scholarly journals Aliovalent doping of CeO2: DFT study of oxidation state and vacancy effects

2014 ◽  
Vol 2 (33) ◽  
pp. 13723-13737 ◽  
Author(s):  
Danny E. P. Vanpoucke ◽  
Patrick Bultinck ◽  
Stefaan Cottenier ◽  
Veronique Van Speybroeck ◽  
Isabel Van Driessche
Keyword(s):  
Oxidation State ◽  
Chemical Properties ◽  
Dft Study ◽  
Leading Term ◽  
At Will ◽  
And Chemical Properties ◽  
Aliovalent Doping

Doping of ceria allows one to tune the mechanical and chemical properties of ceria at will, though the induced vacancies often contribute to the leading term of these modifications.

scholarly journals Dynamic changes of optical and chemical properties of tar ball aerosols by atmospheric photochemical aging

2018 ◽  
Author(s):  
Chunlin Li ◽  
Quanfu He ◽  
Julian Schade ◽  
Johannes Passig ◽  
Ralf Zimmermann ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Refractive Index ◽  
High Molecular Weight ◽  
Oxidation State ◽  
Chemical Properties ◽  
Dynamic Changes ◽  
Photochemical Process ◽  
Tar Balls ◽  
Photochemical Aging ◽  
And Chemical Properties

Abstract. Following wood pyrolysis, tar ball aerosols were generated from wood tar separated into polar and nonpolar phases. Chemical information of fresh tar balls was obtained from the high-resolution time-of-flight aerosol mass spectrometer (HiRes-ToF-AMS) and laser desorption/resonance enhanced multiphoton ionization mass spectrometry (LD-REMPI-MS), and their refractive index between 365 and 425 nm were retrieved using a broadband cavity enhanced spectroscopy. Dynamic changes of the optical and chemical properties for the nonpolar tar ball aerosols in NOx-dependent photochemical process were investigated in an oxidation flow reactor (OFR). Distinct differences in the chemical composition of the polar and nonpolar tar aerosols were identified. Nonpolar tar aerosols contain predominantly high-molecular weight unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs), while polar tar aerosols consist of a high number of oxidized aromatic substances (e.g., methoxy-phenols, benzenediol) with higher O : C ratio and carbon oxidation state. Fresh tar aerosols have light absorption characteristics similar to atmospheric BrC with higher absorption efficiency towards the UV wavelengths. The average retrieved refractive index (RI) are 1.661 + 0.020i and 1.635 + 0.003i for the nonpolar and polar tar aerosols, respectively, with absorption Ångström exponent (AAE) between 5.7 and 7.8 in the wavelength region 365–425 nm. The RI fits a volume mixing rule for internally mixed nonpolar/polar tar aerosols. The RI of the tar aerosols decreased with increasing wavelength under photochemical oxidation. Photolysis by UV light (254 nm), without strong oxidants in the system, slightly decreased the RI and increased the oxidation state of the tar balls. Oxidation under varying OH exposure levels and in the absence of NOx diminished the absorption (bleaching), and increased the O : C ratio. The photobleaching of tar ball aerosols via photochemically induced OH-oxidation is mainly attributed to decomposition of chromophoric aromatics, nitrogen-containing organics, and high-molecular weight components. Photolysis of nitrous oxide (N2O) was used to simulate NOx-dependent photochemical aging of tar balls in the OFR. Under high NOx conditions, photochemical aging lead to the formation of organic-nitrates, increased oxidation degree and increased absorption for the tar ball aerosols. These observations suggest that secondary organic nitrate formation compensates the bleaching by photolysis and OH radical photooxidation to eventually regain some absorption of aged tar balls aerosols. The atmospheric implication and climatic effects from tar balls upon various oxidation processes are briefly discussed.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

The microstructure of a TiB2/Ti-47 Al composite material

1989 ◽  
Vol 47 ◽  
pp. 674-675
Author(s):  
O. Popoola ◽  
A.H. Heuer ◽  
P. Pirouz
Keyword(s):  
Composite Material ◽  
Ion Beam ◽  
Chemical Properties ◽  
Intermetallic Alloys ◽  
Transmission Electron ◽  
Diamond Polishing ◽  
Al Composite ◽  
The Matrix ◽  
Argon Ion ◽  
And Chemical Properties

The addition of fibres or particles (TiB2, SiC etc.) into TiAl intermetallic alloys could increase their toughness without compromising their good high temperature mechanical and chemical properties. This paper briefly discribes the microstructure developed by a TiAl/TiB2 composite material fabricated with the XD™ process and forged at 960°C.The specimens for transmission electron microscopy (TEM) were prepared in the usual way (i.e. diamond polishing and argon ion beam thinning) and examined on a JEOL 4000EX for microstucture and on a Philips 400T equipped with a SiLi detector for microanalyses.The matrix was predominantly γ (TiAl with L10 structure) and α2(TisAl with DO 19 structure) phases with various morphologies shown in figure 1.

Tailoring microstructures of materials through biomimetics

1993 ◽  
Vol 51 ◽  
pp. 500-501
Author(s):  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Chemical Properties ◽  
Design And Synthesis ◽  
Structure Sensitive ◽  
Macro Scale ◽  
Methods Of Synthesis ◽  
Successive Level ◽  
Engineering Materials ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Synthesis Of Materials

Biomimetics involves investigation of structure, function, and methods of synthesis of biological composite materials. The goal is to apply this information to the design and synthesis of materials for engineering applications.Properties of engineering materials are structure sensitive through the whole spectrum of dimensions from nanometer to macro scale. The goal in designing and processing of technological materials, therefore, is to control microstructural evolution at each of these dimensions so as to achieve predictable physical and chemical properties. Control at each successive level of dimension, however, is a major challenge as is the retention of integrity between successive levels. Engineering materials are rarely fabricated to achieve more than a few of the desired properties and the synthesis techniques usually involve high temperature or low pressure conditions that are energy inefficient and environmentally damaging.In contrast to human-made materials, organisms synthesize composites whose intricate structures are more controlled at each scale and hierarchical order.

On some energetic and chemical properties of the calcite surface

1976 ◽  
Vol 73 ◽  
pp. 351-355 ◽  
Author(s):  
Gilles Goujon ◽  
Boyan Mutaftschiev
Keyword(s):  
Chemical Properties ◽  
And Chemical Properties

KARAKTERISTIK TANAH DAN PERBANDINGAN PRODUKSI KELAPA SAWIT (Elaeis guineensis Jacq.) DENGAN METODE TANAM LUBANG BESAR DAN PARIT DRAINASE 2:1 PADA LAHAN SPODOSOL DI KABUPATEN BARITO TIMUR PROPINSI KALIMANTAN TENGAH - INDONESIA

2015 ◽  
Vol 2 (2) ◽  
pp. 148-158
Author(s):  
Surianto
Keyword(s):  
Soil Texture ◽  
Oil Palm ◽  
Soil Profile ◽  
Chemical Properties ◽  
Exchangeable Cations ◽  
Soil Horizon ◽  
Soil Profiles ◽  
Negative Effect ◽  
Hole Profile ◽  
And Chemical Properties

Spodosol soil of Typic Placorthod sub-group of East Barito District is one of the problem soils with the presence of hardpan layer, low fertility, low water holding capacity, acid reaction and it is not suitable for oil palm cultivation without any properly specific management of land preparation and implemented best agronomic practices. A study was carried out to evaluate the soil characteristic of a big hole (A profile) and no big hole (B profile) system and comparative oil palm productivity among two planting systems. This study was conducted in Spodosol soil at oil palm plantation (coordinate X = 0281843 and Y = 9764116), East Barito District, Central Kalimantan Province on February 2014, by surveying of placic and ortstein depth and observing soil texture and chemical properties of 2 (two) oil palm's soil profiles that have been planted in five years. Big hole system of commercial oil palm field planting on the Spodosol soil area was designed for the specific purpose of minimizing the potential of a negative effect of shallow effective planting depth for oil palms growing due to the hardpan layer (placic and ortstein) presence as deep as 0.25 - 0.50 m. The big hole system is a planting hole type which was vertical-sided with 2.00 m x 1.50 m on top and bottom side and 3.00 m depth meanwhile the 2:1 drain was vertical-sided also with 1.50 m depth and 300 m length. Oil palm production was recorded from the year 2012 up to 2014. Results indicated that the fractions both big hole profile (A profile) and no big hole profile (B profile) were dominated by sands ranged from 60% to 92% and the highest sands content of non-big hole soil profile were found in A and E horizons (92%). Better distribution of sand and clay fractions content in between layers of big hole soil profiles of A profile sample is more uniform compared to the B profile sample. The mechanical holing and material mixing of soil materials of A soil profile among the upper and lower horizons i.e. A, E, B and C horizons before planting that resulted a better distribution of both soil texture (sands and clay) and chemical properties such as acidity value (pH), C-organic, N, C/N ratio, CEC, P-available and Exchangeable Bases. Investigation showed that exchangeable cations (Ca, Mg, K), were very low in soil layers (A profile) and horizons (B profile) investigated. The low exchangeable cations due to highly leached of bases to the lower layers and horizons. Besides, the palm which was planted on the big hole system showed good adaptation and response positively by growing well of tertiary and quaternary roots that the roots were penetrable into deeper rooting zone as much as >1.00 m depth. The roots can grow well and penetrate much deeper in A profile compared to the undisturbed hardpan layer (B profile). The FFB (fresh fruit bunches) production of the non-big hole block was higher than the big hole block for the first three years of production. This might be due to the high variation of monthly rainfall in-between years of observation from 2009 to 2014. Therefore, the hardness of placic and ortstein as unpenetrable agents by roots and water to prevent water loss and retain the water in the rhizosphere especially in the drier weather. In the high rainfall condition, the 2:1 drain to prevent water saturation in the oil palm rhizosphere by moving some water into the drain. Meanwhile, the disturbed soil horizon (big hole area) was drier than un disturbance immediately due to water removal to deeper layers. We concluded that both big hole and 2:1 drain are a suitable technology for Spodosol soil land especially in preparing palms planting to minimize the negative effect of the hardpan layer for oil palm growth.

Response of corn (Zea mays L.) to various organic-based fertilizers in marginal upland of Sta. Rita, Samar

2017 ◽  
pp. 31-43
Author(s):  
Berta Ratilla ◽  
Loreme Cagande ◽  
Othello Capuno
Keyword(s):  
Block Design ◽  
Management Strategies ◽  
Chemical Properties ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Physical And Chemical Properties ◽  
Total N ◽  
Randomized Complete Block Design ◽  
Physical And Chemical ◽  
And Chemical Properties

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.

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