On the Penetration of Insecticides Through the Insect Cuticle

1945 ◽  
Vol 22 (1-2) ◽  
pp. 8-20
Author(s):  
J. E. WEBB ◽  
R. A. GREEN
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
High Rate ◽  
Insect Cuticle ◽  
Supporting Evidence ◽  
Rate Of Penetration ◽  
Melophagus Ovinus ◽  
High Carrier ◽  
Test Insect ◽  
Diphenyl Amine

1. Using Melophagus ovinus, the sheep ked, as test insect, it was found that certain organic solvents of diphenylamine, such as the cresols, benzyl alcohol and 4-methyl-cyclohexanol, greatly increase the rate of action of this insecticide. Others, such as carbitol and methyl benzoate, gave little or no improvement in the time of kill. The degree to which a solvent induces rapid penetration of an insecticide is referred to as its ‘carrier efficiency’. 2. The influence of the physical properties of the solvents on carrier efficiency was investigated. It was found that a high carrier efficiency could be correlated with a high rate of penetration through beeswax, a high partition coefficient of the solvent between beeswax and water and a high solubility of insecticide in a solution of the solvent in water. The volatility of the solvent and the solubility of insecticide in solvent were also contributory factors. 3. Mixtures of two solvents, each showing no carrier efficiency but together possessing all the essential physical properties, were tested and showed a carrier efficiency considerably higher than that of either constituent. This is taken as supporting evidence that carrier efficiency depends on certain physical properties of a solvent. 4. Using a range of solvents shown to exhibit various degrees of carrier efficiency with diphenyl-amine, comparable results were obtained with dixanthogen, ω-nitrostyrene dibromide and rotenone and showed that the synergy could be extended to other insecticides. 5. It is suggested that certain solvents increase the rate of penetration of contact insecticides through the insect cuticle: (a) By transporting the insecticide through the lipoid elements of the epicuticle to the interface between this layer and the water permeating the exocuticle. (b) By concentrating the insecticide at the interface between the epicuticle and the exocuticle, as the solvent passes into the exocuticle, and thus increasing the diffusion gradient of the insecticide across that interface. (c) By increasing the solubility of the insecticide in the water permeating exo- and endo-cuticles and thus, by raising its partition coefficient between solvent in the epicuticle and water in the exocuticle, further increasing its rate of diffusion, not only across this interface, but also through exo- and endo-cuticles to the hypodermis.

scholarly journals Effect of Mosses on physical and chemical properties of soil in temperate forests of Garhwal Himalayas

2021 ◽  
pp. 1-10
Author(s):  
Anshu Siwach ◽  
Siddhartha Kaushal ◽  
Ratul Baishya
Keyword(s):  
Physical Properties ◽  
Chemical Properties ◽  
Nutrient Status ◽  
High Rate ◽  
Physical And Chemical Properties ◽  
Garhwal Himalayas ◽  
Forest Sites ◽  
Significant Difference ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Mosses are one of the most important and dominant plant communities, especially in the temperate biome, and play a significant role in ecosystem function and dynamics. They influence the water, energy and element cycle due to their unique ecology and physiology. The present study was undertaken in three different temperate forest sites in the Garhwal Himalayas, viz., Triyuginarayan (Kedarnath Wildlife Sanctuary (KWLS)), Chakrata, and Kanasar forest range. The study was focused on understanding the influence of mosses on soil physical properties and nutrient availability. Different physico-chemical properties were analysed under two different substrata, that is, with and without moss cover in two different seasons, viz., monsoon and winter. We observed mosses to influence and alter the physical properties and nutrient status of soil in both seasons. All soil physical and chemical properties, except magnesium, showed significant difference within the substrates, among all the sites and across the two seasons. Besides the soil characteristics underneath the moss vegetation, the study also highlights the diversity of mosses found in the area. Mosses appear to create high nutrient microsites via a high rate of organic matter accumulation and retain nutrients for longer periods thus, maintaining ecosystem stability.

Effects of physical properties of the breathing gas on decompression-sickness bubbles

1995 ◽  
Vol 79 (5) ◽  
pp. 1828-1836 ◽  
Author(s):  
M. E. Burkard ◽  
H. D. Van Liew
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Bubble Growth ◽  
Decompression Sickness ◽  
Inert Gases ◽  
Inert Gas ◽  
Half Time ◽  
Bubble Density ◽  
Mathematical Relationships

To explore the relative dangers of different inert gases, we developed mathematical relationships concerned with bubble growth, using equations that separate gas properties from other variables. Predictions for saturation exposures were as follows. 1) Peak volume of a bubble is proportional to solubility in tissue when bubble density is high and to the 3/2 power of the ratio of the permeation coefficient to the partition coefficient when density is low. 2) Bubble duration is inversely proportional to the partition coefficient for the inert gas. 3). Sizes and durations of bubbles for one inert gas relative to another depend on whether the tissue is aqueous or lipid but are independent of the magnitude of the decompression and tissue half time. 4). He should give smaller bubbles than N2, except in aqueous tissue with low bubble density; our prediction correlates qualitatively with relative dangers observed with animals but seems to overestimate the safety afforded by He. Numerical simulations illustrate how nonsaturation dives are less predictable because more variables are involved.

Two dimensional honeycomb-kagome Be3Pb2: a mechanically flexible topological insulator with high intrinsic carrier mobilities

2021 ◽  
Author(s):  
Tingting Zhang ◽  
Liyan Zhu
Keyword(s):  
Electronic Structure ◽  
Physical Properties ◽  
Topological Insulator ◽  
Basal Plane ◽  
Two Dimensional ◽  
High Carrier

A two dimensional honeycomb-kagome structured Be3Pb2 exhibits intriguing physical properties, including mechanically soft basal plane, high carrier mobilities, and non-trivial topology in electronic structure.

The Favorable Geological Conditions for Air Foam Drilling

2013 ◽  
Vol 838-841 ◽  
pp. 1316-1319
Author(s):  
Wan Jiang Chen
Keyword(s):  
High Rate ◽  
Formation Pressure ◽  
Rate Of Penetration ◽  
Geological Conditions ◽  
Low Costs ◽  
The Cost ◽  
Foam Drilling ◽  
Oil Formation

Air foam drilling is adopted generally for its high rate of penetration, lower pollution to the reservoirs and low costs. Only when there are low formation pressure, long interval favorable formation, clear non-gas or non-oil formation and lower pay zone, air foam drilling can realize its advantages including maximum increasing rate of penetration, protecting reservoir and lowing the cost.

scholarly journals SIFAT FISIS KAYU BERKUALITAS RENDAH DARI RIAU SETELAH MELALUI PROSES PENGAWETAN POHON DENGAN TEKNIK BANDAGE DAN INFUS

2020 ◽  
Vol 14 (2) ◽  
pp. 30-37
Author(s):  
Evi Sribudiani ◽  
Sonia Somadona ◽  
Rudianda Sulaeman ◽  
Syafrinal Syafrinal ◽  
Sulaeman Yusuf ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Physical Properties ◽  
Strength Class ◽  
Tree Height ◽  
Forest Degradation ◽  
High Rate ◽  
Average Moisture Content ◽  
High Quality ◽  
The Past ◽  
Before And After

The potential of high-quality wood for various purposes over the past decade is very difficult to obtain. This is due to the high rate of doforestation and forest degradation, especially in Riau Province. Examples of the use of high-quality wood, especially in Riau Province, is as material for creating 'pathways' in the context of preserving track culture in the Kuantan Singingi Regency. The purpose of this study is to determine the physical properties of red balam wood and bintangur that grow in Riau before and after the preservation process, and determine the strength class of red balam wood and bintangur that grows in Riau. The research was carried out on the starur trees and red balam with a diameter of 34-38 cm, tree height 18-22 m. The tree sample comes from the Rumbio customary forest and the Minas Tahura KPHP Riau Province. Examination of physical properties using British standards in 1957. The results showed that based on specific gravity, the red balam wood and bintangur before preserved and included as strong class II. The average moisture content of each wood is 14-30%. The largest wood shrinkage development in each wood occurs at the base of the wood.

scholarly journals How a sticky fluid facilitates prey retention in a carnivorous pitcher plant (Nepenthes rafflesiana)

2021 ◽  
Author(s):  
Victor Kang ◽  
Hauke Isermann ◽  
Saksham Sharma ◽  
D Ian Wilson ◽  
Walter Federle
Keyword(s):  
Surface Tension ◽  
Physical Properties ◽  
Viscoelastic Fluid ◽  
Maximum Force ◽  
Insect Cuticle ◽  
Pitfall Traps ◽  
Body Parts ◽  
Pitcher Plants ◽  
Pitcher Plant ◽  
First Contact

Nepenthes pitcher plants live in nutrient-poor soils and produce large pitfall traps to obtain additional nutrients from animal prey. Previous research has shown that the digestive secretion in N. rafflesiana is a sticky viscoelastic fluid that is much more effective at retaining insects than water, even after significant dilution. Although the physical properties of the fluid are important for its retentive function, it is unclear how the fluid interacts with insect cuticle and how its sticky nature affects struggling insects. In this study, we investigated the mechanisms behind the efficient prey retention in N. rafflesiana pitcher fluid. By measuring the attractive forces exerted on insect body parts moving in and out of test fluids, we show that it costs insects significantly more energy to separate from pitcher fluid than from water. Moreover, both the maximum force and the energy required for retraction increase after the first contact with the pitcher fluid. We found that insects sink more easily into pitcher fluid than water and, accordingly, the surface tension of N. rafflesiana pitcher fluid was significantly lower than that of water (60.2 vs. 72.3 mN/m). By analysing the pitcher fluid dewetting behaviour, we demonstrate that it strongly resists dewetting from all surfaces tested, leaving behind residual films and filaments that can facilitate re-wetting. This inhibition of dewetting may be a further consequence of the fluid's viscoelastic nature and likely represents a key mechanism underlying prey retention in Nepenthes pitcher plants.

scholarly journals Selection of Suitable Drilling Parameters for obtaining high Rate of Penetration in Majnoon Oilfield

2019 ◽  
Vol 20 (1) ◽  
pp. 65-68
Author(s):  
Majid M. Majeed ◽  
Ayad A. Alhaleem
Keyword(s):  
Flow Rate ◽  
Extensive Study ◽  
High Rate ◽  
Proper Selection ◽  
Rate Of Penetration ◽  
Technical Paper ◽  
Drilling Parameters ◽  
Weight On Bit ◽  
Drilling Time ◽  
Selection Of

Several directional wells have been drilled in Majnoon oilfield at wide variation in drilling time due to different drilling parameters applied for each well. This technical paper shows the importance of proper selection of the bit, Mud type, applied weight on Bit (WOB), Revolution per minute (RPM), and flow rate based on the previous wells drilled. Utilizing the data during drilling each section for directional wells that's significantly could improve drilling efficiency presented at a high rate of penetration (ROP). Based on the extensive study of three directional wells of 35 degree inclination (MJ-51, MJ-52, and MJ-54) found that the applied drilling parameters for MJ-54 and the bit type within associated drilling parameters to drill 36", 24", 16" and 12 1/4" hole sections is the best, although the drilling parameters in 8 1/2" hole section for MJ-51 and selected bit type are the best for future wells.

scholarly journals The role of cutaneous diphtheria in the acquisition of immunity

1968 ◽  
Vol 66 (1) ◽  
pp. 83-88 ◽  
Author(s):  
P. D. P. Gunatillake ◽  
G. Taylor
Keyword(s):  
Rural Area ◽  
Field Survey ◽  
High Rate ◽  
Natural Immunity ◽  
Carrier Rate ◽  
High Carrier ◽  
Negative Conversion

SUMMARYA field survey conducted amongst children in a semi-rural area of Ceylon has revealed a high rate of Schick negative conversion early in life. A high carrier rate ofC. diphtheriaein cutaneous ulcers which probably accounts for this early Schick conversion has been detected. The role of cutaneous diphtheria and that of non-toxigenic organisms in the acquisition of natural immunity to the disease is discussed.

Relationships between some physical properties of insecticides and their inteinsic and contact toxicities to adult mosquitos (Anopheles stephensi List.)

1966 ◽  
Vol 56 (3) ◽  
pp. 569-579 ◽  
Author(s):  
A. B. Hadaway ◽  
F Barlow
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Anopheles Stephensi ◽  
Organophosphorus Compounds ◽  
Limiting Factor ◽  
Contact Toxicity ◽  
Close Relationship ◽  
Definite Pattern ◽  
The Relationship ◽  
Low Solubility

It had been noticed in earlier work that there was a lack of close relationship between the intrinsic and contact toxicities of various compounds to adults of Anopheles stephensi List., the intrinsic toxicities being determined by topical application of solutions and the contact toxicities by exposure to dry deposits. Since the reasons probably lay in the relative rates at which compounds penetrated the cuticle from solution and from the solid state, and since these rates are likely to be differently affected by the physical properties of the compounds, the intrinsic and contact toxicities to A. stephensi of some closely related carbamates and of a miscellaneous group of organophosphorus compounds were determined, together with the solubility in n-hexane and the partition coefficient between n-hexane and water of each, and the results were compared.No definite pattern in the relationship between these physical properties of the compounds and their intrinsic and contact toxicities emerged from consideration of the results. However, there were indications that very low solubility is a limiting factor in the uptake and penetration into mosquitos of a solid insecticide and is associated with low contact toxicity, and that, when solubility is high enough to ensure solution in the wax layer of the cuticle, contact activity is favoured by a low value for the partition coefficient between hexane and water.

scholarly journals Evaluation of non-English dietary supplement advertisements in an ethnic minority community in America

2007 ◽  
Vol 10 (8) ◽  
pp. 834-837 ◽  
Author(s):  
Eunice P Chung ◽  
Hye J Hwang ◽  
Myo-Kyoung Kim
Keyword(s):  
Los Angeles ◽  
Ethnic Minority ◽  
Dietary Supplement ◽  
Primary Objective ◽  
Health Claims ◽  
High Rate ◽  
Supporting Evidence ◽  
Cross Sectional ◽  
Minority Community ◽  
Ethnic Minority Community

AbstractObjectiveThe primary objective was to evaluate the rate at which non-English dietary supplement advertisements distributed in a sampled ethnic minority community are in compliance with the federal advertising regulations. The secondary objective was to assess the availability of supporting evidence to substantiate the advertised health claims.DesignCross-sectional study.SettingThe contents of dietary supplement advertisements from the Los Angeles Korea Times and the Los Angeles Korea Daily were evaluated during the month of July 2005. After removing duplicate advertisements, the percentage of advertisements making prohibited disease claims and DSHEA (Dietary Supplement Health and Education Act) disclaimer statements was determined. The presence of data substantiating advertised claims was determined by requesting data from the manufacturers and browsing the manufacturers' websites. An observational technique was utilised for content analysis, and data analysis was conducted using quantitative descriptive statistics.ResultsDisease claims were present in 84.5%, while DHSEA disclaimer statements were present in only 18.4% of the advertisements. Data to substantiate the claims were provided by 53.4% of the manufacturers. The majority of the additional information consisted of repetition of the advertised claims and consumer testimonies. Experimental data were available for only 13.6% of the products.ConclusionsThe high rate of non-compliance with federal regulations suggests a need for better oversight of non-English promotions of dietary supplements.

Sign in / Sign up

Export Citation Format

Share Document