic retention time (HRT) of 3.10 h, whereas the maximum volumetric ethanol productivity of 43.54 g/l/h was observed at a HRT of 1.55 h. (orig.)

Airborne concentrations of Polybrominated diethyl etherin residential homes

Directory of Open Access Journals (Sweden)

S. Rahimzadeh

2009-07-01

Full Text Available Background and aims   Polybrominated diphenyl ethers (PBDE have been widely applied to different home and offices' appliances as flame retardant additives to inhibit ignition and enhance  the fire safety. Their toxicity, health effects, and resistance to environmental degradation are  matters of great interested among scientists. Airborne concentrations of PBDE in residential  homes were determined in this study.   Methods   In a cross sectional study, 33 residential homes were selected and airborne concentrations of PBDEs were investigated using PUF disk passive air samplers. Also in two building the concentraction of PBDEs were monitored in two rooms of a department in each building for 12 months.   Results   Average airborne concentration of ?PBDE (sum of congener #s 17, 28, 47, 49, 66, 85, 99, 100, 153, and 154 for all locations monitored was 52 (4-245 pgm -3 . While in one of the buildings the contaminant level of bedroom was significantly higher than the living room, PBDE   concentrations remained relatively constant for whole monitoring period.   Conclusion   The range of concentrations results to a wide variation between inhalation intakes of dwellers of the lowest and the highest contaminated homes (~50 folds.  

Enhanced removal of Methylene Blue by electrocoagulation using iron electrodes

Directory of Open Access Journals (Sweden)

Mohamed S. Mahmoud

2013-06-01

Full Text Available The removal of pollutants from effluents by electrocoagulation has become an attractive method in recent years. The study deals with the enhancement of removal of Methylene Blue dye by using an electromagnetic field during the electrocoagulation process. Effects of electrolyte concentration, dye concentration, intensity and the direction of the electromagnet on the decolorization efficiency have been investigated. The formed ferric hydroxide flocs trap colloidal particles and make solid–liquid separation easier during the next stage. The electrocoagulation stages must be optimized in order to design an economically feasible process. The results showed that the optimum electrolysis was 10–20 min at a current density of 8 mA/cm2, while the optimum concentration of the electrolyte (NaOH was found to be 2 wt.% when the dye concentration was 50 mg/L. The utilization of an electromagnetic field enhanced the dye removal due to the induced motion of paramagnetic ions inside the solution. The power consumption required to remove the dye was reduced by 45% in the case of applying an electromagnetic field.

Review of the use of magnetic concentrates in geochemical exploration

Science.gov (United States)

Overstreet, W.C.; Day, G.W.

1985-01-01

Magnetic concentrates recovered readily by hand magnet from alluvial sediments or panned concentrates have been used successfully in exploration as a geochemical sample medium for Cu, Zn, Co, Cr, Mo, Ni, V, Sn, and Be, particularly in arid environments where alluvial sediments may be contaminated by aeolian debris. Opportunity for this use arose recently as chemical and spectrographic techniques were developed to determine the abundances of a variety of trace elements in Fe-rich media. The use of analytical data from magnetic concentrates was introduced as one of several anomaly-enhancement techniques based on heavy minerals and intended to identify blind ore deposits. An extensive literature, reviewed here, on the relation of the chemical composition of the mineral magnetite, a main component of magnetic concentrates, to geologic conditions of origin, facilitates the interpretation of trace-element data in the context of association with ore deposits.

Enhancement of thermoelectric properties of Mg2Si compounds with Bi doping through carrier concentration tuning

Science.gov (United States)

Lee, Ji Eun; Cho, Sang-Hum; Oh, Min-Wook; Ryu, Byungi; Joo, Sung-Jae; Kim, Bong-Seo; Min, Bok-Ki; Lee, Hee-Woong; Park, Su-Dong

2014-07-01

The Bi-doped Mg2Si powder was fabricated with solid state reaction method and consolidated with hot pressing method and then its thermoelectric properties were investigated. The n-type transport properties were measured in all samples and temperature dependence of the electrical properties shows a behavior of degenerate semiconductors for Bi-doped samples. The electrical resistivity and the Seebeck coefficient were greatly reduced with Bi, which was mainly due to the increment of the carrier concentration. The samples have maximum carrier concentration of 8.2 × 1018 cm-3. The largest ZT value of 0.61 was achieve at 873 K for Mg2.04SiBi0.02. The Bi-doping was found to be an effective n-type dopant to adjust carrier concentration. [Figure not available: see fulltext.

Enhanced Enzymatic Production of Cephalexin at High Substrate Concentration with in situ Product Removal by Complexation

Directory of Open Access Journals (Sweden)

Dengchao Li

2008-01-01

Full Text Available Cephalexin (CEX was synthesized with 7-amino-3-deacetoxycephalosporanic acid (7-ADCA and D(–-phenylglycine methyl ester (PGME using immobilized penicillin G acylase from Escherichia coli. It was found that substrate concentration and in situ product could remarkably influence the ratio of synthesis to hydrolysis (S/H and the efficiency of CEX synthesis. The optimal ratio of enzyme to substrate was 65 IU/mM 7-ADCA. High substrate concentration improved the 7-ADCA conversion from 61 to 81 % in the process without in situ product removal (ISPR, while in the synthetic process with ISPR, high substrate concentration increased the 7-ADCA conversion from 88 to 98 %. CEX was easily separated from CEX/β-naphthol complex and its purity and overall yield were 99 and 70 %, respectively.

Flux Enhancement in Crossflow Membrane Filtration: Fouling and It's Minimization by Flow Reversal. Final Report

International Nuclear Information System (INIS)

Shamsuddin Ilias

2005-01-01

Fouling problems are perhaps the single most important reason for relatively slow acceptance of ultrafiltration in many areas of chemical and biological processing. To overcome the losses in permeate flux associated with concentration polarization and fouling in cross flow membrane filtration, we investigated the concept of flow reversal as a method to enhance membrane flux in ultrafiltration. Conceptually, flow reversal prevents the formation of stable hydrodynamic and concentration boundary layers at or near the membrane surface. Further more, periodic reversal of the flow direction of the feed stream at the membrane surface results in prevention and mitigation of membrane fouling. Consequently, these advantages are expected to enhance membrane flux significantly. A crossflow membrane filtration unit was designed and built to test the concept of periodic flow reversal for flux enhancement. The essential elements of the system include a crossflow hollow fiber membrane module integrated with a two-way valve to direct the feed flow directions. The two-way valve is controlled by a controller-timer for periodic reversal of flow of feed stream. Another important feature of the system is that with changing feed flow direction, the permeate flow direction is also changed to maintain countercurrent feed and permeate flows for enhanced mass transfer driving force (concentration difference). Three feed solutions (Bovine serum albumin (BSA), apple juice and citrus fruit pectin) were studied in crossflow membrane filtration. These solutes are well-known in membrane filtration for their fouling and concentration polarization potentials. Laboratory-scale tests on a hollow-fiber ultrafiltration membrane module using each of the feed solutes show that under flow reversal conditions, the permeate flux is significantly enhanced when compared with the conventional unidirectional flow. The flux enhancement is dramatic (by an order of magnitude) with increased feed concentration and

Sensitivity of the CSR self-interaction to the local longitudinal charge concentration of an electron bunch

CERN Document Server

Li, R

2001-01-01

Recent measurements of the coherent synchrotron radiation (CSR) effects indicated that the observed emittance growth and energy modulation due to the orbit-curvature-induced bunch self-interaction are sometimes bigger than predictions based on Gaussian longitudinal charge distributions. In this paper, by performing a model study, we show both analytically and numerically that when the longitudinal bunch charge distribution involves concentration of charges in a small fraction of the bunch length, enhancement of the CSR self-interaction beyond the Gaussian prediction may occur. The level of this enhancement is sensitive to the level of the local charge concentration.

Rate and selectivity modification in Fischer-Tropsch synthesis over charcoal supported molybdenum by forced concentration cycling

International Nuclear Information System (INIS)

Dun, J.W.; Gulari, E.

1985-01-01

Forced concentration cycling of the feed between pure CO and pure H/sub 2/ was used to successfully change both the selectivities and reactivities of promoted and unpromoted charcoal supported molybdenum catalysts in Fischer-Tropsch synthesis. It was found that with the unpromoted catalyst the rate enhancement increases with temperature and selectivity shifts towards methane. At the lower temperatures concentration cycling increases selectivity to ethane and higher hydrocarbons to levels only achievable with promised catalysts. Periodic operation with the potassium promoted catalyst results in small rate enhancements but the olefin to paraffin ratio is dramatically changed without changing the carbon number distribution

Ficus Deltoidea Enhance Glucose Uptake Activity in Cultured Muscle Cells

International Nuclear Information System (INIS)

Zainah Adam; Shafii Khamis; Amin Ismail; Muhajir Hamid

2015-01-01

Ficus deltoidea or locally known as Mas cotek is one of the common medicinal plants used in Malaysia. Our previous studies showed that this plant have blood glucose lowering effect. Glucose uptake into muscle and adipocytes cells is one of the known mechanisms of blood glucose lowering effect. This study was performed to evaluate the effect of Ficus deltoidea on glucose uptake activity into muscle cells. The cells were incubated with Ficus deltoidea extracts either alone or combination with insulin. Amount of glucose uptake by L6 myotubes was determined using glucose tracer, 2-deoxy-(1- 3 H 1 )-glucose. The results showed that Ficus deltoidea extracts at particular doses enhanced basal or insulin-mediated glucose uptake into muscle cells significantly. Hot aqueous extract enhanced glucose uptake at the low concentration (10 μg/ ml) whereas methanolic extract enhanced glucose uptake at low and high concentrations. Methanolic extract also mimicked insulin activity during enhancing glucose uptake into L^ muscle cells. Glucose uptake activity of Ficus deltoidea could be attributed by the phenolic compound presence in the plant. This study had shown that Ficus deltoidea has the ability to enhance glucose uptake into muscle cells which is partly contributed the antidiabetic activity of this plant. (author)

Potentiation of the action of metronidazole on Helicobacter pylori by omeprazole and bismuth subcitrate

DEFF Research Database (Denmark)

Andersen, L P; Colding, H; Kristiansen, J E

2000-01-01

test (Etest). With 0.5 MIC of either of the two drugs, the susceptibility of all H. pylori4 mg/l) reverted to being metronidazole sensitive. These results suggested that either bismuth salts or proton pump inhibitors may be effective in the treatment of some infections with metronidazole-resistant H...... to regimens that include proton pump inhibitors. In the present study, the synergistic effect of subinhibitory concentrations (0.25-0.5 MIC) of either bismuth subcitrate or omeprazole with metronidazole on the susceptibility of 42 H. pylori strains was investigated by agar dilution method and the Epsilometer......Treatment failures using triple therapy that include metronidazole, are common in patients infected with metronidazole-resistant Helicobacter pylori in the gastric mucosa. Higher eradication rates in such patients have been described when treatment regimens include bismuth salts compared...

Effects of antibiotics on quorum sensing in pseudomonas aeruginosa

DEFF Research Database (Denmark)

Skindersø, Mette Elena; Alhede, Morten; Phipps, Richard Kerry

2008-01-01

in animal infection models. Treatment of cystic fibrosis (CF) patients chronically infected with P. aeruginosa with the macrolide antibiotic azithromycin (AZM) has been demonstrated to improve the clinical outcome. Several studies indicate that AZM may accomplish its beneficial action in CF patients....... Three of the antibiotics tested, AZM, ceftazidime (CFT), and ciprofloxacin (CPR), were very active in the assay and were further examined for their effects on QS-regulated virulence factor production in P. aeruginosa. The effects of the three antibiotics administered at subinhibitory concentrations were...... by impeding QS, thereby reducing the pathogenicity of P. aeruginosa. This led us to investigate whether QS inhibition is a common feature of antibiotics. We present the results of a screening of 12 antibiotics for their QS-inhibitory activities using a previously described QS inhibitor selector 1 strain...

Chemical composition of fennel essential oil and its impact on Staphylococcus aureus exotoxin production.

Science.gov (United States)

Qiu, Jiazhang; Li, Hongen; Su, Hongwei; Dong, Jing; Luo, Mingjing; Wang, Jianfeng; Leng, Bingfeng; Deng, Yanhong; Liu, Juxiong; Deng, Xuming

2012-04-01

In this study, fennel oil was isolated by hydrodistillation, and the chemical composition was determined by gas chromatography/mass spectral analysis. The antimicrobial activity of fennel oil against Staphylococcus aureus was evaluated by broth microdilution. A haemolysis assay, tumour necrosis factor (TNF) release assay, western blot, and real-time reverse transcription (RT)-PCR were applied to investigate the influence of fennel oil on the production of S. aureus virulence-related exoproteins. The data show that fennel oil, which contains a high level of trans-anethole, was active against S. aureus, with MICs ranging from 64 to 256 μg/ml. Furthermore, fennel oil, when used at subinhibitory concentrations, could dose-dependently decrease the expression of S. aureus exotoxins, including α-toxin, Staphylococcal enterotoxins (SEs) and toxic shock syndrome toxin 1 (TSST-1).

Pathomechanism of ring enhancement in intracerebral hematomas on CT

International Nuclear Information System (INIS)

Takasugi, Shinsuke; Kageyama, Takefumi; Yamashita, Shigeru; Kusaka, Kazumasa; Ueda, Shin

1980-01-01

As a simulation of hypertensive intracerebral hematoma, about 3.5 ml of autologus venous blood were injected into an artificial cavity of a unilateral cerebral hemisphere in dogs. The cavity was made by the insertion and inflation of a balloon canula near the basal ganglia region of the dog. At the acute stage after the injection, the hematoma showed a round-shaped and homogeneous high density. 9 days later, a positive ring enhancement appeared around this high-density area in most of the cases. Subsequently, the hematoma changed into an isodensity with a tendency toward the concentric concentration of the ring enhancement and to the final low-density stage with a spotted enhancement in the center. That is our experimental intracerebral hematoma of the dog showed a pattern of the chronological course of the CT appearance quite similar to that of clinical cases of hypertensive intracerebral hematomas. At the onset of the ring enhancement, many new and immature capillaries were noted in the adjacent tissue of the hematoma, corresponding to the positive enhancement. The new capillaries were gradually shifted to the center of the hematoma; the enhancement also coincided with them. The ultrastructures of these new capillaries were examined electronmicroscopically. There was some resemblance to the capillaries of muscle with many pinocytotic vesicles and shallowed tight junctions. These experimental facts suggest that the enhancement phenomenon occurred in close relationship to the newly produced hypervascularization of the capillaries around the hematoma, which was a phenomenon of the healing process of the lesion. Therefore, the pathomechanism of the enhancement was thought to be involved the pooling of the contrast media in the increased vascular bed as well as a loss of blood brain barrier in these newly produced immature capillaries. (J.P.N.)

Effect of halideions on the surface-enhanced Raman spectroscopy of methylene blue for borohydride-reduced silver colloid

International Nuclear Information System (INIS)

Dong Xiao; Gu Huaimin; Liu Fang

2011-01-01

The surface enhanced Raman scattering (SERS) spectrum of methylene blue (MB) was studied when adding a range of halideions to borohydride-reduced silver colloid. The halideions such as chloride, bromide and iodide were added as aggregating agents to study the effects of halideions on SERS spectroscopy of MB and observe which halideion gives the greatest enhancement for borohydride-reduced silver colloids. The SERS spectra of MB were also detected over a wide range of concentrations of halideions to find the optimum concentration of halideions for SERS enhancement. From the results of this study, the intensity of SERS signal of MB was enhanced significantly when adding halideions to the colloid. Among the three kinds of halideions, chloride gives the greatest enhancement on SERS signal. The enhancement factors for MB with optimal concentration of chloride, bromide and iodide are 3.44x10 4 , 2.04x10 4 , and 1.0x10 4 , respectively. The differences of the SERS spectra of MB when adding different kinds and concentrations of halideions to the colloid may be attributed to the both effects of extent of aggregation of the colloid and the modification of silver surface chemistry. The purpose of this study is to further investigate the effect of halideions on borohydride-reduced silver colloid and to make the experimental conditions suitable for detecting some analytes in high efficiency on rational principles.

Enhancing performance of a linear dielectric based concentrating photovoltaic system using a reflective film along the edge

International Nuclear Information System (INIS)

Baig, Hasan; Sarmah, Nabin; Chemisana, Daniel; Rosell, Joan; Mallick, Tapas K.

2014-01-01

In the present study, we model and analyse the performance of a dielectric based linear concentrating photovoltaic system using ray tracing and finite element methods. The results obtained are compared with the experiments. The system under study is a linear asymmetric CPC (Compound Parabolic Concentrator) designed to operate under extreme incident angles of 0° and 55° and have a geometrical concentration ratio of 2.8×. Initial experiments showed a maximum PR (power ratio) of 2.2 compared to a non concentrating counterpart. An improvement to this has been proposed and verified by adding a reflective film along the edges of the concentrator to capture the escaping rays and minimise optical losses. The addition of the reflective film changes the incoming distribution on the solar cell. Results show an increase of 16% in the average power output while using this reflective film. On including the thermal effects it was found that the overall benefit changes to about 6% while using a reflective film. Additionally, the effects of the non-uniformity of the incoming radiation are also analysed and reported for both the cases. It is found that adding the reflective film drops the maximum power at the output by only 0.5% due to the effect of non-uniformity. - Highlights: • Optical, thermal and electrical analysis of a concentrating photovoltaic system. • Improvement in performance by use of reflective film along the edge. • Experimental validation of results. • Effects of non-uniform illumination on the performance of the CPV system. • Impact of temperature profile on the overall performance

Performance of single-junction and dual-junction InGaP/GaAs solar cells under low concentration ratios

International Nuclear Information System (INIS)

Khan, Aurangzeb; Yamaguchi, Masafumi; Takamoto, Tatsuya

2004-01-01

A study of the performance of single-junction InGaP/GaAs and dual-junction InGaP/GaAs tandem cells under low concentration ratios (up to 15 suns), before and after 1 MeV electron irradiation is presented. Analysis of the tunnel junction parameters under different concentrated light illuminations reveals that the peak current (J P ) and valley current (J V ) densities should be greater than the short-circuit current density (J sc ) for better performance. The tunnel junction behavior against light intensity improved after irradiation. This led to the suggestion that the peak current density (J P ) and valley current density (J V ) of the tunnel junction were enhanced after irradiation or the peak current was shifted to higher concentration. The recovery of the radiation damage under concentrated light illumination conditions suggests that the performance of the InGaP/GaAs tandem solar cell can be enhanced even under low concentration ratios

Stimulation of diesel degradation and biosurfactant production by aminoglycosides in a novel oil-degrading bacterium Pseudomonas luteola PRO23

Directory of Open Access Journals (Sweden)

Atanasković Iva M.

2016-01-01

Full Text Available Bioremediation is promising technology for dealing with oil hydrocarbons contamination. In this research growth kinetics and oil biodegradation efficiency of Pseudomonas luteola PRO23, isolated from crude oil-contaminated soil samples, were investigated under different concentrations (5, 10 and 20 g/L of light and heavy crude oil. More efficient biodegradation and more rapid adaptation and cell growth were obtained in conditions with light oil. The 5 to 10 g/L upgrade of light oil concentration stimulated the microbial growth and the biodegradation efficiency. Further upgrade of light oil concentration and the upgrade of heavy oil concentration both inhibited the microbial growth, as well as biodegradation process. Aminoglycosides stimulated biosurfactant production in P. luteola in the range of sub-inhibitory concentrations (0.3125, 0.625 μg/mL. Aminoglycosides also induced biofilm formation. The production of biosurfactants was the most intense during lag phase and continues until stationary phase. Aminoglycosides also induced changes in P. luteola growth kinetics. In the presence of aminoglycosides this strain degraded 82% of diesel for 96 h. These results indicated that Pseudomonas luteola PRO23 potentially can be used in bioremediation of crude oil-contaminated environments and that aminoglycosides could stimulate this process. [Projekat Ministarstva nauke Republike Srbije, br. TR31080

An enhancement to Vynnycky's model for the all-vanadium redox flow battery

International Nuclear Information System (INIS)

Chen, Ching Liang; Yeoh, Hak Koon; Chakrabarti, Mohammed Harun

2014-01-01

Highlights: • Improvements are made on an existing 1-D stationary VRFB model. • Effects of species concentration and electrolyte flow rate are captured. • Predictions on charge-discharge curves are improved over existing 1-D model. - Abstract: An enhanced one-dimensional (1-D) stationary model for the all-vanadium redox flow battery (VRFB) is developed based on an existing 1-D model proposed by Vynnycky [Energy, 36 (2011): 2242 – 2256]. The enhanced model incorporates species conservation equations along with an advection term to describe the concentration changes in the porous electrodes. In addition, a complete Nernst equation, which accounts for proton concentrations in the VRFB is also included to improve the cell voltage prediction without using any arbitrary fitting contact voltage. The enhanced 1-D model is validated against experimental data from the literature and the ability of the model to predict the cell performance is investigated. The cell voltage prediction shows significant improvement over Vynnycky's 1-D model and also compares surprisingly well with higher-dimensional models. This enhanced 1-D model is also capable of capturing the cell performance at different electrolyte flow rates, especially evidenced by the polarization curves. Using both the power based and round-trip efficiencies, the optimal electrolyte flow rate for the VRFB can be determined. This enhanced 1-D model is expected to serve as a useful design tool for the development and optimization of VRFB systems

Steady-state ozone concentration in radiation induced noble gas-oxygen discharges

International Nuclear Information System (INIS)

Elsayed-Ali, H.E.; Miley, G.H.

1985-01-01

Measurements of steady-state ozone concentrations in continuous radiation induced noble gas-O 2 and noble gas-O 2 -SF 6 mixtures has been accomplished. The discharges were created through the bombardment of the gases with energetic particles from the boron-10 (n,α) lithium-7 nuclear reaction. Three noble gases were studied, He, Ne, and Ar at partial pressures of few hundred Torr. The dose rates studied were in the order of 10 15 eV.cm -3 .s -1 . The experimental apparatus and proceedure were previously described. The experimentally observed stead-state ozone concentrations in noble gas-O 2 discharges were about an order of magnitude lower than that observed for oxygen radiolysis at similar dose rates. These results were physically explained by an enhanced role of negative ionic reactions with ozone causing its destruction. In noble gas-O 2 -SF 6 mixtures, the steady-state ozone concentrations were found to be significantly higher (3-6 times) than that without the SF 6 addition. This observation was contrary to only a small increase observed after SF 6 addition to a few hundred Torr oxygen and is explained by an enhanced rate of electron dissociative attachment of ozone in noble gas-O 2 discharges

Interacting Frenkel defects at high concentration and the superionic transition in fluorite crystals

International Nuclear Information System (INIS)

March, N.H.; Tosi, M.P.

1980-11-01

A spherical cell model is proposed to account for the explicit concentration dependence of Frenkel defects in an ionic system. In the model, the linearized Debye-Hueckel equation is soluble exactly, subject to the boundary condition that the electric field is zero at the cell boundary R, related to the concentration α of defects by R proportional to csup(-1/3). This screened field is used to calculate the chemical potential, which in turn leads to a condition for the instability of the interacting defect assembly. This condition allows one to calculate the enhancement of the concentration of defects above its Arrhenius value at the point of instability in terms of (a) the critical concentration csub(c), (b) a/R, where a is the radius of defect and (c) the Debye-Hueckel screening length kappasub(c). It is clear from the cell model that this enhancement factor is reduced somewhat in the relevant range of parameters in some of the fluorites from its value in extended Debye-Hueckel theory. It is anticipated that the instability discussed here should afford an upper bound to csub(c) at the superionic transition, within the range of validity of the model. The excess he at capacity csub(p) is also discussed briefly. (author)

Highly Sensitive Cadmium Concentration Sensor Using Long Period Grating

Directory of Open Access Journals (Sweden)

A. S. Lalasangi

2011-08-01

Full Text Available In this paper we have proposed a simple and effective Long Period Grating chemical sensor for detecting the traces of Cadmium (Cd++ in drinking water at ppm level. Long Period gratings (LPG were fabricated by point-by-point technique with CO2 laser. We have characterized the LPG concentration sensor sensitivity for different solutions of Cd concentrations varying from 0.01 ppm to 0.04 ppm by injecting white Light source and observed transmitted spectra using Optical Spectrum Analyzer (OSA. Proper reagents have been used in the solutions for detection of the Cd species. The overall shift in wavelength is 10 nm when surrounding medium gradually changed from water to 0.04 ppm of cadmium concentrations. A comparative study has been done using sophisticated spectroscopic atomic absorption spectrometer (AAS and Inductively Coupled Plasma (ICP instruments. The spectral sensitivity enhancement was done by modifying grating surface with gold nanoparticles.

Non Pharmacological Cognitive Enhancers - Current Perspectives.

Science.gov (United States)

Sachdeva, Ankur; Kumar, Kuldip; Anand, Kuljeet Singh

2015-07-01

Cognition refers to the mental processes involved in thinking, knowing, remembering, judging, and problem solving. Cognitive dysfunctions are an integral part of neuropsychiatric disorders as well as in healthy ageing. Cognitive Enhancers are molecules that help improve aspects of cognition like memory, intelligence, motivation, attention and concentration. Recently, Non Pharmacological Cognitive Enhancers have gained popularity as effective and safe alternative to various established drugs. Many of these Non Pharmacological Cognitive Enhancers seem to be more efficacious compared to currently available Pharmacological Cognitive Enhancers. This review describes and summarizes evidence on various Non Pharmacological Cognitive Enhancers such as physical exercise, sleep, meditation and yoga, spirituality, nutrients, computer training, brain stimulation, and music. We also discuss their role in ageing and different neuro-psychiatric disorders, and current status of Cochrane database recommendations. We searched the Pubmed database for the articles and reviews having the terms 'non pharmacological and cognitive' in the title, published from 2000 till 2014. A total of 11 results displayed, out of which 10 were relevant to the review. These were selected and reviewed. Appropriate cross-references within the articles along with Cochrane reviews were also considered and studied.

Effect of compost and humic acid in mobility and concentration of cadmium and chromium in soil and plant

Directory of Open Access Journals (Sweden)

A. Chaab

2016-12-01

Full Text Available The effect of compost and humic acid in mobility and concentration of cadmium and chromium in contaminated soil were investigated. Experiment was carried out with three levels of soil cadmium and chromium and two organic matters (compost and humic acid. The study was performed in a randomized complete block design with 3 replicates. Results indicated that application of organic substances enhanced movement of cadmium and chromium in soil column. Humic acid is more effective than compost on the mobility of cadmium and chromium in soil. Mobility of cadmium and chromium in the lower depths of soil column were increased. Cadmium and chromium concentration in shoots and roots enhanced due to increasing those concentration in soil and application of organic substances. Increase in cadmium in shoots can be attributed to the high mobility of this element in maize plant. Maize root chromium concentration was greater than shoot chromium concentration. Humic acid was more effective than compost as cadmium and chromium concentration in root and shoot was concerned. Low mobility of chromium in plant and accumulation of chromium in roots can be reasons of decreasing of chromium concentration in shoot of plant and its bioaccumulation.

High contrast enhancement aspect of dynamic computed tomography with arterial infusion - DCT-AI

International Nuclear Information System (INIS)

Kato, Seishi; Iwasaki, Naoya; Matsumura, Yoshimitsu; Kuramae, Shigeru; Mishiro, Tadashi

1983-01-01

Dynamic computed tomography was performed on 112 cases possibly having hepatic tumors with intraarterial infusion of undiluted contrast into a selectively placed catheter following angiographies. Our dynamic program could evaluate not only early phase of enhancement but also late phase up to 120 sec. Reconstructed views from early scans and magnified views were very useful to evaluate minute sequential changes. Hepatic masses less than 5 cm in size were found in thirty-one cases. Patterns of tumor enhancement and time-density curves have been analysed to correlate them with histology. Four types of tumor enhancement were noted: (1) homogeneous (2) patchy (3) mottled (4) ringed. Characteristic changes were observed in hepatocellular carcinoma - HCC - (mostly mottled) and haemangioma (mostly patchy). The former was divided in two groups reflecting the cellular maturity. The metastatic tumor could be enhanced in a ringed form with dendritic pattern of supplying vascularities in some cases. To support the use of undiluted contrast and to investigate the diagnostic efficacy of high contrast enhancement, experiments were performed by taking transaxial views of an acrylic phantom immersed in different concentrations of contrast. Analysis of CT images taken at different HU values ranging from 0 to 450 demonstrated that the higher the concentration of contrast, the better the spatial resolution was. Also larger magnification could be expected by using higher concentration of contrast. Although our Dynamic Computed Tomography with Arterial Infusion of Contrast still has drawbacks and limited indications, we advocate it as a better way of enhancement to detect and evaluate the hepatic masses, which sometimes elude the examiner's grasp with conventional way of enhancement. (author)

Enhancing Newspaper's Value as Local Advertising Medium.

Science.gov (United States)

Prater, Bruce W.; And Others

1994-01-01

Finds that, to enhance the value of a newspaper's advertising, newspaper executives seek to broaden the scope of their operations by adding new subscribers and advertisers, while marketers tend to prefer narrowing the focus of operations, serving the existing customer base or concentrating exclusively on select market segments. (SR)

Enhanced xanthan production process in shake flasks and pilot ...

African Journals Online (AJOL)

Enhanced xanthan production process in shake flasks and pilot scale bioreactors using industrial semidefined medium. ... by the type and concentration of the different carbon and nitrogen source as well as other medium components. The

Estramustine: A novel radiation enhancer in human carcinoma cells

International Nuclear Information System (INIS)

Ryu, S.; Gabel, M.; Khil, M.S.

1994-01-01

Estramustine (EM), an antimicrotubule agent, binds microtubule-associated proteins, causes spindle disassembly, and arrests cells at the late G 2 /M phase of the cell cycle. Since cells in the G 2 /M phase are the most radiosensitive and some human cancer cells contain high level of EM-binding protein, experiments were carried out to determine whether radiation sensitization could be obtained in human carcinoma cells. Cells containing a high level of EM-binding protein such as prostate carcinoma (DU-145), breast carcinoma (MCF-7), and malignant glioma (U-251) were used to demonstrate radiosensitization. Cervical carcinoma (HeLa-S 3 ) and colon carcinoma (HT-29) cells which are not known to contain EM-binding protein were also employed. Cell survival was assayed by the colony forming ability of single plated cells in culture to obtain dose-survival curves. Pretreatment of DU-145, MCF-7, and U-251 cells to a nontoxic concentration (5 μM) of EM for more than one cell cycle time, substantially enhanced the radiation-induced cytotoxicity. The sensitizer enhancement ratio of these cells ranged from 1.35-1.52. The magnitude of the enhancement was dependent on the drug concentration and exposure time. The rate of cell accumulation in G 2 /M phase, as determined by flow cytometry, increased with longer treatment time in the cell lines which showed radiosensitization. Other antimicrotubule agents such as taxol and vinblastine caused minimal or no radiosensitization at nontoxic concentrations. The data provide a radiobiological basis for using EM as a novel radiation enhancer, with the property of tissue selectivity. 29 refs., 4 figs., 1 tab

Enhancement of organic matter degradation and methane gas production of anaerobic granular sludge by degasification of dissolved hydrogen gas.

Science.gov (United States)

Satoh, Hisashi; Bandara, Wasala M K R T W; Sasakawa, Manabu; Nakahara, Yoshihito; Takahashi, Masahiro; Okabe, Satoshi

2017-11-01

A hollow fiber degassing membrane (DM) was applied to enhance organic matter degradation and methane gas production of anaerobic granular sludge process by reducing the dissolved hydrogen gas (D-H 2 ) concentration in the liquid phase. DM was installed in the bench-scale anaerobic granular sludge reactors and D-H 2 was removed through DM using a vacuum pump. Degasification improved the organic matter degradation efficiency to 79% while the efficiency was 62% without degasification at 12,000mgL -1 of the influent T-COD concentration. Measurement of D-H 2 concentrations in the liquid phase confirmed that D-H 2 was removed by degasification. Furthermore, the effect of acetate concentrations on the organic matter degradation efficiency was investigated. At acetate concentrations above 3gL -1 , organic matter degradation deteriorated. Degasification enhanced the propionate and acetate degradation. These results suggest that degasification reduced D-H 2 concentration and volatile fatty acids concentrations, prevented pH drop, and subsequent enhanced organic matter degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Complementary bowtie aperture for localizing and enhancing optical magnetic field

Science.gov (United States)

Zhou, Nan; Kinzel, Edward C.; Xu, Xianfan

2011-08-01

Nanoscale bowtie antenna and bowtie aperture antenna have been shown to generate strongly enhanced and localized electric fields below the diffraction limit in the optical frequency range. According to Babinet's principle, their complements will be efficient for concentrating and enhancing magnetic fields. In this Letter, we discuss the enhancement of magnetic field intensity of nanoscale complementary bowtie aperture as well as complementary bowtie aperture antenna, or diabolo nanoantenna. We show that the complementary bowtie antenna resonates at a smaller wavelength and thus is more suitable for applications near visible wavelengths. The near-field magnetic intensity can be further enhanced by the addition of groove structures that scatter surface plasmon.

Heat transfer enhancement of car radiator using aqua based magnesium oxide nanofluids

Directory of Open Access Journals (Sweden)

Ali Hafiz Muhammad

2015-01-01

Full Text Available The focus of this research paper is on the application of water based MgO nanofluids for thermal management of a car radiator. Nanofluids of different volumetric concentrations (i.e. 0.06%, 0.09% and 0.12% were prepared and then experimentally tested for their heat transfer performance in a car radiator. All concentrations showed enhancement in heat transfer compared to the pure base fluid. A peak heat transfer enhancement of 31% was obtained at 0.12 % volumetric concentration of MgO in basefluid. The fluid flow rate was kept in a range of 8-16 liter per minute. Lower flow rates resulted in greater heat transfer rates as compared to heat transfer rates at higher flow rates for the same volumetric concentration. Heat transfer rates were found weakly dependent on the inlet fluid temperature. An increase of 8°C in inlet temperature showed only a 6% increase in heat transfer rate.

Multi-detector row helical CT of the liver. Quantitative assessment of iodine concentration of intravenous contrast material on multiphasic CT. A prospective randomized study

International Nuclear Information System (INIS)

Tsurusaki, Masakatsu; Sugimoto, Koji; Fujii, Masahiko; Sugimura, Kazuro

2004-01-01

The purpose of this study was to assess the quantitative effects of contrast material concentration on hepatic parenchymal and vascular enhancement in multiphasic computed tomography (CT), using multi-detector row helical CT. We designed a prospective randomized study to test two different concentrations of contrast material on five phasic scans of the liver. One hundred patients were randomly assigned to two groups: an iodine concentration of 300 mg/mL in group A and 370 mg/mL in group B. All patients received a fixed volume of 100 mL at a 4 mL/sec injection rate. Enhancement values for the hepatic parenchyma and aorta at three levels (upper, middle, and lower level of the liver), and values for portal and hepatic veins were statistically compared between the two groups. Hepatic parenchymal enhancement values at all levels of the liver in portal phase (PP) and equilibrium phase (EP) were significantly higher in group B than in group A (p<0.01). Aortic enhancement values at two levels of the liver (middle and lower) in early hepatic arterial phase (EAP) were significantly higher in group B than in group A (p<0.05), however, there was no significant difference between groups A and B in aortic enhancement during the delayed hepatic arterial phase (DAP). Portal and hepatic venous enhancement values in PP and EP were significantly higher in group B than in group A (p<0.01). On multiphasic dynamic CT, the use of a higher iodine concentration of contrast material results in higher hepatic parenchymal enhancement and aortic enhancement, as well as higher portal and hepatic venous enhancement. (author)

An experimental study on accelerated fouling of aluminum oxide and ferric oxide particles in internally enhanced tubes

Energy Technology Data Exchange (ETDEWEB)

Abedin, Mohammad Zoynal; Kim, Nae Hyun [School of Mechanical System Engineering, Incheon National University, Incheon (Korea, Republic of)

2016-12-15

This paper describes the results of accelerated particulate fouling tests performed on three enhanced tubes and a plain tube. The tests were performed using ferric oxide and aluminum oxide as foulant materials. Three enhanced tubes included 25 start, 10 start helically ribbed tubes and a ripple tube. Effects of the water velocity (0.9 to 1.8 m/s) and foulant concentration (750 to 2500 ppm) were investigated. At 750 ppm, the enhanced tubes fouled almost the same as the plain tube for the entire velocity range tested (0.9 to 1.8 m/s). The enhanced tube fouled faster than the plain tube for cases of high concentration combined with low velocities. Of the three enhanced tubes, the 25 start helically ribbed tube fouled faster than the ripple and the 10 start helically ribbed tubes. One thing to be noted is that the fouling concentrations used in the tests are significantly higher than would be expected in commercial heat exchangers. Also, the velocity range investigated is lower than would be expected in heat exchanger operation.

Can Integrated Micro-Optical Concentrator Technology Revolutionize Flat-Plate Photovoltaic Solar Energy Harvesting?

Science.gov (United States)

Haney, Michael W.

2015-12-01

The economies-of-scale and enhanced performance of integrated micro-technologies have repeatedly delivered disruptive market impact. Examples range from microelectronics to displays to lighting. However, integrated micro-scale technologies have yet to be applied in a transformational way to solar photovoltaic panels. The recently announced Micro-scale Optimized Solar-cell Arrays with Integrated Concentration (MOSAIC) program aims to create a new paradigm in solar photovoltaic panel technology based on the incorporation of micro-concentrating photo-voltaic (μ-CPV) cells. As depicted in Figure 1, MOSAIC will integrate arrays of micro-optical concentrating elements and micro-scale PV elements to achieve the same aggregated collection area and high conversion efficiency of a conventional (i.e., macro-scale) CPV approach, but with the low profile and mass, and hopefully cost, of a conventional non-concentrated PV panel. The reduced size and weight, and enhanced wiring complexity, of the MOSAIC approach provide the opportunity to access the high-performance/low-cost region between the conventional CPV and flat-plate (1-sun) PV domains shown in Figure 2. Accessing this portion of the graph in Figure 2 will expand the geographic and market reach of flat-plate PV. This talk reviews the motivation and goals for the MOSAIC program. The diversity of the technical approaches to micro-concentration, embedded solar tracking, and hybrid direct/diffuse solar resource collection found in the MOSAIC portfolio of projects will also be highlighted.

Enhancement of Chiroptical Signals by Circular Differential Mie Scattering of Nanoparticles.

Science.gov (United States)

Yoo, SeokJae; Park, Q-Han

2015-09-25

We enhance the weak optical signals of small chiral molecules via circular differential Mie scattering (CDMS) of nanoparticles immersed in them. CDMS is the preferential Mie scattering of left- and right-handed circularly polarized light by nanoparticles whose sizes are about the same as the wavelength of light. Solving the Mie scattering theory for chiral media, we find that the CDMS signal of the particle is linearly proportional to the chirality parameter κ of the molecules. This linear amplitude enhancement by CDMS of the particle holds, even for large particles, which have a retardation effect. We also demonstrate that the CDMS of a nanoparticle is sensitive to changes of molecular concentration, and that the nanoparticle can be utilized as a chiroptical biosensor detecting the concentration of analyte. We expect that the enhancement of molecular chiroptical signals by CDMS will pave the way for novel chiroptical spectroscopy using nanostructures.

Sorption of Arsenic from Desalination Concentrate onto Drinking Water Treatment Solids: Operating Conditions and Kinetics

Directory of Open Access Journals (Sweden)

Xuesong Xu

2018-01-01

Full Text Available Selective removal of arsenic from aqueous solutions with high salinity is required for safe disposal of the concentrate and protection of the environment. The use of drinking water treatment solids (DWTS to remove arsenic from reverse osmosis (RO concentrate was studied by batch sorption experiments. The impacts of solution chemistry, contact time, sorbent dosage, and arsenic concentration on sorption were investigated, and arsenic sorption kinetics and isotherms were modeled. The results indicated that DWTS were effective in removing arsenic from RO concentrate. The arsenic sorption process followed a pseudo-second-order kinetic model. Multilayer adsorption was simulated by Freundlich equation. The maximum sorption capacities were calculated to be 170 mg arsenic per gram of DWTS. Arsenic sorption was enhanced by surface precipitation onto the DWTS due to the high amount of calcium in the RO concentrate and the formation of ternary complexes between arsenic and natural organic matter (NOM bound by the polyvalent cations in DWTS. The interactions between arsenic and NOM in the solid phase and aqueous phase exhibited two-sided effects on arsenic sorption onto DWTS. NOM in aqueous solution hindered the arsenic sorption onto DWTS, while the high organic matter content in solid DWTS phase enhanced arsenic sorption.

Carbon dioxide efficiency of terrestrial enhanced weathering.

Science.gov (United States)

Moosdorf, Nils; Renforth, Phil; Hartmann, Jens

2014-05-06

Terrestrial enhanced weathering, the spreading of ultramafic silicate rock flour to enhance natural weathering rates, has been suggested as part of a strategy to reduce global atmospheric CO2 levels. We budget potential CO2 sequestration against associated CO2 emissions to assess the net CO2 removal of terrestrial enhanced weathering. We combine global spatial data sets of potential source rocks, transport networks, and application areas with associated CO2 emissions in optimistic and pessimistic scenarios. The results show that the choice of source rocks and material comminution technique dominate the CO2 efficiency of enhanced weathering. CO2 emissions from transport amount to on average 0.5-3% of potentially sequestered CO2. The emissions of material mining and application are negligible. After accounting for all emissions, 0.5-1.0 t CO2 can be sequestered on average per tonne of rock, translating into a unit cost from 1.6 to 9.9 GJ per tonne CO2 sequestered by enhanced weathering. However, to control or reduce atmospheric CO2 concentrations substantially with enhanced weathering would require very large amounts of rock. Before enhanced weathering could be applied on large scales, more research is needed to assess weathering rates, potential side effects, social acceptability, and mechanisms of governance.

Pool boiling performance of lithium bromide solution on enhanced tubes

International Nuclear Information System (INIS)

Sim, Yong Sub; Kim, Nae Hyun

2015-01-01

In the present study, pool boiling heat transfer coefficients of LiBr solution were obtained for smooth, corrugated, floral and low fin tubes. Test range covered saturation pressure from 7.38 kPa to 101.3 kPa, LiBr concentration from 0% to 50%. Low fin tube yielded the highest heat transfer coefficient followed by floral, corrugated and smooth tube. The sequence was the same independent of saturation pressure or LiBr concentration. For the low fin tube, the heat transfer enhancement ratio ranged from 1.34 to 2.37. Those of floral tube are 1.16 to 1.64 and those of corrugated tube are 0.90 to 1.43. The enhancement ratio decreased as LiBr concentration increased. No general trend is observed for the effect of saturation pressure. Exceptionally high heat transfer coefficient was obtained for the low fin tube in pure water. The reason may be attributed to many small bubbles at high frequency due to the existence of low fins. Boiling heat transfer correlations were developed which are applicable for saturation pressure from 7.38 kPa to 101.3 kPa and LiBr concentration from 0% to 50%.

Dependence of spleen sequestration on erythrocytes following administration of various concentrations of BMHP-197Hg

International Nuclear Information System (INIS)

Kapff, S. v.

1980-01-01

In the course of routine splenic scintiscanning, the effects of BMHP-Hg 197 concentrations on the kinetics of damaged erythrocytes and on image quality have been investigated. The following findings were obtained: 1. Significant displacement of the Price-Jones curve in dependence of BMHP concentrations. 2. No significant enzymatic changes 3. An enhanced labelling index at high concentrations and a higher spleen sequestration rate 4. A significant improvement of scintiscan quality at higher concentrations 5. Erythrocyte washing before incubation with BMHP was unnecessary as it does not improve the results to an extent that would warrant the tedious procedure. (orig.) [de

Subjective and objective image differences in pediatric computed tomography cardiac angiography using lower iodine concentration

International Nuclear Information System (INIS)

Hwang, Jae-Yeon; Choo, Ki Seok; Choi, Yoon Young; Kim, Jin Hyeok; Ryu, Hwaseong; Kim, Yong-Woo; Jeon, Ung Bae; Nam, Kyung Jin; Han, Junhee

2017-01-01

Several recent studies showed the optimal contrast enhancement with a low-concentration and iso-osmolar contrast media in both adult and pediatric patients. However, low contrast media concentrations are not routinely used due to concerns of suboptimal enhancement of cardiac structures and small vessels. To evaluate the feasibility of using iso-osmolar contrast media containing a low iodine dose for CT cardiac angiography at 80 kilovolts (kVp) in neonates and infants. The iodixanol 270 group consisted of 79 CT scans and the iopromide 370 group of 62 CT scans in patients ≤1 year old. Objective measurement of the contrast enhancement was analyzed and contrast-to-noise ratios of the ascending aorta and left ventricle were calculated. Regarding subjective measurement, a four-point scale system was devised to evaluate degrees of contrast enhancement, image noise, motion artifact and overall image quality of each image set. Reader performance for correctly differentiating iodixanol 270 and iopromide 370 by visual assessment was evaluated. Group objective and subjective measurements were nonsignificantly different. Overall sensitivity, specificity and diagnostic accuracy for correctly differentiating iodixanol 270 and iopromide 370 by visual assessment were 42.8%, 59%, and 50%, respectively. The application of iodixanol 270 achieved optimal enhancement for performing pediatric cardiac CT angiography at 80 kVp in neonates and infants. Objective measurements of contrast enhancement and subjective image quality assessments were not statistically different in the iodixanol 270 and iopromide 370 groups. (orig.)

Subjective and objective image differences in pediatric computed tomography cardiac angiography using lower iodine concentration

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jae-Yeon [Pusan National University Yangsan Hospital, Department of Radiology, Yangsan-si, Gyeongsangnam-do (Korea, Republic of); Pusan National University Yangsan Hospital, Research Institute for Convergence of Biomedical Science and Technology, Yangsan-si, Gyeongsangnam-do (Korea, Republic of); Choo, Ki Seok; Choi, Yoon Young; Kim, Jin Hyeok; Ryu, Hwaseong; Kim, Yong-Woo; Jeon, Ung Bae; Nam, Kyung Jin [Pusan National University Yangsan Hospital, Department of Radiology, Yangsan-si, Gyeongsangnam-do (Korea, Republic of); Han, Junhee [Pusan National University Yangsan Hospital, Division of Biostatistics, Research Institute for Convergence of Biomedical Science and Technology, Yangsan-si, Gyeongsangnam-do (Korea, Republic of)

2017-05-15

Several recent studies showed the optimal contrast enhancement with a low-concentration and iso-osmolar contrast media in both adult and pediatric patients. However, low contrast media concentrations are not routinely used due to concerns of suboptimal enhancement of cardiac structures and small vessels. To evaluate the feasibility of using iso-osmolar contrast media containing a low iodine dose for CT cardiac angiography at 80 kilovolts (kVp) in neonates and infants. The iodixanol 270 group consisted of 79 CT scans and the iopromide 370 group of 62 CT scans in patients ≤1 year old. Objective measurement of the contrast enhancement was analyzed and contrast-to-noise ratios of the ascending aorta and left ventricle were calculated. Regarding subjective measurement, a four-point scale system was devised to evaluate degrees of contrast enhancement, image noise, motion artifact and overall image quality of each image set. Reader performance for correctly differentiating iodixanol 270 and iopromide 370 by visual assessment was evaluated. Group objective and subjective measurements were nonsignificantly different. Overall sensitivity, specificity and diagnostic accuracy for correctly differentiating iodixanol 270 and iopromide 370 by visual assessment were 42.8%, 59%, and 50%, respectively. The application of iodixanol 270 achieved optimal enhancement for performing pediatric cardiac CT angiography at 80 kVp in neonates and infants. Objective measurements of contrast enhancement and subjective image quality assessments were not statistically different in the iodixanol 270 and iopromide 370 groups. (orig.)

Technology for improving sludge concentration; Odei noshukusei kaizen gijutsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-10

Sludge generating in a sewage treatment plant is disposed through the processes such as concentration, dehydration, and incineration in sludge disposal facilities. In recent years, there has been a trend that this sludge increases in volume as well as worsens in the concentration. A case is predictable where the sludge load to the dehydrating process is so large that the sludge can no longer be processed in sufficient quantity. In the meantime, if sludge is ozone-treated, viscous substance on the surface of sludge particles can be separated with a comparatively small amount of ozone, with sludge concentration enhanced. At Meidensha, an experimental plant was set up for the ozone treatment of sludge in a sludge intensive treatment plant of a metropolis, with a verification experiment carried out for a sludge concentration improving system by ozone. As a result of comparison of the treatment performance between an assessment system for performing ozone treatment and a reference system for not performing, the average value of the sludge concentration of a gravity concentration tank was 1.9% of the reference system against 1.7% of the assessment system in a continuous treatment experiment in the summer, while the solid collection ratio was 65.8% of the reference system against 95.5% of the assessment system, enabling a superior improving effect to be obtained. (NEDO)

Polytetrafluorethylene-Au as a substrate for surface-enhanced Raman spectroscopy

Directory of Open Access Journals (Sweden)

Siegel Jakub

2011-01-01

Full Text Available Abstract This study deals with preparation of substrates suitable for surface-enhanced Raman spectroscopy (SERS applications by sputtering deposition of gold layer on the polytetrafluorethylene (PTFE foil. Time of sputtering was investigated with respect to the surface properties. The ability of PTFE-Au substrates to enhance Raman signals was investigated by immobilization of biphenyl-4,4'-dithiol (BFD from the solutions with various concentrations. BFD was also used for preparation of sandwich structures with Au or Ag nanoparticles by two different procedures. Results showed that PTFE can be used for fabrication of SERS active substrate with easy handle properties at low cost. This substrate was sufficient for the measurement of SERS spectrum of BFD even at 10-8 mol/l concentration.

Cascade defect production and irradiation enhanced diffusion in Cu3Au

International Nuclear Information System (INIS)

Kirk, M.A.; Funk, L.L.

1986-03-01

By using the ordering alloy Cu 3 Au and measuring resistivity changes during and following fast-neutron irradiations at IPNS, we have studied cascade defect production and irradiation enhanced diffusion between 10 and 460 0 K. Ordering and disordering rates were measured as functions of irradiation temperature, neutron dose, neutron dose rate, time following cessation of flux, and step annealing. Free and clustered vacancy production was observed. The temperature dependence of the production of total migrating vacancy concentrations was determined. Vacancy sink production was linear with neutron dose and is compared with recent transmission electron microscopy experiments on the production of dislocation loops in this alloy. Time dependent and quasi-steady state vacancy concentrations were measured and compared with solutions of reaction rate equations for irradiation enhanced diffusion. The influence of recombination of vacancies with interstitials is observed at low sink concentrations (low neutron doses)

in Situ Formation of a Biocatalytic Alginate Membrane by Enhanced Concentration Polarization

DEFF Research Database (Denmark)

Marpani, Fauziah; Luo, Jianquan; Mateiu, Ramona Valentina

2015-01-01

A thin alginate layer induced on the surface of a commercial polysulfone membrane was used as a matrix for noncovalent immobilization of enzymes. Despite the expected decrease of flux across the membrane resulting from the coating, the initial hypothesis was that such a system should allow high...... immobilized enzyme loadings, which would benefit from the decreased flux in terms of increased enzyme/substrate contact time. The study was performed in a sequential fashion: first, the most suitable types of alginate able to induce a very thin, sustainable gel layer by pressure-driven membrane filtration...... were selected and evaluated. Then, an efficient method to make the gel layer adhere to the surface of the membrane was developed. Finally, and after confirming that the enzyme loading could remarkably be enhanced by using this method, several strategies to increase the permeate flux were evaluated...

MECHANICAL STRENGTH ENHANCEMENT OF OPEN-CELL ALUMINA FOAMS USING OPTIMUM CONCENTRATION OF DEFLOCCULANT

Directory of Open Access Journals (Sweden)

A. Hadi

2015-06-01

Full Text Available Open-cell alumina foams were prepared using the appropriate alumina slurry and polyurethane sponge with linear pore density of approximately 14 pores per inch (ppi as a template by the replica method. The rheological studies showed that the optimum solid content for the slurries without deflocculants was 60 wt. %. In order to increase the slurry solid content, Tiron (1,2-dihydroxy-3,5-benzene disulfonic acid disodium salt was used as dispersant. To determine the optimum concentration of dispersant, the viscosity curves of alumina slurries containing different values of Tiron from 0 to 1.2 wt. % (based on dry material weight were studied. The optimum concentration of Tiron obtained for lowest viscosity was 0.8 wt. %. Thus, the solid content in the slurry could be increased from 60 to 66 wt. %. The effect of increase in the slurry solid content and the way it affects the foam structure and the mechanical strength were investigated. Microstructural observations of the foams show a significant reduction in macroscopic and microscopic defects in the foam struts when the slurry solid content is increased. Total porosity of the produced alumina foams prepared using slurries containing 60 and 66 wt. % solid are 83.3 and 80.4 %, respectively, while the compressive strength of the foams has increased from 1.33 to 3.24 MPa.

A surface enhanced Raman scattering spectroscopic study of UO{sub 2}{sup 2+} at trace concentration

Energy Technology Data Exchange (ETDEWEB)

Franzen, Carola [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Carstensen, Lale [Technische Univ. Dresden (Germany); Firkala, T. [Helmholtz Institute Freiberg for Resource Technology, Freiberg (Germany); Steudtner, Robin [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

2017-06-01

Techniques for rapid screening of uranium in environmental samples are needed. This study entails the development of Surface-Enhanced Raman scattering (SERS) spectroscopy for analyzing uranium(VI) in aqueous media with improved sensitivity.

Photonic reagents for concentration measurement of flu-orescent proteins with overlapping spectra

Science.gov (United States)

Goun, Alexei; Bondar, Denys I.; Er, Ali O.; Quine, Zachary; Rabitz, Herschel A.

2016-05-01

By exploiting photonic reagents (i.e., coherent control by shaped laser pulses), we employ Optimal Dynamic Discrimination (ODD) as a novel means for quantitatively characterizing mixtures of fluorescent proteins with a large spectral overlap. To illustrate ODD, we simultaneously measured concentrations of in vitro mixtures of Enhanced Blue Fluorescent Protein (EBFP) and Enhanced Cyan Fluorescent Protein (ECFP). Building on this foundational study, the ultimate goal is to exploit the capabilities of ODD for parallel monitoring of genetic and protein circuits by suppressing the spectral cross-talk among multiple fluorescent reporters.

Radioimmunoassay of thyrotropin concentrated from serum

International Nuclear Information System (INIS)

Nisula, B.C.; Louvet, J.P.

1978-01-01

A method for concentrating human TSH (hTSH) from serum for use in RIAs is described. The method takes advantage of the affinity of the plant lectin, concanavalin A, for the carbohydrate portion of the hTSH molecule. The hTSH from 2.5 ml serum was adsorbed to concanavalin A covalently linked to sepharose and then radioimmunoassayed using the hTSH antiserum and hTSH for iodination distributed by the National Pituitary Agency. For the RIA standard curve, the hTSH reference preparation was concentrated from a serum wwith undetectable hTSH in order to correct for recovery and to control for nonspecific effects. The percentage of serum hTSH extracted from 2.5 ml serum with the concentration procedure was 76.6 +- 3.4% (mean +- SD). The coefficient of correlation between serum hTSH, determined with the concentration procedure, and serum hTSH determined without was 0.979 (P < 0.001). Over 95% of normal adult men and women had detectable levels of serum hTSH, ranging from < 0.56 to 4.0 μU/ml. The mean of detectable serum hTSH levels in normal adult women (n = 11) was 1.54 +- 1.03 μU/ml (mean +- SD) and in normal men (n = 9) was 2.02 +- 1.15 μU/ml (mean +- SD). Clinically hyperthyroid patients with diffuse and nodular toxic goiters (n = 8) and patients with hypothyroidism secondary to pituitary disease (n = 6), four of whom were taking replacement doses of thyroid hormone, had undetectable serum hTSH levels. Serum hTSH in patients with primary hypothyroidism uniformly exceeded the normal range. This hTSH concentrating procedure enhances the effective sensitivity and, therefore, the clinical utility of the RIA for hTSH in serum

MRI contrast agent concentration and tumor interstitial fluid pressure.

Science.gov (United States)

Liu, L J; Schlesinger, M

2016-10-07

The present work describes the relationship between tumor interstitial fluid pressure (TIFP) and the concentration of contrast agent for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). We predict the spatial distribution of TIFP based on that of contrast agent concentration. We also discuss the cases for estimating tumor interstitial volume fraction (void fraction or porosity of porous medium), ve, and contrast volume transfer constant, K(trans), by measuring the ratio of contrast agent concentration in tissue to that in plasma. A linear fluid velocity distribution may reflect a quadratic function of TIFP distribution and lead to a practical method for TIFP estimation. To calculate TIFP, the parameters or variables should preferably be measured along the direction of the linear fluid velocity (this is in the same direction as the gray value distribution of the image, which is also linear). This method may simplify the calculation for estimating TIFP. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Enhancement of Y123 dye-sensitized solar cell performance using plasmonic gold nanorods.

Science.gov (United States)

Chandrasekhar, P S; Parashar, Piyush K; Swami, Sanjay Kumar; Dutta, Viresh; Komarala, Vamsi K

2018-04-04

The role of the surface plasmon resonance (SPR) of gold nanorods (Au NRs) on the performance of Y123 dye-sensitized solar cells (DSSC) was investigated. DSSCs were fabricated by incorporating different concentrations (0.6 to 3.0 wt%) of Au NRs into TiO2 photoanodes. With an increase in the concentration of the Au NRs, the light absorption by the Y123 dye loaded photoanodes enhanced linearly, but the charge extraction was susceptible to the concentration of the Au NRs. With optimized concentrations (∼1.8 wt%) of the Au NRs, the photocurrent of the DSSC enhanced from 12.45 to 15.74 mA cm-2, and the power conversion efficiency (PCE) improved from 5.31 to 8.86%. The DSSC performance was also verified using Au nanoparticles (the PCE was enhanced from 5.31 to 7.72%) for comparison with the Au NR DSSC performance, which demonstrated the advantage of the Au NRs' shape effect with longitudinal SPR due to the modified light interaction. To explain the experimental observations of the plasmonic DSSC, the Au NRs' extinction efficiency and spatial distribution of the near-fields in complete and porous TiO2 media were also estimated using the finite-element method.

Enhancing arsenic removal from groundwater at household level with naturally occurring iron

Directory of Open Access Journals (Sweden)

Anitha Kumari Sharma

2016-06-01

Full Text Available A supply of drinking water low in Arsenic (As prevents arsenic poisoning. The presence of high concentrations of iron (Fe in groundwater under the alluvial plains of the large rivers in Southeast Asia is a prerequisite for the simple removal of As. This study investigated the mechanisms and possibilities for enhancing As removal with naturally occurring Fe in a reliable, low cost and sustainable way. The results of the study show that As removal with Fe is greatly enhanced by the addition of an oxidizing agent (preferably KMnO4 immediately after the pumping of groundwater. Further enhancement of As removal in the presence of Fe can be achieved by adding a small volume of a concentrated basic solution of MnO4- and AlO2-, which has a combined oxidation, coagulation and buffering capacity. Best results were obtained when this solution was mixed with the groundwater immediately after its pumping until a pale pink color appeared. Maximum required reaction time was 10 minutes and subsequent filtration of the water was able to reduce the As concentration to near zero. Concentrations of MnO4- and AlO2- can be varied in the solution to achieve sufficient As removal to suit different Fe/As ratios and the presence of interfering co-occurring anions.

Magnetic nanoparticles induced dielectric enhancement in (La, Gd)2O3: SiO2 composite systems

Science.gov (United States)

Kao, T. H.; Mukherjee, S.; Yang, H. D.

2013-11-01

Magnetic Gd2O3 and non-magnetic La2O3 nanoparticles (NPs) have been synthesized together with different doping concentrations in SiO2 matrix via sol-gel route calcination at 700 °C and above. Properly annealed NP-glass composite systems show enhancement of dielectric constant and magnetodielectric effect (MDE) near room temperature, depending on superparamagnetic NPs concentrations. From application point of view, the enhancement of dielectric constant along with MDE can be achieved by tuning the NPs size through varying calcination temperature and/or increasing the doping concentration of magnetic rare earth oxide.

Design and Optimization of Fresnel Lens for High Concentration Photovoltaic System

Directory of Open Access Journals (Sweden)

Lei Jing

2014-01-01

Full Text Available A practical optimization design is proposed, in which the solar direct light spectrum and multijunction cell response range are taken into account in combination, particularly for the Fresnel concentrators with a high concentration and a small aspect ratio. In addition, the change of refractive index due to temperature variation in outdoor operation conditions is also considered in the design stage. The calculation results show that this novel Fresnel lens achieves an enhancement of energy efficiency of about 10% compared with conventional Fresnel lens for a given solar spectrum, solar cell response, and corrected sunshine hours of different ambient temperature intervals.

The Effect of Novel Heterocyclic Compounds on Cryptococcal Biofilm

Science.gov (United States)

Korem, Maya; Kagan, Sarah

2017-01-01

Biofilm formation by microorganisms depends on their communication by quorum sensing, which is mediated by small diffusible signaling molecules that accumulate in the extracellular environment. During human infection, the pathogenic yeast Cryptococcus neoformans can form biofilm on medical devices, which protects the organism and increases its resistance to antifungal agents. The aim of this study was to test two novel heterocyclic compounds, S-8 (thiazolidinedione derivative, TZD) and NA-8 (succinimide derivative, SI), for their anti-biofilm activity against strains of Cryptococcus neoformans and Cryptococcus gattii. Biofilms were formed in a defined medium in 96-well polystyrene plates and 8-well micro-slides. The effect of sub-inhibitory concentrations of S-8 and NA-8 on biofilm formation was measured after 48 h by a metabolic reduction assay and by confocal laser microscopy analysis using fluorescent staining. The formation and development of cryptococcal biofilms was inhibited significantly by these compounds in concentrations below the minimum inhibitory concentration (MIC) values. These compounds may have a potential role in preventing fungal biofilm development on indwelling medical devices or even as a therapeutic measure after the establishment of biofilm. PMID:29371559

Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

Energy Technology Data Exchange (ETDEWEB)

Hoelzel, Christina S., E-mail: Christina.Hoelzel@wzw.tum.de [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mueller, Christa [Institute for Agroecology, Organic Farming and Soil Protection, Bavarian State Research Center for Agriculture (LfL), Lange Point 12, 85354 Freising (Germany); Harms, Katrin S. [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mikolajewski, Sabine [Department for Quality Assurance and Analytics, Bavarian State Research Center for Agriculture (LfL), Lange Point 4, 85354 Freising (Germany); Schaefer, Stefanie; Schwaiger, Karin; Bauer, Johann [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany)

2012-02-15

Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

Relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy street canyon: Ambient wind effects

International Nuclear Information System (INIS)

Kwak, Kyung-Hwan; Lee, Sang-Hyun; Seo, Jaemyeong Mango; Park, Seung-Bu; Baik, Jong-Jin

2016-01-01

Rooftop and on-road measurements of O_3, NO_2, NO_x, and CO concentrations were conducted to investigate the relationship between rooftop and on-road concentrations in a busy and shallow street canyon with an aspect ratio of ∼0.3 in Seoul, Republic of Korea, from 15 April to 1 May 2014. The median road-to-roof concentration ratios, correlation coefficients between rooftop and on-road concentrations, and temporal variations of rooftop and on-road concentrations are analyzed according to the rooftop wind directions which are two cross-canyon and two along-canyon directions. The analysis results indicate that the relationship is strong when the rooftop is situated on the downwind side rather than on the upwind side. Relative to the cross-canyon wind directions, one of the along-canyon wind directions can more enhance the relationship. A conceptual framework is proposed to explain the effect of ambient wind direction on the relationship between rooftop and on-road concentrations in a street canyon. - One of the along-canyon wind directions can enhance the relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy and shallow street canyon.

Concentration-dependent effects of fullerenol on cultured hippocampal neuron viability

Directory of Open Access Journals (Sweden)

Zha YY

2012-06-01

Full Text Available Ying-ying Zha,1 Bo Yang,1 Ming-liang Tang,2 Qiu-chen Guo,1 Ju-tao Chen,1 Long-ping Wen,3 Ming Wang11CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 2Suzhou Institute of NanoTech and NanoBionics, Chinese Academy of Sciences, Suzhou, 3Laboratory of Nano-biology, School of Life Sciences, University of Science and Technology of China, Hefei, People's Republic of ChinaBackground: Recent studies have shown that the biological actions and toxicity of the water-soluble compound, polyhydroxyfullerene (fullerenol, are related to the concentrations present at a particular site of action. This study investigated the effects of different concentrations of fullerenol on cultured rat hippocampal neurons.Methods and results: Fullerenol at low concentrations significantly enhanced hippocampal neuron viability as tested by MTT assay and Hoechst 33342/propidium iodide double stain detection. At high concentrations, fullerenol induced apoptosis confirmed by Comet assay and assessment of caspase proteins.Conclusion: These findings suggest that fullerenol promotes cell death and protects against cell damage, depending on the concentration present. The concentration-dependent effects of fullerenol were mainly due to its influence on the reduction-oxidation pathway.Keywords: fullerenol, nanomaterial, neurotoxicity, neuroprotection, hippocampal neuron

Surfactant-Enhanced Size-Excluded Transport of Bacteria Through Unsaturated Porous Media.

Science.gov (United States)

Zhu, J.

2017-12-01

US domestic waste water is rich in surfactants because of the intensive usage of surfactants-containing household product. It results in a surfactants presence environment when this untreated waste water released into subsurface. It was reported that surfactants enhance the colloidal transport in porous media, which have significant effect on issues such as subsurface pathogens contamination and biodegradation. In this study, soil column experiments were conducted. The soil column was remained unsaturated and with a steady flow passing through it. Escherichia coli K-12 transported in the soil column and its breakthrough data was collected in presence of surfactant anionic surfactant linear alkylbenzene sulfonate (LAS) concentration range over 0, 0.25, 0.5, 0.75, 1, and 2 times Critical Micelle Concentration (CMC). It was found that the increase in LAS concentration greatly increases breakthrough concentration C/C0 and decreases breakthrough time tb until LAS concentration reaches 1 xCMC. Numerical models were built simulating and investigating this phenomenon. The goodness of model fitting was greatly improved by adding exclusion factor into the model, which indicated that the presence of surfactant might enhance the exclusion effect. The relationships between LAS concentration and the two coefficients, deposition rate coefficient k and exclusion effect coefficient θim, were found can be fitted by a quasi-Langmuir equation. And the model validation with observed data showed that the model has an acceptable reliability.

Steady-state ozone concentrations in radiation induced noble gas-oxygen discharges

International Nuclear Information System (INIS)

Elsayed-Ali, H.E.; Miley, G.H.

1985-01-01

Measurements of steady-state ozone concentrations in continuous radiation induced noble gas-O/sub 2/ and noble gas-o/sub 2/-SF/sub 6/ mixtures has been accomplished. The discharges were created through the bombardment of the gases with energetic particles from the boron-10 (n,α) lithium-7 nuclear reaction. Three noble gases were studied, He, Ne, and Ar at partial pressures of few hundred Torr. The dose rates studied were in the order of 10/sup 15/ eV . cm/sup -3/ . s/sup -1/. The experimental apparatus and procedure were previously described. The experimentally observed steady-state ozone concentrations in noble gas-O/sub 2/ discharges were about an order of magnitude lower than that observed for oxygen radiolysis at similar dose rates. These results were physically explained by an enhanced role of negative ionic reactions with ozone causing its destruction. In noble gas-O/sub 2/-SF/sub 6/ mixtures, the steady-state ozone concentrations were found to be significantly higher (3-6 times) than that without the SF/sub 6/ addition. This observation was contrary to only a small increase observed after SF/sub 6/ addition to a few hundred Torr oxygen and is explained by an enhanced rate of electron dissociative attachment of ozone in noble gas-O/sub 2/ discharges

AMPK is involved in the regulation of incretin receptors expression in pancreatic islets under a low glucose concentration.

Directory of Open Access Journals (Sweden)

Kazuki Tajima

Full Text Available The precise role of AMP-activated protein kinase (AMPK, a target of metformin, in pancreatic β cells remains controversial, even though metformin was recently shown to enhance the expression of incretin receptors (GLP-1 and GIP receptors in pancreatic β cells. In this study, we investigated the effect of AMPK in the regulation of incretin receptors expression in pancreatic islets. The phosphorylation of AMPK in the mouse islets was decreased by increasing glucose concentrations. We showed the expression of incretin receptors in bell-shaped response to glucose. Expression of the incretin receptors in the isolated islets showed higher levels under a medium glucose concentration (11.1 mM than that under a low glucose concentration (2.8 mM, but was suppressed under a high glucose concentration (22.2 mM. Both treatment with an AMPK inhibitor and DN-AMPK expression produced a significant increase of the incretin receptors expression under a low glucose concentration. By contrast, in hyperglycemic db/db islets, the enhancing effect of the AMPK inhibitor on the expression of incretin receptors was diminished under a low glucose concentration. Taken together, AMPK is involved in the regulation of incretin receptors expression in pancreatic islets under a low glucose concentration.

An ELM Based Online Soft Sensing Approach for Alumina Concentration Detection

Directory of Open Access Journals (Sweden)

Sen Zhang

2015-01-01

Full Text Available The concentration of alumina in the electrolyte is of great significance during the production of aluminum; it may affect the stability of aluminum reduction cell and the current efficiency. However, the concentration of alumina is hard to be detected online because of the special circumstance in the aluminum reduction cell. At present, there is lack of fast and accurate soft sensing methods for alumina concentration and existing methods can not meet the needs for online measurement. In this paper, a novel soft sensing method based on a modified extreme learning machine (MELM for online measurement of the alumina concentration is proposed. The modified ELM algorithm is based on the enhanced random search which is called incremental extreme learning machine in some references. It randomly chooses the input weights and analytically determines the output weights without manual intervention. The simulation results show that the approach can give more accurate estimations of alumina concentration with faster learning speed compared with other methods such as BP and SVM.

Genotypes of Brassica rapa respond differently to plant-induced variation in air CO2 concentration in growth chambers with standard and enhanced venting.

Science.gov (United States)

Edwards, Christine E; Haselhorst, Monia S H; McKnite, Autumn M; Ewers, Brent E; Williams, David G; Weinig, Cynthia

2009-10-01

Growth chambers allow measurement of phenotypic differences among genotypes under controlled environment conditions. However, unintended variation in growth chamber air CO2 concentration ([CO2]) may affect the expression of diverse phenotypic traits, and genotypes may differ in their response to variation in [CO2]. We monitored [CO2] and quantified phenotypic responses of 22 Brassica rapa genotypes in growth chambers with either standard or enhanced venting. [CO2] in chambers with standard venting dropped to 280 micromol mol(-1) during the period of maximum canopy development, approximately 80 micromol mol(-1) lower than in chambers with enhanced venting. The stable carbon isotope ratio of CO2 in chamber air (delta13C(air)) was negatively correlated with [CO2], suggesting that photosynthesis caused observed [CO2] decreases. Significant genotype x chamber-venting interactions were detected for 12 of 20 traits, likely due to differences in the extent to which [CO2] changed in relation to genotypes' phenology or differential sensitivity of genotypes to low [CO2]. One trait, 13C discrimination (delta13C), was particularly influenced by unaccounted-for fluctuations in delta13C(air) and [CO2]. Observed responses to [CO2] suggest that genetic variance components estimated in poorly vented growth chambers may be influenced by the expression of genes involved in CO2 stress responses; genotypic values estimated in these chambers may likewise be misleading such that some mapped quantitative trait loci may regulate responses to CO2 stress rather than a response to the environmental factor of interest. These results underscore the importance of monitoring, and where possible, controlling [CO2].

Low-Concentration Tributyltin Decreases GluR2 Expression via Nuclear Respiratory Factor-1 Inhibition

OpenAIRE

Ishida, Keishi; Aoki, Kaori; Takishita, Tomoko; Miyara, Masatsugu; Sakamoto, Shuichiro; Sanoh, Seigo; Kimura, Tomoki; Kanda, Yasunari; Ohta, Shigeru; Kotake, Yaichiro

2017-01-01

Tributyltin (TBT), which has been widely used as an antifouling agent in paints, is a common environmental pollutant. Although the toxicity of high-dose TBT has been extensively reported, the effects of low concentrations of TBT are relatively less well studied. We have previously reported that low-concentration TBT decreases ?-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptor subunit 2 (GluR2) expression in cortical neurons and enhances neuronal vulnerability ...

Polymer Optical Fiber Compound Parabolic Concentrator fiber tip based glucose sensor: In-Vitro Testing

DEFF Research Database (Denmark)

Hassan, Hafeez Ul; Janting, Jakob; Aasmul, Soren

2016-01-01

We present in-vitro sensing of glucose using a newly developed efficient optical fiber glucose sensor based on a Compound Parabolic Concentrator (CPC) tipped polymer optical fiber (POF). A batch of 9 CPC tipped POF sensors with a 35 mm fiber length is shown to have an enhanced fluorescence pickup...... efficiency with an average increment factor of 1.7 as compared to standard POF sensors with a plane cut fiber tip. Invitro measurements for two glucose concentrations (40 and 400 mg/dL) confirm that the CPC tipped sensors efficiently can detect both glucose concentrations. it sets the footnote at the bottom...

Enhanced removal of Methylene Blue by electrocoagulation using iron electrodes

OpenAIRE

Mohamed S. Mahmoud; Joseph Y. Farah; Taha E. Farrag

2013-01-01

The removal of pollutants from effluents by electrocoagulation has become an attractive method in recent years. The study deals with the enhancement of removal of Methylene Blue dye by using an electromagnetic field during the electrocoagulation process. Effects of electrolyte concentration, dye concentration, intensity and the direction of the electromagnet on the decolorization efficiency have been investigated. The formed ferric hydroxide flocs trap colloidal particles and make solid–liqui...

How capping protein enhances actin filament growth and nucleation on biomimetic beads.

Science.gov (United States)

Wang, Ruizhe; Carlsson, Anders E

2015-11-25

Capping protein (CP), which caps the growing ends of actin filaments, accelerates actin-based motility. Recent experiments on biomimetic beads have shown that CP also enhances the rate of actin filament nucleation. Proposed explanations for these phenomena include (i) the actin funneling hypothesis (AFH), in which the presence of CP increases the free-actin concentration, and (ii) the monomer gating model, in which CP binding to actin filament barbed ends makes more monomers available for filament nucleation. To establish how CP increases the rates of filament elongation and nucleation on biomimetic beads, we perform a quantitative modeling analysis of actin polymerization, using rate equations that include actin filament nucleation, polymerization and capping, as modified by monomer depletion near the surface of the bead. With one adjustable parameter, our simulation results match previously measured time courses of polymerized actin and filament number. The results support a version of the AFH where CP increases the local actin monomer concentration at the bead surface, but leaves the global free-actin concentration nearly constant. Because the rate of filament nucleation increases with the monomer concentration, the increased local monomer concentration enhances actin filament nucleation. We derive a closed-form formula for the characteristic CP concentration where the local free-actin concentration reaches half the bulk value, and find it to be comparable to the global Arp2/3 complex concentration. We also propose an experimental protocol for distinguishing branching nucleation of filaments from spontaneous nucleation.

Decontamination formulation with additive for enhanced mold remediation

Science.gov (United States)

Tucker, Mark D [Albuquerque, NM; Irvine, Kevin [Huntsville, AL; Berger, Paul [Rome, NY; Comstock, Robert [Bel Air, MD

2010-02-16

Decontamination formulations with an additive for enhancing mold remediation. The formulations include a solubilizing agent (e.g., a cationic surfactant), a reactive compound (e.g., hydrogen peroxide), a carbonate or bicarbonate salt, a water-soluble bleaching activator (e.g., propylene glycol diacetate or glycerol diacetate), a mold remediation enhancer containing Fe or Mn, and water. The concentration of Fe.sup.2+ or Mn.sup.2+ ions in the aqueous mixture is in the range of about 0.0001% to about 0.001%. The enhanced formulations can be delivered, for example, as a foam, spray, liquid, fog, mist, or aerosol for neutralization of chemical compounds, and for killing certain biological compounds or agents and mold spores, on contaminated surfaces and materials.

Glacier Melting Increases the Solute Concentrations of Himalayan Glacial Lakes.

Science.gov (United States)

Salerno, Franco; Rogora, Michela; Balestrini, Raffaella; Lami, Andrea; Tartari, Gabriele A; Thakuri, Sudeep; Godone, Danilo; Freppaz, Michele; Tartari, Gianni

2016-09-06

Over the past two decades, we observed a substantial rise in ionic content that was mainly determined by the sulfate concentration at 20 remote high elevation lakes located in central southern Himalaya. At LCN9, which was monitored on an annual basis for the last 20 years, the sulfate concentrations increased over 4-fold. Among the main causes, we exclude a change in the composition of wet atmospheric deposition, as well as a possible influence of decrease in seasonal snow cover duration, which could have exposed larger basin surfaces to alteration processes. Glacier retreat likely was the main factor responsible for the observed increase of sulfate concentrations. We attribute this chemical changes mainly to the sulfide oxidation processes that occur in subglacial environments. Moreover, we observe that the weakened monsoon of the past two decades has only partially contributed to the lakes enrichment through runoff waters that are more concentrated in solutes or lowering the water table, resulting in more rock exposed to air and enhanced mineral oxidation.

The effect of the fungicide captan on Saccharomyces cerevisiae and wine fermentation

Directory of Open Access Journals (Sweden)

Scariot Fernando J.

2016-01-01

Full Text Available Fungicides, particularly those used during grape maturation, as captan, can affect the natural yeast population of grapes, and can reach grape must affecting wine fermentation. The objective of the present work was to study the effect of captan on the viability and fermentative behavior of S. cerevisiae. S. cerevisiae (BY4741 on exponential phase was treated with captan (0 to 40 μM for different periods, and their cell viability analyzed. Cell membrane integrity, thiols concentration, and reactive oxygen species (ROS accumulation was determined. The fermentation experiments were conducted in synthetic must using wine yeast strain Y904. The results showed that under aerobic conditions, 20 μM of captan reduce 90% of yeast viability in 6 hours. Captan treated cells exhibited alteration of membrane integrity, reduction of thiol compounds and increase in intracellular ROS concentration, suggesting a necrotic and pro-oxidant activity of the fungicide. Fermentative experiments showed that concentrations above 2.5 μM captan completely inhibited fermentation, while a dose dependent fermentation delay associated with the reduction of yeast viability was detected in sub-inhibitory concentrations. Petit mutants increase was also observed. In conclusion, the captan induces yeast necrotic cell death on both aerobic and anaerobic conditions causing fermentation delay and/or sucking fermentations.

Antifungal Activity of Thapsia villosa Essential Oil against Candida, Cryptococcus, Malassezia, Aspergillus and Dermatophyte Species

Directory of Open Access Journals (Sweden)

Eugénia Pinto

2017-09-01

Full Text Available The composition of the essential oil (EO of Thapsia villosa (Apiaceae, isolated by hydrodistillation from the plant’s aerial parts, was analysed by GC and GC-MS. Antifungal activity of the EO and its main components, limonene (57.5% and methyleugenol (35.9%, were evaluated against clinically relevant yeasts (Candida spp., Cryptococcus neoformans and Malassezia furfur and moulds (Aspergillus spp. and dermatophytes. Minimum inhibitory concentrations (MICs were measured according to the broth macrodilution protocols by Clinical and Laboratory Standards Institute (CLSI. The EO, limonene and methyleugenol displayed low MIC and MFC (minimum fungicidal concentration values against Candida spp., Cryptococcus neoformans, dermatophytes, and Aspergillus spp. Regarding Candida species, an inhibition of yeast–mycelium transition was demonstrated at sub-inhibitory concentrations of the EO (MIC/128; 0.01 μL/mL and their major compounds in Candida albicans. Fluconazole does not show this activity, and the combination with low concentrations of EO could associate a supplementary target for the antifungal activity. The association of fluconazole with T. villosa oil does not show antagonism, but the combination limonene/fluconazole displays synergism. The fungistatic and fungicidal activities revealed by T. villosa EO and its main compounds, associated with their low haemolytic activity, confirm their potential antimicrobial interest against fungal species often associated with human mycoses.

Phytochemical study of Pilosocereus pachycladus and antibiotic-resistance modifying activity of syringaldehyde

Directory of Open Access Journals (Sweden)

Severino Gonçalves de Brito-Filho

Full Text Available ABSTRACT Pilosocereus pachycladus F. Ritter, Cactaceae, popularly known as "facheiro", is used as food and traditional medicine in Brazilian caatinga ecoregion. The plant is used to treat prostate inflammation and urinary infection. The present work reports the first secondary metabolites isolated from P. pachycladus. Therefore, the isolated compound 4-hydroxy-3,5-dimethoxy benzaldehyde (syringaldehyde was evaluated as modulator of Staphylococcus aureus pump efflux-mediated antibiotic resistance. The isolation of compounds was performed using chromatographic techniques and the structural elucidation was carried out by spectroscopic methods. In order to evaluate syringaldehyde ability to modulate S. aureus antibiotic resistance, its minimum inhibitory concentrations (µg/ml was first determinate, then, the tested antibiotics minimum inhibitory concentrations were determined in the presence of the syringaldehyde in a sub-inhibitory concentration. The chromatographic procedures led to isolation of twelve compounds from P. pachycladus including fatty acids, steroids, chlorophyll derivatives, phenolics and a lignan. The syringaldehyde did not show any antibacterial activity at 256 µg/ml against S. aureus. On the other hand the compound was able to reduce the antibiotic concentration (tetracycline, norfloxacin, ethidium bromide required to inhibit the growth of drug-resistant bacteria, showing the ability of syringaldehyde of inhibiting the efflux pump on these bacteria.

Enhanced electrochemomechanical activity of polyaniline films towards high pH region: contribution of Donnan effect

International Nuclear Information System (INIS)

Takashima, Wataru; Nakashima, Megumi; Pandey, Shyam S.; Kaneto, Keiichi

2004-01-01

Enhancement of electrochemomechanical deformation (ECMD) and expansion of ECMD activity towards high pH have been simultaneously achieved in the electrolytes equilibrated with HCl and NaCl solutions for polyaniline (PANI) film. The maximum deformation has been reached to 6.7% in the mixture of 3 M HCl and 3 M NaCl equilibrated at pH 3 at ambient temperature. By comparing the fact that the ECMD magnitude is 3.2% in 1 M HCl equilibrated at pH 0.5, the simple judicious selection of electrolyte condition leads to the enhancement of ECMD magnitude by around two times. The concentration dependence on both electrical conductivity and absorption spectra elucidates the increase of protonation ratio as a function of electrolyte concentration. The results indicate that the high concentration retains both the electrochemical and ECMD activities in PANI film towards high pH region, which is the enhanced functionality of PANI supported by Donnan effect

Pair housing and enhanced milk allowance increase play behavior and improve performance in dairy calves

DEFF Research Database (Denmark)

Jensen, Margit Bak; Duve, Linda Rosager; Weary, D. M.

2015-01-01

-housed calves could perform social play behavior (play fighting), and the duration of this was greater on d 15 and 29 than on d 43 [8.3, 10.7 and 3.5 (±1.3) corresponding to 69, 115 and 12 s/24 h for d 15, 29, and 43]. Among calves on enhanced milk, pair-housed animals had a greater concentrate intake than...... observed no effect of pair versus individual housing [810 and 840 (±40) g/d]. In conclusion, greater durations of play behavior in enhanced-fed calves suggest an animal welfare benefit of this feeding method. Enhanced-fed calves consumed less concentrate, but pair housing stimulated concentrate intake......To investigate the effects of social housing and milk feeding on play behavior and performance, 48 Holstein-Friesian male and female calves were either individually or pair housed in straw-bedded pens (3.0 m × 4.5 m). Half of the calves in each housing treatment were fed a standard milk allowance...

Mitomycin C dissolved in a reversible thermosetting gel: target tissue concentrations in the rabbit eye.

Science.gov (United States)

Ichien, K; Yamamoto, T; Kitazawa, Y; Oguri, A; Ando, H; Kondo, Y

1997-01-01

To determine whether a new, reversible thermosetting gel enhances mitomycin C transfer to target ocular tissues in the rabbit eye. A 0.1 ml solution of mitomycin C containing 0.22 microgram, 2.9 micrograms, or 28 micrograms of the agent dissolved in a reversible thermosetting gel consisting of methylcellulose, citric acid, and polyethylene glycol was injected subconjunctivally in 30 New Zealand albino rabbits. Scleral and conjunctival tissues were excised at 0.5, 1, 2, 4, or 24 hours after the injection and mitomycin C concentrations in these tissues were determined by high performance liquid chromatography. The concentration over time was approximated to a single exponential curve, and initial mitomycin C concentrations, time constants, and half life values were determined. Finally, the areas under the curves (AUCs) between 0.5 and 24 hours were calculated. The mitomycin C concentrations in the target tissues were dose dependent and decreased rapidly over 24 hours. Both the initial mitomycin C concentrations as well as AUCs in these eyes treated with mitomycin C, dissolved in a reversible thermosetting gel, were higher than those in eyes treated similarly in a previous study in which the gel was not used. Applied subconjunctivally in the rabbit eye, mitomycin C dissolved in the reversible thermosetting gel enhanced transfer of the agent to the sclera and the conjunctiva.

CesRK, a two-component signal transduction system in Listeria monocytogenes, responds to the presence of cell wall-acting antibiotics and affects beta-lactam resistance

DEFF Research Database (Denmark)

Kallipolitis, Birgitte H; Ingmer, Hanne; Gahan, Cormac G

2003-01-01

Listeria monocytogenes is a food-borne pathogen that can cause a variety of illnesses ranging from gastroenteritis to life-threatening septicemia. The beta-lactam antibiotic ampicillin remains the drug of choice for the treatment of listeriosis. We have previously identified a response regulator...... of L. monocytogenes to tolerate ethanol and cell wall-acting antibiotics of the beta-lactam family. Furthermore, CesRK controls the expression of a putative extracellular peptide encoded by the orf2420 gene, located immediately downstream from cesRK. Inactivation of orf2420 revealed that it contributes...... to ethanol tolerance and pathogenesis in mice. Interestingly, we found that transcription of orf2420 was strongly induced by subinhibitory concentrations of various cell wall-acting antibiotics, ethanol, and lysozyme. The induction of orf2420 expression was abolished in the absence of CesRK. Our data suggest...

[Activation of the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones in the presence of nitrofurans and NO generators].

Science.gov (United States)

Zaĭtseva, Iu V; Granik, V G; Belik, A S; Koksharova, O A; Khmel', I A

2010-01-01

Nitrofurans (nitrofurazone, nitrofurantoin, furazidin, nifuroxazide), and nitric oxide generators (sodium nitroprusside and isosorbide mononitrate) in subinhibitory concentrations were shown to significantly increase the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones, signaling molecules of Quorum Sensing (QS) regulatory systems. The highest activation of bioluminescence (up to 250-400 fold) was observed in the presence of nitrofurazone on E. coli DH5alpha biosensors containing lux-reporter plasmids pSB401 or pSB536. However, this activation was not specifically associated with the functioning of QS systems. We suggest that the effect observed results from a direct action of nitrofurans and NO donors on the process of bioluminescence. The data indicate the necessity of using the biosensors that make it possible to detect specific effects of substances tested on QS regulation.

Omega-3 PUFA concentration by a novel PVDF nano-composite membrane filled with nano-porous silica particles.

Science.gov (United States)

Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan

2017-09-01

In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.

Activity enhancement of ligninolytic enzymes of Trametes versicolor ...

African Journals Online (AJOL)

Suspended cultures of white-rot fungus, Trametes versicolor, supplemented with bagasse powder showed a concentration dependent enhancement in the ligninolytic enzymes activity in liquid shake cultures. 2% (w/v) bagasse powder improved greater stability to the enzymes. The optimum pH is 3.5 and the optimum ...

Tolerance response of multidrug-resistant Salmonella enterica strains to habituation to Origanum vulgare L. essential oil

Science.gov (United States)

Monte, Daniel F. M.; Tavares, Adassa G.; Albuquerque, Allan R.; Sampaio, Fábio C.; Oliveira, Tereza C. R. M.; Franco, Octavio L.; Souza, Evandro L.; Magnani, Marciane

2014-01-01

Multidrug-resistant Salmonella enterica isolates from human outbreaks or from poultry origin were investigated for their ability to develop direct-tolerance or cross-tolerance to sodium chloride, potassium chloride, lactic acid, acetic acid, and ciprofloxacin after habituation in subinhibitory amounts ( of the minimum inhibitory concentration – (MIC) and of the minimum inhibitory concentration – MIC) of Origanum vulgare L. essential oil (OVEO) at different time intervals. The habituation of S. enterica to OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by the modulation of MIC values. However, cells habituated to OVEO maintained or increased susceptibility to the tested antimicrobials agents, with up to fourfold double dilution decrease from previously determined MIC values. This study reports for the first time the non-inductive effect of OVEO on the acquisition of direct-tolerance or cross-tolerance in multidrug-resistant S. enterica strains to antimicrobial agents that are largely used in food preservation, as well as to CIP, the therapeutic drug of salmonellosis. PMID:25566231

Triclosan antagonizes fluconazole activity against Candida albicans.

LENUS (Irish Health Repository)

Higgins, J

2012-01-01

Triclosan is a broad-spectrum antimicrobial compound commonly used in oral hygiene products. Investigation of its activity against Candida albicans showed that triclosan was fungicidal at concentrations of 16 mg\\/L. However, at subinhibitory concentrations (0.5-2 mg\\/L), triclosan antagonized the activity of fluconazole. Although triclosan induced CDR1 expression in C. albicans, antagonism was still observed in cdr1Δ and cdr2Δ strains. Triclosan did not affect fluconazole uptake or alter total membrane sterol content, but did induce the expression of FAS1 and FAS2, indicating that its mode of action may involve inhibition of fatty acid synthesis, as it does in prokaryotes. However, FAS2 mutants did not exhibit increased susceptibility to triclosan, and overexpression of both FAS1 and FAS2 alleles did not alter triclosan susceptibility. Unexpectedly, the antagonistic effect was specific for C. albicans under hypha-inducing conditions and was absent in the non-filamentous efg1Δ strain. This antagonism may be due to the membranotropic activity of triclosan and the unique composition of hyphal membranes.

Coefficient of friction and wear rate effects of different composite nanolubricant concentrations on Aluminium 2024 plate

Science.gov (United States)

Zawawi, N. N. M.; Azmi, W. H.; Redhwan, A. A. M.; Sharif, M. Z.

2017-10-01

Wear of sliding parts and operational machine consistency enhancement can be avoided with good lubrication. Lubrication reduce wear between two contacting and sliding surfaces and decrease the frictional power losses in compressor. The coefficient of friction and wear rate effects study were carried out to measure the friction and anti-wear abilities of Al2O3-SiO2 composite nanolubricants a new type of compressor lubricant to enhanced the compressor performances. The tribology test rig employing reciprocating test conditions to replicate a piston ring contact in the compressor was used to measure the coefficient of friction and wear rate. Coefficient of friction and wear rate effects of different Al2O3-SiO2/PAG composite nanolubricants of Aluminium 2024 plate for 10-kg load at different speed were investigated. Al2O3 and SiO2 nanoparticles were dispersed in the Polyalkylene Glycol (PAG 46) lubricant using two-steps method of preparation. The result shows that the coefficient friction and wear rate of composite nanolubricants decreased compared to pure lubricant. The maximum reduction achievement for friction of coefficient and wear rate by Al2O3-SiO2 composite nanolubricants by 4.78% and 12.96% with 0.06% volume concentration. Therefore, 0.06% volume concentration is selected as the most enhanced composite nanolubricants with effective coefficient of friction and wear rate reduction compared to other volume concentrations. Thus, it is recommended to be used as the compressor lubrication to enhanced compressor performances.

Protocol optimization for enhanced production of pigments in Spirulina.

Science.gov (United States)

Kumar, Devendra; Kumar, Neeraj; Pabbi, Sunil; Walia, Suresh; Dhar, Dolly Wattal

2013-01-01

Spirulina has attracted special attention due to its importance as human foodstuff and natural colours with specific functional properties. These functional properties have been attributed to phycobilins, carotenoids, phenolics and unsaturated fatty acids. Present study was conducted under controlled phytotron conditions to identify the efficient strains of Spirulina in terms of pigment synthesis and to optimize their enhanced production. Methodology for enhanced production was standardized by varying specific environmental parameters (light intensity, temperature, carbon dioxide concentration, pH and NaCl level). Different strains of Spirulina depicted variability and environmental parameters showed distinct influence on pigments. Growth and pigment production was recorded to be most efficient under optimized conditions of light intensity (70 μmol m -2  s -1 ), temperature (30 °C), CO 2 concentration (550 ppm and 750 ppm), pH (10.5) and NaCl level (2 g L -1 ).

Enhanced ethanol production by fermentation of Gelidium amansii hydrolysate using a detoxification process and yeasts acclimated to high-salt concentration.

Science.gov (United States)

Ra, Chae Hun; Jung, Jang Hyun; Sunwoo, In Yung; Jeong, Gwi-Taek; Kim, Sung-Koo

2015-06-01

A total monosaccharide concentration of 59.0 g/L, representing 80.1 % conversion of 73.6 g/L total fermentable sugars from 160 g dw/L G. amansii slurry was obtained by thermal acid hydrolysis and enzymatic hydrolysis. Subsequent adsorption treatment using 5 % activated carbon with an adsorption time of 2 min was used to prevent the inhibitory effect of 5-hydroxymethylfurfural (HMF) >5 g/L in the medium. Ethanol production decreased with increasing salt concentration using C. tropicalis KCTC 7212 non-acclimated or acclimated to a high concentration of salt. Salt concentration of 90 psu was the maximum concentration for cell growth and ethanol production. The levels of ethanol production by C. tropicalis non-acclimated or acclimated to 90 psu high-salt concentration were 13.8 g/L with a yield (YEtOH) of 0.23, and 26.7 g/L with YEtOH of 0.45, respectively.

Novel Deployment Mechanism for Conventional Solar Array Enhancement

Directory of Open Access Journals (Sweden)

Hodgetts Paul A.

2017-01-01

Full Text Available A novel mechanism is described, by which flexible blankets could be deployed from existing solar panel designs. These blankets could be covered with flexible cells, or they could be reflective films to form a concentrator array. Either way, the performance of an existing array design could be enhanced.

Enhancement of Biogas Production from Bakery Waste by Pseudomonas aeruginosa

OpenAIRE

S. Potivichayanon; T. Sungmon; W. Chaikongmao; S. Kamvanin

2011-01-01

Production of biogas from bakery waste was enhanced by additional bacterial cell. This study was divided into 2 steps. First step, grease waste from bakery industry-s grease trap was initially degraded by Pseudomonas aeruginosa. The concentration of byproduct, especially glycerol, was determined and found that glycerol concentration increased from 12.83% to 48.10%. Secondary step, 3 biodigesters were set up in 3 different substrates: non-degraded waste as substrate in fir...

Tuning the carbon nanotube photoluminescence enhancement at addition of cysteine through the change of external conditions

Energy Technology Data Exchange (ETDEWEB)

Kurnosov, N.V.; Karachevtsev, M.V.; Leontiev, V.S.; Karachevtsev, V.A., E-mail: karachevtsev@ilt.kharkov.ua

2017-01-15

The enhancement of the photoluminescence (PL) from the semiconducting single-walled carbon nanotubes suspended with single-stranded DNA (ssDNA) in water observed after amino acids doping is the largest at cysteine addition. The PL intensity increased through the passivation of p-defects on the carbon nanotube sidewall by the cysteine molecules due to thiol group. The effect of several external factors on the cysteine-induced enhancement of PL from carbon nanotubes covered with ssDNA was studied: UV irradiation, tip or bath sonication treatment of the suspension, the ionic strength and pH of aqueous suspension. It turned out that all these factors have an essential influence on the dependence of the PL enhancement on the cysteine concentration through inducing of additional defects on nanotube as well as a change of the nanotube surface coverage with polymer. The obtained experimental results demonstrated that PL from carbon nanotubes can be exploited successfully for the monitoring of cysteine concentration in aqueous solution. - Highlights: • Cysteine doping enhances carbon nanotube emission more than other amino acids do. • SWNT emission dependence on cysteine concentration is tuned by UV irradiation and pH. • Type of sonication treatment influences SWNT PL dependence on cysteine concentration. • Polymer coverage and defectiveness of nanotubes effect on nanotube emission. • Graphic abstract.

Optimisation of elevated radon concentration measurement by using electro-chemical etching of nuclear track detectors

International Nuclear Information System (INIS)

Celikovic, I.; Ujic, P.; Fujimoto, K.; Tommasino, L.; Demajo, A.; Zunic, Z.; Celikovic, I.)

2007-01-01

In the paper, two methods for adjusting of passive radon-thoron discriminative dosimeters (UFO detector) for enhanced radon concentration measurement are presented. Achieved upper limit of detection is 5.94 MBq m-3 d [sr

A hybrid nanoantenna for highly enhanced directional spontaneous emission

Energy Technology Data Exchange (ETDEWEB)

Chou, R. Yuanying; Lu, Guowei, E-mail: guowei.lu@pku.edu.cn; Shen, Hongming; He, Yingbo; Cheng, Yuqing [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Perriat, Pascal [MATEIS, UMR 5510 CNRS, INSA-Lyon, Université de Lyon, Villeurbanne Cedex 69621 (France); Martini, Matteo; Tillement, Olivier [ILM, UMR 5306 CNRS, Université de Lyon, Villeurbanne Cedex 69622 (France); Gong, Qihuang [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China)

2014-06-28

Spontaneous emission modulated by a hybrid plasmonic nanoantenna has been investigated by employing finite-difference time-domain method. The hybrid nanoantenna configurations constituted by a gap hot-spot and of a plasmonic corrugated grating and a metal reflector sandwiching a SiO{sub 2} thin layer which appears promising for high spontaneous emission enhancement devices. Simulation assays show that the coupling between the gap-antenna and plasmonic corrugations reaches an ultra-high near-field enhancement factor in the excitation process. Moreover, concerning the emission process, the corrugations concentrate the far-field radiated power within a tiny angular volume, offering unprecedented collection efficiency. In the past decades, many kinds of optical antennas have been proposed and optimized to enhance single molecule detection. However, the excitation enhancement effect for single individual or dimmer plasmonic nanostructure is limited due to intrinsic nonradiative decay of the nanoparticle plasmon and quantum tunneling effect. The proposed hybrid configuration overwhelms the enhancement limit of single individual plasmonic structure. The findings provide an insight into spontaneous emission high enhancement through integrating the functions of different metallic nanostructures.

A hybrid nanoantenna for highly enhanced directional spontaneous emission

International Nuclear Information System (INIS)

Chou, R. Yuanying; Lu, Guowei; Shen, Hongming; He, Yingbo; Cheng, Yuqing; Perriat, Pascal; Martini, Matteo; Tillement, Olivier; Gong, Qihuang

2014-01-01

Spontaneous emission modulated by a hybrid plasmonic nanoantenna has been investigated by employing finite-difference time-domain method. The hybrid nanoantenna configurations constituted by a gap hot-spot and of a plasmonic corrugated grating and a metal reflector sandwiching a SiO 2 thin layer which appears promising for high spontaneous emission enhancement devices. Simulation assays show that the coupling between the gap-antenna and plasmonic corrugations reaches an ultra-high near-field enhancement factor in the excitation process. Moreover, concerning the emission process, the corrugations concentrate the far-field radiated power within a tiny angular volume, offering unprecedented collection efficiency. In the past decades, many kinds of optical antennas have been proposed and optimized to enhance single molecule detection. However, the excitation enhancement effect for single individual or dimmer plasmonic nanostructure is limited due to intrinsic nonradiative decay of the nanoparticle plasmon and quantum tunneling effect. The proposed hybrid configuration overwhelms the enhancement limit of single individual plasmonic structure. The findings provide an insight into spontaneous emission high enhancement through integrating the functions of different metallic nanostructures.

Potential for enhancing external beam radiotherapy for lung cancer using high-Z nanoparticles administered via inhalation

Science.gov (United States)

Hao, Yao; Altundal, Yucel; Moreau, Michele; Sajo, Erno; Kumar, Rajiv; Ngwa, Wilfred

2015-09-01

Nanoparticle-aided radiation therapy is emerging as a promising modality to enhance radiotherapy via the radiosensitizing action of high atomic number (Z) nanoparticles. However, the delivery of sufficiently potent concentrations of such nanoparticles to the tumor remain a challenge. This study investigates the dose enhancement to lung tumors due to high-Z nanoparticles (NPs) administered via inhalation during external beam radiotherapy. Here NPs investigated include: cisplatin nanoparticles (CNPs), carboplatin nanoparticles (CBNPs), and gold nanoparticles (GNPs). Using Monte Carlo-generated megavoltage energy spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumors due to radiation-induced photoelectrons from the NPs administered via inhalation route (IR) in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung via IV. Meanwhile recent experimental studies indicate that 3.5-14.6 times higher concentrations of NPs can reach the lung by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the radiotherapy dose with and without nanoparticles was calculated for a range of NPs concentrations and tumor sizes. The DEF for IR was then compared with that for IV. For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of up to 1.19, 1.26, and 1.51 were obtained for CNPs, CBNPs and GNPs. In comparison values of 1.06, 1.08, and 1.15 were obtained via IV administration. For IR with 14.6 times higher concentrations, even higher DEF values were obtained e.g. 1.81 for CNPs. Results also showed that the DEF increased with increasing field size or decreasing tumor volume, as expected. The results of this work indicate that IR administration of targeted high-Z CNPs/CBNPs/GNPs could enable clinically significant DEF to lung tumors compared to IV

Disorder-induced enhancement of conductance in doped nanowires

Institute of Scientific and Technical Information of China (English)

Xu Ning; Wang Bao-Lin; Sun Hou-Qian; Kong Fan-Jie

2010-01-01

A new mechanism is proposed to explain the enhancement of conductance in doped nanowires. It is shown that the anomalous enhancement of conductance is due to surface doping. The conductance in doped nanowires increases with dopant concentration, which is qualitatively consistent with the existing experimental results. In addition, the I-V curves are linear and thus suggest that the metal electrodes make ohmic contacts to the shell-doped nanowires.The electric current increases with wire diameter (D) and decreases exponentially with wire length (L). Therefore, the doped nanowires have potential application in nanoscale electronic and optoelectronic devices.

Dual Regulation of the Small RNA MicC and the Quiescent Porin OmpN in Response to Antibiotic Stress in Escherichia coli

Directory of Open Access Journals (Sweden)

Sushovan Dam

2017-12-01

Full Text Available Antibiotic resistant Gram-negative bacteria are a serious threat for public health. The permeation of antibiotics through their outer membrane is largely dependent on porin, changes in which cause reduced drug uptake and efficacy. Escherichia coli produces two major porins, OmpF and OmpC. MicF and MicC are small non-coding RNAs (sRNAs that modulate the expression of OmpF and OmpC, respectively. In this work, we investigated factors that lead to increased production of MicC. micC promoter region was fused to lacZ, and the reporter plasmid was transformed into E. coli MC4100 and derivative mutants. The response of micC–lacZ to antimicrobials was measured during growth over a 6 h time period. The data showed that the expression of micC was increased in the presence of β-lactam antibiotics and in an rpoE depleted mutant. Interestingly, the same conditions enhanced the activity of an ompN–lacZ fusion, suggesting a dual transcriptional regulation of micC and the quiescent adjacent ompN. Increased levels of OmpN in the presence of sub-inhibitory concentrations of chemicals could not be confirmed by Western blot analysis, except when analyzed in the absence of the sigma factor σE. We suggest that the MicC sRNA acts together with the σE envelope stress response pathway to control the OmpC/N levels in response to β-lactam antibiotics.

Fluctuation-enhanced electric conductivity in electrolyte solutions.

Science.gov (United States)

Péraud, Jean-Philippe; Nonaka, Andrew J; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L

2017-10-10

We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson-Nernst-Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation-anion diffusion coefficient. Specifically, we predict a nonzero cation-anion Maxwell-Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye-Huckel-Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced "giant" velocity fluctuations and reduced fluctuations of salt concentration.

Improved Intranasal Retentivity and Transnasal Absorption Enhancement by PEGylated Poly-l-ornithine

Directory of Open Access Journals (Sweden)

Yusuke Kamiya

2018-01-01

Full Text Available We reported that the introduction of polyethylene glycol (PEG to poly-l-ornithine (PLO, which is an homopolymeric basic amino acid having absorption-enhancement ability, prolonged retention time in an in vitro inclined plate test, probably due to an increase in viscosity caused by PEGylation. The aim of the present study is to investigate whether the introduction of PEG chains to PLO improves intranasal retention and transnasal absorption in vivo. We performed intranasal administration experiments using PLO and PEG-PLO with a model drug, fluorescein isothiocyanate dextran (FD-4, in rats under closed and open systems. In the open system, transition of plasma FD-4 concentration after co-administration with unmodified PLO was low, and the area under the plasma concentration-time curve (AUC decreased to about 60% of that in the closed system. In contrast, the AUC after co-administration with PEG-PLO in the open system was about 90% of that in the closed system, and the transition of plasma FD-4 concentration and FD-4 absorption profile were similar to those of the closed system. These findings indicate that introducing PEG chains to homopolymeric basic amino acids (HPBAAs is a very useful method for developing a functional absorption enhancer that can exhibit an efficient in vivo absorption-enhancing effect.

Polyamine deprivation-induced enhanced uptake of methylglyoxal bis(guanylhydrazone) by tumor cells.

Science.gov (United States)

Seppänen, P; Alhonen-Hongisto, L; Jänne, J

1981-05-05

1. Putrescine and spermidine depletion produced by alpha-difluoromethylornithine, an irreversible inhibitor or ornithine decarboxylase (EC 4.1.1.17), resulted in a strikingly enhanced cellular uptake of methylglyoxal bis(guanylhydrazone) in cultured Ehrlich ascites carcinoma cells and human lymphocytic leukemia cells. 2. A prior priming of the cells with difluoromethylornithine followed by a short exposure of the cells to methylglyoxal bis(guanylhydrazone) rapidly established intracellular concentrations of the latter drug approaching 10 mM. 3. The enhanced transport of methylglyoxal bis(guanylhydrazone) into the tumor cells apparently required metabolic energy as the uptake of extracellular drug rapidly ceased and intracellular methylglyoxal bis(guanylhydrazone) was excreted into the medium when the glycolysis of the tumor cells was inhibited by iodoacetate. 4. A sequential treatment of cultured tumor cells with difluoromethylornithine until established polyamine depletion followed by an addition of low concentrations of methylglyoxal bis(guanylhydrazone) produced an antiproliferative action not achieved with either of the drugs alone. 5. A similar treatment schedule, i.e a priming of mice inoculated with Ehrlich ascites cells with difluoromethylornithine for a few days, likewise enhanced the uptake of methylglyoxal bis(guanylhydrazone) by the carcinoma cells, but only marginally increased the drug concentration in the liver and small intestine of the animals.

Determination of Juglone concentration for differentiate two Musa spp cultivars

Directory of Open Access Journals (Sweden)

Michel Leiva Mora

2002-04-01

Full Text Available The toxins production by fungal pathogenic can enhance penetration and colonization of the host tissues and reproduce symptoms of diseases. Juglone is the main and the most toxic metabolite characterized from the culture filtrate of Mycosphaerella fijiensis. In the present work it was used different concentrations of juglone (10, 25, 50 and 100 mg.l-1 and a control solution of methanol 10%. Foliar injections were performed in the underside of two last open leaves of Grande naine (AAA and Fougamou (ABB cultivars. The percentage of necrosis per plant was evaluated at 24 hours after the injection. The concentration of 100 mg.l-1 was able to produce necrotic symptoms in both cultivars; nevertheless with the 50 mg.l-1 was possible to obtain differences between the two cultivars. This result established a concentration for screening two Musa spp cultivars with different resistance levels to Black Leaf Streak by the use of juglone. Key word: banana leaf streak, Mycosphaerella fijiensis, selection, toxins

Optimal offering strategy for a concentrating solar power plant

International Nuclear Information System (INIS)

Dominguez, R.; Baringo, L.; Conejo, A.J.

2012-01-01

Highlights: ► Concentrating solar power (CSP) plants are becoming economically viable. ► CSP production is positively correlated with the demand. ► CSP plants can be made dispatchable by using molten salt storage facilities. ► Integrating CSP plants in a market constitutes a relevant challenge. -- Abstract: This paper provides a methodology to build offering curves for a concentrating solar power plant. This methodology takes into account the uncertainty in the thermal production from the solar field and the volatility of market prices. The solar plant owner is a price-taker producer that participates in a pool-based electricity market with the aim of maximizing its expected profit. To enhance the value of the concentrating solar power plant, a molten salt heat storage is considered, which allows producing electricity during periods without availability of the solar resource. To derive offering curves, a mixed-integer linear programming model is proposed, which is robust from the point of view of the uncertainty associated with the thermal production of the solar field and stochastic from the point of view of the uncertain market prices.

Preparation of selective molybdenum concentrate from collective coppermolybdenum concentrate

Directory of Open Access Journals (Sweden)

N. Tusupbaev

2016-06-01

Full Text Available The paper considers possibilities of selective separation of the concentrate of copper and molybdenum from a collective copper-molybdenum concentrate of Aktogay deposit using regrinding and conventional flotation reagents. In the case of conventional flotoreagents, the content of molybdenum in a molybdenum concentrate was 8.0% at extraction effectiveness 83.12%. At 27.96% extraction degree of copper, it’s content in the concentrate equaled to 21.3%. After regrinding, molybdenum content in the concentrate was 24.0% at the extraction effectiveness 59.63%, and copper content in the concentrate was 21.9% at the recovery of 61.23%. Thus, the regrinding of a collective copper-molybdenum concentrate resulted in an increase in the content of molybdenum in molybdenum concentrate by 16%, and the copper concentration increased by 0.6%.

Luminescent Solar Concentrators in the Algal Industry

Science.gov (United States)

Hellier, Katie; Corrado, Carley; Carter, Sue; Detweiler, Angela; Bebout, Leslie

2013-03-01

Today's industry for renewable energy sources and highly efficient energy management systems is rapidly increasing. Development of increased efficiency Luminescent Solar Concentrators (LSCs) has brought about new applications for commercial interests, including greenhouses for agricultural crops. This project is taking first steps to explore the potential of LSCs to enhance production and reduce costs for algae and cyanobacteria used in biofuels and nutraceuticals. This pilot phase uses LSC filtered light for algal growth trials in greenhouses and laboratory experiments, creating specific wavelength combinations to determine effects of discrete solar light regimes on algal growth and the reduction of heating and water loss in the system. Enhancing the optimal spectra for specific algae will not only increase production, but has the potential to lessen contamination of large scale production due to competition from other algae and bacteria. Providing LSC filtered light will reduce evaporation and heating in regions with limited water supply, while the increased energy output from photovoltaic cells will reduce costs of heating and mixing cultures, thus creating a more efficient and cost effective production system.

Monte Carlo simulation study on dose enhancement by gold nanoparticles in brachytherapy

International Nuclear Information System (INIS)

Cho, Sungkoo; Jeong, Jonghwi; Kim, Chanhyeong; Yoon, Myonggeun

2010-01-01

Radiation dose enhancement by injection of a high atomic number (Z) material into tumor volumes has been studied for various radiation sources and different concentrations of gold nanoparticles. Brachytherapy employs low energy photons of less than ∼0.5 MeV, which indeed is the optimal energy range for radiation dose enhancement by introduction of high-Z material. The present study uses the MCNPX TM code to estimate the dose enhancement by gold nanoparticles for the four common brachytherapy sources ( 137 Cs, 192 Ir, 125 I, and 103 Pd). Additionally, cisplatin (H 6 Cl 2 N 2 Pt), a platinum-based chemotherapeutic drug, was used to evaluate the dose enhancement. The simulated source models were evaluated with reference to the calculated TG-43 parameter values. The dose enhancement in the tumor region due to the gold nanoparticles and cisplatin was evaluated according to the dose enhancement factor (DEF). The maximum values of the average DEFs were found to be 1.03, 1.11, 3.43, and 2.17 for the 137 Cs, 192 Ir, 125 I, and 103 Pd sources, respectively. The dose enhancement values for the low-energy sources were significantly higher than those for the high-energy sources. The dose enhancement due to cisplatin was calculated by using the same approach and was found to be comparable to that of the gold nanoparticles. The maximum value of the average DEF for cisplatin was 1.12 for the 5% concentration level in water and a 192 Ir source. We confirmed that cisplatin could be applied to cancer therapy that combines chemotherapeutic drugs with radiation therapy. The results presented herein will be used to study dose enhancement in tumor regions using various radiation modalities with high atomic number materials.

Detection and aggregation of the antitumoral drug parietin in ethanol/water mixture and on plasmonic metal nanoparticles studied by surface-enhanced optical spectroscopy: Effect of pH and ethanol concentration

Science.gov (United States)

Lopez-Tobar, Eduardo; Verebova, Valeria; Blascakova, Ludmila; Jancura, Daniel; Fabriciova, Gabriela; Sanchez-Cortes, Santiago

2016-04-01

In the present paper, we have investigated the effect of ethanol in aqueous media, the pH and the presence of Ag nanoparticles (NPs) on the aggregation processes of the antitumoral anthraquinone parietin in aqueous media and on the metal surface. UV-visible absorption, fluorescence and Raman spectra of parietin were used for such purpose. The present study provides information about the deprotonation and molecular aggregation processes occurring in parietin under different environments: ethanol/water mixture and when adsorbed onto Ag nanoparticles. The effect of ethanol on the optical properties of parietin in alcohol-water mixtures was also investigated at different ethanol concentrations with the time. For the case of the adsorption and organization of parietin molecules on the surface of Ag NPs, special attention was paid to the use of surface-enhanced optical techniques, SEF (surface-enhanced fluorescence) and SERS (surface-enhanced Raman scattering), for the characterization of the parietin aggregates and the ionization of the molecule on the surface. In particular, we have studied the variation of the SEF signal with the pH, which depends on the molecular organization of the molecule on the surface. Furthermore, a detailed analysis of the SERS spectra at different pH was accomplished and the main Raman bands of the protonated, mono-deprotonated and di-deprotonated parietin were identified. Finally, the second ionization pK of parietin on metal NPs was deduced from the SERS spectra.

Superhydrophobic analyte concentration utilizing colloid-pillar array SERS substrates.

Science.gov (United States)

Wallace, Ryan A; Charlton, Jennifer J; Kirchner, Teresa B; Lavrik, Nickolay V; Datskos, Panos G; Sepaniak, Michael J

2014-12-02

The ability to detect a few molecules present in a large sample is of great interest for the detection of trace components in both medicinal and environmental samples. Surface enhanced Raman spectroscopy (SERS) is a technique that can be utilized to detect molecules at very low absolute numbers. However, detection at trace concentration levels in real samples requires properly designed delivery and detection systems. The following work involves superhydrophobic surfaces that have as a framework deterministic or stochastic silicon pillar arrays formed by lithographic or metal dewetting protocols, respectively. In order to generate the necessary plasmonic substrate for SERS detection, simple and flow stable Ag colloid was added to the functionalized pillar array system via soaking. Native pillars and pillars with hydrophobic modification are used. The pillars provide a means to concentrate analyte via superhydrophobic droplet evaporation effects. A ≥ 100-fold concentration of analyte was estimated, with a limit of detection of 2.9 × 10(-12) M for mitoxantrone dihydrochloride. Additionally, analytes were delivered to the surface via a multiplex approach in order to demonstrate an ability to control droplet size and placement for scaled-up uses in real world applications. Finally, a concentration process involving transport and sequestration based on surface treatment selective wicking is demonstrated.

The significance of delayed contrast-enhanced CT in chronic subdural hematomas

International Nuclear Information System (INIS)

Karasawa, Hideharu; Ohya, Shigeru; Ueno, Junji; Watanabe, Saburo; Mikabe, Toshio

1983-01-01

We have previously, reported our delayed contrast-enhanced CT (DCECT) findings in traumatic subdural hygromas and chronic subdural hematomas. The purpose of this report is to clarify the relationship between the contrast media within subdural hematomas and the delayed enhancement. The clinical subjects were 35 cases of traumatic subdural hematomas. DCECT examinations were performed in all cases. The concentrations of the contrast media within the hematoma were measured during the operations. DCECT showed that the density of the hematomas increased 3 to 6 hours after the injection of the contrast media. The contrast media were detected within the hematomas a few hours after the injection. The contrast media were still present 24 hours after the injection, but disappeared in 48 hours. These findings suggest that contrast media go in and then come out of the subdural hematomas and that the main factor related to delayed enhancement is the concentration of the contrast media within the hematomas. DCECT examination may be most helpful in evaluating the dynamic changes in subdural collections. (author)

Effect of elevated CO2 concentration on growth course of tree seed-lings in Changbai Mountain

Institute of Scientific and Technical Information of China (English)

2000-01-01

One-year-old seedlings of Pinus koraiensis, Pinus sylvestriformis, Phellodendron amurense were grown in open-top chambers (OTCs) with 700 and 500 mmol/mol CO2 concentrations, control chamber and on open site (ambient CO2, about 350 mmol/mol CO2) respectively at the Open Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, and the growth course responses of three species to elevated CO2 and temperature during one growing season was studied from May to Oct. 1999. The results showed that increase in CO2 concentration enhanced the growth of seedlings and the effect of 700 mmol/mol CO2 was more remarkable than 500 mmol/mol CO2 on seedling growth. Under the condition of doubly elevated CO2 concentration, the biomass increased by 38% in average for coniferous seedlings and 60% for broad-leaved seedlings. With continuous treatment of high CO2 concentration, the monthly-accumulated biomass of shade-tolerant Pinus koraiensis seedlings was bigger in July than in August and September, while those of Pinus sylvestriformis and Phellodendron amurense seedlings showed an increase in July and August, or did not decrese until September. During the hot August, high CO2 concentration enhanced the growth of Pinus koraiensis seedlings by increasing temperature, but it did not show dominance in other two species.

Radiation tolerance of Si{sub 1−y}C{sub y} source/drain n-type metal oxide semiconductor field effect transistors with different carbon concentrations

Energy Technology Data Exchange (ETDEWEB)

Nakashima, Toshiyuki, E-mail: nakashima_t@cdk.co.jp [Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai-nishi, Miyazaki (Japan); Chuo Denshi Kogyo Co., Ltd., 3400 Kohoyama, Matsubase, Uki, Kumamoto (Japan); Asai, Yuki; Hori, Masato; Yoneoka, Masashi; Tsunoda, Isao; Takakura, Kenichiro [Kumamoto National College of Technology, 2659-2 Suya, Koshi, Kumamoto 861-1102 (Japan); Gonzalez, Mireia Bargallo [Institut de Microelectronica de Barcelona (Centre Nacional de Microelectronica — Consejo Superior de Investigaciones Cientificas) Campus UAB, 08193 Bellaterra (Spain); Simoen, Eddy [imec, Kapeldreef 75, B-3001 Leuven (Belgium); Claeys, Cor [imec, Kapeldreef 75, B-3001 Leuven (Belgium); Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Yoshino, Kenji [Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai-nishi, Miyazaki (Japan)

2014-04-30

The 2-MeV electron radiation damage of silicon–carbon source/drain (S/D) n-type metal oxide semiconductor field effect transistors with different carbon (C) concentrations is studied. Before irradiation, an enhancement of the electron mobility with C concentration of the S/D stressors is clearly observed. On the other hand, after electron irradiation, both the threshold voltage shift and the maximum electron mobility degradation are independent on the C concentration for all electron fluences studied. These results indicate that the strain induced electron mobility enhancement due to the C doping is retained after irradiation in the studied devices. - Highlights: • We have investigated the electron irradiation effect of the Si{sub 1−y}C{sub y} S/D n-MOSFETs. • The threshold voltage variations by irradiation are independent on the C doping. • The electron-mobility decreased for all C concentrations by electron irradiation. • The strain induced mobility enhancement effect is retained after irradiation.

Limitations to CO2-induced growth enhancement in pot studies.

Science.gov (United States)

McConnaughay, K D M; Berntson, G M; Bazzaz, F A

1993-07-01

Recently, it has been suggested that small pots may reduce or eliminate plant responses to enriched CO 2 atmospheres due to root restriction. While smaller pot volumes provide less physical space available for root growth, they also provide less nutrients. Reduced nutrient availability alone may reduce growth enhancement under elevated CO 2 . To investigate the relative importance of limited physical rooting space separate from and in conjunction with soil nutrients, we grew plants at ambient and double-ambient CO 2 levels in growth containers of varied volume, shape, nutrient concentration, and total nutrient content. Two species (Abutilon theophrasti, a C 3 dicot with a deep tap root andSetaria faberii, a C 4 monocot with a shallow diffuse root system) were selected for their contrasting physiology and root architecture. Shoot demography was determined weekly and biomass was determined after eight and ten weeks of growth. Increasing total nutrients, either by increasing nutrient concentration or by increasing pot size, increased plant growth. Further, increasing pot size while maintaining equal total nutrients per pot resulted in increased total biomass for both species. CO 2 -induced growth and reproductive yield enhancements were greatest in pots with high nutrient concentrations, regardless of total nutrient content or pot size, and were also mediated by the shape of the pot. CO 2 -induced growth and reproductive yield enhancements were unaffected by pot size (growth) or were greater in small pots (reproductive yield), regardless of total nutrient content, contrary to predictions based on earlier studies. These results suggest that several aspects of growth conditions within pots may influence the CO 2 responses of plants; pot size, pot shape, the concentration and total amount of nutrient additions to pots may lead to over-or underestimates of the CO 2 responses of real-world plants.

Calcification response of Pleurochrysis carterae to iron concentrations in batch incubations: implication for the marine biogeochemical cycle

Science.gov (United States)

Zou, Xiang; Sun, Shiyong; Lin, Sen; Shen, Kexuan; Dong, Faqin; Tan, Daoyong; Nie, Xiaoqin; Liu, Mingxue; Wei, Jie

2017-12-01

Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form of coccoliths located on the cell surface. Using batch incubations of the coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm (parts per million), 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon (coccoliths), and organic carbon (organic cellular components) showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization-enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.

Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake.

Science.gov (United States)

Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

2015-03-05

High concentrations of cesium (Cs(+)) inhibit plant growth but the detailed mechanisms of Cs(+) uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs(+), chemical library screening was performed using Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs(+) tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs(+) concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs(+). Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs(+) tolerance enhancer isolated here renders plants tolerant to Cs(+) by inhibiting Cs(+) entry into roots via specific binding to the ion thus, for instance, providing a basis for phytostabilisation of radiocesium-contaminated farmland.

Stress concentration factors for pressurized elliptic crossbores in blocks

International Nuclear Information System (INIS)

Badr, Elie A.

2006-01-01

Intersecting bore geometries are used in a number of industrial applications including heavy-walled pressure vessels containing oil holes for lubrication, ports for valves and fluid ends of reciprocating pumps. The bore intersection location is a stress concentration point where the maximum hoop stress can be many times the fluid pressure in the bores. Intersecting circular holes in heavy-walled cylinders and rectangular blocks have been extensively investigated. Specifically, stress/pressure concentration curves for intersecting circular bores in rectangular blocks were presented by Sorem et al. [Sorem JR, Shadley JR, Tipton SM. Design curves for maximum stresses in blocks containing pressurized bore intersections. ASME J Mech Des 1990; 113: 427-31.]. However, stress/pressure concentrations due to intersecting elliptic bores have not been broadly investigated. With the availability of computer numerical control (CNC) machinery, bores with elliptic crosssection can be produced with relative ease. In this paper, hoop stress concentration ratios are developed for elliptic crossbores in rectangular blocks. Results indicate that introducing elliptic crossbores, rather than circular ones, significantly reduces the hoop stress concentration factor at the crossbore intersection. Also, the presence of intersecting crossbores has a major effect on the fatigue life of pressure vessels [Badr EA, Sorem JR, Jr Tipton SM. Evaluation of the autofrettage effect on fatigue lives of steel blocks with crossbores using a statistical and a strain-based method. ASTM J Test Eval 2000; 28: 181-8.] and the reduction of hoop stress concentration is expected to enhance the fatigue life of pressure vessels containing crossbores

Enhanced mobilization of major inorganics during coalification of peats

Energy Technology Data Exchange (ETDEWEB)

Bailey, A.M. [Univ. of Southwestern Louisiana, Lafayette, LA (United States); Cohen, A.D. [Univ. of South Carolina, Columbia, SC (United States); Orem, W.H. [Geological Survey, Reston, VA (United States)

1995-12-01

Release patterns for Na, Cl, Ca, Mg, and Si from Cladium, Rhizophora, and Cyrilla peats have been determined by means of experiments to 60{degrees}C and 2100 psi. Where pore solution concentrations are high, significant mobilization is directly through loss of pore solutions. Changes in organic structures during early stage coalification may also mobilize exchangeable ions. Attack on solid inorganic phases begins during peatification and may be accelerated at temperatures above 40{degrees}C by increased organic acid production. Respective maximum concentrations for acetate, formate, and oxalate are around 900, 700, and 70 mg/l in the Cyrilla experiments at 60{degrees}C. Enhanced concentrations of Si, Al and other inorganics may result from these.

In situ analysis of dynamic laminar flow extraction using surface-enhanced Raman spectroscopy

Science.gov (United States)

Wang, Fei; Wang, Hua-Lin; Qiu, Yang; Chang, Yu-Long; Long, Yi-Tao

2015-12-01

In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions, and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation.

Concentrator Photovoltaics

CERN Document Server

Luque, Antonio L

2007-01-01

Photovoltaic solar-energy conversion is one of the most promising technologies for generating renewable energy, and conversion of concentrated sunlight can lead to reduced cost for solar electricity. In fact, photovoltaic conversion of concentrated sunlight insures an efficient and cost-effective sustainable power resource. This book gives an overview of all components, e.g. cells, concentrators, modules and systems, for systems of concentrator photovoltaics. The authors report on significant results related to design, technology, and applications, and also cover the fundamental physics and market considerations. Specific contributions include: theory and practice of sunlight concentrators; an overview of concentrator PV activities; a description of concentrator solar cells; design and technology of modules and systems; manufacturing aspects; and a market study.

A mechanistic based approach for enhancing buccal mucoadhesion of chitosan

DEFF Research Database (Denmark)

Meng-Lund, Emil; Muff-Westergaard, Christian; Sander, Camilla

2014-01-01

Mucoadhesive buccal drug delivery systems can enhance rapid drug absorption by providing an increased retention time at the site of absorption and a steep concentration gradient. An understanding of the mechanisms behind mucoadhesion of polymers, e.g. chitosan, is necessary for improving the muco......Mucoadhesive buccal drug delivery systems can enhance rapid drug absorption by providing an increased retention time at the site of absorption and a steep concentration gradient. An understanding of the mechanisms behind mucoadhesion of polymers, e.g. chitosan, is necessary for improving...... the mucoadhesiveness of buccal formulations. The interaction between chitosan of different chain lengths and porcine gastric mucin (PGM) was studied using a complex coacervation model (CCM), isothermal titration calorimetry (ITC) and a tensile detachment model (TDM). The effect of pH was assessed in all three models...... and the approach to add a buffer to chitosan based drug delivery systems is a means to optimize and enhance buccal drug absorption. The CCM demonstrated optimal interactions between chitosan and PGM at pH 5.2. The ITC experiments showed a significantly increase in affinity between chitosan and PGM at pH 5...

Enhancing blood donor skin disinfection using natural oils.

Science.gov (United States)

Alabdullatif, Meshari; Boujezza, Imen; Mekni, Mohamed; Taha, Mariam; Kumaran, Dilini; Yi, Qi-Long; Landoulsi, Ahmed; Ramirez-Arcos, Sandra

2017-12-01

Effective donor skin disinfection is essential in preventing bacterial contamination of blood components with skin flora bacteria like Staphylococcus epidermidis. Cell aggregates of S. epidermidis (biofilms) are found on the skin and are resistant to the commonly used donor skin disinfectants chlorhexidine-gluconate and isopropyl alcohol. It has been demonstrated that essential oils synergistically enhance the antibacterial activity of chlorhexidine-gluconate. The objective of this study was to test plant-extracted essential oils in combination with chlorhexidine-gluconate or chlorhexidine-gluconate plus isopropyl alcohol for their ability to eliminate S. epidermidis biofilms. The composition of oils extracted from Artemisia herba-alba, Lavandula multifida, Origanum marjoram, Rosmarinus officinalis, and Thymus capitatus was analyzed using gas chromatography-mass spectrometry. A rabbit model was used to assess skin irritation caused by the oils. In addition, the anti-biofilm activity of the oils used alone or in combination with chlorhexidine-gluconate or chlorhexidine-gluconate plus isopropyl alcohol was tested against S. epidermidis biofilms. Essential oil concentrations 10%, 20%, and 30% were chosen for anti-biofilm assays, because skin irritation was observed at concentrations greater than 30%. All oils except for O. marjoram had anti-biofilm activity at these three concentrations. L. multifida synergistically enhanced the anti-biofilm activity of chlorhexidine-gluconate and resulted in the highest anti-biofilm activity observed when combined with chlorhexidine-gluconate plus isopropyl alcohol. Gas chromatography-mass spectrometry revealed that the main component contributing to the activity of L. multifida oil was a natural terpene alcohol called linalool. The anti-biofilm activity of chlorhexidine-gluconate plus isopropyl alcohol can be greatly enhanced by L. multifida oil or linalool. Therefore, these components could potentially be used to improve blood

Stochastic Capsule Endoscopy Image Enhancement

Directory of Open Access Journals (Sweden)

Ahmed Mohammed

2018-06-01

Full Text Available Capsule endoscopy, which uses a wireless camera to take images of the digestive tract, is emerging as an alternative to traditional colonoscopy. The diagnostic values of these images depend on the quality of revealed underlying tissue surfaces. In this paper, we consider the problem of enhancing the visibility of detail and shadowed tissue surfaces for capsule endoscopy images. Using concentric circles at each pixel for random walks combined with stochastic sampling, the proposed method enhances the details of vessel and tissue surfaces. The framework decomposes the image into two detailed layers that contain shadowed tissue surfaces and detail features. The target pixel value is recalculated for the smooth layer using similarity of the target pixel to neighboring pixels by weighting against the total gradient variation and intensity differences. In order to evaluate the diagnostic image quality of the proposed method, we used clinical subjective evaluation with a rank order on selected KID image database and compared it to state-of-the-art enhancement methods. The result showed that the proposed method provides a better result in terms of diagnostic image quality and objective quality contrast metrics and structural similarity index.

Gold nanoparticle enhancement of stereotactic radiosurgery for neovascular age-related macular degeneration

Science.gov (United States)

Ngwa, Wilfred; Makrigiorgos, G. Mike; Berbeco, Ross I.

2012-10-01

Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries for people over the age of 50. In this work, the dosimetric feasibility of using gold nanoparticles (AuNP) as radiosensitizers to enhance kilovoltage stereotactic radiosurgery for neovascular AMD is investigated. Microdosimetry calculations at the sub-cellular level were carried out to estimate the radiation dose enhancement to individual nuclei in neovascular AMD endothelial cells (nDEF) due to photon-induced photo-/Auger electrons from x-ray-irradiated AuNP. The nDEF represents the ratio of radiation doses to the endothelial cell nuclei with and without AuNP. The calculations were carried out for a range of feasible AuNP local concentrations using the clinically applicable 100 kVp x-ray beam parameters employed by a commercially available x-ray therapy system. The results revealed nDEF values of 1.30-3.26 for the investigated concentration range of 1-7 mg g-1, respectively. In comparison, for the same concentration range, nDEF values of 1.32-3.40, 1.31-3.33, 1.29-3.19, 1.28-3.12 were calculated for 80, 90, 110 and 120 kVp x-rays, respectively. Meanwhile, calculations as a function of distance from the AuNP showed that the dose enhancement, for 100 kVp, is markedly confined to the targeted neovascular AMD endothelial cells where AuNP are localized. These findings provide impetus for considering the application of AuNP to enhance therapeutic efficacy during stereotactic radiosurgery for neovascular AMD.

A review of concentrated flow erosion processes on rangelands: fundamental understanding and knowledge gaps

Science.gov (United States)

Concentrated flow erosion processes are distinguished from splash and sheetflow processes in their enhanced ability to mobilize and transport large amounts of soil, water and dissolved elements. On rangelands, soil, nutrients and water are scarce and only narrow margins of resource losses are tolera...

A Proposed Concentration Curriculum Design for Big Data Analytics for Information Systems Students

Science.gov (United States)

Molluzzo, John C.; Lawler, James P.

2015-01-01

Big Data is becoming a critical component of the Information Systems curriculum. Educators are enhancing gradually the concentration curriculum for Big Data in schools of computer science and information systems. This paper proposes a creative curriculum design for Big Data Analytics for a program at a major metropolitan university. The design…

Enhanced optical and electrical properties of Y-doped ZnO nanoparticles having different Y concentrations

Science.gov (United States)

Üzar, Neslihan

2018-04-01

In this study, undoped ZnO and yttrium (Y)-doped ZnO (YZO) nanoparticles having different Y dopant concentrations (Zn1- x Y x O; x = 0.005, 0.01, 0.015, 0.02) were successfully synthesized by sol-gel dip-coating method. Structural characterizations of the obtained samples were examined with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. SEM analysis shows that the synthesized nanoparticles are mostly dot-like structures. The sizes of nanostructures decrease with increasing Y-doping concentration up to 2 mol % Y and XRD results show that all of samples have wurtzite hexagonal structure of ZnO with (002) c-plane orientation. According to EDS results pure YZO samples are obtained. Optical transmittances of all samples were investigated in the range of 350-750 nm at room temperature. The average optical transmittances of YZO samples in the visible region are approximately over 90%, but the transmittance starts to decrease for Zn0.98Y0.02O sample. Also, it was observed that the optical transmittances of Y-doped samples are higher than that of undoped ZnO. The electrical properties of YZO samples were obtained by resistance measurements at room temperature. The resistivity of samples was found to be 2.25 × 10-3, 1.43 × 10-3, 7.8 × 10-3, and 1.3 × 10-3 Ω-cm for Zn0.995Y0.005O, Zn0.99Y0.01O, Zn0.985Y0.015O and Zn0.98Y0.02O, respectively. All these results show that surface, structural, electrical and optical properties of ZnO samples can be improved with doping Y up to 2 mol % concentrations.

Effect of concentration temperature on some bioactive compounds and antioxidant proprieties of date syrup.

Science.gov (United States)

Abbès, Fatma; Besbes, Souhail; Brahim, Bchir; Kchaou, Wissal; Attia, Hamadi; Blecker, Christophe

2013-08-01

The effect of the concentration temperature on the antioxidant activity, carotenoid and phenolic compounds of date syrup was investigated. Date juice was concentrated at 100  and at "60  in vacuum". After concentration, total phenolic, tannin, non-tannin, flavonoid and carotenoid content were determined spectrophotometrically and high-performance liquid chromatography was used for determination of 5-Hydroxymethyl-2-furfuraldehyde content. The antioxidant activity of date syrup was evaluated by various antioxidant methods including total antioxidant, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test, ferric reducing antioxidant power and β-carotene bleaching. All date syrups showed strong antioxidant activity accompanied by high total phenolic contents. Results showed that concentration at 100  significantly enhanced the antioxidant activities and total phenolic contents of date syrups compared to vacuum concentration at 60 . A good correlation between the antioxidant activity and total phenolic content and flavonoid was observed.

Plackett-Burman Design for rGILCC1 Laccase Activity Enhancement in Pichia pastoris: Concentrated Enzyme Kinetic Characterization

Directory of Open Access Journals (Sweden)

Edwin D. Morales-Álvarez

2017-01-01

Full Text Available Laccases are multicopper oxidases that catalyze aromatic and nonaromatic compounds with concomitant reduction of molecular oxygen to water. They are of great interest due to their potential biotechnological applications. In this work we statistically improved culture media for recombinant GILCC1 (rGILCC1 laccase production at low scale from Ganoderma lucidum containing the construct pGAPZαA-GlucPost-Stop in Pichia pastoris. Temperature, pH stability, and kinetic parameter characterizations were determined by monitoring concentrate enzyme oxidation at different ABTS substrate concentrations. Plackett-Burman Design allowed improving enzyme activity from previous work 36.08-fold, with a laccase activity of 4.69 ± 0.39 UL−1 at 168 h of culture in a 500 mL shake-flask. Concentrated rGILCC1 remained stable between 10 and 50°C and retained a residual enzymatic activity greater than 70% at 60°C and 50% at 70°C. In regard to pH stability, concentrated enzyme was more stable at pH 4.0 ± 0.2 with a residual activity greater than 90%. The lowest residual activity greater than 55% was obtained at pH 10.0 ± 0.2. Furthermore, calculated apparent enzyme kinetic parameters were a Vmax of 6.87 × 10−5 mM s−1, with an apparent Km of 5.36 × 10−2 mM. Collectively, these important stability findings open possibilities for applications involving a wide pH and temperature ranges.

Temporal characteristics of black carbon concentrations and its potential emission sources in a southern Taiwan industrial urban area.

Science.gov (United States)

Cheng, Yu-Hsiang; Lin, Chi-Chi; Liu, Jyh-Jian; Hsieh, Cheng-Ju

2014-03-01

This study investigates the temporal characteristics of black carbon and its potential emission sources, as well as the fractions of BC in PM2.5 levels in Kaohsiung urban area, which is an industrial city in southern Taiwan. Concentrations of BC and PM2.5 are monitored continuously from March 2006 to February 2010, using an aethalometer and a tapered element oscillating microbalance monitor. Additionally, the presence of organic compounds (or UV enhanced species) in particles at the sampling site is determined using the Delta-C (UVBC-BC) value. According to long-term measurement results, BC and PM2.5 concentrations are 3.33 and 34.0 μg m(-3), respectively, in the Kaohsiung urban area. The ratio of BC/PM2.5 is approximately 11 %. Low concentration of BC and PM2.5 in the summer of this study period is mostly likely owing to meteorological conditions that favored dispersion of local air pollutants. Nevertheless, BC concentrations peaked markedly during morning hours (7:00-11:00), likely owing to local traffic congestion. Measurement results suggest that BC is released from local traffic activities and emitted from industrial activities at this sampling site. Additionally, Delta-C values are significantly higher than zero during January-March and November-December periods in this industrial urban area, implying that UV enhanced species can be observed. At this sampling site, these UV enhanced species do not only originate from household activity and solid waste burning but also release from industrial activities. The elevated Delta-C values during nighttime (18:00-6:00) in the autumn and winter seasons are likely related to those UV enhanced species in the atmosphere, which can be condensed on particle surface under low temperature conditions. According to long-term measurement results, significantly positive Delta-C values can be observed under temperatures industrial parks and a coal-fired power plant.

On nutrients and trace metals: Effects from Enhanced Weathering

Science.gov (United States)

Amann, T.; Hartmann, J.

2015-12-01

The application of rock flour on suitable land ("Enhanced Weathering") is one proposed strategy to reduce the increase of atmospheric CO2 concentrations. At the same time it is an old and established method to add fertiliser and influence soil properties. Investigations of this method focused on the impact on the carbonate system, as well as on engineering aspects of a large-scale application, but potential side effects were never discussed quantitatively. We analysed about 120,000 geochemically characterised volcanic rock samples from the literature. Applying basic statistics, theoretical release rates of nutrients and potential contaminants by Enhanced Weathering were evaluated for typical rock types. Applied rock material can contain significant amounts of essential or beneficial nutrients (potassium, phosphorus, micronutrients). Their release can partly cover the demand of major crops like wheat, rice or corn, thereby increasing crop yield on degraded soils. However, the concentrations of considered elements are variable within a specific rock type, depending on the geological setting. High heavy metal concentrations are found in (ultra-) basic rocks, the class with the highest CO2 drawdown potential. More acidic rocks contain less or no critical amounts, but sequester less CO2. Findings show that the rock selection determines the capability to supply significant amounts of nutrients, which could partly substitute industrial mineral fertiliser usage. At the same time, the release of harmful trace element has to be considered. Through careful selection of regionally available rocks, benefits could be maximised and drawbacks reduced. The deployment of Enhanced Weathering to sequester CO2 and to ameliorate soils necessitates an ecosystem management, considering the release and fate of weathered elements in plants, soils and water. Cropland with degraded soils would benefit while having a net negative CO2 effect, while other carbon dioxide removal strategies, like

Elliptical concentrators.

Science.gov (United States)

Garcia-Botella, Angel; Fernandez-Balbuena, Antonio Alvarez; Bernabeu, Eusebio

2006-10-10

Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used to produce optical devices, including the use of reflective and refractive components or inverse engineering techniques. However, many of these optical components are based on translational symmetries, rotational symmetries, or free-form surfaces. We study a new family of nonimaging concentrators called elliptical concentrators. This new family of concentrators provides new capabilities and can have different configurations, either homofocal or nonhomofocal. Translational and rotational concentrators can be considered as particular cases of elliptical concentrators.

IS ENHANCED-ECCENTRIC RESISTANCE TRAINING SUPERIOR TO TRADITIONAL TRAINING FOR INCREASING ELBOW FLEXOR STRENGTH?

Directory of Open Access Journals (Sweden)

Thomas W. Kaminski

2003-06-01

Full Text Available Protocols for strengthening muscle are important for fitness, rehabilitation, and the prevention of myotendinous injuries. In trained individuals, the optimal method of increasing strength remains unclear. The purpose of this study was to compare the effects of a traditional method of strengthening with a method that allowed for enhanced-eccentric training, on changes in elbow flexor strength in trained subjects. Thirty-nine (8 male, 31 female trained subjects with normal elbow function participated in this study. Subjects were rank-ordered according to isometric force production and randomly assigned to one of three training groups: control (CONT, traditional concentric/eccentric (TRAD, and concentric/enhanced-eccentric (NEG. The training groups completed 24 training sessions. An evaluator blinded to training group performed all testing. Mixed model ANOVA techniques were used to determine if differences existed in concentric one repetition maximum strength, and isometric force production among groups. Changes in peak and average isokinetic force production were also compared. Type 1 error was maintained at 5%. While both groups improved concentric one repetition maximum (NEG = 15.5%, TRAD = 13.8% neither training group statistically differed from changes demonstrated by the CONT group. Nor did either training group show significant improvements in isometric or isokinetic force production over the CONT group. These results do not support the superiority of enhanced-eccentric training for increasing force production in trained subjects.

Eco-friendly luminescent solar concentrators with low reabsorption losses and resistance to concentration quenching based on aqueous-solution-processed thiolate-gold nanoclusters

Science.gov (United States)

Huang, H. Y.; Cai, K. B.; Chang, L. Y.; Chen, P. W.; Lin, T. N.; Lin, C. A. J.; Shen, J. L.; Talite, M. J.; Chou, W. C.; Yuan, C. T.

2017-09-01

Heavy-metal-containing quantum dots (QDs) with engineered electronic states have been served as luminophores in luminescent solar concentrators (LSCs) with impressive optical efficiency. Unfortunately, those QDs involve toxic elements and need to be synthesized in a hazardous solvent. Recently, biocompatible, eco-friendly gold nanoclusters (AuNCs), which can be directly synthesized in an aqueous solution, have gained much attention for promising applications in ‘green photonics’. Here, we explored the solid-state photophysical properties of aqueous-solution-processed, glutathione-stabilized gold nanoclusters (GSH-AuNCs) with a ligand-to-metal charge-transfer (LMCT) state for developing ‘green’ LSCs. We found that such GSH-AuNCs exhibit a large Stokes shift with almost no spectral overlap between the optical absorption and PL emission due to the LMCT states, thus, suppressing reabsorption losses. Compared with GSH-AuNCs in solution, the photoluminescence quantum yields (PL-QYs) of the LSCs can be enhanced, accompanied with a lengthened PL lifetime owing to the suppression of non-radiative recombination rates. In addition, the LSCs do not suffer from severe concentration-induced PL quenching, which is a common weakness for conventional luminophores. As a result, a common trade-off between light-harvesting efficiency and solid-state PL-QYs can be bypassed due to nearly-zero spectral overlap integral between the optical absorption and PL emission. We expect that GSH-AuNCs hold great promise for serving as luminophores for ‘green’ LSCs by further enhancing solid-state PL-QYs.

Eco-friendly luminescent solar concentrators with low reabsorption losses and resistance to concentration quenching based on aqueous-solution-processed thiolate-gold nanoclusters.

Science.gov (United States)

Huang, H Y; Cai, K B; Chang, L Y; Chen, P W; Lin, T N; Lin, C A J; Shen, J L; Talite, M J; Chou, W C; Yuan, C T

2017-09-15

Heavy-metal-containing quantum dots (QDs) with engineered electronic states have been served as luminophores in luminescent solar concentrators (LSCs) with impressive optical efficiency. Unfortunately, those QDs involve toxic elements and need to be synthesized in a hazardous solvent. Recently, biocompatible, eco-friendly gold nanoclusters (AuNCs), which can be directly synthesized in an aqueous solution, have gained much attention for promising applications in 'green photonics'. Here, we explored the solid-state photophysical properties of aqueous-solution-processed, glutathione-stabilized gold nanoclusters (GSH-AuNCs) with a ligand-to-metal charge-transfer (LMCT) state for developing 'green' LSCs. We found that such GSH-AuNCs exhibit a large Stokes shift with almost no spectral overlap between the optical absorption and PL emission due to the LMCT states, thus, suppressing reabsorption losses. Compared with GSH-AuNCs in solution, the photoluminescence quantum yields (PL-QYs) of the LSCs can be enhanced, accompanied with a lengthened PL lifetime owing to the suppression of non-radiative recombination rates. In addition, the LSCs do not suffer from severe concentration-induced PL quenching, which is a common weakness for conventional luminophores. As a result, a common trade-off between light-harvesting efficiency and solid-state PL-QYs can be bypassed due to nearly-zero spectral overlap integral between the optical absorption and PL emission. We expect that GSH-AuNCs hold great promise for serving as luminophores for 'green' LSCs by further enhancing solid-state PL-QYs.

Enhanced dilepton radiation at RHIC

CERN Document Server

Toia, Alberica

2009-01-01

Recently, there is growing evidence that a new state of matter is formed in Au+Au collisions at RHIC: a strongly coupled Quark Gluon Plasma of partonic degrees of freedom which develops a collective motion. Dilepton spectra are not affected by strong interaction and can therefore probe the whole time evolution of the collision. Thus they may be sensitive to the onset of deconfinement, chiral symmetry restoration, as well as the production of thermal photons. The PHENIX experiment measured the production of e+e− pairs in p+p and Au+Au collisions at . An enhanced dilepton yield in the mass range is measured. The excess increases faster with centrality than the number of participating nucleons, and is concentrated at . At higher pT the excess below 300 MeV/c2 has been related to an enhanced production of direct photons, possibly of thermal origin.

Measurement of chloride-ion concentration with long-period grating technology

Science.gov (United States)

Tang, Jaw-Luen; Wang, Jian-Neng

2007-06-01

A simple and low-cost long-period fiber grating (LPG) sensor suited for chloride-ion concentration measurement is presented. The LPG sensor is found to be sensitive to the refractive index of the medium around the cladding surface of the sensing grating, thus offering the prospect of development of practical sensors such as an ambient index sensor or a chemical concentration indicator with high stability and reliability. We measured chloride ions in a typical concrete sample immersed in salt water solutions with different weight concentrations ranging from 0% to 25%. Results show that the LPG sensor exhibited a linear decrease in the transmission loss and resonance wavelength shift when the concentration increased. The measurement accuracy for the concentration of salt in water solution is estimated to be 0.6% and the limit of detection for chloride ions is about 0.04%. To further enhance its sensitivity for chloride concentrations, we coated a monolayer of colloidal gold nanoparticles as the active material on the grating surface of the LPG sensor. The operating principle of sensing is based on the sensitivity of localized surface plasmon resonance of self-assembled gold colloids on the grating section of the LPG. With this method, a factor of two increase in the sensitivity of detecting chemical solution concentrations was obtained. The advantages of this type of fiber-optic sensor are that it is compact, relatively simple to construct and easy to use. Moreover, the sensor has the potential capability for on-site, in vivo and remote sensing, and it has potential use as a disposable sensor.

Reduced Coniferin and Enhanced 6-Methoxypodophyllotoxin Production in

NARCIS (Netherlands)

Ruslan Wirasutisna, Komar; Batterman, Sieben; Koulman, Albert; Kayser, Oliver; Woerdenbag, Herman J; Quax, Wim J

2010-01-01

Treatment of cell suspension cultures of Linum flavum L. with Na2EDTA reduced the coniferin and enhanced the 6-methoxypodophyllotoxin (6-MPT) production in a concentration-dependent way, in a range of 0.1–5 mM. On day 14 after treatment with Na2EDTA , an inhibition of the coniferin production up to

MCS precipitation and downburst intensity response to increased aerosol concentrations

Science.gov (United States)

Clavner, M.; Cotton, W. R.; van den Heever, S. C.

2015-12-01

Mesoscale convective systems (MCSs) are important contributors to rainfall in the High Plains of the United States as well as producers of severe weather such as hail, tornados and straight-line wind events known as derechos. Past studies have shown that changes in aerosol concentrations serving as cloud condensation nuclei (CCN) alter the MCS hydrometeor characteristics which in turn modify precipitation yield, downdraft velocity, cold-pool strength, storm propagation and the potential for severe weather to occur. In this study, the sensitivity of MCS precipitation characteristics and convective downburst velocities associated with a derecho to changes in CCN concentrations were examined by simulating a case study using the Regional Atmospheric Modeling System (RAMS). The case study of the 8 May 2009 "Super-Derecho" MCS was chosen since it produced a swath of widespread wind damage in association with an embedded large-scale bow echo, over a broad region from the High Plains of western Kansas to the foothills of the Appalachians. The sensitivity of the storm to changes in CCN concentrations was examined by conducting a set of three simulations which differed in the initial aerosol concentration based on output from the 3D chemical transport model, GEOS-Chem. Results from this study indicate that while increasing CCN concentrations led to an increase in precipitation rates, the changes to the derecho strength were not linear. A moderate increase in aerosol concentration reduced the derecho strength, while the simulation with the highest aerosol concentrations increased the derecho intensity. These changes are attributed to the impact of enhanced CCN concentration on the production of convective downbursts. An analysis of aerosol loading impacts on these MCS features will be presented.

Concentrated Ownership

DEFF Research Database (Denmark)

Rose, Caspar

2014-01-01

This entry summarizes the main theoretical contributions and empirical findings in relation to concentrated ownership from a law and economics perspective. The various forms of concentrated ownership are described as well as analyzed from the perspective of the legal protection of investors......, especially minority shareholders. Concentrated ownership is associated with benefits and costs. Concentrated ownership may reduce agency costs by increased monitoring of top management. However, concentrated ownership may also provide dominating owners with private benefits of control....

Enhanced transbuccal salmon calcitonin (sCT) delivery: effect of chemical enhancers and electrical assistance on in vitro sCT buccal permeation.

Science.gov (United States)

Oh, Dong-Ho; Chun, Kyeung-Hwa; Jeon, Sang-Ok; Kang, Jeong-Won; Lee, Sangkil

2011-10-01

This study investigates the combined effect of absorption enhancers and electrical assistance on transbuccal salmon calcitonin (sCT) delivery, using fresh swine buccal tissue. We placed 200 IU (40 μg/mL) of each sCT formulation--containing various concentrations of ethanol, N-acetyl-L-cysteine (NAC), and sodium deoxyglycocholate (SDGC)--onto the donor part of a Franz diffusion cell. Then, 0.5 mA/cm(2) of fixed anodal current was applied alone or combined with chemical enhancers. The amount of permeated sCT was analyzed using an ELISA kit, and biophysical changes of the buccal mucosa were investigated using FT-IR spectroscopy, and hematoxylin-eosin staining methods were used to evaluate histological alteration of the buccal tissues. The flux (J(s)) of sCT increased with the addition of absorption enhancer groups, but it was significantly enhanced by the application of anodal iontophoresis (ITP). FT-IR study revealed that all groups caused an increase in lipid fluidity but only the groups containing SDGC showed statistically significant difference. Although the histological data of SDGC groups showed a possibility for tissue damage, the present enhancing methods appear to be safe. In conclusion, the combination of absorption enhancers and electrical assistance is a potential strategy for the enhancement of transbuccal sCT delivery. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of lidocaine gels for enhanced local anesthetic action.

Science.gov (United States)

Shin, Sang-Chul; Cho, Cheong-Weon; Yang, Kyu-Ho

2004-12-09

In relieving local pains, lidocaine, one of ester type local anesthetics, has been used. To develop the lidocaine gels of enhanced local anesthetic effects, hydroxypropyl methylcellulose (HPMC) based bioadhesive polymer gel containing an enhancer was formulated. As the drug concentration in the gels increased up to 3%, the permeation rate of drug linearly increased, thereafter reaching a plateau. As the temperature of surrounding solutions increased, the permeation of drug increased. The activation energy of drug permeation was 3.29 kcal/mol for lidocaine. The permeation rate of drug through skin was studied using various enhancers, such as glycols, non-ionic surfactants, and bile salts. Among the enhancers studied, diethylene glycol showed the greatest enhancing effects on drug permeation through skin. The analgesic activity was examined using a tail-flick analgesimeter. In the area under the efficacy curve (AUEC) of the rat-tail flick tests, lidocaine gel containing diethylene glycol showed about 3.89-fold increase in analgesic activity compared with the control. The addition of vasoconstrictor in the gels prolonged the analgesic effects. The result of this study supports that the bioadhesive gel with efficient anesthetic effect could be developed using HPMC with combination of enhancer and vasoconstrictor.

Effects of Organic Corrosion Inhibitor and Chloride Ion Concentration on Steel Depassivation and Repassivation in Solution

Institute of Scientific and Technical Information of China (English)

WANG Zixiao; YU Lei; LIU Zhiyong; SONG Ning

2015-01-01

Effect of an organic corrosion inhibitor (OCI) named PCI-2014 added in chloride solution on the critical chlo-ride concentration of mild steel depassivation and the critical OCI concentrations for repairing the steel in different chlo-ride solution were investigated. The results show that the critical chloride concentration increases exponentially with raises of PCI-2014 concentration in the solution. Within a certain chloride ion concentration range, the critical PCI-2014 concentration for repairing the corroded steel is also increases exponentially with enhancement of chloride content in the solution. Atomic force microscopy images display the molecular particles of inhibitor are adsorbed on the steel surface and formed a protective layer. Analysis of X-ray photoelectron spectroscopy shows the chloride ions at the surface of steel are displaced by atoms or molecules of the inhibitor in chloride condition.

Health Care Market Concentration Trends In The United States: Evidence And Policy Responses.

Science.gov (United States)

Fulton, Brent D

2017-09-01

Policy makers and analysts have been voicing concerns about the increasing concentration of health care providers and health insurers in markets nationwide, including the potential adverse effect on the cost and quality of health care. The Council of Economic Advisers recently expressed its concern about the lack of estimates of market concentration in many sectors of the US economy. To address this gap in health care, this study analyzed market concentration trends in the United States from 2010 to 2016 for hospitals, physician organizations, and health insurers. Hospital and physician organization markets became increasingly concentrated over this time period. Concentration among primary care physicians increased the most, partially because hospitals and health care systems acquired primary care physician organizations. In 2016, 90 percent of Metropolitan Statistical Areas (MSAs) were highly concentrated for hospitals, 65 percent for specialist physicians, 39 percent for primary care physicians, and 57 percent for insurers. Ninety-one percent of the 346 MSAs analyzed may have warranted concern and scrutiny because of their concentration levels in 2016 and changes in their concentrations since 2010. Public policies that enhance competition are needed, such as stricter enforcement of antitrust laws, reducing barriers to entry, and restricting anticompetitive behaviors. Project HOPE—The People-to-People Health Foundation, Inc.

Melting of nanoparticles-enhanced phase change material (NEPCM) in vertical semicircle enclosure: numerical study

Energy Technology Data Exchange (ETDEWEB)

Jourabian, Mahmoud [University of Trieste, Piazzale (Italy); Farhadi, Mousa [Babol Noshirvani University of Technology, Shariati Avenue (Iran, Islamic Republic of)

2015-09-15

Convection melting of ice as a Phase change material (PCM) dispersed with Cu nanoparticles, which is encapsulated in a semicircle enclosure is studied numerically. The enthalpy-based Lattice Boltzmann method (LBM) combined with a Double distribution function (DDF) model is used to solve the convection-diffusion equation. The increase in solid concentration of nanoparticles results in the enhancement of thermal conductivity of PCM and the decrease in the latent heat of fusion. By enhancing solid concentration of nanoparticles, the viscosity of nanofluid increases and convective heat transfer dwindles. For all Rayleigh numbers investigated in this study, the insertion of nanoparticles in PCM has no effect on the average Nusselt number.

Melting of nanoparticles-enhanced phase change material (NEPCM) in vertical semicircle enclosure: numerical study

International Nuclear Information System (INIS)

Jourabian, Mahmoud; Farhadi, Mousa

2015-01-01

Convection melting of ice as a Phase change material (PCM) dispersed with Cu nanoparticles, which is encapsulated in a semicircle enclosure is studied numerically. The enthalpy-based Lattice Boltzmann method (LBM) combined with a Double distribution function (DDF) model is used to solve the convection-diffusion equation. The increase in solid concentration of nanoparticles results in the enhancement of thermal conductivity of PCM and the decrease in the latent heat of fusion. By enhancing solid concentration of nanoparticles, the viscosity of nanofluid increases and convective heat transfer dwindles. For all Rayleigh numbers investigated in this study, the insertion of nanoparticles in PCM has no effect on the average Nusselt number.

Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment.

Science.gov (United States)

Zaloga, Jan; Stapf, Marcus; Nowak, Johannes; Pöttler, Marina; Friedrich, Ralf P; Tietze, Rainer; Lyer, Stefan; Lee, Geoffrey; Odenbach, Stefan; Hilger, Ingrid; Alexiou, Christoph

2015-08-14

Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON(LA-BSA), which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON(LA-BSA) particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON(LA-BSA) changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.

Spectral and Concentration Sensitivity of Multijunction Solar Cells at High Temperature: Preprint

Energy Technology Data Exchange (ETDEWEB)

Friedman, Daniel J.; Steiner, Myles A.; Perl, Emmett E.; Simon, John

2017-06-14

We model the performance of two-junction solar cells at very high temperatures of ~400 degrees C and beyond for applications such as hybrid PV/solar-thermal power production, and identify areas in which the design and performance characteristics behave significantly differently than at more conventional near-room-temperature operating conditions. We show that high-temperature operation reduces the sensitivity of the cell efficiency to spectral content, but increases the sensitivity to concentration, both of which have implications for energy yield in terrestrial PV applications. For other high-temperature applications such as near-sun space missions, our findings indicate that concentration may be a useful tool to enhance cell efficiency.

Enhanced EGFP Fluorescence Emission in Presence of PEG Aqueous Solutions and PIB1000-PEG6000-PIB1000 Copolymer Vesicles

Directory of Open Access Journals (Sweden)

Noor Muhammad

2013-01-01

Full Text Available An EGFP construct interacting with the PIB1000-PEG6000-PIB1000 vesicles surface reported a ~2-fold fluorescence emission enhancement. Because of the constructs nature with the amphiphilic peptide inserted into the PIB core, EGFP is expected to experience a “pure” PEG environment. To unravel this phenomenon PEG/water solutions at different molecular weights and concentrations were used. Already at ~1 : 10 protein/PEG molar ratio the increase in fluorescence emission is observed reaching a plateau correlating with the PEG molecular weight. Parallel experiments in presence of glycerol aqueous solutions did show a slight fluorescence enhancement however starting at much higher concentrations. Molecular dynamics simulations of EGFP in neat water, glycerol, and PEG aqueous solutions were performed showing that PEG molecules tend to “wrap” the protein creating a microenvironment where the local PEG concentration is higher compared to its bulk concentration. Because the fluorescent emission can be perturbed by the refractive index surrounding the protein, the clustering of PEG molecules induces an enhanced fluorescence emission already at extremely low concentrations. These findings can be important when related to the use of EGFP as reported in molecular biology experiments.

An improved geographically weighted regression model for PM2.5 concentration estimation in large areas

Science.gov (United States)

Zhai, Liang; Li, Shuang; Zou, Bin; Sang, Huiyong; Fang, Xin; Xu, Shan

2018-05-01

Considering the spatial non-stationary contributions of environment variables to PM2.5 variations, the geographically weighted regression (GWR) modeling method has been using to estimate PM2.5 concentrations widely. However, most of the GWR models in reported studies so far were established based on the screened predictors through pretreatment correlation analysis, and this process might cause the omissions of factors really driving PM2.5 variations. This study therefore developed a best subsets regression (BSR) enhanced principal component analysis-GWR (PCA-GWR) modeling approach to estimate PM2.5 concentration by fully considering all the potential variables' contributions simultaneously. The performance comparison experiment between PCA-GWR and regular GWR was conducted in the Beijing-Tianjin-Hebei (BTH) region over a one-year-period. Results indicated that the PCA-GWR modeling outperforms the regular GWR modeling with obvious higher model fitting- and cross-validation based adjusted R2 and lower RMSE. Meanwhile, the distribution map of PM2.5 concentration from PCA-GWR modeling also clearly depicts more spatial variation details in contrast to the one from regular GWR modeling. It can be concluded that the BSR enhanced PCA-GWR modeling could be a reliable way for effective air pollution concentration estimation in the coming future by involving all the potential predictor variables' contributions to PM2.5 variations.