Search

1:CAS:528:DyaE1MXkvVWju70%3D. 10.1088/0022-3719/12/5/017 3 Habenicht C, Knupfer M, Büchner B. Investigation of the dispersion and the effective masses of excitons in bulk MoS2 using transition electron energy-loss spectroscopy. 4 of the main manuscript are caused by electron-electron interactions, but do not cause electron correlations, which can be seen in the large spectral weight transfer in Fig. Even at room temperature, the effective mass of electrons in crystals is not always equal to the single electron mass, I m i SB 0 sb [11], including in TMDCs[14]. We hope we have settled or answered most, if not all, of the issues presented in the Matters Arising and our result opens discussions on roles of electronic correlation on effective mass of electron, electronic and optical structures in strongly correlated electron systems. [Extracted from the article]

Electronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c-axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p–d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional-like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography. Electronic and interlayer correlations are expected to affect the electronic and optical properties of transition metal dichalcogenides. Here, by using spectroscopic ellipsometry in the broad energy range, the authors uncover new electronic transitions and correlated plasmons in bulk MoS2. [ABSTRACT FROM AUTHOR]

Aegilops cylindrica Host. is a salt-tolerant wild relative of wheat. The expression of AecDREB2 and AecP5CS genes involved in salinity tolerance was investigated. Salt stress caused significant upregulation of AecDREB2 expression while it did not affect the transcripts of AecP5CS. Despite no significant difference in the AecDREB2 expression in the root and shoot tissues, the AecP5CS transcription profiles of the shoots was much higher than the roots supporting our data of proline accumulation in these tissues. In addition, the homology between AecP5CS and TaP5CS as well as between AecDREB2 and AetDREB2 may suggest the location of our studied genes in the D genome of Ae. cylindrica and a clear orthologous relationship. It is concluded that proline did not play an explicit role in the adaptation response of Ae. cylindrica to a high level of salt stress, while DREB2 plays a pivotal role in the regulatory network of salt tolerance in this species. [ABSTRACT FROM AUTHOR]

The vast genetic resources of wild barley (Hordeum vulgare ssp. spontaneum, hereafter WB) may hold unique assets for improving barley (H. vulgare ssp. vulgare) cultivars for drought stress. To evaluate genetic potential and characterization of variation among a diverse collection of barley and WB genotypes, mostly originated from Iran, a field experiment was performed under three moisture environments (control, mild and intense drought stress) during two years (2012-2014). Considerable variation was observed among the wild and cultivated genotypes for drought tolerance and agronomic traits. Principal component analysis (PCA) grouped genotypes studied into three groups (WB, two-row barley and sixrow barley groups). However, Iranian and foreign WB genotypes were not completely separated, showing a high variation within both gene pools. The high significance of genotype by environment interaction, confirms importance of using accurate target environments for drought stress breeding. A number of WB genotypes with the highest values of the number of tillers, number of seed per spike, seed weight, grain yield and yield stability index under stressed environments were identified as superior genotypes. Most of these genotypes originate from Iran, highlighting the importance of this germplasm in barley breeding. [ABSTRACT FROM AUTHOR]

Development of drought-tolerant cultivars is hampered by a lack of effective selection criteria. In this research, response of 36 genotypes of rapeseed from seven species of Brassica including B. napus, B. rapa, B. juncea, B. carinata, B. oleracea, B. nigra and B. fruticulosa was assessed under three moisture levels (no stress, mild stress and intense stress) in the field during 2011-2012. Five drought-tolerance indices were calculated: stress tolerance (TOL), stress susceptibility index (SSI), mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI). Increasing water stress levels caused significantly more reductions in the seed yield of all species. Species B. napus had the highest yields in normal and intense stress conditions while B. carinata showed better performance in mild stress condition. Correlation coefficients revealed that among drought tolerance indices, GMP, STI and MP are superior criteria for selecting high-yield genotypes under stress and non-stress conditions. B. napus and B. carinata were the most drought tolerant while B. rapa and B. oleracea were the most susceptible species of Brassica based on yield potential. Application of principle component analysis (PCA) for distinguishing drought and susceptible species are discussed. [ABSTRACT FROM AUTHOR]

Tall fescue and meadow fescue are naturally infected with fungal endophytes, Neotyphodium coenophialum and Neotyphodium uncinatum, respectively. Seed traits are an important measure of the effects of the endophytic fungi which has been less addressed. In this study we used endophyte-infected (EI) and endophyte-free (EF) clones of tall and meadow fescue genotypes in the field to investigate the effects of endophytes on seed production traits and subsequently on seed germination and seedling emergence. Endophyte infection increased the plant seed weight, the number of seeds per plant and the number of panicles per plant in both plant species. Seed germination was not affected by endophytes in tall fescue, while it was improved in endophyteinfected plants of meadow fescue. A negative endophyte effect was detectable for seedling emergence percentage and emergence rate of tall fescue, whereas EI plants of meadow fescue were positively affected by the endophyte for these characteristics. The better performance of EI plants for seed production traits may increase their relative fitness in populations and cause them to be more stable in different environmental conditions. [ABSTRACT FROM AUTHOR]

Bacterial infection is considered a predisposing factor for disorders of the biliary tract. This study aimed to determine the diversity of bacterial communities in bile samples and their involvement in the occurrence of biliary tract diseases. A total of 102 bile samples were collected during endoscopic retrograde cholangiopancreatography (ERCP). Characterization of bacteria was done using culture and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) methods. Antimicrobial susceptibility of the isolates was determined based on the Clinical and Laboratory Standards Institute (CLSI) guidelines and identity of the nucleotide sequences of differentiated bands from the DGGE gels was determined based on GenBank data. In total, 41.2 % (42/102) of the patients showed bacterial infection in their bile samples. This infection was detected in 21 % (4/19), 45.4 % (5/11), 53.5 % (15/28), and 54.5 % (24/44) of patients with common bile duct stone, microlithiasis, malignancy, and gallbladder stone, respectively. Escherichia coli showed a significant association with gallstones. Polymicrobial infection was detected in 48 % of the patients. While results of the culture method established coexistence of biofilm-forming bacteria ( Pseudomonas aeruginosa, E. coli, Klebsiella pneumoniae, Enterococcus spp., and Acinetobacter spp.) in different combinations, the presence of Capnocytophaga spp., Lactococcus spp., Bacillus spp., Staphylococcus haemolyticus, Enterobacter or Citrobacter spp., Morganella spp., Salmonella spp., and Helicobacter pylori was also characterized in these samples by the PCR-DGGE method. Multidrug resistance phenotypes (87.5 %) and resistance to third- and fourth-generation cephalosporins and quinolones were common in these strains, which could evolve through their selection by bile components. Ability for biofilm formation seems to be a need for polymicrobial infection in this organ. [ABSTRACT FROM AUTHOR]

Wastewater from municipal and industrial sources is becoming increasingly important in being reused, for example, for irrigation purposes. Wastewater is commonly stored in treatment lagoons in which evaporation is the main cause of water loss. Nonetheless, modeling wastewater evaporation ( WWE) has received little attention. Driven by this knowledge gap, this study was performed to explore extent to which impurities affect water evaporation. A dimensional analysis was used to formulate WWE as a function of clear water evaporation ( CWE), wastewater properties and climatic variables. We based our modeling approach on experimental data collected from the Neishaboor municipal wastewater treatment plant, Iran. As a result of this analysis, a multiplicative model to formulate WWE as a function of the influencing variables is proposed which indicated a reasonably well accuracy ( RMSE = 1.09 mm) for the WWE estimation. Clear water evaporation indicated to be the most correlated variable in the model such that a constant coefficient can also be used to estimate WWE from CWE at the cost of losing accuracy only by 4.6 %. [ABSTRACT FROM AUTHOR]

Physiological basis of genetic variability in drought response and its association with yield and related indices is not clear in Brassica. In this study 36 accessions belonged to seven species of Brassica were evaluated under normal, moderate and severe stress environments. Physiological traits along with seed yield, seed yield components, oil content and two selection indices (stress tolerance index, STI and drought susceptibility index, DSI) were studied. Moderate and intense stress caused reduction in seed yield and the most studied traits. Based on the STI, B. carinata and B. juncea were identified as the superior species in moderate stress condition while B. oleracea was the most tolerant under intense stress. Moderate drought stress significantly increased the ratio of chlorophyll a to chlorophyll b (Chla/Chlb) while severe stress decreased it. Although relative water content (RWC) had positive correlation with STI, its heritability was low. Chlorophyll content (TChl) was associated with STI and had moderate heritability. Positive correlation was found between proline content and DSI under both stress conditions. Results showed large variation is among studied species for drought tolerance and related traits indicating that selection in this germplasm would be useful. Changes in chlorophyll content can be recognized as a key component affecting drought tolerance in Brassica. [ABSTRACT FROM AUTHOR]

The Bowen ration energy balance (BREB) is considered as a standard method for estimating lake evaporation. The BREB method however requires numerous input data which may not be readily available especially in developing countries. This limitation could be solved by using methods with fewer data requirements. Evaporation from lakes and reservoirs in Iran is commonly estimated using pan evaporation because there have not been a consensus on which methods are most applicable under the limited data condition and arid climate. Therefore, the objective of this research was to determine the most appropriate evaporation methods over Doosti dam reservoir in Iran. Eighteen existing methods were tested and ranked based on the BREB method. The Jensen-Haise, Makkink, Penman and deBruin methods were among the most consistent methods with BREB in which the RMSD values were obtained 1.2, 1.34, 1.62 and 1.65 mm d, respectively. Finally, we concluded that methods which rely only on air temperature, or air temperature combined with sunshine data (e.g., Jensen-Haise and Makkink), were relatively cost-effective options for estimating evaporation at the study area due to their simplicity, least sensitivity and high accuracy. [ABSTRACT FROM AUTHOR]

Numerous equations exist for estimating reference evapotranspiration (ETo). Relationships were often subject to rigorous local calibration, hence having limited global validity. The Penman-Monteith (P − M) equation is widely perceived as the best equation for estimating daily and monthly ETo in all climates. The main shortcoming of the P − M equation is that it requires numerous weather data that may not always be available. This study evaluates the methods to estimate missing data in the context of their influence on the performance of the ETo equations. The performance of other ETo equations under missing data are also compared. ETo equations are ranked individually in semi − humid and semi − arid climates based on their accuracy. Results indicate that the P − M equation is more sensitive in semi − arid climate than semi − humid climate under missing data conditions. The accuracy of the P − M equation under these conditions increases remarkably if any available relationships between dew point and minimum temperatures and also long-term average wind speed for each station are exploited. Finally, the minimum data requirements necessary for adequate performance of the P − M equation are air temperature for semi − humid climates, air temperature and wind speed for semi − arid climates, and the availability of a relationship between dew point and minimum temperature, especially for semi − arid climate. In absence of the satisfaction of such minimum requirements, the Hargreaves-Samani equation is preferable for semi − humid climates and the Hargreaves equation modified by Droogers and Allen () for semi − arid climates. [ABSTRACT FROM AUTHOR]

Background and the purpose of the study: Different methods have been proposed to modify glassy carbon electrode in order to determine dopamine (DA), as one of the most important neurotransmitters in central nervous systems of mammalian. These methods are time comsuming and in some cases expensive. In this work, a very simple and cheap pretreatment method is developed for the bare glassy carbon electrode (GCE) to determine DA in the presence of Ascorbic acid (AA). Methods: Cyclic voltammetry as an electrochemical activation procedure was used for activation of glassy carbon electrode in order to separate diffrential pulse peaks of DA and AA. The effect of different parameters such as pH for supporting electrolyte, range of potential and the number of cycles were investigated. Finally, differential pulse voltammetry was used to determine DA in the presence of AA. Results: On the activated electrode under optimum condition, anodic peak of AA shifted to negative potentials and peak current decreased, but the peak current of DA increased. The peak current was linearly proportional to the bulk concentration of DA in the range of 6.5 x 10-7- 1.8x10-5 mol 1-1. The limit of detection was 6.2x10-7 mol 1-1. Conclusion: A simple and cheap method was developed for the activation of glassy carbon electrode. It was possible to determine DA in the presence of A A on the treated electrode. The proposed method was used to determine DA in pharmacutical samples. [ABSTRACT FROM AUTHOR]