Attacks prohibition

They should have been warning shots. The mechanoids had a direct-attack prohibition loaded into their processors which only Neville Latham could cancel. 

Electroforrning is the production or reproduction of articles by electro deposition upon a mandrel or mold that is subsequendy separated from the deposit. The separated electro deposit becomes the manufactured article. Of all the metals, copper and nickel are most widely used in electroforming. Mandrels are of two types permanent or expendable. Permanent mandrels are treated in a variety of ways to passivate the surface so that the deposit has very Httie or no adhesion to the mandrel, and separation is easily accompHshed without damaging the mandrel. Expendable mandrels are used where the shape of the electroform would prohibit removal of the mandrel without damage. Low melting alloys, metals that can be chemically dissolved without attack on the electroform, plastics that can be dissolved in solvents, ate typical examples. 

The sulfate process is based on the attack of activated beryl by sulfuric acid to form water-soluble Be and A1 sulfates and insoluble silica. A flow diagram summarizing this process is given in Scheme 1. Activated beryl must be used since the natural ore is resistant to acid attack except by HF, which is prohibitively expensive. High-grade beryl ore (> 10% BeO) is normally activated by a heat-treatment process... 

Products containing ephedra were used extensively by the American public for weight loss and to enhance athletic performance. Ephedra, a stimulant similar to amphetamine, increases blood pressure and heart rate after only one dose, significantly increasing a person s risk of heart attack, stroke, and death. Because ephedra is a dietary supplement, the FDA did not review its safety or efficacy before it became available to the American public. According to law, the FDA could only prohibit the sale of the dietary supplement if it was proven to present a significant or unreasonable risk of injury. 

In this context, the Convention requires that States Parties cooperate with the OPCW in facilitating the coordination and delivery of assistance and protection to minimise the consequences of a chemical weapons attack, in countering the threat of use of chemical weapons, and in eliminating the threats posed by activities prohibited under Article I of the Convention. Article X stipulates that each State Party has the right to request and to receive assistance and protection against the use or threat of use of chemical weapons. 

Throughout recent decades, efforts were made to limit or ban biological weapons, but several nations ignored the 1972 Convention on the Prohibition of the Development, Production, and Stockpiling of Biologic and Toxic Weapons and their Destruction. Between 1975 and 1983, Laos and Cambodia came under attack by planes and helicopters that delivered Yellow Rain suspected to contain lethal T-2 mycotoxins. 

The increasing popularity of biodegradable materials, which are more susceptible to microbial attack, has boosted the demand for preservation. If the product does not already contain ingredients that are themselves preservatives, such as cationic surfactants, acids, or bases, preservatives may need to be added. The required level of preservatives can be related to water availability (AW), which is defined as the ratio between the water vapor pressure over a substance and the water vapor pressure over pure water at the same temperature [17], In general, an A W of below 70% should be targeted to prohibit microorganism growth [18],... 

Associated with the propensity to intramolecular delivery of the organocopper reagent is the benefit of high regioselectivity, since an intramolecular trajectory prohibits the alternative a-attack. This is best exemplified by the reaction behavior of the cyclic system 161 (Scheme 6.33). For this substrate, y-attack is sterically hindered. Hence, treatment of the acetate of 161 with a higher order methyl cuprate... 

The robot and robotics have been subject of countless publications. It is difficult, however, to obtain a clear picture of their acceptability some see the robot as an indispensible technological tool for the 21st century others attack it as a cause of unemployment. The development of robotics has been much less rapid than experts had expected early in the 1980s. What are the reasons for this slow-down prohibitive costs, technological difficulties or organizational obstacles ... 

The tantalum(V) calix[4]arene complex 44 provides an interesting scaffold for the construction of an j -PhC2C=CPh ligand upon reaction with an excess of phenylethynyllithium (Scheme 10). The coupling reaction is presumed to proceed via bis-alkynyl 45, which is subsequently attacked at the a-carbon of one of the acetylide ligands to give anion 46, isolated as its lithium salt. The addition of a further equivalent of LiC CPh is probably prohibited by orbital constraints. ... 

Prohibit degrative attack to Lewis acidic center... 

An alternative to Equation 10-1 would be to have Br2 ionize to Br and Br8, with a subsequent attack of Br on the double bond to produce the carbocation. The fact is that energy required for such an ionization of Br2 is prohibitively large even in water solution (AH0 > 80 kcal). One might well wonder why Equation 10-1 could possibly... 

A clever application of the VNS reaction was recently reported to afford direct amination of nitroben-zenes, an otherwise prohibitive process, using 4-amino-1,2,4-triazole (Scheme 16).144 Exclusive attack at position 4 was observed in all cases studied (R = H, Me, Cl, CO2H, OMe, F, I, CN) with yields in the range 22-91%. 

Loss of stereospecificity, however, has also been reported in the addition of amines. The use of homogeneous Pd° catalysts in the addition of dimethylamine to a cyclohexenyl acetate led to substantial stereochemical scrambling (equation 186). Employment of polymer-bound Pd° catalysts, however, gave complete stereospecificity via ligand addition.398 The epimerization noted in this reaction is apparently due to acetate attack at the metal center, which is prohibited by steric congestion of the metal in the polymer matrix (equation 187).398... 

All the other cycloadditions, such as the [4+2] cycloadditions of allyl cations and anions, and the [8+2] and [6+4] cycloadditions of longer conjugated systems, have also been found to be suprafacial on both components, wherever it has been possible to test them. Thus the trans phenyl groups on the cyclopentene 2.65 show that the two new bonds were formed suprafacially on the rrans-stilbene. The tricyclic adducts 2.61, 2.77, 2.79, and 2.83, and the tetracyclic adduct 2.82, show that both components in each case have reacted suprafacially, although only suprafacial reactions are possible in cases like these, since the products from antarafacial attack on either component would have been prohibitively strained. Nevertheless, the fact that they have undergone cycloaddition is important, for it is the failure of thermal [2+2], [4+4] and [6+6], and photochemical [4+2], [8+2] and [6+4] pericyclic cycloadditions to take place, even when all-suprafacial options are open to them, that is significant. 

Aromatic carboxylic acids, a,/f-unsaturated carboxylic acids, their esters, amides, aldehydes and ketones, are prepared by the carbonylation of aryl halides and alkenyl halides. Pd, Rh, Fe, Ni and Co catalysts are used under different conditions. Among them, the Pd-catalysed carbonylations proceed conveniently under mild conditions in the presence of bases such as K2CO3 and Et3N. The extremely high toxicity of Ni(CO)4 almost prohibits the use of Ni catalysts in laboratories. The Pd-catalysed carbonylations are summarized in Scheme 3.9 [215], The reaction is explained by the oxidative addition of halides, and insertion of CO to form acylpalladium halides 440. Acids, esters, and amides are formed by the nucleophilic attack of water, alcohols and amines to 440. Transmetallation with hydrides and reductive elimination afford aldehydes 441. Ketones 442 are produced by transmetallation with alkylmetal reagents and reductive elimination. 

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