Mini droplets to super droplets: evolution of self-assembled Au droplets on GaAs(111)B and (110)

2014 ◽  
Vol 47 (2) ◽  
pp. 505-510 ◽  
Author(s):  
Mao Sui ◽  
Ming-Yu Li ◽  
Eun-Soo Kim ◽  
Jihoon Lee
Keyword(s):  
Growth Parameters ◽  
Average Diameter ◽  
Growth Conditions ◽  
Average Density ◽  
Minor Effect ◽  
Average Height ◽  
Deposition Amount ◽  
Self Assembled ◽  
A Minor ◽  
20 Nm

In this article, the effect of deposition amount on self-assembled Au droplets fabricated on GaAs(111)B and (110) is presented. The investigation is systematically performed by the variation of the Au deposition amount from 2 to 20 nm while fixing the other growth parameters such as annealing temperature and duration to clearly observe the effect. Under identical growth conditions, the self-assembled Au droplets show significantly different size and density depending on the amount of Au deposition:i.e.the average height varies by 436% from 21.8 to 95.5 nm and the average diameter swings by 827% from 52 to 430 nm, showing that the size increase is dominated by the lateral expansion. Meanwhile the average density varies by over two orders of magnitude from 1.24 × 108to 4.48 × 1010 cm−2on GaAs(111)B. With relatively low Au deposition amounts, below 3 nm, round dome-shaped mini Au droplets with high packing density can be fabricated, while super large Au droplets result with higher deposition amounts, above 10 nm, with a density two orders of magnitude lower. It is also found that the surface index has a minor effect on the fabrication of self-assembled Au droplets with the variation of deposition amount. The results are systematically analyzed and discussed in terms of atomic force microscopy and scanning electron microscopy images, line profiles, power spectrums, r.m.s. surface roughness, and size and density plots.

Hydrothermal Growth of ZnO Hexagonal Nanocrystals: Effect of Growth Conditions

2012 ◽  
Vol 21 ◽  
pp. 57-63 ◽  
Author(s):  
Sujira Promnimit ◽  
S. Baruah ◽  
U. Lamdu ◽  
Joydeep Dutta
Keyword(s):  
Growth Parameters ◽  
Zno Nanorods ◽  
Average Diameter ◽  
Growth Conditions ◽  
Hydrothermal Route ◽  
Hydrolysis Time ◽  
Aspect Ratios ◽  
Zno Nanocrystals ◽  
Seeding Method ◽  
Wide Range

Hexagonal ZnO nanocrystals were synthesized through a hydrothermal route under mild conditions (growth temperature of 90°C at atmospheric pressure). Pre-synthesized ZnO nanoparticles were used to serve as nucleation sites for the growth of the nanocrystals. The growth of ZnO nanorods was found to be surface independent. The dimensions of the hexagonal ZnO nanocrystals were observed to be dependent on the concentration of the reactants used (sources of Zn2+ and OH-ions), pH of the growth bath and also on the duration of crystal growth. The average diameter and height of the ZnO nanocrystals was found to be directly proportional to the concentration of the reactants as well as hydrolysis time. The orientation of the nanocrystals was found to be dependent upon the seeding method employed. Hexagonal single crystals of a wide range of dimensions and aspect ratios could be successfully synthesized through a control of growth parameters.

Controlling Growth of InAs/GaAs Self-Assembled Quantum Dots to Give 1.3 μm Room Temperature Emission

1999 ◽  
Vol 571 ◽  
Author(s):  
Surama Malik ◽  
Philip Siverns ◽  
David Childs ◽  
Christine Roberts ◽  
Jean-Michel Hartmann ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excited States ◽  
Room Temperature ◽  
Growth Parameters ◽  
High Growth ◽  
Growth Conditions ◽  
Time Resolved ◽  
Confining Potential ◽  
Decay Times ◽  
Self Assembled

ABSTRACTWe have investigated the extent to which the emission wavelength of self-assembled InAs/GaAs quantum dots can be controlled by growth parameters using conventional solid source MBE. Changing from conventionally high growth rates to a very low growth rate (LGR) and a relatively high substrate temperature, tunes the photoluminescence (PL) emission from 1.1 μm to 1.3 μm at room temperature. Atomic force micrographs obtained from uncapped samples reveal that these LGRQDs are larger, lower in density and extremely uniform in size. The improved size uniformity is reflected in the reduction of the PL linewidth from 78 meV to 22 meV. Under conditions of high excitation, emission from the ground and two excited states each separated by ∼70 meV is observed. This implies a parabolic confining potential. Time resolved photoluminescence (TRPL) measurements of dots grown under the various growth conditions yield radiative lifetimes which reflect the depth of the confining potential. A comparison of the decay times measured for the excited states show that the relaxation of carriers within the dots cannot be ascribed to phonon effects.

EFFECT OF GRASS SPECIES AND ROW SPACING ON DANDELION ESTABLISHMENT AND GROWTH

1979 ◽  
Vol 59 (4) ◽  
pp. 1031-1036 ◽  
Author(s):  
A. L. DARWENT ◽  
C. R. ELLIOTT
Keyword(s):  
Average Density ◽  
Phleum Pratense ◽  
Grass Species ◽  
Row Spacing ◽  
Minor Effect ◽  
Meadow Fescue ◽  
Intermediate Wheatgrass ◽  
Red Fescue ◽  
A Minor ◽  
Phleum Pratense L

The size of dandelions (Taraxacum officinale Weber) growing in intermediate wheatgrass (Agropyron intermedium (Host.) Beauv.), crested wheatgrass (A. cristatum L.), a northern biotype of bromegrass (Bromus inermis Leyss.), a southern biotype of bromegrass, meadow fescue (Festuca elatior L.), creeping red fescue (F. rubra var. genuina L.) and timothy (Phleum pratense L.) was effectively reduced by decreasing the row spacing of each grass from 100 cm to 20 cm. Russian wild ryegrass (Elymus junceus Fisch.) had only a minor effect on dandelion size regardless of the row spacing at which it was planted. Within any given row spacing between 20 and 100 cm, dandelion density was not affected by grass species. However, as the row spacing decreased the average density of dandelions growing in the seven grass species also decreased.

Growth of InAs Quantum Dots on a Low Lattice-Mismatched AlGaSb Layer Prepared on GaAs (001) Substrates

2004 ◽  
Vol 99-100 ◽  
pp. 49-54 ◽  
Author(s):  
N. Yamamoto ◽  
K. Akahane ◽  
S. Gozu ◽  
Noboru Ohtani
Keyword(s):  
Quantum Dots ◽  
Communication Networks ◽  
Optical Communication ◽  
Growth Conditions ◽  
Average Density ◽  
Average Height ◽  
Growth Technique ◽  
Long Wavelength ◽  
Atomic Force ◽  
Structural Selectivity

Optical communication wavelength emissions from the quantum dots (QDs) structures prepared on (001)-oriented GaAs substrates are discussed. A new growth technique of low-stressed InAs QDs on the AlGaSb layer in a low lattice-mismatched (1.3%) InAs/AlGaSb system is presented. The average height and diameter of the 4-ML InAs QDs on AlGaSb are evaluated to 5.8 nm and 45.2 nm respectively with an average density of 2.18 x 1010 /cm2 using atomic force microscope (AFM) measurements. There is structural selectivity between the QDs layer and the flat hetero-interface under changing growth conditions in the InAs/AlGaSb system. Long-wavelength PL emissions around 1.3 µm and 1.55 µm can be achieved by embedding InAs QDs in AlGaSb layers. Therefore it is expected that low-stressed InAs QDs grown on a AlGaSb layer prepared on a GaAs substrate will be useful in the fabrication of novel QDs devices for optical-communication networks.

scholarly journals Combined and Distinct Roles of Agr Proteins in Clostridioides difficile 630 Sporulation, Motility, and Toxin Production

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. e03190-20
Author(s):  
Ummey Khalecha Bintha Ahmed ◽  
Tyler M. Shadid ◽  
Jason L. Larabee ◽  
Jimmy D. Ballard
Keyword(s):  
Toxin Production ◽  
Growth Conditions ◽  
Minor Effect ◽  
Accessory Gene ◽  
Related Factors ◽  
Content Type ◽  
Multiple Functions ◽  
Accessory Gene Regulator ◽  
Clostridioides Difficile ◽  
A Minor

ABSTRACTThe Clostridioides difficile accessory gene regulator 1 (agr1) locus consists of two genes, agrB1 and agrD1, that presumably constitute an autoinducing peptide (AIP) system. Typically, AIP systems function through the AgrB-mediated processing of AgrD to generate a processed form of the AIP that provides a concentration-dependent extracellular signal. Here, we show that the C. difficile 630 Agr1 system has multiple functions, not all of which depend on AgrB1. CRISPR-Cas9n deletion of agrB1, agrD1, or the entire locus resulted in changes in transcription of sporulation-related factors and an overall loss in spore formation. Sporulation was recovered in the mutants by providing supernatant from stationary-phase cultures of the parental strain. In contrast, C. difficile motility was reduced only when both AgrB1 and AgrD1 were disrupted. Finally, in the absence of AgrB1, the AgrD1 peptide accumulated within the cytoplasm and this correlated with increased expression of tcdR (15-fold), as well as tcdA (20-fold) and tcdB (5-fold), which encode the two major C. difficile toxins. The combined deletion of agrB1/agrD1 or deletion of only agrD1 did not significantly alter expression of tcdR or tcdB but did show a minor effect on tcdA expression. Overall, these data indicate that the Agr1-based system in C. difficile 630 carries out multiple functions, some of which are associated with prototypical AIP signaling and others of which involve previously undescribed mechanisms of action.IMPORTANCEC. difficile is a spore-forming, toxigenic, anaerobic bacterium that causes severe gastrointestinal illness. Understanding the ways in which C. difficile senses growth conditions to regulate toxin expression and sporulation is essential to advancing our understanding of this pathogen. The Agr1 system in C. difficile has been thought to function by generating an extracellular autoinducing peptide that accumulates and exogenously activates two-component signaling. The absence of the peptide or protease should, in theory, result in similar phenotypes. However, in contrast to longstanding assumptions about Agr, we found that mutants of individual agr1 genes exhibit distinct phenotypes in C. difficile. These findings suggest that the Agr1 system may have other regulatory mechanisms independent of the typical Agr quorum sensing system. These data not only challenge models for Agr’s mechanism of action in C. difficile but also may expand our conceptions of how this system works in other Gram-positive pathogens.

Improvement of monitoring of tertiary filtration with particle counting

2006 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
V. Miska ◽  
J.H.J.M. van der Graaf ◽  
J. de Koning
Keyword(s):  
Particle Surface ◽  
Minor Effect ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Mass Distributions ◽  
Particle Counting ◽  
Total Particle ◽  
Particle Counts ◽  
A Minor ◽  
Sample Dilution

Nowadays filtration processes are still monitored with conventional analyses like turbidity measurements and, in case of flocculation–filtration, with phosphorus analyses. Turbidity measurements have the disadvantage that breakthrough of small flocs cannot be displayed, because of the blindness regarding changes in the mass distributions. Additional particle volume distributions calculated from particle size distributions (PSDs) would provide a better assessment of filtration performance. Lab-scale experiments have been executed on a flocculation–filtration column fed with effluent from WWTP Beverwijk in The Netherlands. Besides particle counting at various sampling points, the effect of sample dilution on the accuracy of PSD measurements has been reflected. It was found that the dilution has a minor effect on PSD of low turbidity samples such as process filtrate. The correlation between total particle counts, total particle volume (TPV) and total particle surface is not high but is at least better for diluted measurements of particles in the range 2–10 μm. Furthermore, possible relations between floc-bound phosphorus and TPV removal had been investigated. A good correlation coefficient is found for TPV removal versus floc-bound phosphorus removal for the experiments with polyaluminiumchloride and the experiments with single denitrifying and blank filtration.

scholarly journals Electrochromic Performance and Capacitor Performance of α-MoO3 Nanorods Fabricated by a One-Step Procedure

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 783
Author(s):  
Ying Duan ◽  
Chen Wang ◽  
Jian Hao ◽  
Yang Jiao ◽  
Yanchao Xu ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Average Diameter ◽  
Fast Response ◽  
Cycle Stability ◽  
Electrochromic Devices ◽  
Step Procedure ◽  
One Step ◽  
Supercapacitor Performance ◽  
First Time ◽  
Prepared Nanorods

In this paper, we propose for the first time the synthesis of α-MoO3 nanorods in a one-step procedure at mild temperatures. By changing the growth parameters, the microstructure and controllable morphology of the resulting products can be customized. The average diameter of the as-prepared nanorods is about 200 nm. The electrochromic and capacitance properties of the synthesized products were studied. The results show that the electrochromic properties of α-MoO3 nanorods at 550 nm have 67% high transmission contrast, good cycle stability and fast response time. The MoO3 nanorods also exhibit a stable supercapacitor performance with 98.5% capacitance retention after 10,000 cycles. Although current density varies sequentially, the nanostructure always exhibits a stable capacitor to maintain 100%. These results indicate the as-prepared MoO3 nanorods may be good candidates for applications in electrochromic devices and supercapacitors.

scholarly journals Linkage mapping identifies a non-synonymous mutation in FLOWERING LOCUS T (FT-B1) increasing spikelet number per spike

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonathan Brassac ◽  
Quddoos H. Muqaddasi ◽  
Jörg Plieske ◽  
Martin W. Ganal ◽  
Marion S. Röder
Keyword(s):  
Flowering Time ◽  
Aspartic Acid ◽  
Synonymous Substitution ◽  
Minor Effect ◽  
Phenotypic Variance ◽  
Spikelet Number ◽  
Wheat Varieties ◽  
Trait Locus ◽  
A Minor ◽  
Spikelet Number Per Spike

AbstractTotal spikelet number per spike (TSN) is a major component of spike architecture in wheat (Triticumaestivum L.). A major and consistent quantitative trait locus (QTL) was discovered for TSN in a doubled haploid spring wheat population grown in the field over 4 years. The QTL on chromosome 7B explained up to 20.5% of phenotypic variance. In its physical interval (7B: 6.37–21.67 Mb), the gene FLOWERINGLOCUST (FT-B1) emerged as candidate for the observed effect. In one of the parental lines, FT-B1 carried a non-synonymous substitution on position 19 of the coding sequence. This mutation modifying an aspartic acid (D) into a histidine (H) occurred in a highly conserved position. The mutation was observed with a frequency of ca. 68% in a set of 135 hexaploid wheat varieties and landraces, while it was not found in other plant species. FT-B1 only showed a minor effect on heading and flowering time (FT) which were dominated by a major QTL on chromosome 5A caused by segregation of the vernalization gene VRN-A1. Individuals carrying the FT-B1 allele with amino acid histidine had, on average, a higher number of spikelets (15.1) than individuals with the aspartic acid allele (14.3) independent of their VRN-A1 allele. We show that the effect of TSN is not mainly related to flowering time; however, the duration of pre-anthesis phases may play a major role.

scholarly journals IL-6 Is Not Absolutely Essential for the Development of a TH17 Immune Response after an Aerosol Infection with Mycobacterium tuberculosis H37rv

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 9
Author(s):  
Kristina Ritter ◽  
Jan Christian Sodenkamp ◽  
Alexandra Hölscher ◽  
Jochen Behrends ◽  
Christoph Hölscher
Keyword(s):  
Immune Response ◽  
Inflammatory Diseases ◽  
Mycobacterial Infection ◽  
Minor Effect ◽  
Mycobacterium Tuberculosis H37rv ◽  
Th 17 ◽  
Anti Inflammatory ◽  
A Minor ◽  
Aerosol Infection ◽  
Deficient Mice

Anti-inflammatory treatment of chronic inflammatory diseases often increases susceptibility to infectious diseases such as tuberculosis (TB). Since numerous chronic inflammatory and autoimmune diseases are mediated by interleukin (IL)-6-induced T helper (TH) 17 cells, a TH17-directed anti-inflammatory therapy may be preferable to an IL-12-dependent TH1 inhibition in order to avoid reactivation of latent infections. To assess, however, the risk of inhibition of IL-6-dependent TH17-mediated inflammation, we examined the TH17 immune response and the course of experimental TB in IL-6- and T-cell-specific gp130-deficient mice. Our study revealed that the absence of IL-6 or gp130 on T cells has only a minor effect on the development of antigen-specific TH1 and TH17 cells. Importantly, these gene-deficient mice were as capable as wild type mice to control mycobacterial infection. Together, in contrast to its key function for TH17 development in other inflammatory diseases, IL-6 plays an inferior role for the generation of TH17 immune responses during experimental TB.

scholarly journals Sweet taste of heavy water

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Natalie Ben Abu ◽  
Philip E. Mason ◽  
Hadar Klein ◽  
Nitzan Dubovski ◽  
Yaron Ben Shoshan-Galeczki ◽  
...  
Keyword(s):  
Heavy Water ◽  
Calcium Release ◽  
Homology Modelling ◽  
Taste Receptor ◽  
Chemical Properties ◽  
Sweet Taste ◽  
Minor Effect ◽  
Dynamics Simulations ◽  
A Minor ◽  
Physical And Chemical

AbstractHydrogen to deuterium isotopic substitution has only a minor effect on physical and chemical properties of water and, as such, is not supposed to influence its neutral taste. Here we conclusively demonstrate that humans are, nevertheless, able to distinguish D2O from H2O by taste. Indeed, highly purified heavy water has a distinctly sweeter taste than same-purity normal water and can add to perceived sweetness of sweeteners. In contrast, mice do not prefer D2O over H2O, indicating that they are not likely to perceive heavy water as sweet. HEK 293T cells transfected with the TAS1R2/TAS1R3 heterodimer and chimeric G-proteins are activated by D2O but not by H2O. Lactisole, which is a known sweetness inhibitor acting via the TAS1R3 monomer of the TAS1R2/TAS1R3, suppresses the sweetness of D2O in human sensory tests, as well as the calcium release elicited by D2O in sweet taste receptor-expressing cells. The present multifaceted experimental study, complemented by homology modelling and molecular dynamics simulations, resolves a long-standing controversy about the taste of heavy water, shows that its sweet taste is mediated by the human TAS1R2/TAS1R3 taste receptor, and opens way to future studies of the detailed mechanism of action.

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