scholarly journals Boron Particles Production in Nonequilibrium Laser-Chemical Radical Reactions During the IR Multiphoton Dissociation of HCIC=CBCI2H Molecules

1989 ◽  
Vol 10 (2) ◽  
pp. 81-92 ◽  
Author(s):  
G. I. Abdushelishvili ◽  
T. G. Abzianidze ◽  
A. G. Bakhtadze ◽  
P. D. Kervalishvili ◽  
G. I. Tkeshelashvili ◽  
...  
Keyword(s):  
Experimental Results ◽  
Radical Reactions ◽  
Bimolecular Reactions ◽  
Elementary Boron ◽  
Multiphoton Dissociation ◽  
Boron Particles ◽  
High Degree ◽  
Degree Of Fragmentation

The study of IR MPD of HCIC=CBCI2H molecule by CO2.-laser is presented. We provide experimental results showing high degree of fragmentation of this molecule (down to elementary boron) during nonequilibrium laser induced radical bimolecular reactions.

scholarly journals Forest fragmentation in the landscape in the Atlantic Forest Biome: A systematic review of the literature

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Stephany Diolino Cunha ◽  
Bruna Sampaio Crivilin ◽  
Matheus da Silva Araújo ◽  
Luís Antônio Coimbra Borges
Keyword(s):  
Systematic Review ◽  
Landscape Ecology ◽  
Forest Fragmentation ◽  
Atlantic Forest ◽  
Forest Fragments ◽  
Review Of The Literature ◽  
Search Terms ◽  
High Degree ◽  
Forest Biome ◽  
Degree Of Fragmentation

Forest fragmentation is defined as the process by which a continuous area of habitat is reduced in size and divided between spaces. Therefore, due to the increase in these areas, this study aimed to conduct a systematic review of the literature on forest fragments in the Atlantic Forest biome in order to verify their main characteristics and landscape ecology. Publications in search platforms referring to the period from 2000 to 2020 were analyzed such as: SciELO, Google academic and CAPES journals portal. The search terms entered were: “Studies of forest fragments in the Atlantic Forest biome” and “Landscape ecology in forest fragments”. A total of 15 articles were selected from among the works found, and 5 of these were chosen to be evaluated in the present study. Four of the five works were carried out in the state of Espírito Santo, close to basins and sub-basins, and only one work was carried out in a state park. Thus, the evaluated works with the theme, study of fragmentation and ecology of the landscape showed a high degree of fragmentation, meaning that they have fragments smaller than 5 hectares; in addition, all fragments have an irregular edge effect. Therefore, measures aimed at the conservation of biodiversity are needed in all places so that there is ecological restoration of the landscape and conservation of fauna and flora in the Atlantic Forest biome. 

scholarly journals SEQUENCE-BASED PREDICTION OF PROTEIN B-FACTORS WITH DUAL SUPERVIZED LEARNING MODELS

2010 ◽  
Vol 22 (05) ◽  
pp. 385-391
Author(s):  
Yu-Cheng Liu ◽  
Shien-Ching Hwang ◽  
Yu-Feng Huang ◽  
Win-Li Lin ◽  
Yen-Jen Oyang ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Prediction Accuracy ◽  
Active Sites ◽  
Pearson Correlation ◽  
Experimental Results ◽  
Structural Flexibility ◽  
Dual Model ◽  
Functional Sites ◽  
High Degree ◽  
Model Approach

The B-factor, which is also known as temperature factor or Debby–Waller factor, is an important structural flexibility index of the ground-state protein conformation. In particular, the B-factors associated with a segment of residues, reflect the local flexibility of the corresponding protein tertiary substructure. Recent studies have shown that, for certain families of proteins, there exists a high-degree of correlation between the B-factors and the protein functional sites, including antigenic regions, enzyme active sites, and nucleotide binding sites. This paper presents a sequence–based predictor of B-factors with a dual-model approach.  The design of the dual-model approach has been aimed at exploiting the bi-modal distribution of B-factors in order to achieve higher prediction accuracy. In this paper, the prediction accuracy is measured by Pearson correlation coefficient. Experimental results show that the dual-model predictor proposed in this article is capable of delivering superior correlation coefficient in comparison with two predictors reported in two latest papers.  Though experimental results show that the dual-model proposed in this paper really works more effectively than the conventional approach, it is of interest to continue investigating more advanced designs since there exists a strong correlation between B-factors and protein functional sites. In this respect, identifying additional physiochemical properties that are related to structural flexibility deserves a high-degree of attention.

Nucleation and Growth of Bubbles in Elastomers

1971 ◽  
Vol 44 (5) ◽  
pp. 1363-1379 ◽  
Author(s):  
Charles W. Stewart
Keyword(s):  
Surface Tension ◽  
Homogeneous Nucleation ◽  
Nucleation And Growth ◽  
Experimental Results ◽  
Dissolved Gas ◽  
Rate Of Growth ◽  
High Degree ◽  
Approximate Expressions ◽  
Temperature Surface

Abstract The theory of homogeneous nucleation of bubbles is combined with an expression, for their rate of growth in elastomers to obtain approximate expressions for calculating the number of bubbles formed under a high degree of supersaturation. Experimental results are given for several elastomers with argon as the dissolved gas under a variety of foaming conditions. The theory adequately describes the manner in which the number of bubbles formed depends on the temperature, surface tension of the polymer, and permeability of the dissolved gas.

scholarly journals Estimating landscape structure effects on pollination for management of agricultural landscapes

2021 ◽  
Author(s):  
Ehsan Rahimi ◽  
Shahindokht Barghjelveh ◽  
Pinliang Dong
Keyword(s):  
Landscape Composition ◽  
Agricultural Landscapes ◽  
Edge Density ◽  
Forest Patches ◽  
Habitat Amount ◽  
High Degree ◽  
Very High ◽  
Landscape Composition And Configuration ◽  
Degree Of Fragmentation ◽  
Significant Factors

Abstract The present study aims to examine the effects of habitat fragmentation to find a pattern of forest patches in agricultural landscapes that provide the highest pollination level. For this purpose, using simulated agricultural landscapes, including different forest proportions and degrees of fragmentation, pollination in different scenarios was estimated. We used landscape metrics to measure the landscape composition and configuration of each simulated landscape and estimated their statistical relationship with pollination. Our results showed that the effects of fragmentation on pollination were affected by two significant factors; 1- habitat amount and 2- small patches' capacity to supply pollination. Our results showed that when small patches' capacity in supplying pollination was low, fragmentation decreased pollination. When this capacity was very high, landscapes with a high degree of fragmentation showed higher levels of pollination. There was an exception for habitat amounts less than 0.1 of the entire landscape that increasing edge density, aggregation, and the number of patches, resulted in increasing pollination in all scenarios.

A comparative ion chemistry study of acetone, diacetone alcohol, and mesityl oxide

1986 ◽  
Vol 64 (10) ◽  
pp. 1979-1988 ◽  
Author(s):  
Afaf Kamar ◽  
Alexander Baldwin Young ◽  
Raymond Evans March
Keyword(s):  
Infrared Multiphoton Dissociation ◽  
Mesityl Oxide ◽  
Alternative Form ◽  
Dehydration Process ◽  
Ion Chemistry ◽  
Bimolecular Reactions ◽  
Common Structure ◽  
Diacetone Alcohol ◽  
Multiphoton Dissociation ◽  
Ion Species

The evolution of ion species by unimolecular and bimolecular reactions, both concurrent and sequential, has been investigated for each of 2-propanone, d6-2-propanone, 4-hydroxy-4-methyl-2-pentanone, and 4-methyl-3-penten-2-one. Infrared multiphoton dissociation (IRMPD) has been used in order to differentiate between gaseous ionic isomers. It is concluded that the isomeric species, protonated 2-propanone dimer and protonated 4-hydroxy-4-methyl-2-pentanone, both of m/z 117, are of different structures. The ion species C6H11O+ of m/z 99, and its perdeuterated analogue, which is observed in all three systems, may exist in two forms, one of which is unique to 2-propanone while an alternative form appears to be common to 4-hydroxy-4-methyl-2-pentanone and 4-methyl-3-penten-2-one. The ion species of m/z 83 (C5H7O+) which is observed only in the latter two systems only could not be differentiated and may have a common structure. In the protonated dimers of 2-propanone and 4-hydroxy-4-methyl-2-pentanone, evidence obtained by IRMPD indicates that the activation energy for dedimerization (134 kJ mol−1) is less than that for the dehydration process.

Research and Application of Retention Agent in Reversible Thermochromism Materials Papermaking

2015 ◽  
Vol 731 ◽  
pp. 452-456
Author(s):  
Xiao Xiu Hao ◽  
Na Wei ◽  
Cheng Sun ◽  
Shu Hui Yang
Keyword(s):  
Retention Rate ◽  
Degree Of Substitution ◽  
Experimental Results ◽  
Pulp Fiber ◽  
Modified Starch ◽  
Cationic Starch ◽  
Optimum Dosage ◽  
Reversible Thermochromism ◽  
High Degree

This paper discusses the effects of different retention agent such as: CPAM, APAM, PAE+CPAM, cationic starch with high degree of substitution and modified starch on the reversible thermochromism materials in anti-counterfeiting paper retention rate, and then determined the optimum dosage of retention agent in the slurry. According to the anti-counterfeit paper color value, the mechanism of reversible thermochromism paper was studied. The experimental results show that when the slurry with retention agent, the reversible thermochromism materials in the anti-counterfeit paper retention increased significantly. This suggests that retention agent in pulp fiber has played the role of bridge and link, thus ensuring the security of reversible thermochromism paper.

Analysis of the Mechanics for Drawing Polyvinyl Chloride Tubes over an Expanding Mandrel

1996 ◽  
Vol 210 (1) ◽  
pp. 65-74 ◽  
Author(s):  
S Kakadjian ◽  
G Craggs ◽  
I M Ward
Keyword(s):  
Polyvinyl Chloride ◽  
Large Scale ◽  
Deformation Behaviour ◽  
Experimental Results ◽  
Test Facility ◽  
Processing Temperature ◽  
Theoretical Predictions ◽  
Stress And Deformation ◽  
Product Thickness ◽  
High Degree

An analysis is presented of the mandrel drawing process in which a tubular polyvinyl chloride (PVC) billet is drawn over an expanding mandrel so as to achieve a tubular product having a high degree of molecular orientation in the hoop and axial directions and enhanced mechanical properties. The stress and deformation behaviour of material moving over the mandrel are determined from equilibrium considerations and modelling of the material using the Ogden representation. Experimental results from drawing tests carried out on a large-scale test facility are presented and the effects of mandrel semi-angle, mandrel exit diameter and processing temperature on drawing behaviour are evaluated. Good agreement is shown between the experimental results and theoretical predictions of final product thickness, die exit stress and drawing load.

Wellbore Stability of Shale below Salt Formation of Faqui Oilfield in Iraq

2014 ◽  
Vol 641-642 ◽  
pp. 451-457
Author(s):  
Fan Zhang ◽  
Yun Long Mu ◽  
Shuang Cheng ◽  
Jin Gen Deng ◽  
Bao Hua Yu ◽  
...  
Keyword(s):  
Strength Criterion ◽  
Wellbore Stability ◽  
Experimental Results ◽  
Salt Formation ◽  
Deviation Angle ◽  
Collapse Pressure ◽  
Stress Orientations ◽  
Dip Angle ◽  
High Degree ◽  
Coulomb Criterion

Serious borehole collapse has occurred in shale below salt formation of Fauqi oilfield in Iraq. The Lots of bedding shale cavings returned to ground. The strength of bedding shale cores with different bedding dip angle are tested, which changes along in a high degree with the dip angle and reach the minimum in 50°-60°. The experimental results are regressed by different strength criterion, which demonstrate that McLamore strength criterion is more accurate. The collapse pressure of shale below salt formation is calculated by Mohr-Coulomb criterion and McLamore criterion respectively. The maximum collapse pressure by Mohr-Coulomb criterion occurs in the maximum in-stress orientations and 90° deviation angle, and that by McLamore criterion occurs in the maximum in-stress orientations and 50°-60° deviation angle. By analyzing the actual drilling situation, McLamore criterion is proved to be more accurate and can be used in Fauqi oilfield.

Experimental Investigation of Heat Exchanger Tubesheet Hole Enlargement

2003 ◽  
Vol 125 (1) ◽  
pp. 19-25 ◽  
Author(s):  
A. N. Shuaib ◽  
N. Merah ◽  
M. K. Khraisheh ◽  
I. M. Allam ◽  
S. S. Al-Anizi
Keyword(s):  
Heat Exchanger ◽  
Strain Hardening ◽  
Experimental Results ◽  
Average Strength ◽  
Tube Material ◽  
Pull Out ◽  
Maximum Value ◽  
Manufacturer Association ◽  
High Degree ◽  
Different Levels

An experimental study has been conducted to evaluate the effect of roller expansion of heat exchanger tubes in enlarged tubesheet holes on joint strength, tube wall reduction (i.e., thinning), and strain hardening of the tubes and surrounding tubesheet ligaments. Different levels of tube-to-tubesheet hole clearance, or overtolerance (OT), were investigated to simulate tubesheet in-service, and during-maintenance, hole enlargement process. The experimental results have shown that, in spite of increasing overtolerance level by up to seven times the maximum value allowed by the Tubular Exchanger Manufacturer Association (TEMA) standard, the average strength of the test joints has not declined below the strength of joints in the allowed TEMA OT range. Percent wall reduction (WR) of the expanded tube was found to increase linearly with increasing overtolerance value; although its maximum value remained well below the wall reduction limit for which a joint is rejected in industry. An observed increase in hardness of the expanded tube material is evidence of the high degree of strain hardening to which the expanded tubes are subjected compared with the surrounding ligaments. Pull-out forces, calculated using existing analytical methods, were found to compare well with the experimental results.

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