Artificial methods

Plants consume nitrogen compounds present in the soil, and if growth is to continue, these compounds must be replenished, as by the addition of fertilizers. Until relatively recently, the fertilizer used for thi purpose consisted chiefly of animal wastes. Now chemists have learned to convert atmospheric nitrogen into fertilizer compounds by artificial methods. 

When the trouble is black thread, planters use paints, coal-tar washes, asphalt, and other treatments with varying degrees of success. New tests have shown that Fylomac 90, applied in a 0.25% solution, effects a cure in eight successive applications. In one of the most recent studies on this, Carpenter (8) tested 22 fungicides on Phytophthora panel trouble in Costa Rica. His work was under ideal conditions for the disease and with a well tested invariably successful, artificial method of inoculation. He found only one fungicide sufficiently good for his purpose—Ortho-cide 50 [captan, n-(trichloromethylthio)-4-cyclohexene-l,2-dicarboximide], wettable, mixed with Filmfast sticker. 

In order to understand the role of flavonoids in pollen, flavonoid-deficient mutants have been produced through artificial methods, such as cosuppression, antisense expression, chemical mutagenesis, and ionizing radiation. Examples include and A. thali-... 

Ivories of Unknown Provenance. The data for the Khorsabad ivories are consistent with the suggested age. These data do not, however, eliminate the possibility of artificial methods for simulating the patina and texture, generally acquired by long-term burial, by chemical extraction... 

Special circumstances must exist to measure the spectral absorption characteristics of the Rhodonines in-vitro in the laboratory (where in-vitro implies the separation of the chromophores from their connection to the neurons) under steady-state conditions. The material must be in the liquid crystalline state and an artificial method of de-excitation must be provided. 

As described earlier, dry, scaly skin looks like skin diseases can be induced by several artificial methods. These are useful model to find out new strategy to improve dry, scaly skin condition. Following are the examples of recent studies about new methods to cure dry, scaly skin. 

Ions and small molecules may be transported across cell membranes or lipid bilayers by artificial methods that employ either a carrier or channel mechanism. The former mechanism is worthy of brief investigation as it has several ramifications in the design of selectivity filters in artificial transmembrane channels. To date there are few examples where transmembrane studies have been carried out on artificial transporters. The channel mechanism is much more amenable to analysis by traditional biological techniques, such as planar bilayer and patch clamp methods, so perhaps it is not surprising that more work has been done to model transmembrane channels. 

On the other hand, PAMPA is a purely artificial method and PAMPA membranes do not reassemble real lipid bilayer structures as barriers for permeation but much thicker barriers. The thickness and material of the supporting PVDF filters also influences artificially the permeation of compounds depending on the lipophilicity of the compounds more than the thin polycarbonate filter does in CACo2 experiments. Also the best choice of membrane constituents for PAMPA experiments is still under investigation and it seems that it will depend a lot on the goal of the PAMPA experiment which membrane is used (e.g. blood brain barrier permeation or intestinal absorption). One has to take into account that PAMPA today is a summary term on a lot of different methods applied in different laboratories using different membrane constituents, sink conditions, permeation times etc., which makes inter laboratory comparison difficult. 

A second, seemingly less artificial, method would be to add a certain amount of block copolymer to one of the homopolymers and let it diffuse to the interface. This method has not been used to prepare fracture samples with deuterium-labeled block copolymers for several practical reasons Dissolving 5% of copolymer in a sheet of 50x100x2 mm dimensions requires 500 mg of deuterated polymer while a similar interface can be obtained by spin-casting with approximately 5 mg. The time involved to achieve true diffusional equilibrium over millimeter-scale thicknesses is prohibitively long at typical welding temperatures and the presence of a background concentration of deuterium-labeled polymer... 

Moreover, it is easier to produce mutants from such spores by artificial methods, such as X-ray or ultra-violet irradiation or the use of certain chemicals, than from sterile mycelium. The conidia can be freeze-dried and thus stored indefinitely. Finally, should the strain begin to lose its vigor it can be restored by growth on Paspalum plants which may be readily infected with conidia. 

Examination of the thermodynamics and kinetics of proposed chemical reactions for the artificial photosynthesis of ammonia presents several problems, not the least of which is the logical and rhetorical one of discussing mechanisms for a process while suggesting that it does not occur. The latter problem can be largely resolved by understanding beforehand that the purpose of the present section is to call into question and to dispute the proposition that ammonia is synthesized photocatalytically by irradiation of N2 and H20 by the artificial methods described already. We can examine the application in reported ammonia photosynthesis reactions of both categories of catalyst discussed in Section IV.A. 

Late 1890s Artificial methods of the production of pure vanillin are developed. 

There is no better way to present Howard s views than to quote extensively from his book, entitled An Agricultural Testament, in which he laments the shift from nature s methods of crop production to the newer artificial methods, which he claims lead to the loss of soil fertility. As soil fertility decreases, according to Howard, there follow the many other effects involving increased plant disease and insect damage, poor food quality for animals and man, and a marked deterioration in health. Especially surprising is his severe criticism of agricultural research methods, since he was a botanist engaged in research. Quotations from Howards s book follow. 

This faculty is developed in him through the action of external objects, that is to say, by the occurrence of certain composite sensations whose constancy or coherence in change are independent of him through communication with other beings like himself and finally through various artificial methods which these first developments have led him to invent. 

Table 2.2 Example for the attempt to improve resolution through efficiency increase when transferring from HPLC to UHPLC. All numbers are theoretically modeled on the basis of the artificial method 1 ( method 2 is not feasible in practice).

There is no obvious explanation for the exceptionally large number of mouse subgroups. Among possibilities considered by Hood et al. are the artificial method of induction of mouse myelomas and their peri-... 

Rubber can be divided into natural rubber and synthetic rubber on the basis of its source. Natural rubber is prepared from rubber-containing plants in nature, such as a high-elasticity material produced from natural rubber trees. Synthetic rubber is a synthetic macromolecular elastic material prepared by artificial methods. The main varieties of synthetic rubber are styrene-butadiene rubber, butadiene rubber, chlo-roprene rubber, isoprene rubber, butyl rubber, and ethylene-propylene-diene monomer rubber. 

This article is concerned with the control of membrane electrofusion. This technique has several attractive features compared to other artificial methods. Because it is based entirely on the electrical properties of the cells, the detailed biochemical and biological properties of the cells have little influence on the fusion process. Therefore, the method is applicable to a majority of cells. The only... 

---