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Competing interests The authors declare that they have started the process of patent application in the US patent office relating to the selleckchem content of this manuscript. The authors will ask Iran Nanotechnology Initiative Council and Chemnitz University of Technology in Chemnitz, Germany for financial support for patent application fees. Authors’ contributions AN is the director of this experimental study and has drafted this manuscript. MG, as a MSc student, is jointly supervised by SJA to simulate the compound in question, as discussed in [3] and background sections of this paper, and by AN to carry out the experimental measurements, as discussed in this paper. MHY participated in the experimental studies by PL measurements. MK-0457 molecular weight All authors read and approved the final manuscript.”
“Background Dye-sensitized solar cells (DSSCs) are regarded as promising low-cost solar cells with high light-to-energy conversion efficiency. Systems

based on titanium dioxide (TiO2) nanoparticle films sensitized with ruthenium (Ru)-based dyes have achieved a light-to-energy conversion efficiency of more than 11% [1, 2]. Other metal oxides, including tin dioxide, indium (III) oxide, niobium pentoxide, and zinc oxide (ZnO), have also been used as photoelectrode materials [3–5]. Among these materials, ZnO has attracted considerable attention

Dolutegravir because it has an energy-band structure similar to that of TiO2 but possesses a higher electron mobility and allows more flexibility in synthesis and morphologies [6, 7]. The photovoltaic performance of a DSSC relies on the characteristics of its photoanode, which plays a central role in converting light into electrical energy. A DSSC photoanode typically consists of a mesoporous oxide film on a transparent conducting glass substrate. Dye molecules that capture photons from light during device operation are attached to the surface of oxide film. Photoexcitation of the dye molecules leads to the injection of electrons into the oxide film. Therefore, an oxide film with a large interfacial surface area and superior electron transport properties is vital for learn more strong light harvesting and efficient device performance. Consequently, numerous researchers have attempted to develop novel nanostructures with these desirable properties [8–12]. Another important strategy that has been widely adopted in DSSCs to boost optical absorption is light scattering [13]. The basic principle of the light scattering method is to confine light propagation and extend the traveling distance of light within the oxide film. In this way, the opportunity of photon absorption by the dye molecules is increased, so is the cell conversion efficiency.

e., identification of bacteria

and microorganismal pathogens within the peritoneal fluid, the presence of yeasts (if applicable), and the antibiotic susceptibilities Raf inhibitor of bacterial isolates. Statistical analysis Following data entry into a computerized database, the results will be expressed as standard statistical metrics: median (range), mean ± standard deviation for continuous variables, and the number of patients (with the corresponding percentages) for other qualitative variables. The primary endpoints will include Clinical profiles of intra-abdominal infections Epidemiological profiles (the learn more epidemiology of the microorganisms isolated from intra-abdominal samples and these organisms’ resistance to antibiotics) Management profiles

Comparisons will be performed using the Student’s t-test, χ 2 analysis, or the Kruskall-Wallis/Wilcoxon tests, as dictated by the natural parameters of the data in question. Statistical significance check details will be defined as a P-value less than 0.05 (P < 0.05). Multivariate analysis will be carried out by means of stepwise logistic regressions in order to assess the predictive factors of mortality during hospitalization. Adjusted odds ratios (OR) and their 95% confidence intervals (CI) will also be included. Inclusion Criteria Patients undergoing surgery or interventional drainage to address complicated IAI, or patients who have yieded positive microbiological cultures upon postoperative drainage (intra-abdominal samples taken from surgery or drainage) will be Cyclic nucleotide phosphodiesterase included. Exclusion Criteria

Patients with pancreatitis and primary peritonitis will be excluded. References 1. Menichetti F, Sganga G: Definition and classification of intra-abdominal infections. J Chemother 2009, 21:3–4.PubMed 2. Pieracci FM, Barie PS: Management of severe sepsis of abdominal origin. Scand J Surg 2007, 96:184–196.PubMed 3. Marshall JC, Maier RV, Jimenez M, Dellinger EP: Source control in the management of severe sepsis and septic shock: an evidence-based review. Crit Care Med 2004, 32:513–526.CrossRef 4. Schoeffel U, Jacobs E, Ruf G, Mierswa F, von Specht BU, Farthmann EH: Intraperitoneal micro-organisms and the severity of peritonitis. Eur J Surg 1995, 161:501–508.PubMed 5. Azzarello G, Lanteri R, Rapisarda C, Santangelo M, Racalbuto A, Minutolo V, Di Cataldo A, Licata A: Ultrasound-guided percutaneous treatment of abdominal collections. Chir Ital 2009, 61:337–340.PubMed 6. Gazelle GS, Mueller PR: Abdominal abscess: Imaging and intervention. Radiol Clin North Am 1994, 32:913–932.PubMed 7. VanSonnenberg E, Ferrucci JT, Mueller PR, Wittenberg J, Simeone JF: Percutaneous drainage of abscesses and fluid collections: Technique, results, and applications. Radiology 1982, 142:1–10.PubMed 8.

Figure 3 In vivo activity of Bac7(1-35). Survival curves (A) and viable bacterial counts in liver and spleen homogenates (B) of mice infected with S. enterica after treatment via i.p. with Bac7(1-35) are shown. CBA/Ca mice were infected via i.p. with S. enterica ATCC 14028

(102 CFU/mouse) and Bac7(1-35) at 30 mg/kg was immediately injected via i.p. after bacterial challenge (dotted line). Control mice were given 0.2 ml of PBS (continuous line). Mice were monitored for survival over a 60-day period after infection. *p < 0.05 treated vs untreated mice. Three days after bacterial infection, untreated (squares) and peptide-treated (triangles) mice were killed, and liver (full symbols) and spleen (empty symbols) homogenates were prepared as described in section Methods. Results

are expressed as number see more of CFU/g organ; bars represent the mean value for each group. In parallel to survival experiments, a group of mice was also analyzed for bacterial load at 3 days post-inoculation, when the infected animals did not show any visible sign of disease. Viable bacterial cells were counted in murine liver and spleen of infected mice and results are reported in Figure 3B. The number of viable bacterial cells in liver and spleen homogenates decreased significantly in the animals treated with the peptide at 30 mg/kg, despite a remarkable variability in each group. In 1/3 of the animals bacteria were undetectable in both the spleen and liver. This ABT-737 in vitro result www.selleckchem.com/products/4egi-1.html is in keeping Glycogen branching enzyme with the percentage of mice cured extrapolated by the survival curve (Figure 3A). Given that i.p. injection of as few as 100 salmonellae is lethal for mice, the increased survival times and the eradication of the infection in 1/3 of the peptide-treated animals is a promising result. In addition, the

protective role showed by Bac7(1-35) suggests that the peptide may exert its bactericidal action also in infected cells, since S. typhimurium is an intracellular pathogen and Bac7(1-35) is able to penetrate host cells [14, 15]. In vivo Time-Domain Optical Imaging Following the results with the mouse model of infection, we investigated the in vivo biodistribution of Bac7(1-35) by using a time-domain optical imaging instrument [24] and a derivative of Bac7(1-35), fluorescently labelled with the dye Alexa680, showing an antimicrobial activity comparable to that of the unlabelled peptide (data not shown). The Bac7(1-35)-Alexa680 peptide shows a fast elimination kinetics after i.p. injection, characterized by a specific fluorescence intensity signal in the kidney first and then in the bladder. The compound reaches the kidney and the bladder in respectively 1 and 3 hours after the injection. The in vivo and ex vivo analyses performed after 24 h confirm that the compound has been totally excreted (Figure 4).

These endosymbionts are dispersed throughout different arthropod classes, including a wide range of insect species [18]. Although their biological role needs to be largely elucidated, these ‘arthropod Rickettsia’ can act as reproductive parasites. In the ladybirds

Adalia bipunctata and Adalia decempunctata as well as in the buprestid beetle Brachys tessellatus the endosymbiont has been demonstrated to cause male embryonic lethality [19–21]. Further, parthenogenesis selleck chemicals induction is described in the parasitoid wasps Pnigalio soemius and Neochrysocharis formosa [22, 23]. Perotti et al. [24] also found evidence of an obligate Rickettsia in the booklouse Liposcelis bostrychophila with a key role for egg production. Pitavastatin supplier Endosymbiotic bacteria have been described in harmful as well as beneficial arthropods. The presence and role of endosymbionts are well studied in certain groups of beneficial arthropods, including hymenopteran parasitoids and coccinellid predators [25]. However, relatively few studies Ruboxistaurin have focused on the endosymbiotic bacteria of predatory Heteroptera (true bugs), despite their economic importance as biological control agents of agricultural pests [26]. In the

present study, the microbial community of Macrolophus spp. is examined. Macrolophus is a genus of polyphagous mirid predators commonly used in European greenhouses for the biological control of whiteflies, spider mites, thrips, aphids, and leaf miners [27, 28]. The two major species that have been used in commercial biological control are M. caliginosus and M. pygmaeus. It has been established that M. pygmaeus carries Wolbachia, which induces strong CI in its host and may thus have a substantial impact on the practical use of the predator in programmes of biological pest control [29]. However, other endosymbiotic bacteria have not been demonstrated to

infect Macrolophus spp. The microbial population of M. pygmaeus and M. caliginosus was examined by 16S rRNA gene sequencing and denaturing gradient gel electrophoresis (PCR-DGGE). The latter technique has been used to characterize complex bacterial compositions of environmental Alanine-glyoxylate transaminase samples [30, 31], but also proved useful to explore bacterial communities in arthropods [32–34]. Furthermore, a fluorescence in situ hybridization (FISH) analysis was performed to visualize the co-localization of different endosymbionts. Improving our understanding of the composition and functions of the endosymbiotic community of these predatory insects may contribute to optimizing their use as natural enemies of agricultural pests. Methods Insect populations Adults of different Macrolophus populations were collected from sites in Greece, Spain and Italy (Table 1) and preserved in 70% ethanol. A laboratory strain of M. pygmaeus originating from Koppert B.V.

A recent investigation found that condensed tannins could exhibit a reduction in MK5108 price methane production in an in vitro gas production test [21]. Further investigation into the diversity of 16S rRNA gene library of rumen methanogen in the condensed tannin

treatment library revealed 21.9% higher diversity of sequences related to the TALC methanogens and a lower diversity of those associated with orders Methanobacteriales (15.1%) and Methanomicrobiales (6.8%) [22]. This shows a possible association between reduction in methane production and diversity of rumen methanogen. In the current study, yak has present higher methanogen diversity and significant different methanogen community structures compared with cattle (Figure 1). While there are many factors which may explain these differences in methanogen diversity, it is possible that these differences between the methanogen OSI-027 diversity in yak and cattle could be related to the significant difference in enteric methane production by both these ruminant species. Long [23] reported a significantly high level of propionic acid, which leads to efficient energy utilization and this further suggested a low methane production

in yak. Yak has also been found Apoptosis inhibitor to exhibit lower methane output [9]. In the present study, yak had higher levels of acetate, proprionate, isobutyric, isovaleric and total volatile fatty acids than cattle, but cattle had higher acetate to proprionate (A/P) ratios (Table 2). This may also suggest different methanogenesis pathways. Therefore, the diversity and community structure of methanogens

in yak, which is the lower methane producing ruminant species in current study, correlates with data reported by Tan et al [22]. Table 2 The concentrations of volatile fatty acids from yak and cattle Protein kinase N1 rumen samples Volatile fatty acids Yak (mmol/L) Cattle (mmol/L) Standard error Significance Acetate 58.56 42.57 3.18 p < 0.004 Propionate 12.13 7.35 0.93 p < 0.001 Isobutyric 0.88 0.60 0.06 p < 0.016 Butyrate 9.03 7.25 0.49 p < 0.09 Isovaleric 1.02 0.51 0.12 p < 0.027 Valeric 0.07 0.13 0.06 p < 0.728 Total volatile fatty acids 81.69 58.41 4.61 p < 0.001 A/P (Acetate to Propionate) 4.83 5.80 0.19 p < 0.004 * Concentrations of volatile fatty acids was analysed by gas chromatograph equipped with a DB-FFAP column (30 m × 0.25 μm × 0.25 μm; Agilent Technologies). Wright et al [24] revealed 65 sequences of methanogens by phylogenetic analysis from the Australian sheep rumen, and 62 of them belonged to the genus Methanobrevibacter. They were grouped with Methanobrevibacter NT7, Methanobrevibacter SM9, Methanobrevibacter M6, Methanobrevibacter ruminantium, Methanobrevibacter acididurans and Methanobrevibacter thaueri.

aureus (end concentration OD600 = 6). The gel was washed twice for 15 min in dH2O and incubated for 18 h at 37°C in 0.1 M Na-phosphate buffer pH 6.8. Afterwards the gel was incubated for 3 min in staining solution (0.4% methylene blue, 0.01% KOH, 22% EtOH) and destained in cold water for several hours. Murein hydrolase activities

produced clear bands. Coagulase test Overnight cultures were pelleted at full speed, 0.5 ml supernatant was transferred into fresh tubes and 2 mM PMSF was added. The supernatants were normalized to an OD600 of 1 of the original culture with PBS. 0.1 ml supernatant was added to 0.25 ml reconstituted rabbit plasma (BBL Coagulase Plasmas, BD) and incubated at 37°C. Every 30 min tubes were examined for coagulation. #this website randurls[1|1|,|CHEM1|]# Qualitative hemolysis assay Cells were grown overnight in Todd-Hewitt (TH) medium [58], which was originally developed for the production

of streptococcal hemolysins [59]. To visualize hemolysis production of sessile bacteria, overnight cultures were normalized to an OD600 = 1 in PBS pH 7.4. Fifty μl was dispensed into 5 mm wide holes punched into 5% sheep blood agar. Plates were incubated overnight at 37°C and then stored at 4°C. To determine hemolysis in liquid media, the overnight cultures grown in TH medium were normalized SB273005 ic50 to the same OD600 with PBS and pelleted for 10 min at 5’900 g. The supernatant was filtered (pore size 0.22 μm, TPP) and 140 μl added to the holes in sheep blood agar. Plates Urease were incubated as above. Quantitative hemolytic activity Cells were grown for 24 h in TH medium and

normalized with PBS pH 7.4 to the same OD600. After pelleting the cells, the filtered supernatants (pore size 0.22 μm, TPP) were diluted up to 1:50’000 in TH medium. Sterile sheep blood was treated with 26 mM sodium citrate and 15 mM NaCl and diluted 1:100 in PBS pH 7.4. After washing the erythrocytes four times in PBS pH 7.4, they were resuspended to a dilution of 1:100 in PBS pH 7.4. Five hundred μl of washed erythrocytes were added to 500 μl of the diluted supernatants and incubated for 30 min at 37°C, followed by 30 min at 4°C. Finally the samples were centrifuged for 1 min at 7’000 g and the absorption of hemoglobin in the supernatant was measured at 415 nm [58]. Determination of protease activity on skim milk agar plates Skim milk agar plates were prepared as follows: Skim milk (Difco) and Bacto agar (Difco) were dissolved separately in 250 ml dH2O, each with an end concentration of 75 g/l and 15 g/l, respectively. After autoclaving for 15 min at 110°C and cooling down to 50°C, the skim milk and Bacto agar solutions were mixed together. Overnight cultures grown in LB broth were normalized to an OD600 = 1 with 0.85% NaCl and 50 μl was added into punched holes in skim milk agar.

The alignments were done using MUSCLE [46]. Acknowledgements The work was financed by Colciencias (project No. 657045921709). We would like to thank J.M. Anzola, D. Riaño, J. Rodríguez and D. Chaves for discussions and help with the bioinformatics analysis. Electronic supplementary material Additional file 1: Title:

Inventory of GGDEF proteins in K. pneumoniae 342, MGH 78578 and NTUH-K2044. (PDF 235 KB) Additional find more file 2: Title: Inventory of EAL proteins in K. pneumoniae 342, MGH 78578 and NTUH-K2044. (PDF 202 KB) References 1. Hoyos-Orrego SR-RO, Hoyos-Posada C, Mesa-Restrepo C, Alfaro-Velásquez M: Características clínicas, epidemiológicas y de susceptibilidad a los antibióticos en casos de bacteriemia por Klebsiella pneumoniae en neonatos. PP2 Rev CES Med 2007,21(2):31–39. 2. Struve C, Krogfelt KA: Pathogenic potential of environmental Klebsiella pneumoniae isolates. Environ Microbiol 2004,6(6):584–590.PubMedCrossRef 3. Podschun R, Ullmann U: Klebsiella spp. as nosocomial pathogens: epidemiology, taxonomy, typing methods, and pathogenicity factors. Clin Microbiol Rev 1998,11(4):589–603.PubMed 4. Yu VL, Hansen DS, Ko WC, Sagnimeni A, Klugman KP, von Gottberg A, Goossens H, Wagener MM, Benedi VJ: Virulence characteristics of Klebsiella and clinical manifestations of K.

pneumoniae bloodstream infections. Emerg Infect Dis 2007,13(7):986–993.PubMedCrossRef 5. Marschall J, Fraser VJ, Doherty J, Warren DK: Between community and hospital: healthcare-associated gram-negative bacteremia among hospitalized patients. Infect Control Hosp Epidemiol 2009,30(11):1050–1056.PubMedCrossRef 6. Fouts DE, Tyler HL, DeBoy RT, Daugherty S, Ren Q, Badger JH, Durkin AS, Huot H, Shrivastava S, Kothari S, et al.: Complete genome sequence of the N2-fixing broad host range endophyte Klebsiella pneumoniae 342 Org 27569 and virulence predictions verified in mice. PLoS Genet 2008,4(7):e1000141.PubMedCrossRef 7. Balestrino D, Ghigo JM, Charbonnel N, Haagensen JA, Forestier C: The characterization of functions involved in the establishment and maturation of Klebsiella pneumoniae in vitro biofilm reveals dual roles for surface exopolysaccharides. Environ Microbiol 2008,10(3):685–701.PubMedCrossRef

8. Boddicker JD, Anderson RA, Jagnow J, Clegg S: Signature-tagged mutagenesis of Klebsiella pneumoniae to identify genes that influence biofilm MK 8931 formation on extracellular matrix material. Infect Immun 2006,74(8):4590–4597.PubMedCrossRef 9. Balestrino D, Haagensen JA, Rich C, Forestier C: Characterization of type 2 quorum sensing in Klebsiella pneumoniae and relationship with biofilm formation. J Bacteriol 2005,187(8):2870–2880.PubMedCrossRef 10. Di Martino P, Cafferini N, Joly B, Darfeuille-Michaud A: Klebsiella pneumoniae type 3 pili facilitate adherence and biofilm formation on abiotic surfaces. Res Microbiol 2003,154(1):9–16.PubMedCrossRef 11. Johnson JG, Clegg S: Role of MrkJ, a phosphodiesterase, in type 3 fimbrial expression and biofilm formation in Klebsiella pneumoniae.

In this study, we utilized a shotgun metagenomic approach to examine the multiple effects of NO3- addition on vernal pool microbial communities in a microcosm experiment [17]. Two metagenomes were created, one for replicate microcosms that

received NO3- (labeled +NO3-) and one for replicate microcosms where NO3- was not added (labeled –N). Our previous study using these microcosms found that the addition of NO3- increased denitrification, while denitrification MRT67307 molecular weight was not detected in the absence of NO3- [17]. This functional change was not accompanied by any change in the denitrifier community structure, which was profiled with the nosZ gene using terminal restriction fragment length polymorphism (TRFLP) [17]. It is unclear, however, if this lack of response by the denitrifying community was physiological in nature or related to our functional gene choice. For the

shotgun metagenomic method utilized here, the microbial genomes were randomly amplified, thus allowing for the potential inclusion of multiple N cycling genes, as well as genes involved in other microbial processes. In addition to denitrifier community structure, our previous analyses used TRFLP to profile the structure of general bacteria and fungi, which also did not respond to NO3- addition [17]. Because shotgun metagenomes also provide taxonomic Selleckchem SB-715992 information for microbial selleckchem communities, we hypothesized that inclusion of more than one functional gene and obtaining taxonomic composition using a shotgun metagenomic approach would reveal community structural responses to NO3- pulses not observed with the profiling technique, TRFLP. Results For the +NO3- metagenome, there were 28,688 DNA fragments for a total of 9,085,193 bp and an average sequence length of 316 bp. The PAK5 –N metagenome contained

a larger number of DNA fragments with 81,300 and a total sequence length of 30,630,623 bp with an average fragment size of 376 bp. The metagenomes were uploaded to the Meta Genome Rapid Annotation of Sequence Technology (MG-RAST) server [18] and were analyzed unassembled with a BLASTX comparison to the SEED subsystems [19], which provided both taxonomic composition and metabolic functions. After applying our filters of 10-5 or lower e-value and 50 bp or greater sequence similarity, 7,406 sequences (+NO3-) and 14,063 sequences (−N) from the metagenomes matched with subsystems following the BLASTX analysis. The number of sequence matches to taxa with the BLASTX comparison were 6,342 (+NO3-) and 12,241 (−N). Each of these characterized DNA fragments represented an environmental gene tag (EGT), or a short segment of a gene found in the microcosm samples. The MG-RAST output included metabolic functions at four different levels, with subsystem category as the highest level and a specific gene as the lowest (see Table 1 for an example).

avium or 2D6 mutant were fixed and permeabilized at 4 h after infection. Antibody against SP-D protein was used and a second antibody labeled with Texas red was used. find more The arrows point to the green bacteria and red protein. Figure 4 Quantification of the SP = D protein expression assay in 100 U937 cells. The numbers represent the mean ± SD of three experiments. To investigate check details whether the complemented

M. avium 2D6 mutant phagosomes showed similar protein expression as that of wild-type, we infected the cells with 2D6 complemented bacteria [11] for 4 h, with MAC 109 as a positive control. The vacuoles containing the complemented M. avium 2D6 mutant showed expression of SP-D protein (Fig. 5A-5C) similarly to vacuoles containing the wild-type bacterium (Fig. 5D and 5E), though the percentage of infected cells showing the protein expression was 15% less than in macrophages infected with the wild-type I-BET151 chemical structure bacterium. Quantification of expression is shown in Fig. 4. Figure 5 Fluorescent microscopy images of U937 macrophages infected with fluorescein-labeled complemented M. avium 2D6 mutant. The SP-D protein is shown in red. Arrows point to bacteria (green) and SP-D protein (red). SP-D is present in macrophages infected with the MAC 104 strain and absent in the 2D6 mutant-infected macrophages. T-type

Ca++ channel is an integral membrane protein, which controls the rapid entry of Ca++ into excitable cells, and is activated by CaM-Kinase II (Swiss-Prot database). To verify our initial observation by MS/MS, we carried out parallel infection assays with fluorescein-labeled 2D6 and MAC 109 bacteria for 24 h. As shown in Fig. 6A and 6B, the majority of the cells infected with 2D6 mutant showed T-type Ca++ channel protein staining; whereas,

those infected with the wild-type MAC 109 and uninfected control U937 cells failed to express the protein (Fig. 6C and 6D, Fig. 6E and 6F, respectively). The observation was in agreement with the proteomic data showing that T-type Ca++ channel is expressed in mononuclear phagocytes infected with 2D6 attenuated mutant, but not when infected with MAC 109. Figure 6 Fluorescent microscopy Cediranib (AZD2171) images of U937 macrophages infected with fluorescein-labeled M. avium MAC 109 strain or 2D6 mutant. Macrophages were fixed and permeabilized 24 h after infection. Antibody anti-T-type Ca++ channel protein was used for 1 h, washed, and second antibody labeled with Texas red was applied for an additional hour. The arrows point to the green bacteria and red protein (A-F). To determine whether the phagosomes of macrophages infected with the complemented M. avium 2D6 mutant phagosomes failed to express the T-type Ca++ channel, mononuclear cells infected with complemented M. avium 2D6 bacteria and 2D6-attenuated mutant were evaluated. As shown in Fig. 7A and 7B, vacuoles with the complemented bacteria, in contrast to the 2D6 mutant (Fig. 7C and 7D), did not express T-type Ca++ channel protein.

The extracted ΦB values of these samples are presented in the Figure 4. The highest ΦB value see more attained by the CRT0066101 manufacturer sample annealed in O2 ambient (3.72 eV) was higher than that of metal-organic decomposed CeO2 (1.13 eV) spin-coated on n-type GaN substrate [20]. No ΦB value has been extracted for the sample annealed in N2 ambient due to the low E B and high J of this sample, wherein the gate oxide breaks down prior to the FN tunneling mechanism. Figure 7 Experimental data fitted well with

FN tunneling model. Experimental data (symbol) of samples annealed in O2, Ar (HJQ and KYC, unpublished work), and FG ambient fitted well with FN tunneling model (line). Table 1 compares the computed ΔE c values from the XPS characterization with the ΦB value extracted from the FN tunneling model. From this table, it is distinguished that the E B of the sample annealed in O2 ambient is dominated by the breakdown of IL as Z-DEVD-FMK molecular weight the obtained

value of ΦB from the FN tunneling model is comparable with the value of ΔE c(IL/GaN) computed from the XPS measurement. For samples annealed in Ar and FG ambient, the acquisition of ΦB value that is comparable to the ΔE c(Y2O3/GaN) indicates that the E B of these samples is actually dominated by the breakdown of bulk Y2O3. Since the leakage current of the sample annealed in N2 ambient is not governed by FN tunneling mechanism, a conclusion in determining whether the

E B of this sample is dominated by the breakdown of IL, Y2O3, or a combination of both cannot be deduced. Based on the obtained values of ΔE c(Y2O3/GaN), ΔE c(IL/GaN), and ΔE c(Y2O3/IL), the E B of this sample is unlikely to be dominated by IL due to the acquisition of a negative ΔE c(IL/GaN) value for this sample. Thus, the E B of this sample is most plausible to be dominated by either Y2O3 or a combination of Y2O3 and IL. However, the attainment of ΔE c(Y2O3/IL) value which is larger than that of ΔE c(Y2O3/GaN) value obtained for the samples annealed in Ar and FG ambient eliminates the latter possibility. The reason behind Oxymatrine it is if the E B of the sample annealed in N2 ambient is dominated by the combination of Y2O3 and IL, this sample should be able to sustain a higher E B and a lower J than the samples annealed in Ar and FG ambient. Therefore, the E B of the sample annealed in N2 ambient is most likely dominated by the breakdown of bulk Y2O3. Table 1 Comparison of the obtained Δ E c and Φ B values   XPS: conduction band offset     J-E   Y 2 O 3 /GaN IL/GaN Y 2 O 3 /IL Barrier height O2 3.00 3.77 0.77 3.72 Ar 1.55 1.40 0.15 1.58 FG 0.99 0.68 0.31 0.92 N2 0.70 −2.03 2.73 a aNot influenced by FN tunneling. Therefore, barrier height is not extracted from the FN tunneling model.