The importance of moisture changes at the grain surface.

2017 ◽  
pp. 689-695 ◽  
Author(s):  
D. M. Armitage ◽  
D. A. Cook
Keyword(s):  
Grain Surface

Cell parameters refinements showing an influence of the chemical nature of the grain surface on the crystalline characteristics of fine grained powders

1998 ◽  
Vol 08 (PR5) ◽  
pp. Pr5-85-Pr5-89
Author(s):  
P. Sarrazin ◽  
F. Bernard ◽  
G. Calvarin ◽  
J. C. Niepce ◽  
B. Thierry
Keyword(s):  
Chemical Nature ◽  
Cell Parameters ◽  
Fine Grained ◽  
Grain Surface

Emergence of size induced metallic state in the ferromagnetic insulating Pr0.8Sr0.2MnO3 manganite: Breaking of surface polarons

2015 ◽  
Vol 8 (2) ◽  
pp. 2084-2093 ◽  
Author(s):  
PROLOY TARAN DAS ◽  
Arun Kumar Nigam ◽  
Tapan Kumar Nath
Keyword(s):  
Transport Properties ◽  
Metallic State ◽  
Temperature Dependent ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
System A ◽  
Surface Disorder ◽  
Bulk System ◽  
Magnetic Transport ◽  
Grain Surface

Nano-dimensional effects on electronic-, magneto-transport properties of granular ferromagnetic insulating (FMI) Pr0.8Sr0.2MnO3 (PSMO) manganite (down to 40 nm) have been investigated in details. From the electronic and magnetic transport properties, a metallic state has been observed in grain size modulation by suppressing the ferromagnetic insulating state of PSMO bulk system. A distinct metal-insulator transition (MIT) temperature around 150 K has been observed in all nanometric samples. The observed insulator to metallic transition with size reduction can be explained with surface polaron breaking model, originates due to enhanced grain surface disorder. This proposed phenomenological polaronic model plays a significant role to understand the polaronic destabilization process on the grain surface regime of these phase separated nano-mangnatie systems. Temperature dependent resistivity and magnetoresistance data in presence of external magnetic fields are investigated in details with various compatible models.

scholarly journals Anion-Regulated Synthesis of ZnO 1D Necklace-Like Nanostructures with High Photocatalytic Activity

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Xiaoyun Qin ◽  
Dongdong Shi ◽  
Bowen Guo ◽  
Cuicui Fu ◽  
Jin Zhang ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
High Photocatalytic Activity ◽  
Simple Method ◽  
Functional Theory ◽  
Photocatalytic Ability ◽  
New Ideas ◽  
Subsequent Calcination ◽  
Grain Surface ◽  
Hexagonal Nanoplates

Abstract One-dimensional (1D) nanomaterials with specific architectures have received increasing attention for both scientific and technological interests for their applications in catalysis, sensing, and energy conversion, etc. However, the development of an operable and simple method for the fabrication of 1D nanostructures remains a challenge. In this work, we developed an “anion-regulated morphology” strategy, in which anions could regulate the dimensionally-restricted anisotropic growth of ZnO nanomaterials by adjusting the surface energy of different growth facets. ZnO 1D necklace-like nanostructures (NNS) could be prepared through a hydrothermal treatment of zinc acetate and urea mixture together with a subsequent calcination procedure at 400 °C. While replacing the acetate ions to nitrate, sulfate, and chlorion ions produced ZnO nanoflowers, nanosheets and hexagonal nanoplates, respectively. Density functional theory calculations were carried out to explain the mechanism behind the anions-regulating anisotropic crystal growth. The specified ZnO 1D NNS offered improved electron transport while the grain surface could supply enlarged specific surface area, thus providing advanced photocatalytic ability in the following photodegradation of methyl orange (MO). Among the four photocatalysts with different morphologies, ZnO 1D NNS, possessing the highest catalytic activity, degraded 57.29% MO in the photocatalytic reaction, which was 2 times, 10 times and 17 times higher than nanoflowers, nanosheets and hexagonal nanoplates, respectively. Our work provides new ideas for the construction and application of ZnO 1D nanomaterials.

scholarly journals Grain-surface reactions in molecular clouds: the effect of cosmic rays and quantum tunnelling

2014 ◽  
Vol 440 (4) ◽  
pp. 3557-3567 ◽  
Author(s):  
L. Reboussin ◽  
V. Wakelam ◽  
S. Guilloteau ◽  
F. Hersant
Keyword(s):  
Cosmic Rays ◽  
Molecular Clouds ◽  
Surface Reactions ◽  
Quantum Tunnelling ◽  
Grain Surface

Reaction Mechanisms of Li5La3Ta2O12 Powder with Ambient Air: H+/Li+ Exchange with Water

2012 ◽  
Vol 463-464 ◽  
pp. 123-127 ◽  
Author(s):  
Wei Guo Wang ◽  
Qian Feng Fang ◽  
Gang Ling Hao
Keyword(s):  
Internal Friction ◽  
Lithium Ion ◽  
Ambient Air ◽  
Exchange Property ◽  
Measured Temperature ◽  
Internal Friction Peak ◽  
Lower Temperature ◽  
Lithium Ion Conductors ◽  
Grain Surface ◽  
Water Gas

The proton/lithium exchange property of the garnet-related lithium-ion conductors Li5La3Ta2O12 is shown to occur at room temperature under ambient air. The internal friction, TGA analysis, and IR spectroscopy techniques are used to investigate the reaction mechanism. XRPD analysis demonstrates the topotactic character of the exchange reaction. The water gas in ambient air is adsorbed on the grain surface and then to exchange proton for lithium ion into the garnet structure,(Li5-xHx)La3Ta2O12. The H+/Li+ exchanging processes are reversible. When the measured temperature is higher over 573K, the internal friction peak gradually shifts toward lower temperature and the like garnet-like phase is recovered.

scholarly journals Surface Reactions in Interstellar Space

2002 ◽  
Vol 12 ◽  
pp. 55-57 ◽  
Author(s):  
Eric Herbst
Keyword(s):  
Surface Chemistry ◽  
Gas Phase ◽  
Condensed Phase ◽  
Current Knowledge ◽  
Surface Reactions ◽  
Future Research ◽  
Interstellar Space ◽  
Interstellar Molecules ◽  
Grain Surface

AbstractIt is impossible to explain the abundances of some gas-phase and most condensed-phase interstellar molecules without the use of grain chemistry. Nevertheless, grain-surface chemistry is relatively poorly understood for a variety of reasons. Our current knowledge of this chemistry and its use in interstellar models is discussed along with specific needs for future research.

scholarly journals Community structure of fungal pathogens causing spikelet rot disease of naked oat from different ecological regions of China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Longlong Liu ◽  
Mingchuan Ma ◽  
Zhang Liu ◽  
Lijun Zhang ◽  
Jianping Zhou
Keyword(s):  
Fungal Pathogens ◽  
The Other ◽  
Qinghai Province ◽  
Naked Oat ◽  
Ecological Regions ◽  
Yield And Quality ◽  
Spray Inoculation ◽  
Grain Yield And Quality ◽  
Rot Disease ◽  
Grain Surface

AbstractSpikelet rot disease (SRD) is an emerging disease of the grain surface of naked oat in China that affects both grain yield and quality. The typical symptom is discoloration from the black structures of the causal fungi. Here, we investigated the fungal communities on the grain surfaces of cultivar Bayou 13 grown in ten ecological oat-producing regions of China, to identify the main pathogens of naked oat SRD. Our results showed that the growth of Alternaria spp. and Davidiella spp. exhibited a competitive relationship and was mainly affected by the elevations of all 10 ecological regions. The dominant pathogens were Davidiella spp. in Shannan Prefecture in Tibet and Haidong Prefecture in Qinghai Province and Alternaria spp. in the other eight regions. The ratios of black pathogens of interest to all pathogens in Shannan Prefecture and Haidong Prefecture were significantly lower than those of the other eight regions, thus indicating that SRD mainly occurred in regions below 2000 m (elevation). We isolated black fungal pathogens from grain surfaces and deduced that they were Alternaria spp. by sequence comparison. The blackened appearance of the grain surfaces was more evident under spray inoculation with a spore suspension of Alternaria than under the control in greenhouse experiments. The recovered pathogen was the same as the pathogen used for inoculation. We thus concluded that Alternaria alone causes naked oat SRD and mainly infects naked oat in regions below 2000 m, which provides a basis for the recognition and management of SRD of naked oat.

scholarly journals Nautilus multi-grain model: Importance of cosmic-ray-induced desorption in determining the chemical abundances in the ISM

2018 ◽  
Vol 615 ◽  
pp. A20 ◽  
Author(s):  
Wasim Iqbal ◽  
Valentine Wakelam
Keyword(s):  
Grain Size ◽  
Surface Temperature ◽  
Gas Phase ◽  
Numerical Models ◽  
Cosmic Ray ◽  
Grain Sizes ◽  
Small Grains ◽  
Grain Model ◽  
Grain Surface ◽  
The Impact

Context. Species abundances in the interstellar medium (ISM) strongly depend on the chemistry occurring at the surfaces of the dust grains. To describe the complexity of the chemistry, various numerical models have been constructed. In most of these models, the grains are described by a single size of 0.1 μm. Aims. We study the impact on the abundances of many species observed in the cold cores by considering several grain sizes in the Nautilus multi-grain model. Methods. We used grain sizes with radii in the range of 0.005 μm to 0.25 μm. We sampled this range in many bins. We used the previously published, MRN and WD grain size distributions to calculate the number density of grains in each bin. Other parameters such as the grain surface temperature or the cosmic-ray-induced desorption rates also vary with grain sizes. Results. We present the abundances of various molecules in the gas phase and also on the dust surface at different time intervals during the simulation. We present a comparative study of results obtained using the single grain and the multi-grain models. We also compare our results with the observed abundances in TMC-1 and L134N clouds. Conclusions. We show that the grain size, the grain size dependent surface temperature and the peak surface temperature induced by cosmic ray collisions, play key roles in determining the ice and the gas phase abundances of various molecules. We also show that the differences between the MRN and the WD models are crucial for better fitting the observed abundances in different regions in the ISM. We show that the small grains play a very important role in the enrichment of the gas phase with the species which are mainly formed on the grain surface, as non-thermal desorption induced by collisions of cosmic ray particles is very efficient on the small grains.

Editorial: Let’s Stop Treating Our Youth Like Dummies

2018 ◽  
Vol 24 (2) ◽  
pp. 57-58
Author(s):  
William E. Field ◽  
Yuan-hsin Cheng ◽  
Roger Tormoehlen ◽  
Robert Aherin ◽  
Charles Schwab ◽  
...  
Keyword(s):  
High School ◽  
High School Students ◽  
School Students ◽  
Training Event ◽  
Grain Surface ◽  
Full Body

At a recent training event to evaluate various types of rescue devices and strategies to extricate victims from partial entrapment in free-flowing grain, a group of volunteer high school students were invited to participate as test subjects. For each test, two youth were equipped with full-body harnesses and lifelines, asked to stand on the grain surface in a semi-trailer load of dry corn, and then allowed to be drawn into the grain as the bottom discharge gate under each youth was opened. Both “victims” were drawn into the grain at either end of the trailer at the same time, each located over the deepest section of the trailer directly above a hopper. Photos were taken of the entrapped youth showing no more than their heads and shoulders above the grain surface. Keywords:

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