scholarly journals THE CHEMISTRY OF DAYLIGHT VISION

1946 ◽  
Vol 29 (5) ◽  
pp. 277-297 ◽  
Author(s):  
Alfred Frederick Bliss
Keyword(s):  
Magnesium Sulfate ◽  
Inorganic Phosphate ◽  
Chemical Properties ◽  
Partial Purification ◽  
First Order ◽  
Large Numbers ◽  
Cone Cells ◽  
Polar Organic Solvents ◽  
Color Filters ◽  
Good Agreement

1. While several reports of photosensitive pigments from the retinas of animals possessing large numbers of cone cells have been published, the only study which could be confirmed was Wald's discovery of iodopsin, a red-sensitive pigment from chicken eyes. 2. In its chemical properties, such as the range of pH stability and the effect of polar organic solvents, iodopsin resembles rhodopsin but is considerably more labile. 3. A partial purification from inert yellow impurities has been effected by prehardening the retinas in pH 4.9 acetate buffer before extraction by 2 per cent digitonin. Rhodopsin was an inevitable contaminant in most methods of extraction, but could be reduced to about 10 per cent of the absorption due to iodopsin by extraction of unhardened retinas with 4 per cent Merck's saponin in ¾ saturated magnesium sulfate for about 1 hour. 4. The rate of bleaching of iodopsin was found to be first order and linear with respect to energy. 5. The bleaching effectiveness spectrum of iodopsin was determined with the aid of color filters of known energy transmission, and shows a maximum at 560 mµ in the yellow green with a lower plateau in the blue. The spectrum is in good agreement with the sensitivity of the human cones except for the wavelength of maximum bleaching effectiveness. The maximum sensitivity of the human cones is found at 540 mµ. 6. Previous reports of changes in pH and inorganic phosphate level of retinas due to bleaching could not be confirmed.

scholarly journals Pitting Corrosion of Type 316L Stainless Steel Elaborated by the Selective Laser Melting Method: Influence of Microstructure

2021 ◽  
Author(s):  
V. Vignal ◽  
C. Voltz ◽  
S. Thiébaut ◽  
M. Demésy ◽  
O. Heintz ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
316L Stainless Steel ◽  
Electrochemical Impedance ◽  
Chemical Properties ◽  
Passive Films ◽  
First Order ◽  
Average Grain Size ◽  
Type 316L ◽  
Pure Matrix ◽  
Type 316L Stainless Steel

AbstractThe microstructure of two sets of 316L alloys (SLM and wrought structure) is determined using SPECTROMAXx stationary metal analyzer, FE-SEM/EDS and XRD. The physical–chemical properties of the passive films are also investigated by means of XPS, Auger after sputtering and electrochemical impedance spectroscopy measurements. Differences and similarities between the two sets of alloys are then identified. The corrosion behavior of alloys is investigated in NaCl solution at the macro- and microscale (microcapillary technique). It was found that the inclusion/particles cleanliness is the first-order parameter explaining differences between 316L(WS) and 316L(SLM). In the absence of particles (pure matrix), the two sets of alloys have the same corrosion behavior. Residual stresses, the average grain size, the PREN and the passive films properties are of second order.

Analysis of the First Order and Slowly Varying Motions of an Axisymmetric Floating Body in Bichromatic Waves

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
João Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Vertical Cylinder ◽  
Vertical Axis ◽  
Second Order ◽  
The Body ◽  
Floating Body ◽  
Drift Motion ◽  
First Order ◽  
Motion Responses ◽  
Simple Geometry ◽  
Good Agreement

The paper presents an experimental and numerical investigation on the motions of a floating body of simple geometry subjected to harmonic and biharmonic waves. The experiments were carried out in three different water depths representing shallow and deep water. The body is axisymmetric about the vertical axis, like a vertical cylinder with a rounded bottom, and it is kept in place with a soft mooring system. The experimental results include the first order motion responses, the steady drift motion offset in regular waves and the slowly varying motions due to second order interaction in biharmonic waves. The hydrodynamic problem is solved numerically with a second order boundary element method. The results show a good agreement of the numerical calculations with the experiments.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

Models for New Corrugated and Porous Solar Air Collectors under Transient Operation

2017 ◽  
Vol 42 (1) ◽  
Author(s):  
Qahtan Adnan Abed ◽  
Viorel Badescu ◽  
Adrian Ciocanea ◽  
Iuliana Soriga ◽  
Dorin Bureţea
Keyword(s):  
Climatic Conditions ◽  
Meteorological Conditions ◽  
Bias Error ◽  
First Order ◽  
Solar Air Collector ◽  
Section Surface ◽  
South Eastern Europe ◽  
Main Components ◽  
Theoretical Results ◽  
Good Agreement

AbstractMathematical models have been developed to evaluate the dynamic behavior of two solar air collectors: the first one is equipped with a V-porous absorber and the second one with a U-corrugated absorber. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between them being the absorbers. V-corrugated absorbers have been treated in literature but the V-porous absorbers modeled here have not been very often considered. The models are based on first-order differential equations which describe the heat exchange between the main components of the two types of solar air heaters. Both collectors were exposed to the sun in the same meteorological conditions, at identical tilt angle and they operated at the same air mass flow rate. The tests were carried out in the climatic conditions of Bucharest (Romania, South Eastern Europe). There is good agreement between the theoretical results and experiments. The average bias error was about 7.75 % and 10.55 % for the solar air collector with “V”-porous absorber and with “U”-corrugated absorber, respectively. The collector based on V-porous absorber has higher efficiency than the collector with U-corrugated absorber around the noon of clear days. Around sunrise and sunset, the collector with U-corrugated absorber is more effective.

Doppler-Shifted Cyclotron Resonance in Thin Metal Films

1972 ◽  
Vol 50 (18) ◽  
pp. 2122-2137
Author(s):  
R. Turner ◽  
J. F. Cochran
Keyword(s):  
Magnetic Field ◽  
Metal Films ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Free Electrons ◽  
Fermi Surfaces ◽  
First Order ◽  
Simple Quantum ◽  
The Magnetic Field ◽  
Good Agreement

According to Van Gelder the microwave absorption by a thin metal film in the presence of a static magnetic field normal to the film contains a series of peaks as the magnetic field is varied. In the present paper it is argued that these peaks correspond to Doppler-shifted cyclotron resonances of the carriers in the metal due to the quantization of electron momenta normal to the plane of the film. A simple quantum calculation is presented for the case of free electrons where the film is thin enough that to first order the microwave fields within are determined only by the boundary conditions and Maxwell's equations. The quantum expression is in good agreement with the absorption calculated using semiclassical arguments which can be readily extended to more complicated Fermi surfaces.

Essential Lessons in a Potential Sarin Attack Disaster Plan for a Resource-Constrained Environment

2017 ◽  
Vol 12 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Matthew John Watermeyer ◽  
Nicole Dippenaar ◽  
Nelly Clotildea Tchouambou Simo ◽  
Sean Buchanan ◽  
Abdullah Ebrahim Laher
Keyword(s):  
Disaster Relief ◽  
Chemical Properties ◽  
Chemical Weapon ◽  
Resource Constrained ◽  
Delivery Methods ◽  
Disaster Plan ◽  
Large Numbers ◽  
Rapid Deployment ◽  
Relief Organizations ◽  
Fast Acting

AbstractSarin is a potent nerve agent chemical weapon that was originally designed for military purposes as a fast-acting anti-personnel weapon that would kill or disable large numbers of enemy troops. Its potent toxicity, ease of deployment, and rapid degradation allow for rapid deployment by an attacking force, who can safely enter the area of deployment a short while after its release. Sarin has been produced and stockpiled by a number of countries, and large quantities of it still exist despite collective agreements to cease manufacture and destroy stockpiles. Sarin’s ease of synthesis, which is easily disseminated across the Internet, increases the risk that terrorist organizations may use sarin to attack civilians. Sarin has been used in a number of terrorist attacks in Japan, and more recently in attacks in the Middle East, where nonmilitary organizations have led much of the disaster relief and provision of medical care. In the present article, we examine and discuss the available literature on sarin’s historical use, delivery methods, chemical properties, mechanism of action, decontamination process, and treatment. We present a management guideline to assist with the recognition of an attack and management of victims by medical professionals and disaster relief organizations, specifically in resource-constrained and austere environments. (Disaster Med Public Health Preparedness. 2018;12:249–256)

HYDROLYSIS OF LECITHIN BY PLANT PLASTID ENZYMES

1955 ◽  
Vol 33 (1) ◽  
pp. 575-589 ◽  
Author(s):  
Morris Kates
Keyword(s):  
Phosphatidic Acid ◽  
Inorganic Phosphate ◽  
Organic Phosphate ◽  
Water Soluble ◽  
Lag Phase ◽  
Carrot Root ◽  
First Order ◽  
Spinach Chloroplasts ◽  
Egg Lecithin ◽  
Hydrolysis Of

Enzymatic liberation of choline from egg lecithin by plastid fractions from sugar beet, spinach, and cabbage leaves and from carrot root was a rapid, first order reaction (up to 70% hydrolysis), and was not preceded by a lag phase. None of the choline-containing products of lecithin degradation (lysolecithin, glycerylphosphorylcholine, or phosphorylcholine) lost choline on incubation with spinach chloroplasts. Inorganic phosphate liberation from lecithin by the plastids was preceded by a lag phase and was much slower than choline liberation. Spinach chloroplasts catalyzed the liberation of inorganic phosphate from L-α-phosphatidic acid and from L-α-glycerophosphate. The water-soluble organic phosphate liberated from lecithin by spinach chloroplasts was identified chromatographically as phosphorylcholine. The ether-soluble organic phosphate produced during the hydrolysis of egg lecithin by carrot plastids was isolated and identified as L-α-phosphatidic acid. These observations suggest that the enzymatic hydrolysis of lecithin by plant plastids involves the following reactions: (1) lecithin → L-α-phosphatidic acid + choline; (2) L-α-phosphatidic acid → inorganic phosphate + diglyceride and/or (3) L-α-phosphatidic acid → glycerophosphate + fatty acids and (4) glycerophosphate → inorganic phosphate + glycerol; and (5) lecithin → phosphorylcholine + diglyceride. The L-α-structure for egg lecithin was confirmed.

scholarly journals Aplikasi PCO Plus pada Tanah Bekas Tambang Batu Bata Merah terhadap Serapan P, Ca dan B serta Fruitset Cabai Merah Besar (Capsicum annuum L.)

Agrikultura ◽  
2017 ◽  
Vol 28 (2) ◽  
Author(s):  
Stefina Liana Sari ◽  
Rija Sudirja ◽  
Emma Trinurani Sofyan
Keyword(s):  
Capsicum Annuum ◽  
Block Design ◽  
Organic Fertilizer ◽  
Chemical Properties ◽  
Soil Productivity ◽  
Degraded Soil ◽  
Capsicum Annuum L ◽  
Compound Fertilizer ◽  
Randomized Block Design ◽  
Large Numbers

ABSTRACTApplication of liquid organic fertilizer formula plus on degraded soil to improve the productivity of the land and chili (Capsicum annuum L.) productionSoil exploitation in large numbers occurred in the District Wanaraja of Garut Regency. Excavation of soil more than 2 meters from the top layer for the manufacture of red bricks has exceeded the ability of the soil to re-establish its structure. So that the soils, which were agricultural lands, can be classified as degraded soils with less fertility and chemical properties. Lans reuse for agriculture requires adequate recovery and fertilizer input. This study aimed to determine the formula of LOF (liquid organic fertilizer) plus used with NPK compound fertilizer on degraded soil to improve the soil productivity. The design used was a Simple Randomized Block Design (RBD) by 10 combinations of LOF plus treatment with NPK compound fertilizer as follows: A = Control (degraded soil, no fertilizer), B = 0% LOF + 1 NPK, C = 0.25% LOF + 1 NPK, D = 0.50% LOF + 1 NPK, E = 0.75% LOF + 1 NPK, F = 1.00 % LOF + 1 NPK, G = 0.5% LOF + 3/4 NPK, H = 0.5% LOF + 1/2 NPK, I = 0.5% LOF + 1/4 NPK, J = 0.5 LOF + 0 NPK, and K = 1 NPK of normal soil that all replicated three times. The results showed that the degraded soil of red bricks required concentration of LOF above 0.5% to 1% when applied with 1 dose of standard NPK. It is able to balance the uptake of nutrients P, Ca, and B and percentage of fruitset in chili commodities equivalent to normal soil.Keywords: Chilli, Liquid Organic Faertilizer (LOF), NPK, Soil degrededABSTRAKEksploitasi tanah dalam jumlah yang besar terjadi di Kecamatan Wanaraja, Kabupaten Garut. Terjadinya penggalian tanah lebih dari 2 meter dari lapisan atas untuk pembuatan batu bata merah melampaui kemampuan tanah untuk membentuk struktur tanah kembali, sehingga tanah-tanah yang sebelumnya merupakan tanah pertanian ini dapat digolongkan menjadi tanah terdegradasi dengan sifat kimia kurang subur dan pemanfaatan kembali untuk pertanian memerlukan pemulihan dan input pupuk yang cukup. Penelitian ini bertujuan untuk mengetahui formula pupuk cair organik (PCO) plus yang digunakan bersama NPK pada tanah terdegradasi guna meningkatkan kembali produktvitas tanahnya. Rancangan yang digunakan adalah RAK sederhana dengan 10 kombinasi perlakuan PCO plus bersama NPK yaitu A = Kontrol (tanah terdegradasi, tanpa pupuk), B = 0% PCO + 1 NPK, C = 0,25% PCO + 1 NPK, D = 0,50% PCO + 1 NPK, E = 0,75% PCO + 1 NPK, F = 1,00% PCO + 1 NPK, G = 0,5% PCO + 3/4 NPK, H = 0,5% PCO + 1/2 NPK, I = 0,5% PCO + 1/4 NPK, J = 0,5 PCO + 0 NPK, dan K = 1 NPK tanah normal. Semua perlakuan diulang tiga kali. Hasil penelitian menunjukkan bahwa tanah terdegradasi bekas tambang batu bata merah memerlukan konsentrasi PCO di atas 0,5% sampai dengan 1% apabila diaplikasikan bersama 1 dosis NPKstandar. Hal ini mempu mengimbangi serapan hara P, Ca, dan B serta persen fruitset pada komoditas cabai setara dengan tanah normal.Kata Kunci: Cabai, NPK, Pupuk Cair Organik (PCO), Tanah terdegradasi

Dielectric Characterisation of Plastics for Microwave Oven Applications

2005 ◽  
Vol 480-481 ◽  
pp. 161-164 ◽  
Author(s):  
Luís Cadillon Costa ◽  
A. Correia ◽  
A. Viegas ◽  
João Bessa Sousa ◽  
François Henry
Keyword(s):  
Low Cost ◽  
Chemical Properties ◽  
Microwave Frequency ◽  
Microwave Oven ◽  
Complex Dielectric Constant ◽  
First Order ◽  
Constant E ◽  
Materials Used ◽  
Resonant Method ◽  
And Chemical Properties

The materials used in microwave oven cavities must have specific dielectric properties in order to maintain the efficiency of the food heating. Plastics, by their mechanical and chemical properties and low cost, are one of those potential materials. In this study, we present the results of the measurements of complex dielectric constant, ´´ ´ * e e e í − = , in the microwave frequency region, on different plastics: polyoxymethylene (POM), polypropylene (PP) and polybutylene terephtalate (PBT), using the cavity resonant method. We measure the shift in the resonant frequency of the cavity, Df, caused by the insertion of the sample, which can be related to the real part of the complex permitivitty, e´, while the change in the inverse of the quality factor of the cavity, D(1/Q), gives the imaginary part, e´´. The relations are simple when we consider only the first order perturbation in the electric field caused by the sample.

Free Vibration of Curvilinearly Stiffened Shallow Shells

2013 ◽  
Author(s):  
Peng Shi ◽  
Rakesh K. Kapania
Keyword(s):  
Free Vibration ◽  
Ritz Method ◽  
Beam Theory ◽  
Fe Method ◽  
Shallow Shells ◽  
First Order ◽  
Stiffened Shells ◽  
Method Base ◽  
Doubly Curved ◽  
Good Agreement

The free vibration of curvilinearly stiffened doubly curved shallow shells is investigated by the Ritz method. Base on the first order shear deformation shell theory and Timoshenko’s 3-D curved beam theory, the strain and kinetic energies of the stiffened shells are introduced. Numerical results with different geometrical shells and boundary conditions, and different stiffener locations and curvatures are analyzed to verify the feasibility of the presented Ritz method for solving the problems. The results show good agreement with those using the FE method.

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