e+ e- ANNIHILATION INTO $\overline{N}N$ PAIRS

2003 ◽  
Vol 18 (02n06) ◽  
pp. 370-373 ◽  
Author(s):  
Y. YAN ◽  
C. KOBDAJ ◽  
W. UCHAI ◽  
AMAND FAESSLER ◽  
T. GUTSCHE ◽  
...  
Keyword(s):  
Experimental Data ◽  
Vector Meson ◽  
Quark Model ◽  
Step Process ◽  
Meson Decays ◽  
Quantum Numbers ◽  
One Step ◽  
The One

The reactions of electron-position annihilation into nucleon-antinucleon pairs have been studied in a nonperturbative quark model. The work suggests that the two-step process, in which the primary [Formula: see text] pair forms first a meson and then the meson decays into baryon pair, is dominant over the one-step process in which the primary [Formula: see text] pair is directly dressed by two additional [Formula: see text] pairs to form a baryon pair. The experimental data indicates that there exists a vector meson with quantum numbers IG(JPC) = 0-(1--) and a mass around 2 GeV.

Preparation of nanocellulose by hydrolysis with ionic liquids and two-step hydrolysis with ionic liquids and enzymes

2021 ◽  
Vol 116 ◽  
pp. 5-14
Author(s):  
Marta Babicka ◽  
Magdalena Woźniak ◽  
Kinga Szentner ◽  
Sławomir Borysiak ◽  
Krzysztof Dwiecki ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Degree Of Crystallinity ◽  
Cellulolytic Enzyme ◽  
X Ray Diffraction ◽  
Production Methods ◽  
Step Process ◽  
X Ray ◽  
One Step ◽  
Xrd Patterns ◽  
The One

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl 3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.

Heteroepitaxy on (001) Silicon: Growth Mechanisms and Defect Formation.

1988 ◽  
Vol 116 ◽  
Author(s):  
P. Pirouz ◽  
F. Ernst ◽  
T. T. Cheng
Keyword(s):  
Defect Formation ◽  
Lattice Mismatch ◽  
Minor Role ◽  
Alternative Mechanism ◽  
Growth Mechanisms ◽  
Planar Defects ◽  
Step Process ◽  
One Step ◽  
The One ◽  
A Minor

AbstractIn the growth of thin films of compound semiconductors on (001) silicon substrates by vapor deposition techniques, it is usual to employ a two-step process. In this method, an initial (buffer) layer is first grown at a relatively low temperature; once a continuous film has formed on the substrate, its temperature is raised for the subsequent bulk growth. Carrying out the growth in a one-step process by heating the substrate to the final temperature before allowing the gases into the CVD reactor usually results in a polycrystalline aggregate. In this paper, classical nucleation and growth mechanisms are used to explain-the reasons for the different morphology of the one-step and two-step growth films.The heteroepitaxial films on (001) silicon often contain a high density of stacking faults and twins. The occurrence of these planar defects is usually attributed to stresses that arise from lattice mismatch and/or thermal mismatch (differences in coefficients of thermal expansion) between the substrate and the epilayer. It is argued that, in fact, mismatch stresses play a minor role in the generation of planar defects. Instead, an alternative mechanism for their formation is proposed which is based on the facetted shape of nuclei and errors in stacking of {111} planes which occur during deposition on the facets.Conventional and high resolution transmission electron microscopy have been used to investigate three systems grown by CVD or MOCVD: SiC/Si, GaAs/Si and GaP/Si. These systems have different lattice and thermal mismatches, and the results support the proposed model for the formation of defects.

scholarly journals Operator Approach to the Master Equation for the One-Step Process

2016 ◽  
Vol 108 ◽  
pp. 02027 ◽  
Author(s):  
M. Hnatič ◽  
E. G. Eferina ◽  
A. V. Korolkova ◽  
D. S. Kulyabov ◽  
L. A. Sevastyanov
Keyword(s):  
Master Equation ◽  
Operator Approach ◽  
Step Process ◽  
One Step ◽  
The One

Removal of silicon from green liquor with carbon dioxide in the chemical recovery process of wheat straw soda pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 35-40 ◽  
Author(s):  
XINXING XIA ◽  
MINGZHU DU ◽  
XIUJUAN GENG
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Wheat Straw ◽  
Reaction Temperature ◽  
Recovery Process ◽  
Chemical Recovery ◽  
Step Process ◽  
Green Liquor ◽  
One Step ◽  
The One

Green liquor in the chemical recovery process of wheat straw pulping was treated with carbon dioxide to precipitate silicon by a one-step process and a seeding process to address problems caused by high silicon content. The total silicon removal, the particle size, and the sedimentation performance of silica were investigated. The results showed that the pH of green liquor decreased with increasing amounts of carbon dioxide, becoming stable after the pH decreased to 8.2. Reaction temperature had no significant effect on the removal of silicon. About 99% of silicon removal was achieved at a pH of 9.2 at room temperature. In the one-step process, the particle size increased and the silica sedimentation performance improved with decreasing pH. The particle size decreased and the sedimentation performance improved with increasing reaction temperature. At a pH of 9.5 and reaction temperature of 80°C, the particle size was 10.43 μm. In the seeding process, 40% green liquor was treated with carbon dioxide at 80°C until the pH was about 10.5, then the 40% treated green liquor was mixed with the remaining 60% of green liquor. The mixture was then treated with carbon dioxide at a reaction temperature of 80°C until the pH reached 9.5. In that situation, the particle size reached 14.11 μm. Compared with the one-step process, the particle size of silica generated by the seeding process was bigger and the sedimentation performance was improved.

scholarly journals Reducing copper leaching from treated wood by sol-gel derived TiO2 and SiO2 depositions

Holzforschung ◽  
2013 ◽  
Vol 67 (4) ◽  
pp. 429-435 ◽  
Author(s):  
Muhammad Shabir Mahr ◽  
Thomas Hübert ◽  
Ina Stephan ◽  
Michael Bücker ◽  
Holger Militz
Keyword(s):  
Cell Wall ◽  
Diffusion Barrier ◽  
Sol Gel ◽  
Effective Diffusion ◽  
Treated Wood ◽  
Emission Rates ◽  
Step Process ◽  
Copper Leaching ◽  
One Step ◽  
The One

Abstract The antileaching efficacy of sol-gel-derived TiO2- and SiO2-based precursors has been evaluated through laboratory leaching trials with pine sapwood in two different ways. In a one-step process, wood was vacuum impregnated by the precursor solutions containing CuCl2. The copper (Cu) emission rates of the sol-gel-based impregnated woods were up to 70% lower than that of wood treated with pure CuCl2 solution at the same level of concentration. More improvement (80%) could be achieved in a two-step process, in which sol-gel precursors were introduced into an already CuCl2-treated wood. The refinement was attributed to several effects. In the one-step approach, Cu was embedded in the TiO2/SiO2 gels formed in the wood texture. During a two-step impregnation, gel layers that were formed in the wooden interior acted as an effective diffusion barrier. The sol-gel impregnations made wood more hydrophobic; therefore, the low amount of water that penetrated the cell wall was less efficient to leach out Cu.

Synergistic Toughening Effects of Nano-CaCO3 and POE on Ternary-Phase Polypropylene Nanocomposites

2007 ◽  
Vol 334-335 ◽  
pp. 553-556 ◽  
Author(s):  
Min Zhi Rong ◽  
Ming Qiu Zhang ◽  
Chuan Guo Ma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Synergistic Effect ◽  
Ternary Phase ◽  
Binary Blends ◽  
Step Process ◽  
Phase Structures ◽  
Polypropylene Nanocomposites ◽  
One Step ◽  
The One

Microstructure and mechanical properties of ternary PP/POE/nano-CaCO3 composites were investigated. Two different phase structures were obtained mainly by adjusting processing sequence. The one-step process led to the isolated distribution of elastomer and CaCO3 particles in PP matrix, while the two-step one attained an encapsulated microstructure. In comparison with binary blends of PP/POE or pure PP, toughness of the ternary composites was significantly increased. Meanwhile, their stiffness and tensile strength kept nearly unchanged or slightly enhanced, implying that there is a synergistic effect between nano-CaCO3 and POE components.

Theory and phenomenology of radiative meson decays

1977 ◽  
Vol 55 (15) ◽  
pp. 1301-1309 ◽  
Author(s):  
P. J. O'Donnell
Keyword(s):  
Experimental Data ◽  
Quark Model ◽  
Radiative Decays ◽  
Meson Decays ◽  
Vector Dominance ◽  
Radiative Meson Decays

The experimental data on the radiative decays of mesons (not involving charm) are reviewed. The consistency of these data with SU(3) symmetry, vector dominance, and the quark model is discussed.

INCLUSIVE (3He, t) REACTION IN DELTA EXCITATION REGION

1995 ◽  
Vol 04 (01) ◽  
pp. 181-191 ◽  
Author(s):  
NEELIMA G. KELKAR ◽  
B.K. JAIN
Keyword(s):  
Experimental Data ◽  
Angular Distribution ◽  
Cross Sections ◽  
Eikonal Approximation ◽  
Fermi Gas ◽  
Distorted Wave ◽  
Excitation Region ◽  
One Step ◽  
The One ◽  
Nuclear Response

Using the one step reaction mechanism, calculations are presented for the overall features of the inclusive (3 He , t) reaction on various target nuclei in the delta excitation region. The interaction for the elementary pp→nΔ++ process is given by one-pion-exchange, and is written in the covariant relativistic form. The values of the parameters in the interaction are chosen such that the interaction successfully describes the spin averaged experimental elementary cross-sections. The distortion in the entrance and exit channels is described in the eikonal approximation, and the nuclear response is described in the “distorted wave Fermi gas model”. The cross-sections for the triton energy spectrum, angular distribution, and the total events at 0° on several nuclei, are calculated and compared with the corresponding experimental data. The main features of the measured cross-sections are reproduced.

The One Step Process

1984 ◽  
pp. 630-639
Author(s):  
Michael P. Stanislawski
Keyword(s):  
Step Process ◽  
One Step ◽  
The One

Protecting group free synthesis of urea-linked glycoconjugates: efficient synthesis of β-urea glycosides in aqueous solution

2014 ◽  
Vol 12 (23) ◽  
pp. 3924-3931 ◽  
Author(s):  
Yoshiyasu Ichikawa ◽  
Takahiro Minami ◽  
Shohei Kusaba ◽  
Nobuyoshi Saeki ◽  
Yuta Tonegawa ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Protecting Group ◽  
Efficient Synthesis ◽  
Acidic Aqueous Solution ◽  
Step Process ◽  
One Step ◽  
The One

The one step process, involving reactions between urea and protecting group free d-glucose, N-acetyl-d-glucosamine or d-xylose in acidic aqueous solution, furnishes the corresponding β-urea glycosides.

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